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CHAPTER 2 REVIEW OF RELATED LITERATURE AND STUDIES

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Chapter 2 Research Papers: Introduction and Literature Review

First Online: 17 July 2020

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Anna Southern 3

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Wallwork, A., Southern, A. (2020). Chapter 2 Research Papers: Introduction and Literature Review. In: 100 Tips to Avoid Mistakes in Academic Writing and Presenting. English for Academic Research. Springer, Cham. https://doi.org/10.1007/978-3-030-44214-9_2

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Chapter 2. Research Design

Getting started.

When I teach undergraduates qualitative research methods, the final product of the course is a “research proposal” that incorporates all they have learned and enlists the knowledge they have learned about qualitative research methods in an original design that addresses a particular research question. I highly recommend you think about designing your own research study as you progress through this textbook. Even if you don’t have a study in mind yet, it can be a helpful exercise as you progress through the course. But how to start? How can one design a research study before they even know what research looks like? This chapter will serve as a brief overview of the research design process to orient you to what will be coming in later chapters. Think of it as a “skeleton” of what you will read in more detail in later chapters. Ideally, you will read this chapter both now (in sequence) and later during your reading of the remainder of the text. Do not worry if you have questions the first time you read this chapter. Many things will become clearer as the text advances and as you gain a deeper understanding of all the components of good qualitative research. This is just a preliminary map to get you on the right road.

Research Design Steps

Before you even get started, you will need to have a broad topic of interest in mind. [1] . In my experience, students can confuse this broad topic with the actual research question, so it is important to clearly distinguish the two. And the place to start is the broad topic. It might be, as was the case with me, working-class college students. But what about working-class college students? What’s it like to be one? Why are there so few compared to others? How do colleges assist (or fail to assist) them? What interested me was something I could barely articulate at first and went something like this: “Why was it so difficult and lonely to be me?” And by extension, “Did others share this experience?”

Once you have a general topic, reflect on why this is important to you. Sometimes we connect with a topic and we don’t really know why. Even if you are not willing to share the real underlying reason you are interested in a topic, it is important that you know the deeper reasons that motivate you. Otherwise, it is quite possible that at some point during the research, you will find yourself turned around facing the wrong direction. I have seen it happen many times. The reason is that the research question is not the same thing as the general topic of interest, and if you don’t know the reasons for your interest, you are likely to design a study answering a research question that is beside the point—to you, at least. And this means you will be much less motivated to carry your research to completion.

Researcher Note

Why do you employ qualitative research methods in your area of study? What are the advantages of qualitative research methods for studying mentorship?

Qualitative research methods are a huge opportunity to increase access, equity, inclusion, and social justice. Qualitative research allows us to engage and examine the uniquenesses/nuances within minoritized and dominant identities and our experiences with these identities. Qualitative research allows us to explore a specific topic, and through that exploration, we can link history to experiences and look for patterns or offer up a unique phenomenon. There’s such beauty in being able to tell a particular story, and qualitative research is a great mode for that! For our work, we examined the relationships we typically use the term mentorship for but didn’t feel that was quite the right word. Qualitative research allowed us to pick apart what we did and how we engaged in our relationships, which then allowed us to more accurately describe what was unique about our mentorship relationships, which we ultimately named liberationships ( McAloney and Long 2021) . Qualitative research gave us the means to explore, process, and name our experiences; what a powerful tool!

How do you come up with ideas for what to study (and how to study it)? Where did you get the idea for studying mentorship?

Coming up with ideas for research, for me, is kind of like Googling a question I have, not finding enough information, and then deciding to dig a little deeper to get the answer. The idea to study mentorship actually came up in conversation with my mentorship triad. We were talking in one of our meetings about our relationship—kind of meta, huh? We discussed how we felt that mentorship was not quite the right term for the relationships we had built. One of us asked what was different about our relationships and mentorship. This all happened when I was taking an ethnography course. During the next session of class, we were discussing auto- and duoethnography, and it hit me—let’s explore our version of mentorship, which we later went on to name liberationships ( McAloney and Long 2021 ). The idea and questions came out of being curious and wanting to find an answer. As I continue to research, I see opportunities in questions I have about my work or during conversations that, in our search for answers, end up exposing gaps in the literature. If I can’t find the answer already out there, I can study it.

—Kim McAloney, PhD, College Student Services Administration Ecampus coordinator and instructor

When you have a better idea of why you are interested in what it is that interests you, you may be surprised to learn that the obvious approaches to the topic are not the only ones. For example, let’s say you think you are interested in preserving coastal wildlife. And as a social scientist, you are interested in policies and practices that affect the long-term viability of coastal wildlife, especially around fishing communities. It would be natural then to consider designing a research study around fishing communities and how they manage their ecosystems. But when you really think about it, you realize that what interests you the most is how people whose livelihoods depend on a particular resource act in ways that deplete that resource. Or, even deeper, you contemplate the puzzle, “How do people justify actions that damage their surroundings?” Now, there are many ways to design a study that gets at that broader question, and not all of them are about fishing communities, although that is certainly one way to go. Maybe you could design an interview-based study that includes and compares loggers, fishers, and desert golfers (those who golf in arid lands that require a great deal of wasteful irrigation). Or design a case study around one particular example where resources were completely used up by a community. Without knowing what it is you are really interested in, what motivates your interest in a surface phenomenon, you are unlikely to come up with the appropriate research design.

These first stages of research design are often the most difficult, but have patience . Taking the time to consider why you are going to go through a lot of trouble to get answers will prevent a lot of wasted energy in the future.

There are distinct reasons for pursuing particular research questions, and it is helpful to distinguish between them. First, you may be personally motivated. This is probably the most important and the most often overlooked. What is it about the social world that sparks your curiosity? What bothers you? What answers do you need in order to keep living? For me, I knew I needed to get a handle on what higher education was for before I kept going at it. I needed to understand why I felt so different from my peers and whether this whole “higher education” thing was “for the likes of me” before I could complete my degree. That is the personal motivation question. Your personal motivation might also be political in nature, in that you want to change the world in a particular way. It’s all right to acknowledge this. In fact, it is better to acknowledge it than to hide it.

There are also academic and professional motivations for a particular study. If you are an absolute beginner, these may be difficult to find. We’ll talk more about this when we discuss reviewing the literature. Simply put, you are probably not the only person in the world to have thought about this question or issue and those related to it. So how does your interest area fit into what others have studied? Perhaps there is a good study out there of fishing communities, but no one has quite asked the “justification” question. You are motivated to address this to “fill the gap” in our collective knowledge. And maybe you are really not at all sure of what interests you, but you do know that [insert your topic] interests a lot of people, so you would like to work in this area too. You want to be involved in the academic conversation. That is a professional motivation and a very important one to articulate.

Practical and strategic motivations are a third kind. Perhaps you want to encourage people to take better care of the natural resources around them. If this is also part of your motivation, you will want to design your research project in a way that might have an impact on how people behave in the future. There are many ways to do this, one of which is using qualitative research methods rather than quantitative research methods, as the findings of qualitative research are often easier to communicate to a broader audience than the results of quantitative research. You might even be able to engage the community you are studying in the collecting and analyzing of data, something taboo in quantitative research but actively embraced and encouraged by qualitative researchers. But there are other practical reasons, such as getting “done” with your research in a certain amount of time or having access (or no access) to certain information. There is nothing wrong with considering constraints and opportunities when designing your study. Or maybe one of the practical or strategic goals is about learning competence in this area so that you can demonstrate the ability to conduct interviews and focus groups with future employers. Keeping that in mind will help shape your study and prevent you from getting sidetracked using a technique that you are less invested in learning about.

STOP HERE for a moment

I recommend you write a paragraph (at least) explaining your aims and goals. Include a sentence about each of the following: personal/political goals, practical or professional/academic goals, and practical/strategic goals. Think through how all of the goals are related and can be achieved by this particular research study . If they can’t, have a rethink. Perhaps this is not the best way to go about it.

You will also want to be clear about the purpose of your study. “Wait, didn’t we just do this?” you might ask. No! Your goals are not the same as the purpose of the study, although they are related. You can think about purpose lying on a continuum from “ theory ” to “action” (figure 2.1). Sometimes you are doing research to discover new knowledge about the world, while other times you are doing a study because you want to measure an impact or make a difference in the world.

Purpose types: Basic Research, Applied Research, Summative Evaluation, Formative Evaluation, Action Research

Basic research involves research that is done for the sake of “pure” knowledge—that is, knowledge that, at least at this moment in time, may not have any apparent use or application. Often, and this is very important, knowledge of this kind is later found to be extremely helpful in solving problems. So one way of thinking about basic research is that it is knowledge for which no use is yet known but will probably one day prove to be extremely useful. If you are doing basic research, you do not need to argue its usefulness, as the whole point is that we just don’t know yet what this might be.

Researchers engaged in basic research want to understand how the world operates. They are interested in investigating a phenomenon to get at the nature of reality with regard to that phenomenon. The basic researcher’s purpose is to understand and explain ( Patton 2002:215 ).

Basic research is interested in generating and testing hypotheses about how the world works. Grounded Theory is one approach to qualitative research methods that exemplifies basic research (see chapter 4). Most academic journal articles publish basic research findings. If you are working in academia (e.g., writing your dissertation), the default expectation is that you are conducting basic research.

Applied research in the social sciences is research that addresses human and social problems. Unlike basic research, the researcher has expectations that the research will help contribute to resolving a problem, if only by identifying its contours, history, or context. From my experience, most students have this as their baseline assumption about research. Why do a study if not to make things better? But this is a common mistake. Students and their committee members are often working with default assumptions here—the former thinking about applied research as their purpose, the latter thinking about basic research: “The purpose of applied research is to contribute knowledge that will help people to understand the nature of a problem in order to intervene, thereby allowing human beings to more effectively control their environment. While in basic research the source of questions is the tradition within a scholarly discipline, in applied research the source of questions is in the problems and concerns experienced by people and by policymakers” ( Patton 2002:217 ).

Applied research is less geared toward theory in two ways. First, its questions do not derive from previous literature. For this reason, applied research studies have much more limited literature reviews than those found in basic research (although they make up for this by having much more “background” about the problem). Second, it does not generate theory in the same way as basic research does. The findings of an applied research project may not be generalizable beyond the boundaries of this particular problem or context. The findings are more limited. They are useful now but may be less useful later. This is why basic research remains the default “gold standard” of academic research.

Evaluation research is research that is designed to evaluate or test the effectiveness of specific solutions and programs addressing specific social problems. We already know the problems, and someone has already come up with solutions. There might be a program, say, for first-generation college students on your campus. Does this program work? Are first-generation students who participate in the program more likely to graduate than those who do not? These are the types of questions addressed by evaluation research. There are two types of research within this broader frame; however, one more action-oriented than the next. In summative evaluation , an overall judgment about the effectiveness of a program or policy is made. Should we continue our first-gen program? Is it a good model for other campuses? Because the purpose of such summative evaluation is to measure success and to determine whether this success is scalable (capable of being generalized beyond the specific case), quantitative data is more often used than qualitative data. In our example, we might have “outcomes” data for thousands of students, and we might run various tests to determine if the better outcomes of those in the program are statistically significant so that we can generalize the findings and recommend similar programs elsewhere. Qualitative data in the form of focus groups or interviews can then be used for illustrative purposes, providing more depth to the quantitative analyses. In contrast, formative evaluation attempts to improve a program or policy (to help “form” or shape its effectiveness). Formative evaluations rely more heavily on qualitative data—case studies, interviews, focus groups. The findings are meant not to generalize beyond the particular but to improve this program. If you are a student seeking to improve your qualitative research skills and you do not care about generating basic research, formative evaluation studies might be an attractive option for you to pursue, as there are always local programs that need evaluation and suggestions for improvement. Again, be very clear about your purpose when talking through your research proposal with your committee.

Action research takes a further step beyond evaluation, even formative evaluation, to being part of the solution itself. This is about as far from basic research as one could get and definitely falls beyond the scope of “science,” as conventionally defined. The distinction between action and research is blurry, the research methods are often in constant flux, and the only “findings” are specific to the problem or case at hand and often are findings about the process of intervention itself. Rather than evaluate a program as a whole, action research often seeks to change and improve some particular aspect that may not be working—maybe there is not enough diversity in an organization or maybe women’s voices are muted during meetings and the organization wonders why and would like to change this. In a further step, participatory action research , those women would become part of the research team, attempting to amplify their voices in the organization through participation in the action research. As action research employs methods that involve people in the process, focus groups are quite common.

If you are working on a thesis or dissertation, chances are your committee will expect you to be contributing to fundamental knowledge and theory ( basic research ). If your interests lie more toward the action end of the continuum, however, it is helpful to talk to your committee about this before you get started. Knowing your purpose in advance will help avoid misunderstandings during the later stages of the research process!

The Research Question

Once you have written your paragraph and clarified your purpose and truly know that this study is the best study for you to be doing right now , you are ready to write and refine your actual research question. Know that research questions are often moving targets in qualitative research, that they can be refined up to the very end of data collection and analysis. But you do have to have a working research question at all stages. This is your “anchor” when you get lost in the data. What are you addressing? What are you looking at and why? Your research question guides you through the thicket. It is common to have a whole host of questions about a phenomenon or case, both at the outset and throughout the study, but you should be able to pare it down to no more than two or three sentences when asked. These sentences should both clarify the intent of the research and explain why this is an important question to answer. More on refining your research question can be found in chapter 4.

