AN INVESTIGATION of HUMAN INDUCED VIBRATIONS on CLEMSON MEMORIAL STADIUM Benjamin Morris Clemson University, [email protected]
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Clemson University TigerPrints All Theses Theses 5-2009 AN INVESTIGATION OF HUMAN INDUCED VIBRATIONS ON CLEMSON MEMORIAL STADIUM Benjamin Morris Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_theses Part of the Civil Engineering Commons Recommended Citation Morris, Benjamin, "AN INVESTIGATION OF HUMAN INDUCED VIBRATIONS ON CLEMSON MEMORIAL STADIUM" (2009). All Theses. 577. https://tigerprints.clemson.edu/all_theses/577 This Thesis is brought to you for free and open access by the Theses at TigerPrints. It has been accepted for inclusion in All Theses by an authorized administrator of TigerPrints. For more information, please contact [email protected]. AN INVESTIGATION OF HUMAN INDUCED VIBRATIONS ON CLEMSON MEMORIAL STADIUM A Thesis Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Master of Science Civil Engineering by Benjamin Scott Morris May 2009 Accepted by: Dr. Bryant G. Nielson, Committee Chair Dr. Scott D. Schiff, Committee Chair Mr. Stephen F. Csernak, P.E. ABSTRACT Human induced stadium vibrations have become of increasing concern to design engineers and facility managers as more energetic crowds and increasingly efficient structures have increased the likelihood of serviceability issues. The “in-time” bouncing of spectators due to music has caused one such issue in the south upper deck of Clemson University’s Memorial Stadium. To gain an understanding of the severity of vibrations in Memorial Stadium, a combination of experimental and analytical modeling is utilized. Data collected by an array of accelerometers installed on a main post tensioned precast cantilever girder provides a season and a half of response histories in various states of occupancy and excitation. Utilizing data obtained due to ambient vibrations, the Enhanced Frequency Domain Decomposition (EFDD) methodology is used to extract modal properties including frequencies, mode shapes, and modal damping at various levels of occupancy. A finite element model of the girder, initially created utilizing structural drawings and design level properties for an empty stadium, is calibrated using the dynamic characteristics of the empty stadium. This process is carried out considering the first three modes. The calibrated model can be used to analyze various crowd loading scenarios including passive, active, and harmonic loadings with known responses and unknown responses. ii Comparing the results of the FE model to relevant data sets shows the EFDD method in combination with ambient vibration data to be an effective means of analyzing a large structure that would have otherwise been difficult to analyze by traditional forced vibration techniques. The calibrated model provides a benchmark for future health monitoring or performance studies. iii DEDICATION I dedicate this thesis to my parents, Scott and Gayle Morris, my brother, Jeff, and rest of my Clemson family for their unending guidance and support. iv ACKNOWLEDGEMENTS I would first like to thank my professors, Dr. Bryant Nielson, Dr. Scott Schiff, and Prof. Stephen Csernak. This project would not have been possible without their help and guidance. I would like to thank the Clemson University Athletic Department for funding this project. A special thanks is in order to Gary Wade of Athletic Facilities, he truly had all the keys to my success. I want to thank John Elsea and Daniel Metz for all of their help throughout the project, most notably for their assistance in installing the instrumentation in the stadium. Additional thanks goes to Dr. Samit Ray Chaudhuri of the University of California, Irvine, for his assistance in the implementation of the Frequency Domain Decomposition Method. v TABLE OF CONTENTS Page ABSTRACT ....................................................................................................................ii DEDICATION ............................................................................................................... iv ACKNOWLEDGEMENTS ............................................................................................. v LIST OF TABLES .......................................................................................................viii LIST OF FIGURES ........................................................................................................ ix CHAPTER ONE INTRODUCTION ........................................................................................................... 1 1.1: Project Description ....................................................................................... 2 1.2: Scope and Objectives.................................................................................... 3 1.3: Outline of Thesis .......................................................................................... 5 CHAPTER TWO LITERATURE REVIEW ................................................................................................ 8 2.1: Occurrences of Human Induced Vibrations ................................................... 8 2.2: Vibration Monitoring .................................................................................. 12 2.3: System Identification Techniques ............................................................... 15 2.4: Finite Element Model Optimization ............................................................ 18 CHAPTER THREE FIELD STUDY OF CLEMSON MEMORIAL STADIUM ........................................... 27 3.1: Stadium Geometry and Construction Methods ............................................ 27 3.2: Instrumentation Installation ........................................................................ 33 3.3: In-situ data collection ................................................................................. 40 CHAPTER FOUR DATA PROCESSING................................................................................................... 43 4.1: Girder Finite Element Model Creation ........................................................ 43 4.2: Modal Parameter Extraction ....................................................................... 56 4.3: Finite Element Model Updating .................................................................. 77 CHAPTER FIVE UPDATED MODEL EVALUATION ......................................................................... 101 5.1: Human induced rhythmic loading estimates .............................................. 102 5.2: Full Occupancy Rhythmic Loading .......................................................... 104 5.2: Partial Occupancy Rhythmic Loading ....................................................... 109 CHAPTER SIX CONCLUSIONS ......................................................................................................... 116 vi 6.1: Recommendations for Clemson Memorial Stadium .................................. 118 6.2: Future Work ............................................................................................. 122 APPENDICES ............................................................................................................ 124 APPENDIX “A” MATLAB SCRIPTS ....................................................................................... 125 APPENDIX “B” SAP S2K FILES .............................................................................................. 144 REFERENCES............................................................................................................ 170 vii LIST OF TABLES Table Page 4.1 Natural Frequency Identification Comparison ...........................................61 4.2 FDD Verification Mode Shape Extraction Results ....................................64 4.3 Target Parameters and Frequencies for Updating Algorithm Verification .......................................................................87 4.4 Analytical Updating Results—Three Frequencies, Seven Parameters ........88 4.5 Analytical Updating Results—Six Frequencies, Seven Parameters ............88 4.6 FEM Updating Results—Parameters .........................................................91 4.7 FEM Updating Results—Frequencies .......................................................91 5.1 Perceived Percent Occupancy of Crowd Based on Figure 5.6 .................. 110 viii LIST OF FIGURES Figure Page 3.1 Plan View of Memorial Stadium in 2008 ...................................................28 3.2 Typical girder types (a) South Upper Deck (b)North Upper Deck .............29 3.3 Profile of Typical Girder ...........................................................................30 3.4 Cross-Sectional View of Double Girder ....................................................31 3.5 Bottom Precast Handrail ...........................................................................32 3.6 Girder at Portal .........................................................................................32 3.7 Top Precast Handrail .................................................................................32 3.8 Instrument Layout .....................................................................................34 4.1 Girder Instrumentation ..............................................................................45 4.2 Construction Joint Relative Tilt .................................................................45 4.3 Stadium Section (Coleman 1980) ..............................................................46 4.4 Girder Bearing Detail (Coleman 1980) ......................................................47