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SUSPENDED SCOREBOARD SEISMIC LATERAL RESPONSE

PROJECT ID: CEEN-2019CPST-001

by

Franco & Co. Madison Hilario Franco Huacoto Andrew Barfield

A Capstone Project Final Report

Submitted to

Trevor Hawkes Vector Structural Engineering

Department of Civil and Environmental Engineering Brigham Young University

April 16, 2020

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Executive Summary PROJECT TITLE: SUSPENDED SCOREBOARD SEISMIC LATERAL RESPONSE PROJECT ID: CEEn-2018CPST-0.1 PROJECT SPONSOR: Vector Structural Engineering TEAM NAME: Franco & Co. Our project relates to large suspended scoreboards, sometimes referred to as jumbotrons, and their behavior during seismic events. An important design consideration is whether a seismic event could cause the suspended structure to collide with surrounding structure or other suspended items such as speakers. The dynamic behavior of such large suspended structures is not specifically addressed in the building codes or other standards we use. Our purpose is to quantify and better understand the risk of collision. This will be accomplished by developing a model and system of equations to determine the maximum horizontal movement, as well as a user-friendly approach to solve this problem in the future without expensive software, without time-consuming analysis, and without requiring excessive input related to the supporting building structure. This project is to be completed before April 15, 2020.

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Table of Contents

Executive Summary 1 Table of Contents 2 Introduction 3 Design, Analysis, and Results 3 Lessons Learned 5 Conclusion 5 Recommendations 6 Acknowledgments 6

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List of Figures

Figure 1: 3D Analysis 8 Figure 2: 2D Analysis 9

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Introduction The goal for our project was to develop a model or system of equations to accurately predict the horizontal displacement of a suspended scoreboard in a seismic event. This included exploring different modeling softwares as well as research to determine the most effective way to model a suspended scoreboard. After the conclusion of the research phase, the bulk of project time was spent building a suspended scoreboard model to be analyzed and obtaining output displacement values.

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Design, Analysis & Results The beginning stages of our work required mostly research. We began by reviewing the behavior of a pendulum and a swinging bar, and then researching software that would best model the analysis we were hoping to run. Our research indicated that we could use one of two different softwares for our analysis: SAP 2000 and Perform 3D. Perform 3D could most accurately model the reactions that we need to analyze, however the software was unavailable due to cost and availability. After guidance from our faculty advisor, Dr. Fonseca, we determined that we could accurately model our reaction in SAP 2000 using the Modal Time History Analysis function. We also searched for other research done on this subject. However, we found that there is virtually no academic research previously done on this subject. The research we did find was outdated and minimally applicable. We began our modeling and analysis by creating a 3D model of the scoreboard hanging from a 3D frame with a 20-kip load applied to each of the bottom corners of the box (Figure 1). We then ran a Modal Time History Analysis. We didn’t fully understand the input values for the analysis, so our first run produced displacement values of over 12 feet; which is obviously unreasonable. We met with our faculty advisor to better understand the inputs in order to create a more accurate analysis. Following this, our model started to produce more accurate displacement values, however, because of the complexity of the model, there were too many variables and complications. This made it difficult to create a reasonable, simple and accurate equation.

Figure 1: 3D Analysis

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We talked with our sponsor and brainstormed other ideas of how to model and analyze the situation. We decided to change the model style and the type of analysis. We changed the model to a 2D block hanging from pinned cables (Figure 2). We applied 2 inches of displacement at the pinned joints and created a load pattern that applied this displacement as a sine function for 5 cycles. We then created a time history function to run the special load case. This produced displacement at the pinned joints of the cable but did not displace the box. During this time, COVID-19 interrupted normal class and meeting schedules. Because of the stay at home order, we were unable to meet to work on the project and SAP2000 does not allow for collaboration of a single file. We were able to work individually on the file through BYU Citrix and pass along the file as we worked on it one by one. This significantly slowed down the process of us creating an accurate model, and we found that the program would crash often because of the strain on the Citrix server.

Figure 2: 2D Analysis

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Lessons Learned We gained valuable experience using SAP2000, which will translate to other finite element analysis softwares that we are likely to use throughout our careers. Having never been in a seismic class, we learned about how the frequency and amplitude of an earthquake can affect a structure and its natural frequency. We also learned the balance between modeling a system completely accurately and modeling the system accurately enough to obtain usable results.

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Conclusions The purpose of this project was to develop a model and accurately predict the horizontal displacement of a suspended scoreboard in a seismic event. To achieve this goal, the team needed to perform research to determine the best approach to the problem. When the model built with SAP 2000 was analyzed, we determined that there were too many variables for the results to be reliable. In addition, some variables would not be readily available in a real-world scenario. We conclude that although some displacement values were produced, this project requires further study and research to be reliable. For example, further analysis using the existing SAP2000 model or a different software.

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Recommendations Based on the results of the project, our recommendation is that an individual who is very familiar with SAP200 should be able to make the final adjustments to our model that would provide the necessary accuracy. Reliable displacement values would then be easily obtainable for a variety of suspended scoreboard conditions.

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Appendix A

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