Chances are, you will have already done some prior reading before coming up with your interest and your questions, but you may not have conducted a systematic literature review. This is the next crucial stage to be completed before venturing further. You don’t want to start collecting data and then realize that someone has already beaten you to the punch. A review of the literature that is already out there will let you know (1) if others have already done the study you are envisioning; (2) if others have done similar studies, which can help you out; and (3) what ideas or concepts are out there that can help you frame your study and make sense of your findings. More on literature reviews can be found in chapter 9.

In addition to reviewing the literature for similar studies to what you are proposing, it can be extremely helpful to find a study that inspires you. This may have absolutely nothing to do with the topic you are interested in but is written so beautifully or organized so interestingly or otherwise speaks to you in such a way that you want to post it somewhere to remind you of what you want to be doing. You might not understand this in the early stages—why would you find a study that has nothing to do with the one you are doing helpful? But trust me, when you are deep into analysis and writing, having an inspirational model in view can help you push through. If you are motivated to do something that might change the world, you probably have read something somewhere that inspired you. Go back to that original inspiration and read it carefully and see how they managed to convey the passion that you so appreciate.

At this stage, you are still just getting started. There are a lot of things to do before setting forth to collect data! You’ll want to consider and choose a research tradition and a set of data-collection techniques that both help you answer your research question and match all your aims and goals. For example, if you really want to help migrant workers speak for themselves, you might draw on feminist theory and participatory action research models. Chapters 3 and 4 will provide you with more information on epistemologies and approaches.

Next, you have to clarify your “units of analysis.” What is the level at which you are focusing your study? Often, the unit in qualitative research methods is individual people, or “human subjects.” But your units of analysis could just as well be organizations (colleges, hospitals) or programs or even whole nations. Think about what it is you want to be saying at the end of your study—are the insights you are hoping to make about people or about organizations or about something else entirely? A unit of analysis can even be a historical period! Every unit of analysis will call for a different kind of data collection and analysis and will produce different kinds of “findings” at the conclusion of your study. [2]

Regardless of what unit of analysis you select, you will probably have to consider the “human subjects” involved in your research. [3] Who are they? What interactions will you have with them—that is, what kind of data will you be collecting? Before answering these questions, define your population of interest and your research setting. Use your research question to help guide you.

Let’s use an example from a real study. In Geographies of Campus Inequality , Benson and Lee ( 2020 ) list three related research questions: “(1) What are the different ways that first-generation students organize their social, extracurricular, and academic activities at selective and highly selective colleges? (2) how do first-generation students sort themselves and get sorted into these different types of campus lives; and (3) how do these different patterns of campus engagement prepare first-generation students for their post-college lives?” (3).

Note that we are jumping into this a bit late, after Benson and Lee have described previous studies (the literature review) and what is known about first-generation college students and what is not known. They want to know about differences within this group, and they are interested in ones attending certain kinds of colleges because those colleges will be sites where academic and extracurricular pressures compete. That is the context for their three related research questions. What is the population of interest here? First-generation college students . What is the research setting? Selective and highly selective colleges . But a host of questions remain. Which students in the real world, which colleges? What about gender, race, and other identity markers? Will the students be asked questions? Are the students still in college, or will they be asked about what college was like for them? Will they be observed? Will they be shadowed? Will they be surveyed? Will they be asked to keep diaries of their time in college? How many students? How many colleges? For how long will they be observed?

Recommendation

Take a moment and write down suggestions for Benson and Lee before continuing on to what they actually did.

Have you written down your own suggestions? Good. Now let’s compare those with what they actually did. Benson and Lee drew on two sources of data: in-depth interviews with sixty-four first-generation students and survey data from a preexisting national survey of students at twenty-eight selective colleges. Let’s ignore the survey for our purposes here and focus on those interviews. The interviews were conducted between 2014 and 2016 at a single selective college, “Hilltop” (a pseudonym ). They employed a “purposive” sampling strategy to ensure an equal number of male-identifying and female-identifying students as well as equal numbers of White, Black, and Latinx students. Each student was interviewed once. Hilltop is a selective liberal arts college in the northeast that enrolls about three thousand students.

How did your suggestions match up to those actually used by the researchers in this study? It is possible your suggestions were too ambitious? Beginning qualitative researchers can often make that mistake. You want a research design that is both effective (it matches your question and goals) and doable. You will never be able to collect data from your entire population of interest (unless your research question is really so narrow to be relevant to very few people!), so you will need to come up with a good sample. Define the criteria for this sample, as Benson and Lee did when deciding to interview an equal number of students by gender and race categories. Define the criteria for your sample setting too. Hilltop is typical for selective colleges. That was a research choice made by Benson and Lee. For more on sampling and sampling choices, see chapter 5.

Benson and Lee chose to employ interviews. If you also would like to include interviews, you have to think about what will be asked in them. Most interview-based research involves an interview guide, a set of questions or question areas that will be asked of each participant. The research question helps you create a relevant interview guide. You want to ask questions whose answers will provide insight into your research question. Again, your research question is the anchor you will continually come back to as you plan for and conduct your study. It may be that once you begin interviewing, you find that people are telling you something totally unexpected, and this makes you rethink your research question. That is fine. Then you have a new anchor. But you always have an anchor. More on interviewing can be found in chapter 11.

Let’s imagine Benson and Lee also observed college students as they went about doing the things college students do, both in the classroom and in the clubs and social activities in which they participate. They would have needed a plan for this. Would they sit in on classes? Which ones and how many? Would they attend club meetings and sports events? Which ones and how many? Would they participate themselves? How would they record their observations? More on observation techniques can be found in both chapters 13 and 14.

At this point, the design is almost complete. You know why you are doing this study, you have a clear research question to guide you, you have identified your population of interest and research setting, and you have a reasonable sample of each. You also have put together a plan for data collection, which might include drafting an interview guide or making plans for observations. And so you know exactly what you will be doing for the next several months (or years!). To put the project into action, there are a few more things necessary before actually going into the field.

First, you will need to make sure you have any necessary supplies, including recording technology. These days, many researchers use their phones to record interviews. Second, you will need to draft a few documents for your participants. These include informed consent forms and recruiting materials, such as posters or email texts, that explain what this study is in clear language. Third, you will draft a research protocol to submit to your institutional review board (IRB) ; this research protocol will include the interview guide (if you are using one), the consent form template, and all examples of recruiting material. Depending on your institution and the details of your study design, it may take weeks or even, in some unfortunate cases, months before you secure IRB approval. Make sure you plan on this time in your project timeline. While you wait, you can continue to review the literature and possibly begin drafting a section on the literature review for your eventual presentation/publication. More on IRB procedures can be found in chapter 8 and more general ethical considerations in chapter 7.

Once you have approval, you can begin!

Research Design Checklist

Before data collection begins, do the following:

Write a paragraph explaining your aims and goals (personal/political, practical/strategic, professional/academic).
Define your research question; write two to three sentences that clarify the intent of the research and why this is an important question to answer.
Review the literature for similar studies that address your research question or similar research questions; think laterally about some literature that might be helpful or illuminating but is not exactly about the same topic.
Find a written study that inspires you—it may or may not be on the research question you have chosen.
Consider and choose a research tradition and set of data-collection techniques that (1) help answer your research question and (2) match your aims and goals.
Define your population of interest and your research setting.
Define the criteria for your sample (How many? Why these? How will you find them, gain access, and acquire consent?).
If you are conducting interviews, draft an interview guide.
If you are making observations, create a plan for observations (sites, times, recording, access).
Acquire any necessary technology (recording devices/software).
Draft consent forms that clearly identify the research focus and selection process.
Create recruiting materials (posters, email, texts).
Apply for IRB approval (proposal plus consent form plus recruiting materials).
Block out time for collecting data.
At the end of the chapter, you will find a " Research Design Checklist " that summarizes the main recommendations made here ↵
For example, if your focus is society and culture , you might collect data through observation or a case study. If your focus is individual lived experience , you are probably going to be interviewing some people. And if your focus is language and communication , you will probably be analyzing text (written or visual). ( Marshall and Rossman 2016:16 ). ↵
You may not have any "live" human subjects. There are qualitative research methods that do not require interactions with live human beings - see chapter 16 , "Archival and Historical Sources." But for the most part, you are probably reading this textbook because you are interested in doing research with people. The rest of the chapter will assume this is the case. ↵

One of the primary methodological traditions of inquiry in qualitative research, ethnography is the study of a group or group culture, largely through observational fieldwork supplemented by interviews. It is a form of fieldwork that may include participant-observation data collection. See chapter 14 for a discussion of deep ethnography.

A methodological tradition of inquiry and research design that focuses on an individual case (e.g., setting, institution, or sometimes an individual) in order to explore its complexity, history, and interactive parts. As an approach, it is particularly useful for obtaining a deep appreciation of an issue, event, or phenomenon of interest in its particular context.

The controlling force in research; can be understood as lying on a continuum from basic research (knowledge production) to action research (effecting change).

In its most basic sense, a theory is a story we tell about how the world works that can be tested with empirical evidence. In qualitative research, we use the term in a variety of ways, many of which are different from how they are used by quantitative researchers. Although some qualitative research can be described as “testing theory,” it is more common to “build theory” from the data using inductive reasoning , as done in Grounded Theory . There are so-called “grand theories” that seek to integrate a whole series of findings and stories into an overarching paradigm about how the world works, and much smaller theories or concepts about particular processes and relationships. Theory can even be used to explain particular methodological perspectives or approaches, as in Institutional Ethnography , which is both a way of doing research and a theory about how the world works.

Research that is interested in generating and testing hypotheses about how the world works.

A methodological tradition of inquiry and approach to analyzing qualitative data in which theories emerge from a rigorous and systematic process of induction. This approach was pioneered by the sociologists Glaser and Strauss (1967). The elements of theory generated from comparative analysis of data are, first, conceptual categories and their properties and, second, hypotheses or generalized relations among the categories and their properties – “The constant comparing of many groups draws the [researcher’s] attention to their many similarities and differences. Considering these leads [the researcher] to generate abstract categories and their properties, which, since they emerge from the data, will clearly be important to a theory explaining the kind of behavior under observation.” (36).

An approach to research that is “multimethod in focus, involving an interpretative, naturalistic approach to its subject matter. This means that qualitative researchers study things in their natural settings, attempting to make sense of, or interpret, phenomena in terms of the meanings people bring to them. Qualitative research involves the studied use and collection of a variety of empirical materials – case study, personal experience, introspective, life story, interview, observational, historical, interactional, and visual texts – that describe routine and problematic moments and meanings in individuals’ lives." ( Denzin and Lincoln 2005:2 ). Contrast with quantitative research .

Research that contributes knowledge that will help people to understand the nature of a problem in order to intervene, thereby allowing human beings to more effectively control their environment.

Research that is designed to evaluate or test the effectiveness of specific solutions and programs addressing specific social problems. There are two kinds: summative and formative .

Research in which an overall judgment about the effectiveness of a program or policy is made, often for the purpose of generalizing to other cases or programs. Generally uses qualitative research as a supplement to primary quantitative data analyses. Contrast formative evaluation research .

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Research carried out at a particular organizational or community site with the intention of affecting change; often involves research subjects as participants of the study. See also participatory action research .

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The large group of interest to the researcher. Although it will likely be impossible to design a study that incorporates or reaches all members of the population of interest, this should be clearly defined at the outset of a study so that a reasonable sample of the population can be taken. For example, if one is studying working-class college students, the sample may include twenty such students attending a particular college, while the population is “working-class college students.” In quantitative research, clearly defining the general population of interest is a necessary step in generalizing results from a sample. In qualitative research, defining the population is conceptually important for clarity.

A fictional name assigned to give anonymity to a person, group, or place. Pseudonyms are important ways of protecting the identity of research participants while still providing a “human element” in the presentation of qualitative data. There are ethical considerations to be made in selecting pseudonyms; some researchers allow research participants to choose their own.

A requirement for research involving human participants; the documentation of informed consent. In some cases, oral consent or assent may be sufficient, but the default standard is a single-page easy-to-understand form that both the researcher and the participant sign and date. Under federal guidelines, all researchers "shall seek such consent only under circumstances that provide the prospective subject or the representative sufficient opportunity to consider whether or not to participate and that minimize the possibility of coercion or undue influence. The information that is given to the subject or the representative shall be in language understandable to the subject or the representative. No informed consent, whether oral or written, may include any exculpatory language through which the subject or the representative is made to waive or appear to waive any of the subject's rights or releases or appears to release the investigator, the sponsor, the institution, or its agents from liability for negligence" (21 CFR 50.20). Your IRB office will be able to provide a template for use in your study .

An administrative body established to protect the rights and welfare of human research subjects recruited to participate in research activities conducted under the auspices of the institution with which it is affiliated. The IRB is charged with the responsibility of reviewing all research involving human participants. The IRB is concerned with protecting the welfare, rights, and privacy of human subjects. The IRB has the authority to approve, disapprove, monitor, and require modifications in all research activities that fall within its jurisdiction as specified by both the federal regulations and institutional policy.

Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design (2020)

Chapter: chapter 2 - literature review and synthesis.

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

4 Literature Review and Synthesis Literature Review Purpose of Literature Review Performance-based seismic design (PBSD) for infrastructure in the United States is a developing field, with new research, design, and repair technologies; definitions; and method- ologies being advanced every year. A synthesis report, NCHRP Synthesis 440: Performance- Based Seismic Bridge Design (Marsh and Stringer 2013), was created to capture PBSD understanding up to that point. This synthesis report described the background, objec- tives, and research up until 2011 to 2012 and synthesized the information, including areas where knowledge gaps existed. The literature review in this research report focuses on new infor mation developed after the efforts of NCHRP Synthesis 440. The intention is that this research report will fuel the next challenge: developing a methodology to implement PBSD for bridge design. Literature Review Process Marsh and Stringer (2013) performed an in-depth bridge practice review by sending a questionnaire to all 50 states, with particular attention to regions with higher seismic hazards. The survey received responses from a majority of those agencies. This process was continued in the current project with a request for new information or research that the state depart- ment of transportation (DOT) offices have participated in or are aware of through other organizations. The research team reached out to the list of states and researchers in Table 1. An X within a box is placed in front of their names if they responded. The team also examined the websites of the state DOTs that participated to investigate whether something was studied locally, especially work being developed in California. The research team made an additional effort to perform a practice review of bridge designs, research, and other design industries, specifically in the building industry. The building industry has been developing PBSD for more than 20 years, and some of their developments are appli- cable to bridge design. These combined efforts have allowed the research team to assemble an overview of the state of PBSD engineering details and deployment since Marsh and Stringerâs (2013) report was published. NCHRP Synthesis 440 primarily dealt with the effects of strong ground motion shaking. Secondary effects such as tsunami/seiche, ground failure (surface rupture, liquefaction, or slope failure), fire, and flood were outside the scope of this study. Regardless, their impact on bridges may be substantial, and investigation into their effects is undoubtedly important. C H A P T E R 2

Literature Review and Synthesis 5 The following e-mail was sent to the owners and researchers. Dear (individual): We are assisting Modjeski & Masters with the development of proposed guidelines for Performance- Based Seismic Bridge Design, as part of NCHRP [Project] 12-106. Lee Marsh and our Team at BergerABAM are continuing our efforts from NCHRP Synthesis 440, which included a literature review up to December of 2011. From this timeframe forward, we are looking for published research, contractual language, or owner documents that deal with the following categories: 1. Seismic Hazards (seismic hazard levels, hazard curves, return periods, geo-mean vs. maximum direc- tion, probabilistic vs. deterministic ground motions, conditional mean spectrum, etc.) 2. Structure Response (engineering design parameters, materials and novel columns, isolation bearings, modeling techniques, etc.) 3. Damage Limit States (performance descriptions, displacement ductility, drift ratios, strain limits, rotation curvature, etc.) 4. Potential for Loss (damage descriptions, repairs, risk of collapse, economical loss, serviceability loss, etc.) 5. Performance Design Techniques (relating hazard to design to performance to risk, and how to assess [these] levels together) If you are aware of this type of resource, please provide a contact that we can work with to get this information or provide a published reference we can gather. Your assistance is appreciated. We want to minimize your time, and ask that you respond by Wednesday, 8 February 2017. Thank you again, Research Team Synthesis of PBSD (2012â2016) Objectives of NCHRP Synthesis 440 The synthesis gathered data from a number of different but related areas. Marsh and Stringer (2013), herein referred to as NCHRP Synthesis 440, set the basis for this effort. The research report outline follows what has been added to the NCHRP Synthesis 440 effort since 2012. The information gathered that supplements NCHRP Synthesis 440 includes, but is not limited to, the following topics. â¢ Public and engineering expectations of seismic design and the associated regulatory framework Participation State Alaska DOT Arkansas DOT California DOT (Caltrans) Illinois DOT Indiana DOT Missouri DOT Montana DOT Nevada DOT Oregon DOT South Carolina DOT Utah DOT Washington State DOT Table 1. List of state DOT offices and their participation.

6 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design â¢ Seismic hazard analysis â¢ Structural analysis and design â¢ Damage analysis â¢ Loss analysis â¢ Organization-specific criteria for bridges â¢ Project-specific criteria Where new or updated information is available for these areas, a summary is included. Marsh and Stringer (2013) also identified gaps in the knowledge base of PBSD, current as of 2012, that need to be closed. Knowledge gaps certainly exist in all facets of PBSD; however, key knowledge gaps that should be closed in order to implement PBSD are covered. â¢ Gaps related to seismic hazard prediction â¢ Gaps related to structural analysis â¢ Gaps related to damage prediction â¢ Gaps related to performance â¢ Gaps related to loss prediction â¢ Gaps related to regulatory oversight and training â¢ Gaps related to decision making These knowledge gaps have been filled in somewhat in this research report but, for the most part, these areas are still the key concepts that require additional development to further the development of a PBSD guide specification. Public and Engineering Expectations of Seismic Design and the Associated Regulatory Framework The public expectation of a structure, including a bridge, is that it will withstand an earthquake, but there is a limited understanding of what that actually means. Decision makers struggle to understand how a bridge meeting the current requirements of the AASHTO Guide Specifications for LRFD Seismic Bridge Design (2011), herein referred to as AASHTO guide specifications, will perform after either the expected (design) or a higher level earthquake. Decision makers understand the basis of life safety, wherein the expectation is that no one will perish from a structure collapsing, but often mistakenly believe that the structure will also be usable after the event. In higher level earthquakes, even in some lower level events, this is not true without repair, retrofit, or replacement. In the past decade, there has been an increased awareness by owners and decision makers as to the basis of seismic design. As a result, a need has developed for performance criteria so that economic and social impacts can be interwoven with seismic design into the decision processes (see Figure 1). Several states, including California, Oregon, and the State of Washington, are working toward resiliency plans, although these are developed under different titles or programs within the states. Resiliency has been defined in several ways: (1) amount of damage from an event measured in fatalities, structural replacement cost, and recovery time and (2) the time to resto- ration of lifelines, reoccupation of homes and structures, and, in the short term, resumption of normal living routines. The California DOT Caltrans has generated risk models and is in the process of developing a new seismic design specification to address PBSD in bridge design. The risk models and specifications are not published yet, but the use in PBSD is discussed in greater detail later in this chapter.

Literature Review and Synthesis 7 The State of Washington The State of Washingtonâs resiliency plan, outlined in Washington State Emergency Management CouncilâSeismic Safety Committee (2012), works to identify actions and policies before, during, and after an earthquake event that can leverage existing policies, plans, and initiatives to realize disaster resilience within a 50-year life cycle. The hazard level used for trans- portation planning is the 1000 year event. The goals for transportation systems vary depending on the type of service a route provides, as shown in following components of the plan. For major corridors such as Interstates 5, 90, and 405 and floating bridges SR 520, I-90, and Hood Canal, the target timeframe for response and recovery is between 1 to 3 days and 1 to 3 months, depending on location. The current anticipated timeframe based on current capacity and without modifications is between 3 months to 1 year and 1 to 3 years, depending on location. The actual response and recovery time will depend on a number of factors. For example: 1. The number of Washington State DOT personnel who are able to report to work may be limited by a variety of circumstances, including where personnel were at the time of the earthquake and whether they sustained injuries. 2. Bridges and roadways in earthquake-affected areas must be inspected. How long this takes will depend on the number and accessibility of the structures and the availability of qualified inspectors. 3. Some bridges and segments of road may be rendered unusable or only partially usable as a result of the earthquake or secondary effects. The response and recovery timeframe will depend on the number, the location, and the extent of the damage. 4. Certain earthquake scenarios could result in damage to the Ballard Locks and cause the water level in Lake Washington to drop below the level required to operate the floating bridges. 5. Depending on the scenario and local conditions, liquefaction and slope failure could damage both interstates and planned detours. During the first 3 days after the event, the Washington State Department of Transportation (Washington State DOT) will inspect bridges and begin repairs as needed. Washington State DOTâs first priority will be to open key routes for emergency response vehicles. Subsequent phases of recovery will include setting up detours where necessary and regulating the type and Figure 1. PBSD decision-making process (Guidelines Figure 2.0-1). References to guidelines figures and tables within parentheses indicate the proposed AASHTO guidelines.

8 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design volume of traffic, to give the public as much access as possible while damaged roads and bridges are repaired. For major and minor arterials, which encompass arterial roadways (including bridges) other than the interstates (so therefore includes state highways and many city and county roads), the target timeframe for response and recovery is between 0 to 24 hours and 3 months to 1 year, depending on location; the percentage of roadways that are open for use will increase over this period. Anticipated timeframe based on current capacity is between 1 week to 1 month and 1 to 3 years, depending on location; the percentage of roadways that are open for use will increase over this period. The goal of Washington State Emergency Management Councilâs resiliency plan is to establish a means to coordinate agencies, publicâprivate partnerships, and standards toward these resiliency goals. The plan outlines goals for recovery times for transportation systems in terms of hours, days, weeks, months, and years, with targets to achieve different levels of recovery (see Table 2) as follows. Similar recovery timeframe processes were established for service sectors (e.g., hospitals, law enforcement, and education); utilities; ferries, airports, ports, and navigable waterways; mass transit; and housing. The overall resiliency plan also discusses the degree to which the recovery of one component or sector would depend on the restoration of another. The key interdependencies that the participants identified include information and communication technologies, transportation, electricity, fuel, domestic water supplies, wastewater systems, finance and banking, and planning and community development. It appears that the implementation of the Washington State Emergency Management Councilâs initiative, originally assumed to take 2.5 to 3 years in 2012, has not seen significant development since then. However, the Stateâs initiative to develop a more resilient community has been extended down to the county level, with King Countyâs efforts referenced in Rahman et al. (2014) and, at the city level, with the City of Seattle referenced in CEMP (2015). This reflects the commitment needed not only by the legislature and the state departments but also by other agencies (e.g., county, city, or utilities) and the public to take an interest in, and provide funding for, the development of a resiliency plan. The recovery continuum is presented graphically in Figure 2. Developing this relationship with other agency plans is an iterative process that will take time, as shown in Figure 3. Identifying the critical sectors of the agency is necessary to develop a resiliency model and determine how to approach a disaster recovery framework. King County worked from Washington Stateâs initiative to develop Figure 4. The Oregon DOT Oregon DOT has developed a variation of the approach identified by the State of Wash- ington; further discussion is found later in this chapter. Other Resilience Documents The building industry has recently seen the development of two additional documents that address PBSD in terms of expectations and process. The REDi Rating System from REDi (2013) sets an example for incorporating resilience- based design into the PBSD process. This document outlines structural resilience objectives for organizational resilience, building resilience, loss assessment, and ambient resilience to evaluate and rate the decision making and design methodology using PBSD for a specific project.

Literature Review and Synthesis 9 The document is one of the only references that addresses a system to develop probabilistic methods to estimate downtime. The overall intent is to provide a roadmap to resilience. This roadmap is intended to allow owners to resume business operation and to provide livable conditions quickly after an earthquake. The Los Angeles Tall Buildings Structural Design Council (LATBSDC 2014) created an alter- native procedure specific to their location. Design specification criteria are identified and modi- fications are described as appropriate for the PBSD approach to tall buildings in this localized Minimal (A minimum level of service is restored, primarily for the use of emergency responders, repair crews, and vehicles transporting food and other critical supplies.) Functional (Although service is not yet restored to full capacity, it is sufficient to get the economy moving againâfor example, some truck/freight traffic can be accommodated. There may be fewer lanes in use, some weight restrictions, and lower speed limits.) Operational (Restoration is up to 80 to 90 percent of capacity: A full level of service has been restored and is sufficient to allow people to commute to school and to work.) Time needed for recovery to 80 to 90 percent operational given current conditions. Source: Washington State Emergency Management CouncilâSeismic Safety Committee (2012). Table 2. Washington Stateâs targets of recovery.

10 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design Source: Adapted from FHWA by CEMP (2015). Figure 2. Recovery continuum process. Source: CEMP (2015). Figure 3. Relationship of disaster recovery framework to other city plans. region. This procedure is a good example of how PBSD criteria and methodology need to be established locally, with a knowledge of risk, resources, and performance needs in order to set the criteria for true PBSD. Seismic Hazard Prediction As outlined in NCHRP Synthesis 440, the seismic hazard includes the regional tectonics and the local site characteristics from either a deterministic or probabilistic viewpoint. The deterministic form allows the assessment of shaking at a site as a function of the controlling earthquake that can occur on all the identified faults or sources. The probabilistic approach

Literature Review and Synthesis 11 defines an acceleration used in design that would be exceeded during a given window of time (e.g., a 7% chance of exceedance in 75 years). The following subsections provide a summary of procedures currently used within AASHTO, as well as new issues that should be eventually addressed in light of approaches used by the building industry. AASHTO Probabilistic Approach As summarized in the AASHTO guide specifications, the current approach used by AASHTO involves the use of a probabilistic hazard model with a nominal return period of 1000 years. Baker (2013) noted that the probabilistic seismic hazard analysis involves the following five steps: 1. Identify all earthquake sources capable of producing damaging ground motions. 2. Characterize the distribution of earthquake magnitudes (the rates at which earthquakes of various magnitudes are expected to occur). 3. Characterize the distribution of source-to-site distances associated with potential earthquakes. 4. Predict the resulting distribution of ground motion intensity as a function of earthquake magnitude, distance, and so forth. 5. Combine uncertainties in earthquake size, location, and ground motion intensity, using a calculation known as the total probability theorem. While implementation of the five steps in the probabilistic approach is beyond what most practicing bridge engineers can easily perform, AASHTO, working through the U.S. Geological Survey, developed a website hazard tool that allows implementation of the probabilistic proce- dure based on the latitude and longitude of a bridge site. The product of the website includes peak ground acceleration (PGA), spectral acceleration at 0.2 s (Ss), and spectral acceleration at 1 s (S1). These values are for a reference-site condition comprising soft rock/stiff soil, having a time-averaged shear wave velocity (Vs) over the upper 100 feet of soil profile equal to 2500 feet per second (fps). The Geological Survey website can also correct for local site conditions following procedures in the AASHTO Guide Specifications for LRFD Seismic Bridge Design. One of the limitations of the current U.S. Geological Survey hazard website is that it is based on a seismic hazard model developed in 2002. The Geological Survey updated its seismic model in 2008 and then in 2014; however, these updates are currently not implemented within the AASHTO hazard model on the Geological Surveyâs website. Oregon and the State of Washington have updated the seismic hazard map used by the Oregon DOT and the Washington State Source: Rahman et al. (2014). Figure 4. Resilient King County critical sectors and corresponding subsectors.

12 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design DOT to include the 2014 U.S. Geological Survey hazard model; however, most state DOTs are still using the out-of-date hazard model. Use of the outdated hazard model introduces some inconsistencies in ground motion prediction, relative to the current Geological Survey hazard website tool at some locations. Discussions are ongoing between NCHRP and the U.S. Geological Survey to update the 2002 website tool. Another issue associated with the current AASHTO probabilistic method is that it is based on the geomean of the ground motion. In other words, the ground motion prediction equations in the hazard model are based on the geomean of recorded earthquake motions. These motions are not necessarily the largest motion. The building industry recognized that the maximum direction could result in larger ground motions and introduced maximum direction corrections. These corrections increase spectral acceleration by a factor of 1.1 and S1 by a factor of 1.3. The relevance of this correction to bridges is discussed in the next subsection of this review. The building industry also introduced a risk-of-collapse correction to the hazard model results. This correction is made to Ss and S1. The size of the correction varies from approximately 0.8 to 1.2 within the continental United States. It theoretically adjusts the hazard curves to provide a 1% risk of collapse in 50 years. The risk-of-collapse corrections were developed by the U.S. Geological Survey for a range of building structures located throughout the United States. Although no similar corrections have been developed for bridges, the rationale for the adjust- ment needs to be further evaluated to determine if the rationale should be applied to bridge structures. As a final point within this discussion of probabilistic methods within the AASHTO guide specifications, there are several other areas of seismic response that need to be considered. These include near-fault and basin effects on ground motions, as well as a long-period transition factor. The near-fault and basin adjustments correct the Ss and S1 spectral accelerations for locations near active faults and at the edge of basins, respectively. These adjustments typically increase spectral accelerations at longer periods (> 1 s) by 10% to 20%, depending on specifics of the site. The long-period transition identifies the point at which response spectral ordinates are no longer proportional to the 1/T decay with increasing period. These near-fault, basin, and long-period adjustments have been quantified within the building industry guidance documents but remain, for the most part, undefined within the AASHTO guide specifications. As bridge discussions and research move closer to true probabilistic format for PBSD, these issues need to be addressed as part of a future implementation process. Correction for Maximum Direction of Motion Over the last decade, a debate has been under way within the building industry regarding the appropriate definition of design response spectra (Stewart et al. 2011). The essence of the argument relates to the representation of bidirectional motion via response spectra. In both the AASHTO LRFD Bridge Design Specifications (2014), as well as the AASHTO Guide Specifications for LRFD Seismic Bridge Design (SGS), response spectra are established by defining spectral ordinates at two or three different periods from design maps developed by the U.S. Geological Survey for a return period of 1000 years. The resulting spectra are then adjusted for local site conditions, resulting in the final design spectra. In establishing the design maps for parameters such as Ss and S1, the U.S. Geological Survey has traditionally relied upon probabilistic seismic hazard analysis, which utilizes ground motion prediction equations (GMPEs) defined by the geometric mean of the two principal directions of recorded motion. In 2006, Boore introduced a new rotation independent geometric mean definition termed GMRotI50 (Boore et al. 2006). Then, in 2010, Boore developed a new defini- tion that does not rely upon the geometric mean termed RotD50 spectra, which can be generi- cally expressed as RotDNN spectra, where NN represents the percentile of response (i.e., 50 is

Literature Review and Synthesis 13 consistent with the median, 0 is the minimum, and 100 is the maximum). The NGAâWest2 project GMPEs utilized RotD50 spectra for the ground motion models; however, the 2009 National Earthquake Hazards Reduction Program (NEHRP) provisions adopted a factor to modify the median response, RotD50, to the maximum possible response, RotD100 as the spectra for the design maps (Stewart et al. 2011). Introducing RotD100 resulted in a 10% to 30% increase in spectral ordinates results relative to the geometric mean, which has traditionally been used as a basis of seismic design. In order to appreciate the impact of these choices, a brief discussion of RotDNN spectra is warranted. As described in Boore (2010), for a given recording station, the two orthogonal- component time series are combined into a single time series corresponding to different rotation angles, as shown in Equation 1: aROT(t ; Î¸) = a1(t)cos(Î¸) + a2(t)sin(Î¸) (1) where a1(t ) and a2(t ) are the orthogonal horizontal component acceleration time series and Î¸ is the rotation angle. For example, consider the two orthogonal horizontal component time series, H1 and H2, shown in Figure 5. The single time series corresponding to the rotation angle Î¸ is created by combining the Direction 1 and Direction 2 time series. Then, the response spectrum for that single time series can be obtained, as shown in the figure. The process is repeated for a range of azimuths from 0Â° to one rotation-angle increment less than 180Â°. If the rotation-angle increment is Î¸, then there will be 180/Î¸ single time series, as well as 180/Î¸ corresponding response spectra. For example, if Î¸ = 30Â°, then there will be six single time series (the original two, as well as four generated time series), as well as six response spectra, as shown in Figure 6. Once the response spectra for all rotation angles are obtained, then the nth percentile of the spectral amplitude over all rotation angles for each period is computed (e.g., RotD50 is the median value and RotD100 is the largest value for all rotation angles). For example, at a given period of 1 s, the response spectra values for all rotation angles are sorted, and the RotD100 value would be the largest value from all rotation angles while RotD50 would be the median. This is repeated for all periods, with potentially different rotation angles, producing the largest Source: Palma (2019). Figure 5. Combination of time series to generate rotation dependent spectra.

14 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design response at any given period (period-dependent rotation angle.) Figure 7 shows an example of the two orthogonal horizontal components, as well as the RotD50 and RotD100 spectra for the as-recorded ground motion from the 2011 Christchurch, New Zealand, earthquake at Kaiapoi North School station. As can be seen in the sample spectra (see Figure 7), the RotD100 spectrum represents a sub- stantial increase in demand when compared with the RotD50 spectrum. The main question facing the bridge community from this point onward is the appropriate selection of response spectra definition. This question can only be answered by developing sample designs to both the RotD50 and RotD100 spectra, which would then be evaluated via no-linear time history analysis. Such a study will require multiple bridge configurations and multiple ground motions. As an example of the potential impact, Figure 8 shows the results of a single-degree-of- freedom bridge column designed according to both RotD50 and RotD100 spectra, along with the resulting nonlinear time history analysis. The column was designed using direct displacement- based design to achieve a target displacement of 45 cm. It is clear from the results in Figure 8d that the nonlinear response of the column designed to the RotD100 spectrum matches the target Source: Palma (2019). Figure 6. Example of time series rotations with an angle increment (p) of 30Ã§. Source: Palma (2019). Figure 7. Sample spectra for a recorded ground motion pair.

Literature Review and Synthesis 15 reasonably well, while designing to the RotD50 spectrum results in displacements that are much greater than expected. This is, of course, only one result of an axisymmetric system. In the future (and outside the scope of this project), a systematic study could be conducted for both single degree of freedom and multiple degrees of freedom systems. The literature on this topic can be divided into two categories: (1) response spectra definitions and (2) impact on seismic response. The majority of the literature addresses the former. For example, Boore et al. (2006) and Boore (2010) introduced orientation-independent measures of seismic intensity from two horizontal ground motions. Boore et al. (2006) proposed two measures of the geometric mean of the seismic intensity, which are independent of the in-situ orientations of the sensors. One measure uses period-dependent rotation angles to quantify the spectral intensity, denoted GMRotDnn. The other measure is the GMRotInn, where I stands for period-independent. The ground motion prediction equations of Abrahamson and Silva (1997), Figure 8. Single bridge column designed according to both RotD50 and RotD100 spectra (Tabas EQ = Tabas earthquake and displ. = displacement).

16 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design Boore et al. (1997), Campbell and Bozorgnia (2003), and Sadigh et al. (1997) have been updated using GMRotI50 as the dependent variable. Since more users within the building industry expressed the desire to use the maximum spec- tral response over all the rotation angles without geometric means, Boore (2010) introduced the measures of ground-shaking intensity irrespective of the sensor orientation. The measures are RotDnn and RotInn, whose computation is similar to GMRotDnn and GMRotInn without computing the geometric means. With regard to impact on seismic response, the opinion paper by Stewart et al. (2011) and the work by Mackie et al. (2011) on the impact of incidence angle on bridge response are relevant. Specifically, Stewart et al. (2011) noted the importance of computational analysis of structures (which had not been done as of 2011) in proposing appropriate spectra definitions. Other Methodologies for Addressing Seismic Ground Motion Hazards There are several other reports that address the question of the methodology that may be utilized in developing the seismic hazard. These recent studies endeavored to create a method- ology that is easier for engineers, as users, to understand how to tie the seismic hazard to the performance expectation. The variability of these approaches also demonstrates the broad range of options and therefore a limited understanding by practitioners in the bridge design industry. Following are some examples that apply to PBSD. Wang et al. (2016) performed a probabilistic seismic risk analysis (SRA) based on a single ground motion parameter (GMP). For structures whose responses can be better predicted using multiple GMPs, a vector-valued SRA (VSRA) gives accurate estimates of risk. A simplified approach to VSRA, which can substantially improve computational efficiency without losing accuracy, and a new seismic hazard de-aggregation procedure are proposed. This approach and the new seismic hazard de-aggregation procedure would allow an engineer to determine a set of controlling earthquakes in terms of magnitude, sourceâsite distance, and occurrence rate for the site of interest. Wang et al. presented two numerical examples to validate the effectiveness and accuracy of the simplified approach. Factors affecting the approximations in the simplified approach were discussed. Kwong and Chopra (2015) investigated the issue of selecting and scaling ground motions as input excitations for response history analyses of buildings in performance-based earthquake engineering. Many ground motion selection and modification procedures have been developed to select ground motions for a variety of objectives. This report focuses on the selection and scaling of single, horizontal components of ground motion for estimating seismic demand hazard curves of multistory frames at a given site. Worden et al. (2012) used a database of approximately 200,000 modified Mercalli intensity (MMI) observations of California earthquakes collected from U.S. Geological Survey reports, along with a comparable number of peak ground motion amplitudes from California seismic networks, to develop probabilistic relationships between MMI and peak ground velocity (PGV), PGA, and 0.3-s, 1-s, and 3-s 5% damped pseudo-spectral acceleration. After associating each ground motion observation with an MMI computed from all the seismic responses within 2 kilometers of the observation, a joint probability distribution between MMI and ground motion was derived. A reversible relationship was then derived between MMI and each ground motion parameter by using a total least squares regression to fit a bilinear function to the median of the stacked probability distributions. Among the relationships, the fit-to-peak ground velocity has the smallest errors, although linear combinations of PGA and PGV give nominally better results. The magnitude and distance terms also reduce the overall residuals and are justifiable on an information theoretical basis.

Literature Review and Synthesis 17 Another approach to developing the appropriate seismic hazard comes out of Europe. Delavaud et al. (2012) presented a strategy to build a logic tree for ground motion prediction in European countries. Ground motion prediction equations and weights have been determined so that the logic tree captures epistemic uncertainty in ground motion prediction for six different tectonic regions in Europe. This includes selecting candidate GMPEs and simultaneously running them through a panel of six experts to generate independent logic trees and rank the GMPEs on available test data. The collaboration of this information is used to set a weight to the GMPEs and create a consensus logic tree. This output then is run through a sensitivity analysis of the proposed weights on the seismic hazard before setting a final logic tree for the GMPEs. Tehrani and Mitchell (2014) used updated seismic hazard maps for Montreal, Canada to develop a uniform hazard spectra for Site Class C and a seismic hazard curve to analyze bridges in the localized area. Kramer and Greenfield (2016) evaluated three case studies following the 2011 Tohoku earthquake to better understand and design for liquefaction. Existing case history databases are incomplete with respect to many conditions for which geotechnical engineers are often required to evaluate liquefaction potential. These include liquefaction at depth, liquefaction of relatively dense soils, and liquefaction of gravelly soils. Kramer and Greenfieldâs investigation of the three case histories will add to the sparse existing data for those conditions, and their interpretations will aid in the validation and development of predictive procedures for liquefaction potential evaluation. Structural Analysis and Design Predicting the structural response to the earthquake ground motions is critical for the PBSD process. NCHRP Synthesis 440 outlined several analysis methods that can be used to accomplish this task. The multimodal linear dynamic procedures are outlined in AASHTO LRFD Bridge Design Specifications (AASHTO 2014) and AASHTO Guide Specifications for LRFD Seismic Bridge Design (AASHTO 2011), although the Guide Specifications also include the parameters for performing a model pushover analysis in addition to prescriptive detail practices to ensure energy-dissipating systems behave as intended and other elements are capacity-protected. Other methods of analysis may be better suited for PBSD, but the initial PBSD approach will likely follow the procedures of the AASHTO guide specifications, with multi-level hazards and performance expectations. Limited research and code development have been accomplished since NCHRP Synthesis 440, but one new analysis method, outlined in Babazadeh et al. (2015), includes a three-dimensional finite element model simulation that is used to efficiently predict intermediate damage limit states in a consistent manner, with the experimental observations extracted from the actual tested columns. Other recent articles of structural analysis identified areas of improvement in the current design methodology that may be beneficial to PBSD. Huff and Pezeshk (2016) compared the substitute structure method methodology for isolated bearings with the displacement-based design methodology for ordinary bridges and showed that these two methodologies vary in estimating inelastic displacements. Huff (2016a) identified issues that are generally simplified or ignored in current practice of predicting inelastic behavior of bridges during earthquakes, both on the capacity (in the section of the element type and geometric nonlinearities) and demand (issues related to viscous dampening levels) sides of the process. The current SGS methodology for nonlinear static procedures were compared in Hajihashemi et al. (2017) with recent methodologies for multimodal pushover procedures that take into account all significant modes of the structure and with modified equivalent linearization procedures developed for

18 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design FEMA-440 (FEMA 2005). All of these analysis articles identify areas of current discussion on how to improve the analytical procedures proposed in the SGS. NCHRP Synthesis 440 focused primarily on new analysis methods, but a recent increased focus, in both academia and industry, has to do with new materials and systems and their impacts on PBSD. The evolution of enhanced seismic performance has been wrapped into several research topics, such as accelerated bridge construction (ABC), novel columns, and PBSD. The following are several aspects, though not all-encompassing, which have been improved upon in the last 6 years or so. Improving Structural Analysis Through Better Material Data The analysis and performance of a bridge are controlled with material property parameters incorporated into the seismic analysis models, specifically for the push-over analysis method. AASHTO Guide Specifications for LRFD Seismic Bridge Design (AASHTO 2011) specifies the strain limits to use for ASTM A706 (Grade 60) and ASTM A615 Grade 60 reinforcement. These strain limits come from Caltrans study of 1,100 mill certificates for ASTM A706 Grade 60 in the mid-1990s for projects in Caltrans bridge construction. The results were reported as elongationânot strainâat peak stress, so select bar pull tests were performed to correlate elongation to strain at peak stress. This was assumed to be a conservative approach, though it has recently been validated with a new ASTM A706 Grade 80 study at North Carolina State University by Overby et al. (2015a), which showed Caltrans numbers, by comparison, for Grade 60 are reasonable and conservative. Overby et al. (2015b) developed stress strain parameters for ASTM A706 Grade 80 reinforcing steel. Approximately 800 tests were conducted on bars ranging from #4 to #18 from multiple heats from three producing mills. Statistical results were presented for elastic modulus, yield strain and stress, strain-hardening strain, strain at maximum stress, and ultimate stress. Research is currently under way at North Carolina State University that aims to identify strain limit states, plastic hinge lengths, and equivalent viscous damping models for bridge columns constructed from A706 Grade 80 reinforcing steel. Work is also under way at the University of California, San Diego, on applications of Grade 80 rebar for capacity-protected members such as bridge cap beams. Design Using New Materials and Systems Structural analysis and design are fundamentally about structural response to the earthquake ground motion and the analysis methods used to develop this relationship. The complexity of the analysis depends on the geometry of the structure and elements and the extent of inelastic behavior. This is coupled with the damage, or performance criteria but has been broken out for the purposes of this report and NCHRP Synthesis 440. Next generation bridge columns, often referred to as novel columns, are improving as a tool for engineers to control both the structural analysis, as the make-up of the material changes the inelastic behavior, and the element performance of bridges in higher seismic hazards. The energy-dissipating benefits of low damage materialsâsuch as ultrahigh-performance concrete (UHPC), engineered cementi- tious composites (ECC), and shape memory alloy, fiber-reinforced polymer (FRP) wraps and tubes, elastomeric bearings, and post-tensioned strands or barsâcan be utilized by engineers to improve seismic performance and life-cycle costs after a significant seismic event. Recent (Saiidi et al. 2017) studies tested various combinations of these materials to determine if there are columns that can be built with these materials that are equivalent to, or better than, conventional reinforced concrete columns (in terms of cost, complexity, and construction duration) but that improve seismic performance, provide greater ductility, reduce damage, and accommodate a quicker recovery time and reduce loss in both the bridge and the economic environment.

Literature Review and Synthesis 19 Accelerated bridge construction is also a fast-developing field in bridge engineering, with draft guide specifications for design and construction currently being developed for adop- tion by AASHTO for AASHTO LRFD Bridge Design Specifications (AASHTO 2014). ABC has economic impacts that go beyond seismic engineering, but research is focusing on details and connections for accelerated construction in higher seismic regions, moving two research paths forward at the same time. Tazarv and Saiidi (2014) incorporated ABC research with novel column research to evaluate combined novel column materials that can be constructed quickly. The research focused on the performance of materials and how to incorporate them into practice. Key mechanical properties of reinforcing SMA were defined as follows: â¢ Observed yield strength (fyo) is the stress at the initiation of nonlinearity on the first cycle of loading to the upper plateau. â¢ Austenite modulus (k1) is the average slope between 15% to 70% of fyo. â¢ Post yield stiffness (k2) is the average slope of curve between 2.5% and 3.5% of strain on the upper plateau of the first cycle of loading to 6% strain. â¢ Austenite yield strength (fy) is the stress at the intersection of line passing through origin with slope of k1 and line passing through stress at 3% strain with slope of k2. â¢ Lower plateau inflection strength (fi) is the stress at the inflection point of lower plateau during unloading from the first cycle to 6% strain. â¢ Lower plateau stress factor, Î² = 1 â (fi/fy). â¢ Residual strain (eres) is the tensile strain after one cycle to 6% and unloading to 1 ksi (7 MPa). â¢ Recoverable super-elastic strain (er) is maximum strain with at least 90% strain recovery capacity. Using the ASTM standard for tensile testing, er â¤ 6%. â¢ Martensite modulus (k3) is the slope of the curve between 8% to 9% strain, subsequent to one cycle of loading to 6% strain, unloading to 1 ksi (7 MPa) and reloading to the ultimate stress. â¢ Secondary post-yield stiffness ratio, Î± = k3/k1. â¢ Ultimate strain (eu) is strain at failure. A graphical representation is shown in Figure 9, and minimum and expected mechanical properties are listed in Table 3. Other researchers, such as at the University of Washington, are currently testing grouted bars using conventional grouts and finding that these development lengths can be reduced greatly. However, it is the force transfer of the grouted duct to the reinforcing outside the duct that may Figure 9. NiTi SE SMA nonlinear model.

20 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design require additional length to adequately develop the energy-dissipating or capacity-protecting system that was intended by the designer for performance of the bridge in a high seismic event. Tazarv and Saiidi (2014) identified other material properties such as UHPC and ECC, shown in Tables 4 and 5, respectively. Tazarv and Saiidi (2014) also addressed grouted splice sleeve couplers, self-consolidating concrete (SCC), and other connection types that could be used in ABC and novel column configurations, testing these materials in the laboratory to see if various combinations produced a logical system to be carried forward in research, design, and implementation. Trono et al. (2015) studied a rocking post-tensioned hybrid fiber-reinforced concrete (HyFRC) bridge column that was designed to limit damage and residual drifts and that was tested dynamically under earthquake excitation. The column utilized post-tensioned strands, HyFRC, and a combination of unbonded and headed longitudinal reinforcement. There have been two projects related to the field of novel columns and ABC through the National Cooperative Highway Research Program. One project was NCHRP Project 12-101, which resulted in NCHRP Report 864, 2 volumes (Saiidi et al. 2017), and the other project was NCHRP Project 12-105, which resulted in NCHRP Research Report 935 (Saiidi et al. 2020). NCHRP Project 12-101 identified three novel column systemsâspecifically, SMA and ECC, ECC and FRP, and hybrid rocking column using post-tensioned strands and fiber-reinforced Parameter Tensile Compressive,ExpectedbExpectedbMinimuma Table 3. Minimum expected reinforcing NiTi SE SMA mechanical properties. Properties Range Poissonâs Ratio 0.2 Creep Coefficient* 0.2 to 0.8 Total Shrinkage** *Depends on curing conditions and age of loading. up to 900x10-6 Equation Compressive Strength (f'UHPC) f'UHPC 20 to 30 ksi, (140 to 200 MPa) Coefficient of Thermal Expansion (5.5 to 8.5)x10 -6/Â°F, (10 to 15)x10-6/Â°C Specific Creep* (0.04 to 0.3)x10 -6/psi, (6 to 45)x10-6/MPa A time-dependent equation for UHPC strength is available. Tensile Cracking Strength (ft,UHPC) ft,UHPC = 6.7 (psi) f'UHPCEUHPC = 49000 (psi) 0.9 to 1.5 ksi, (6 to 10 MPa) Modulus of Elasticity (EUHPC) 6000 to 10000 ksi, (40 to 70 GPa) **Combination of drying shrinkage and autogenous shrinkage and depends on curing method. Table 4. UHPC mechanical properties.

Literature Review and Synthesis 21 polymer confinementâand compared them to a conventional reinforced column. The research and properties of the material are provided; incorporating laboratory tests and calibration, design examples are created to help engineers understand how to use these advanced materials in a linear elastic seismic demand model and to determine performance using a pushover analysis. It is worth noting that ductility requirements do not accurately capture the perfor- mance capabilities of these novel columns, and drift ratio limits are being used instead, similar to the building industry. NCHRP Project 12-101 also provided evaluation criteria that can be evaluated and incorporated by AASHTO into a guide specification or into AASHTO Guide Specifications for LRFD Seismic Bridge Design (AASHTO 2011) directly. NCHRP Project 12-105 synthesized research, design codes, specifications, and contract language throughout all 50 states and combined the knowledge base and lessons learned for ABC into proposed guide specifications for both design and construction. This work focused on connections, and most of that information is related to seismic performance of ABC elements and systems. Earthquake resisting elements (ERE) and earthquake resisting systems (ERS) are specifically identified, defined, and prescribed for performance in AASHTO guide specifica- tions (AASHTO 2011) but only implicitly applied in AASHTO LRFD Bridge Design Specifications (AASHTO 2014). Since NCHRP Project 12-105 is applicable to both of these design resources, ERE and ERS are discussed in terms of how to apply performance to the force-based seismic design practice of AASHTO LRFD Bridge Design Specifications (AASHTO 2014). The proposed guide specification language also identifies when performance of materials have to be incor- porated into the design, say in higher seismic hazards, and when it is acceptable to apply ABC connections and detailing practices with prescriptive design methodologies. As the industryâs understanding of performance increases, the engineering industry is accepting the benefits that come from a more user-defined engineering practice that is implemented by identifying material properties; evaluating hazards and soil and structural responses; and verifying performance through strain limits, damage limits states, moment curvature, displacements, and ductility. These tools and advancements in ABC and novel column designs, including other material property performance and analytical methodologies, are allowing PBSD to advance in other areas, such as hazard prediction, loss prediction, and the owner decision-making process. Feng et al. (2014a) studied the application of fiber-based analysis to predict the nonlinear response of reinforced concrete bridge columns. Specifically considered were predictions of overall force-deformation hysteretic response and strain gradients in plastic hinge regions. The authors also discussed the relative merits of force-based and displacement-based fiber elements and proposed a technique for prediction of nonlinear strain distribution based on the modified compression field theory. Fulmer et al. (2013) developed a new steel bridge system that is based upon ABC techniques that employ an external socket to connect a circular steel pier to a cap beam through the use of grout and shear studs. The resulting system develops a plastic hinge in the pipe away from the column-to-cap interface. An advantage of the design is ease of construction, as no field welding Properties Range Flexural Strength 1.5 to 4.5 ksi (10 to 30 MPa) Modulus of Elasticity 2600 to 5000 ksi (18 to 34 GPa) Ultimate Tensile Strain 1 to 8% Ultimate Tensile Strength 0.6 to 1.7 ksi (4 to 12 MPa) First Crack Strength 0.4 to 1.0 ksi (3 to 7 MPa) Compressive Strength 3 to 14 ksi (20 to 95 MPa) Table 5. ECC mechanical properties.

22 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design is required: the two assemblies are placed together and the annular space between the column and cap filled with grout. Figure 10 shows the details of this connection, and Figure 11 shows a test of the system. Another system being investigated is isolation bearings or dampening devices. Xie and Zhiang (2016) investigated the effectiveness and optimal design of protective devices for the seismic protection of highway bridges. Fragility functions are first derived by probabilistic seismic demand analysis, repair cost ratios are then derived using a performance-based methodol- ogy, and the associated component failure probability. Subsequently, the researchers tried to identify the optimal design parameters of protective devices for six design cases with various combinations of isolation bearings and fluid dampers and discussed the outcomes. Damage mitigation through isolation and energy dissipation devices is continually improving based on research, development, and implementation in the field. Recent events within the State of Washington, Alaska, and other state agencies have shown that the benefits of these tools can be compromised if the intended performance cannot be sustained for the 75-year design life of the structure. Mackie and Stojadinovic (2015) outlined performance criteria for fabrica- tion and construction that need to be administered properly, and engineers should consider the effects of moisture, salts, or other corrosive environmental conditions that can affect the performance of the isolation or energy-dissipating system. Another constraint with these systems can be the proprietary nature that occurs as a specific isolation or energy-dissipating system is utilized to develop a specific performance expectation that can only be accomplished with the prescribed system. This proprietary nature of these systems can create issues for certain funding sources that require equal bidding opportunities and the project expense that can accompany a proprietary system. To address this type of design constraint, Illinois DOT has been developing an earthquake-resisting system (ERS) to leverage the displacement capacity available at typical bearings in order to provide seismic protection to substructures of typical bridges. LaFave et al. (2013a) identified the effects and design parameters, Source: Fulmer et al. (2013). 5" 4 at 5" O.C. A A A-A Connection Details 45Â° UT 100% 3 8" 12 Studs Spaced Around Cross Section 30Â°Typ. 15Â° Offset Studs Inside Pipe from Cap Beam CL HSS16x0.500 Pipe 24x0.500 2'-0"2 14 " 4 at 5" O.C. 212"-34 "Ã Shear Studs 1'-11" Pipe Stud Detail Grout Provided By and Placed by NCSU Figure 10. Grouted shear stud bridge system.

Literature Review and Synthesis 23 such as fuse capacity, shear response, and sliding response, which can be used to account for more standard bearing configurations in seismic analysis, especially lower seismic hazard regions. A variation on the use of bearings in order to improve seismic performance of a pier wall configuration was outlined in Bignell et al. (2006). Historically, pinned, rocking, and sliding bearings have been used with interior pier walls and steel girder superstructures. These bearing configurations were compared with replacement elastomeric bearing configurations and details for structural analysis techniques, damage limit states, and structural fragility, and performance through probability distributions were utilized as a PBSD process for determining solutions to seismic isolation and enhanced seismic performance. The foundation conditions, pier wall effects, bearing type, and even embankment effects to structural performance were included in this evaluation. Another approach to enhanced performance is modifications to foundation elements or increased understanding and modeling of soilâstructure interaction, specifically where lateral spread or liquefaction design conditions make conventional bridge design and elements imprac- tical. One example of this is the seismic design and performance of bridges constructed with rocking foundations, as evaluated in Antonellis and Panagiotou (2013). This type of rocking goes beyond the loss of contact area currently allowed in the guide specifications. The applica- tion of columns supported on rocking foundations accommodates large deformations, while there is far less damage, and can re-center after large earthquakes. Another approach is to tie a tolerable displacement of an individual deep foundation element to a movement that would cause adverse performance, excessive maintenance issues, or functionality problems with the bridge structure. Roberts et al. (2011) established a performance-based soilâstructureâinteraction design approach for drilled shafts. Chiou and Tsai (2014) evaluated displacement ductility of an in-ground hinging of a fixed head pile. Assessment formulas were developed for the displacement ductility capacity of a fixed-head pile in cohesion-less soils. The parameters in the formulas included the sectional over-strength ratio and curvature ductility capacity, as well as a modification factor for consider- ing soil nonlinearity. The modification factor is a function of the displacement ratio of the pileâs ultimate displacement to the effective soil yield displacement, which is constructed through a number of numerical pushover analyses. Source: Fulmer et al. (2013). Figure 11. Photograph of completed system before seismic testing showing hinge locations.

24 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design Damage Analysis As stated in NCHRP Synthesis 440, it is a fundamental need for the PBSD methodology to determine the type of damage and the likelihood that such damage will occur in the particular components of the structural system. This determination is of vital importance, as the damage sustained by a structure (and its nonstructural components) is directly relatable to the use or loss of a system after an earthquake. Therefore, there is a need to be able to reliably link structural and nonstructural response (internal forces, deformations, accelerations, and displacements) to damage. This is the realm of damage analyses, where damage is defined as discrete observable damage states (e.g., yield, spalling, longitudinal bar buckling, and bar fracture). Although the primary focus of the discussions is on structural components, similar considerations must be made for nonstructural components as well. NCHRP Synthesis 440 outlined an initial discussion on types of structural damage observed during historic earthquakes and laboratory experiments, prefaced the methods that have been developed to predict damage, identified structural details and concepts that could be used to reduce damage even in strong ground shaking, and reviewed post-event inspection tools. The new materials discussed in previous sections also apply to this discussion but are not repeated herein. Accurate damage prediction relies upon accurate definitions of performance limit states at the material level (i.e., strain limits) and the corresponding relationship between strain and displacement. Examples of recent research follow. Research by Feng et al. (2014b, 2014c) used finite element analysis validated by experimental test results to develop a model for predicting the tension strain corresponding to bar buckling. The model considers the impact of loading history on the boundary conditions of longitudinal bar restraint provided by the transverse steel. Goodnight et al. (2016a) identified strain limits to initiate bar buckling based on experimental results from 30 column tests (Equation 2). Following additional bidirectional tests on 12 columns, Equation 2 was revised to Equation 3. In addition, strain limit state equations were proposed for the compression strain in concrete to cause spiral yielding (Goodnight et al. 2017a). Goodnight et al. (2016b) also developed a new plastic hinge length model based on the data collected during those tests, which accounts for the actual curvature distribution in RC bridge columns. The revised model separates the strain penetration component from the flexural component while also recognizing that the hinge length for compression is smaller than that for tension. Brown et al. (2015) developed strain limit state (Equation 4) (tube wall local buckling) and equivalent viscous damping equations for reinforced concrete filled steel tubes (RCFSTs). The recommendations of the authors were based upon reversed cyclic tests of 12 RCFSTs of variable D/t (diameter to thickness) ratios. 0.03 700 0.1 (2)bucklingbar f E P f A s s yhe s ce g Îµ = + Ï â â² 0.032 790 0.14 (3)bucklingbar f E P f A s s yhe s ce g Îµ = + Ï â â² 0.021 9100 (4)tension buckling D t yÎµ = â â¥ Îµ

Literature Review and Synthesis 25 where rs = reinforcement ratio, fyhe = expected yield strength of the steel tube (ksi), Es = elastic modulus of steel (ksi), P = axial load (kip), f â²ce = expected concrete strength (ksi), Ag = gross area of concrete (in.2), D = diameter of tube (in.), t = thickness of tube (in.), and ey = yield strain for steel (in./in.). Loss Analysis The PBSD combines the seismic hazard, structural, and damage analysis into a performance matrix that can be estimated into a loss metric. There are many loss metrics that can be used by, and that are important to, stakeholders and decision makers (discussed in detail in NCHRP Synthesis 440), but all these metrics can be boiled down to three main categories: deaths, dollars, and downtime. Bertero (2014) discussed earthquake lessons, in terms of loss, to be considered in both design and construction of buildings. At the beginning of 2010, two large earthquakes struck the Americas. The January 12, 2010, Haiti earthquake with a magnitude 7.0 produced about 300,000 deaths (second by the number of fatalities in world history after the 1556 Shaanxi, China earthquake). A month later, the February 27, 2010, Maule Chilean earthquake with a magnitude 8.8 (an energy release 500 times bigger than that from the Haiti earthquake) produced 500 deaths, most due to the resulting tsunami. However, the Chilean earthquake caused more than $30 billion of direct damage, left dozens of hospitals and thousands of schools nonoperational, and caused a general blackout for several hours, as well as the loss of service of essential communications facilities, crucial to take control of the chaotic after-earthquake situ- ation. Bertero (2014) compared the severity of both earthquakes and comments on their effects to life and the economy of the affected countries, as well as the features of the seismic codes or the absence of codes. An example of risk analysis with PBSD is utilized in Bensi et al. (2011), with the development of a Bayesian network (BN) methodology for performing infrastructure seismic risk assessment and providing decision support with an emphasis on immediate post-earthquake applications. A BN is a probabilistic graphical model that represents a set of random variables and their probabilistic dependencies. The proposed methodology consists of four major components: (1) a seismic demand model of ground motion intensity as a spatially distributed random field, accounting for multiple sources and including finite fault rupture and directivity effects; (2) a model for seismic performance of point-site and distributed components; (3) models of system performance as a function of component states; and (4) models of post-earthquake decision making for inspection and operation or shutdown of components. The use of the term Bayesian to describe this approach comes from the well-known Bayes rule, attributed to the 18th-century mathematician and philosopher Thomas Bayes: A B AB B B A B A( ) ( )( ) ( ) ( ) ( )= =Pr Pr Pr Pr Pr Pr (5) Pr(AB) is the probability of joint occurrence of Events A and B; Pr(A) is the marginal probability of Event A; Pr(A|B) is the conditional probability of Event A, given that Event B

26 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design has occurred; and Pr(B) is the marginal probability of Event B. The quantity Pr(B | A) is known as the likelihood of the observed Event B. Note that the probability of Event A appears on both sides of Equation 5. The Bayes rule describes how the probability of Event A changes given information gained about the occurrence of Event B. For discrete nodes, a conditional probability table is attached to each node that provides the conditional probability mass function (PMF) of the random variable represented by the node, given each of the mutually exclusive combinations of the states of its parents. For nodes without parents (e.g., X1 and X2 in Figure 12), known as root nodes, a marginal probability table is assigned. The joint PMF of all random variables X in the BN is constructed as the product of the conditional PMFs: (6) 1 p x p x Pa xi ii nâ( ) ( )( )= = Bensi et al. (2011) goes on to introduce BN models further and discusses how to incorporate BN-based seismic demand models into bridge design. The BN methodology is applied to modeling of random fields, construction of an approximate transformation matrix, and numer- ical investigation of approximation methods, including a discussion on the effect of correlation approximations on system reliability. Modeling component performance with BNs to capture seismic fragility of point-site components and distributed components, as well as modeling system performance of BNs with both qualitative and conventional methods, is explained. This reference goes on to identify efficient minimal link set (MLS), minimal cut set (MCS) formulations, optimal ordering of efficient MLS and MCS formulations, and heuristic augmen- tation that can be utilized with the BN methodology. Bensi et al. (2011) continues the PBSD process by addressing the owner decision-making process (see more discussion later in the report) and how to incorporate this model into that process. Two example problems are provided utilizing this methodology, including a California high-speed rail system that incorporates the bridge modeling into the example. Similarly, in Tehrani and Mitchell (2014), the seismic performance of 15 continuous four- span bridges with different arrangements of column heights and diameters was studied using incremental dynamic analysis (IDA). These bridges were designed using the Canadian Highway Bridge Design Code provisions (CSA 2006). The IDA procedure has been adopted by some guidelines to determine the seismic performance, collapse capacity, and fragility of buildings. Similar concepts can be used for the seismic assessment of bridges. Fragility curves can be devel- oped using the IDA results to predict the conditional probability that a certain damage state is exceeded at a given intensity measure value. Assuming that the IDA data are lognormally distributed, it is possible to develop the fragility curves at collapse (or any other damage state) by computing only the median collapse capacity and the logarithmic standard deviation of the IDA results for any given damage state. The fragility curves can then be analytically computed using Equation 7 as follows: ln ln (7)50% TOT P failure S x x S a a C( )( ) ( )= = Î¦ â Î² ï£® ï£°ï£¯ ï£¹ ï£»ï£º where function F = cumulative normal distribution function, SCa 50% = median capacity determined from the IDA, and Î²TOT = total uncertainty caused by record-to-record variability, design requirements, test data, and structural modeling. Figure 12. A simple BN.

Literature Review and Synthesis 27 The seismic risk associated with exceeding different damage states in the columns, includ- ing yielding, cover spalling, bar buckling, and structural collapse (i.e., dynamic instability) was predicted. Some simplified equations were derived for Montreal, Quebec, Canada, to estimate the mean annual probability of exceeding different damage states in the columns using the IDA results. Repair and retrofit procedures are linked to loss predictions, as outlined in the FHWAâs retro- fitting manual (Buckle et al. 2006). Several chapters/articles address analysis, methodologies, effects, analytical tools, and costs for retrofit and repairs to mitigate damage or return a structure to a serviceable condition. Zimmerman et al. (2013) is one example, in which numerical techniques and seismic retrofit solutions for shear-critical reinforced concrete columns was investigated, utilizing test data of a reinforced concrete column with widely spaced transverse reinforcement. The study focused on the analysis method of nonlinear trusses and the retrofit option known as supplemental gravity columns, which is an example of how loss prediction and the analysis process are linked and should be iterated through PBSD. Organization-Specific Criteria for Bridges and Project-Specific Criteria NCHRP Synthesis 440 has two sections of criteria: organization-specific criteria for bridges and project-specific criteria. New information for both of these sections since NCHRP Synthesis 440 published is combined. The California DOT (Caltrans) Caltrans is currently updating their Seismic Design Criteria (SDC) to specify requirements to meet the performance goals for newly designed Ordinary Standard and Recovery Standard con- crete bridges. Nonstandard bridges require Project-Specific Seismic Design Criteria, in addition to the SDC, to address their nonstandard features. For both standard and nonstandard bridges, Caltrans is also categorizing their inventory in terms of Ordinary Bridges, Recovery Bridges, and Important Bridges. Some states have had issues with terms like Important or Essential, as a bridge is considered important to those that utilize each bridge. Caltrans is using these terms to correlate with loss analysis of an ownerâs infrastructure and the time to reopen the bridge to support lifeline and recovery corridors. The bridge performance is also evaluated using a dual-seismic hazard; for Caltrans SDC they are listed as a Safety Evaluation Earthquake (SEE) for Ordinary Bridges. Both SEE and Functional Evaluation Earthquake (FEE) for Recovery Bridges are summarized in Table 6. Caltrans SDC revisions will also provide updates to the design parameters in Chapter 3 of the SDC and updates to both the analysis methods and displacement ductility demand values in Chapter 4 of the SDC. The adjustments to the displacement ductility demand values are revised to limit the bridge displacements beyond the initial yielding point of the ERE, specifically if a recovery standard bridge is being designed. The revisions to their SDC is an example of how PBSD is being gradually introduced as a better method of dealing with the hazards, soilâstructure interaction, analysis tools, methodologies, material properties, damage states, performance, and loss. Similar revisions are being made to Seismic Design Specifications of Highway Bridges, as detailed in Japan Road Association (JRA) revisions in 2012. A synopsis of the revisions is provided in Kuwabara et al. (2013). The JRA specifications apply to Japanese road bridges and consist of five parts: Part I, Common; Part II, Steel Bridges; Part III, Concrete Bridges; Part IV, Substruc- tures; and Part V, Seismic Design. The revisions are based on improvements in terms of safety,

28 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design serviceability, and durability of bridges. Based on those lessons, design earthquake ground motions corresponding to the subduction-type earthquake were revised, and the requirements for easy and secure maintenance (inspection and repair works) for the bridges were clearly specified. JRA has clarified their performance of ERE conventionally reinforced columns for a dual-level (SPL 2 and SPL 3) seismic performance evaluation, as summarized in Table 7. The JRA 2012 revisions also address connection failures between reinforced concrete steel piles and the pile-supported spread footing to improve structural detailing and performance at the head of the piles. This is similar to research performed by the University of Washington, see Stephens et al. (2015) and Stephens et al. (2016) for both Caltrans and Washington State DOT, respectively, to evaluate capacity protecting this region and even considering the development of plastic hinges at these locations for combined hazard events or large lateral spreading and liquefaction occurrences. Caltrans also funded a study by Saini and Saiidi (2014) to address probabilistic seismic design of bridge columns using a probabilistic damage control approach and reliability analysis. Source: Caltrans. BRIDGE CATEGORY SEISMIC HAZARD EVALUATION LEVEL POST EARTHQUAKE DAMAGE STATE EXPECTED POST EARTHQUAKE SERVICE LEVEL Table 6. Caltrans draft proposed seismic design bridge performance criteria. SPL2 SPL3 Note: SPL1: Fully operational is required. Limit state of bridge is serviceability limit state. Negligible structural damage and nonstructural damage are allowed. Table 7. Seismic performance of bridge and limit states of conventionally reinforced concrete bridge column.

Literature Review and Synthesis 29 The probabilistic damage control approach uses the extent of lateral displacement nonlinearity defined by Damage Index (DI) to measure the performance of bridge columns. DI is a measure of damage from the lower measure of zero damage to the ultimate measure of a collapse mecha- nism for an element that has been subjected to base excitations. The performance objective was defined based on predefined apparent Damage States (DS), and the DS were correlated to DIs based on a previous study at the University of Nevada, Reno (Figure 13) (Vosooghi and Saiidi 2010). A statistical analysis of the demand damage index (DIL) was performed to develop fragility curves (load model) and to determine the reliability index for each DS. The results of the reliability analyses were analyzed, and a direct probabilistic damage control approach was developed to calibrate design DI to obtain a desired reliability index against failure. The calculated reliability indices and fragility curves showed that the proposed method could be effectively used in seismic design of new bridges, as well as in seismic assessment of existing bridges. The DS and DI are summarized with performance levels defined by Caltrans in Table 8, which shows the correlation between DS and DI. Figure 14 shows a fragility curve using lognormal distribution. Figure 15 shows both the fragility curves (upper two graphs) and reliability indices (lower two graphs) for four column bents (FCBs), with 4-foot diameter columns that are 30 feet in length in Site D for both the 1000 year and 2500 year seismic events. Note: O-ST = ordinary standard bridge, O-NST = ordinary nonstandard bridge, Rec. = recovery bridge, Imp. = important bridge, and NA = not applicable. Damage State (DS) Service to Public Service to Emergency Emergency Repair Design Damage Index (DI) Earthquake Levels (Years) Table 8. Design performance levels. DI P (D I { D S) Figure 13. Correlation between DS and DI.

30 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design Figure 14. Fragility curve. 100% 80% 60% 40% 20% 0% 0.00 0.20 0.40 0.60 0.80 1.00 P (D I L ) DIL 4.0 3.0 2.0 1.0 0.0 R el ia bi lit y In de x | D S DS3 DS4 DS5 DS6 Damage State (DS) 6.0 5.0 4.0 3.0 2.0 1.0 0.0 R el ia bi lit y In de x | D S DS3 DS4 DS5 DS6 Damage State (DS) (a) (b) (d)(c) 0.00 0.20 0.40 0.60 0.80 1.00 DIL 100% 80% 60% 40% 20% 0% P (D I L ) Figure 15. Fragility curves and reliability indices for FCBs with 4-foot columns in Site D. The Oregon DOT The Oregon DOT is developing a global plan for addressing resiliency in order to improve recovery for the next Cascadia Earthquake and Tsunami, using PBSD in terms of applying applicable hazards, identifying critical services, developing a comprehensive assessment of structures and systems, and updating public policies. The resilience goals are similar to those discussed at the beginning of this chapter, with the following statement: Oregon citizens will not only be protected from life-threatening physical harm, but because of risk reduction measures and pre-disaster planning, communities will recover more quickly and with less continuing vulnerability following a Cascadia subduction zone earthquake and tsunami.

Literature Review and Synthesis 31 Research has shown that the next great (magnitude 9.0) Cascadia subduction zone earth- quake is pending, as shown in Figure 16. This comparison of historical subduction zone earthquakes in northern California, Oregon, and Washington covers 10000 years of seismic history. The evidence of a pending event has made decision makers and the public take notice and put forth resources to develop strategies revolving around PBSD. Oregonâs performance-based features are modified from NCHRP Synthesis 440 to account for a third hazard condition: Cascadia Subduction Zone Earthquake (CSZE) in Oregon DOTâs Bridge Design and Drafting ManualâSection 1, Design (Oregon DOT 2016a; see also Oregon DOT 2016b). Design of new bridges on and west of US 97 references two levels of perfor- mance criteria: life safety and operational. Design of new bridges east of US 97 requires life safety criteria only. Seismic design criteria for life safety and operational criteria are described as follows. â¢ âLife Safetyâ Criteria: Design all bridges for a 1,000-year return period earthquake (7 percent prob- ability of exceedance in 75 years) to meet the âLife Safetyâ criteria using the 2014 USGS Hazard Maps. The probabilistic hazard maps for an average return period of 1,000 years and 500 years are available at ODOT Bridge Section website, but not available on USGS website. To satisfy the âLife Safetyâ criteria, use Response Modification Factors from LRFD Table 3.10.7.1-1 using an importance category of âother.â â¢ âOperationalâ Criteria: Design all bridges on and west of US 97 to remain âOperationalâ after a full rupture of Cascadia Subduction Zone Earthquake (CSZE). The full-rupture CSZE hazard maps are available at the ODOT Bridge Section website. To satisfy the âOperationalâ criteria, use Response Modification Factors from LRFD Table 3.10.7.1-1 using an importance category of âessential.â When requested in writing by a local agency, the âOperationalâ criteria for local bridges may be waived. The CSZE is a deterministic event, and a deterministic design response spectrum must be generated. To allow for consistency and efficiency in design for the CSZE, an application for generating the design response spectra has been developed by Portland State University (Nako et al. 2009). AASHTO guide specifications values for Table 3.4.2.3-1 are modified into two tables for (1) values of Site Factor, Fpga, at zero-period on the acceleration spectrum and (2) values of Site Factor, Fa, for short-period range of acceleration spectrum. Table 3.4.2.3-2 is replaced with values of Site Factor, Fv, for long-period range of acceleration spectrum. For seismic retrofit projects, the lower level ground motion is modified to be the CSZE with full rupture, as seen in Table 9. Performance levels, including performance level zero (PL0), are specified based on bridge importance and the anticipated service life (ASL) category required. Source: OSSPAC (2013). Figure 16. Cascadia earthquake timeline.

32 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design The South Carolina DOT South Carolina Department of Transportation (South Carolina DOT) has updated its geo- technical design manual (South Carolina DOT 2019). Chapters 12, 13, and 14 for geo technical seismic analysis, hazard, and design, respectively, have been updated to current practices and research, including incorporation of PBSD hazard prediction. South Carolina DOT is also updating their site coefficients to be more appropriate for South Carolinaâs geologic and seismic conditions; see Andrus et al. (2014). Note that with the revisions, South Carolina DOT issued a design memorandum in November 2015 that revised the substructure unit quantitative damage criteria (maximum ductility demand) table (Table 7.1 of the SCDOT Seismic Design Specifications for Highway Bridges). See Table 10. The Utah DOT The Utah DOT and Brigham Young University (see Franke et al. 2014a, 2014b, 2015a, 2015b, 2015c, 2016) are researching the ability for engineers to apply the benefits of the full performance- based probabilistic earthquake analysis without requiring specialized software, training, or education. There is an emphasis on differences between deterministic and performance-based procedures for assessing liquefaction hazards and how the output can vary significantly with these two methodologies, especially in areas of low seismicity. Guidance is provided regarding when to use each of the two methodologies and how to bind the analysis effort. Additionally, a simplified performance-based procedure for assessment of liquefaction triggering using liquefaction loading maps was developed with this research. The components of this tool, as well as step-by-step procedures for the liquefaction initiation and lateral spread displacement models, are provided. The tool incorporates the simplified performance-based procedures determined with this research. National Highway Institute Marsh et al. (2014) referenced a manual for the National Highway Instituteâs training course for engineers to understand displacement-based LRFD seismic analysis and design of bridges, which is offered through state agencies and open to industry engineers and geotechnical engi- neers. This course helps designers understand the principles behind both force-based AASHTO (AASHTO 2014) and displacement-based AASHTO (AASHTO 2011) methodologies, including a deeper understanding of what performance means in a seismic event. Other similar courses are also being offered to industry and are improving the understanding of practicing engineers. Federal Emergency Management Agency The Federal Emergency Management Agency (FEMA) has developed a series of design guidelines for seismic performance assessment of buildings and three of the five documents EARTHQUAKE GROUND MOTION BRIDGE IMPORTANCE and SERVICE LIFE CATEGORY Table 9. Modifications to minimum performance levels for retrofitted bridges.

Literature Review and Synthesis 33 are referenced in FEMA (2012a, 2012b, 2012c). A step-by-step methodology and explanation of implementation are provided for an intensity-based assessment and for a time-based assess- ment. The process of identifying and developing appropriate fragility curves is demonstrated. A software program called Performance Assessment Calculation Tool has also been developed with a user manual that is included in the FEMA documents to help engineers apply PBSD to the building industry. Japan Road Association The Japan Road Association (JRA) Design Specifications have been revised based on the performance-based design code concept in response to the international harmonization of design codes and the flexible employment of new structures and new construction methods. Figure 17 shows the code structure for seismic design using the JRA Design Specifications. The performance matrix is based on a two-level ground motion (Earthquakes 1 and 2), with the first one based on an interpolate-type earthquake and magnitude of around 8, and the second one with a magnitude of around 7 with a short distance to the structure. Kuwabara et al. (2013) outlined the incremental revisions from the JRA Design Specif i- cations between 2002 and 2012. These revisions include, but are not limited to, the ductility design method of reinforced concrete bridges, plastic hinge length equation, evaluation of hollow columns, and the introduction of high-strength steel reinforcement. Following the 2016 earthquake in Kumamoto, Japan, a new version of the JRA Design Specifications is in the works. Note: Analysis for FEE is not required for OC III bridges. Source: South Carolina DOT (2015). Design Earthquake Operational Classification (OC)Bridge Systems Table 10. South Carolina DOT substructure unit quantitative damage criteria (maximum ductility demand ld).

34 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design Identification of Knowledge Gaps The resources to develop guide specifications for PBSD are improving with examples such as the upcoming Seismic Design Criteria, Version 2 from Caltrans, which will address aspects of PBSD and the building industryâs efforts to develop practices in PBSD and tools for engineers and owners to collaborate on solutions based on performance criteria and expectations. There is still a perception that the bridge industry could better predict likely performance in large, damaging earthquakes than is being done at the present, and there are still gaps in that knowledge base that need to be closed. Most of the knowledge gaps listed in Marsh and Stringer (2013) are still applicable today; see Table 11. The technology readiness levels represent what has been developed and used; what research is done, ongoing, and being discussed; and what only exists in concept. Knowledge gaps certainly exist in all facets of PBSD; however, other key knowledge gaps beyond those listed in NCHRP Synthesis 440 (Marsh and Stringer 2013) that should be closed in order to improve the implementation of PBSD are covered. Objectives of Codes Mandated Specifications Overall Goals Functional Requirements (Basic Requirements) Performance Requirement Level Verification Methods and Acceptable Solutions Can be Modified or May be Selected with Necessary Verifications Importance, Loads, Design Ground Motion, Limit States Principles of Performance Verification Verifications of Seismic Performances (Static and Dynamic Verifications) Evaluation of Limit States of Members (RC and Steel Columns, Bearings, Foundations and Superstructure) Unseating Prevention Systems Principles of Seismic Design Figure 17. Code structure for seismic design using JRA design specifications. TRL Description 0-25 25-50 50-75 75-100 1 PBSD concept exists 2 Seismic hazard deployable 3 Structural analysis deployable 4 Damage analysis deployable 5 Loss analysis deployable 6 Owners willing and skilled in PBSD 7 Design guidelines 8 Demonstration projects 9 Proven effectiveness in earthquake Technology Readiness Level (TRL) % of Development Complete Table 11. Technology readiness levels for PBSD.

Literature Review and Synthesis 35 Gaps related to structural analysis can include minimum and expected properties for reinforcing greater than Grade 80, stainless steel, and other materials that can improve serviceability and in some conditions performance. Oregon DOT has been using stainless steel in their bridges located along the coastline and other highly corrosive environments to extend the service life of the bridge; however, many of these locations are also prone to large CSZE and the use of these materials in earthquake resisting elements is still being developed. In the State of Washingtonâs resiliency plan, outlined in Washington State Emergency Management CouncilâSeismic Safety Committee (2012), what is missing is a link between damage levels and return to service. This is a knowledge gap given what we know structurally and what this report is suggesting as a desired goal for post-earthquake recovery. Gaps related to decision makers can include bridge collapse. It is not intended that the PBSD guide specifications will address tsunami events, but the JRA specifications do address tsunami as well as landslide effects. Figures 18 and 19 are examples of these other types of failure systems and show the collapse of bridges caused by effects other than ground motion (Kuwabara et al. 2013). The decision to combine these types of effects with a seismic hazard, even combining liquefaction, down drag, and lateral spreading effects, needs additional clarification and is currently left up to the owner to assess implications of probability, safety, and cost ramifications. Liang and Lee (2013) summarized that in order to update the extreme event design limit states in the AASHTO 2014, combinations of all nonextreme and extreme loads need to be formulated on the same probability-based platform. Accounting for more than one-time variable load creates a complex situation, in which all of the possible load combinations, even many that are not needed for the purpose of bridge design, have to be determined. A formulation of a criterion to determine if a specific term is necessary to be included or rejected is described, and a comparison of the value of a given failure probability to the total pre-set permissible design failure probability can be chosen as this criterion. Figure 18. Collapse of bridge due to landslide. (Note: Reprinted courtesy of the National Institute of Standards and Technology, U.S. Department of Commerce. Not copyrightable in the United States). Source: Kuwabara et al. (2013).

36 Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design While the seismic hazard definition was once thought to be relatively well understood, there is a growing knowledge gap related to the effect of rotation angle on intensity of ground motions and how the use of a geometric mean of the motions, or other methods of including the effect of rotation angle (RotDxx), should be incorporated into seismic design. This issue is not specific to PBSD; like all seismic design methods, PBSD is reliant on a full understanding of the hazard definition for proper implementation. The knowledge gaps identified in NCHRP Synthesis 440 are still applicable. Many of these knowledge gaps will become evident to both engineers and decision makers as the PBSD guidelines are developed. Overall, the baseline information to develop PBSD guide specifica- tions are in place. Industryâs end goal of understanding the relationship between risk-based decision making and design decisions and methodologies to meet performance goals is going to be an iterative process. Figure 19. Collapse of bridge due to tsunami. (Note: Reprinted courtesy of the National Institute of Standards and Technology, U.S. Department of Commerce. Not copyrightable in the United States). Source: Kuwabara et al. (2013).

Performance-based seismic design (PBSD) for infrastructure in the United States is a developing field, with new research, design, and repair technologies; definitions; and methodologies being advanced every year.

The TRB National Cooperative Highway Research Program's NCHRP Research Report 949: Proposed AASHTO Guidelines for Performance-Based Seismic Bridge Design presents a methodology to analyze and determine the seismic capacity requirements of bridge elements expressed in terms of service and damage levels of bridges under a seismic hazard. The methodology is presented as proposed AASHTO guidelines for performance-based seismic bridge design with ground motion maps and detailed design examples illustrating the application of the proposed guidelines and maps.

Supplemental materials to the report include an Appendix A - SDOF Column Investigation Sample Calculations and Results and Appendix B - Hazard Comparison.

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Research Methods

Chapter 2 introduction.

Maybe you have already gained some experience in doing research, for example in your bachelor studies, or as part of your work.

The challenge in conducting academic research at masters level, is that it is multi-faceted.

The types of activities are:

Finding and reviewing literature on your research topic;
Designing a research project that will answer your research questions;
Collecting relevant data from one or more sources;
Analyzing the data, statistically or otherwise, and
Writing up and presenting your findings.

Some researchers are strong on some parts but weak on others.

We do not require perfection. But we do require high quality.

Going through all stages of the research project, with the guidance of your supervisor, is a learning process.

The journey is hard at times, but in the end your thesis is considered an academic publication, and we want you to be proud of what you have achieved!

Probably the biggest challenge is, where to begin?

What will be your topic?
And once you have selected a topic, what are the questions that you want to answer, and how?

In the first chapter of the book, you will find several views on the nature and scope of business research.

Since a study in business administration derives its relevance from its application to real-life situations, an MBA typically falls in the grey area between applied research and basic research.

The focus of applied research is on finding solutions to problems, and on improving (y)our understanding of existing theories of management.

Applied research that makes use of existing theories, often leads to amendments or refinements of these theories. That is, the applied research feeds back to basic research.

In the early stages of your research, you will feel like you are running around in circles.

You start with an idea for a research topic. Then, after reading literature on the topic, you will revise or refine your idea. And start reading again with a clearer focus ...

A thesis research/project typically consists of two main stages.

The first stage is the research proposal .

Once the research proposal has been approved, you can start with the data collection, analysis and write-up (including conclusions and recommendations).

Stage 1, the research proposal consists of he first three chapters of the commonly used five-chapter structure :

Chapter 1: Introduction
An introduction to the topic.
The research questions that you want to answer (and/or hypotheses that you want to test).
A note on why the research is of academic and/or professional relevance.
Chapter 2: Literature
A review of relevant literature on the topic.
Chapter 3: Methodology

The methodology is at the core of your research. Here, you define how you are going to do the research. What data will be collected, and how?

Your data should allow you to answer your research questions. In the research proposal, you will also provide answers to the questions when and how much . Is it feasible to conduct the research within the given time-frame (say, 3-6 months for a typical master thesis)? And do you have the resources to collect and analyze the data?

In stage 2 you collect and analyze the data, and write the conclusions.

Chapter 4: Data Analysis and Findings
Chapter 5: Summary, Conclusions and Recommendations

This video gives a nice overview of the elements of writing a thesis.

Chapter 2 Synopsis: The Organization of a Research Article

This chapter outlined the organizational structure of a research article, which is commonly referred to as IMRD/C. Each of those sections has specific goals and strategies that writers can use to optimize their ability to communicate research successfully. One way to envision the relationships between each of the IMRD/C sections is with the image of an hourglass.

Visual depiction of the sections of a research article in the shape of an hourglass. The beginning (introduction) and end (discussion/conclusion) sections are the broader parts of the hourglass while the Methods and Results constitute the more specific middle sections.

The hourglass demonstrates the generality of the Introduction and the Discussion/Conclusion sections in contrast to the more specific nature of the middle two sections — Methods and Results. In the next four chapters, you’ll learn about each of those sections, respectively.

Key Takeaways

Each research article will contain distinct sections that tend to be rather consistent across disciplines, but could contain some individual variation within your discipline or even academic journal. The argument in an overall research article moves from being general to specific then back to more general again.

Preparing to Publish Copyright © 2023 by Sarah Huffman; Elena Cotos; and Kimberly Becker is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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COMMENTS

PDF CHAPTER 2: Literature Review
CHAPTER 2: Literature Review. This chapter will explore the literature that is relevant to understanding the development of, and interpreting the results of this convergent study. The first two parts of this review of the literature will describe two types of research: research on teaching and research on teachers' conceptions.
PDF CHAPTER II: LITERATURE REVIEW
Male workforce participation has been on a continuously downward trend as well, since the 1960s decreasing from 84% participation in 1960 to 71% in 2008 with projections. showing a continuing decrease (U.S. Census Bureau, 2008). Men 25-54 years of age have a. workforce participation rate of 89.3% (U.S. Census, 2008).
(PDF) CHAPTER 2 REVIEW OF RELATED LITERATURE
INTRODUCTION. A review of literature is a classification and evaluation of what accredited scholars and. researchers have written on a topic, organized according to a guiding concept such as a ...
PDF Chapter 2: The Literature Review Preparing to Write
to refine your initial research question, and to identify gaps. For your committee, the literature review also demonstrates that you are knowledgeable about related research and scholarly traditions in your field. Preparing to Write . The literature review is more than just a list of previous research papers in the field. If you think
PDF CHAPTER 2 Introduction & Literature Review A distribute
CHAPTER 19 2 Introduction & Literature Review. A . common misconception about phenomenological research is that the researcher begins the research without reviewing lit-erature. Concerns about literature reviews span several topics with regard to the integrity of method. For instance, there is a risk of
PDF CHAPTER 2 LITERATURE REVIEW 2.1 INTRODUCTION
33. CHAPTER 2. LITERATURE REVIEW. 2.1 INTRODUCTION. In Chapter 1, the background and problem, purpose, objectives, research approach and significance of the study were described. As part of the discussion of the background to the problem, the researcher referred to literature regarding the rehabilitation of PLWSC, the impact of disability as a ...
PDF A Complete Dissertation
Chapter 1. A Complete Dissertation 7 purpose, or it does not stand alone as a document. Chapter 2: Literature Review This chapter situates the study in the con-text of previous research and scholarly mate - rial pertaining to the topic, presents a critical synthesis of empirical literature according to relevant themes or variables, justifies how
PDF What Is a Literature Review?
Slide 1. Mainly Chapter 2 of a doctoral dissertation. An exhaustive exposition of the literature sources (especially methods and findings) that a researcher consulted in order to understand and investigate his or her research problem. Built from the annotated bibliography assignment (#4) from the Methods of Inquiry (MOI) course.
How to Write a Literature Review
Examples of literature reviews. Step 1 - Search for relevant literature. Step 2 - Evaluate and select sources. Step 3 - Identify themes, debates, and gaps. Step 4 - Outline your literature review's structure. Step 5 - Write your literature review.
PDF Chapter 2 Literature Review
13. Chapter 2 Literature Review. 2.1 INTRODUCTION. The purpose of this literature review is to provide the reader with a general overview of environmental modeling as it pertains to GIS. Recently, this concept has become a popular subject in many science and engineering fields. Within the past five years, many conferences have been hosted which ...
Research Paper, Chapter 2 Example 6 pages
Chapter 2 Review Of Related Literature This chapter will provide related literature that the researcher deemed relevant to further strengthen the importance of our study.. What is E-Learning/Online learning E-learning is exclusively defined as "instructional content or learning experiences delivered or enabled by electronic technology" (Servage, 2005:306).
(PDF) Chapter 2 Review of Related Literature
study. Chapter 2 is divided into 4 parts, namely : (1) E-. Learning, (2) Conventional classroom learning, (3) English. Achievement; and (4) Synthesis. The first topic, E-Learning, is a discussion ...
CHAPTER 2 REVIEW OF RELATED LITERATURE AND STUDIES
A Critical Paper: The Miseducation of the Filipinos. Ezekiel Succor. Download Free PDF. View PDF. CHAPTER 2 REVIEW OF RELATED LITERATURE AND STUDIES This chapter presents the related literature and studies after the thorough and in-depth search done by the researchers.
Chapter 2 Research Papers: Introduction and Literature Review
Section2 discusses the compositional and morphological features of layers, which can be investigated using various analytical and mineralogical techniques. Section3 outlines the various substrates (marble, limestone, wall and easel paintings, mortars, written materials, and glass) described in the literature.
Dissertation & Thesis Outline
Example: Mix of different constructions Chapter 2 contains a review of the relevant literature that I used for the purposes of this paper. The methods used in the study are then described in Chapter 3, after which the results are presented and discussed in Chapter 4. Sample verbs for variation in your chapter outline
Chapter 2. Research Design
Chapter 2. Research Design Getting Started. When I teach undergraduates qualitative research methods, the final product of the course is a "research proposal" that incorporates all they have learned and enlists the knowledge they have learned about qualitative research methods in an original design that addresses a particular research question.
Chapter-II
This chapter presents the conceptual and research literature which were found by the researchers to significantly support and strengthen the study. Conceptual Literature The researchers provide a review of literature in three areas related to the present studies: the digital modular; the modular distance learning; and the new normal education.
Chapter 2
The research team made an additional effort to perform a practice review of bridge designs, research, and other design industries, specifically in the building industry. The building industry has been developing PBSD for more than 20 years, and some of their developments are appli- cable to bridge design.
Chapter II
CHAPTER 2 REVIEW OF RELATED LITERATURE INTRODUCTION. A review of literature is a classification and evaluation of what accredited scholars and researchers have written on a topic, organized according to a guiding concept such as a research objective, thesis or the problem / issue to be addressed. It is the scholarly core of the dissertation.
Chapter 2 Introduction
Chapter 2 Introduction. Chapter 2. Introduction. Maybe you have already gained some experience in doing research, for example in your bachelor studies, or as part of your work. The challenge in conducting academic research at masters level, is that it is multi-faceted. The types of activities are: Writing up and presenting your findings.
Chapter 2 Synopsis: The Organization of a Research Article
Chapter 2 Synopsis: The Organization of a Research Article. This chapter outlined the organizational structure of a research article, which is commonly referred to as IMRD/C. Each of those sections has specific goals and strategies that writers can use to optimize their ability to communicate research successfully. One way to envision the ...
Writing a Research Paper Introduction
Table of contents. Step 1: Introduce your topic. Step 2: Describe the background. Step 3: Establish your research problem. Step 4: Specify your objective (s) Step 5: Map out your paper. Research paper introduction examples. Frequently asked questions about the research paper introduction.
A Quantitative Study of the Impact of Social Media Reviews on Brand
the 2010 Pew Research report, the millennial is defined as having been born between 1977 and 1992 (Norén, L. 2011). The reviewers of the millennial generation have a high power of