Structural Responses and Finite Element Modeling of Hakka Tulou Rammed Earth Structures Daniel Stanislawski Thesis submitted to the College of Engineering and Mineral Resources at West Virginia University in partial fulfillment of the requirements for the degree of Master of Science in Civil Engineering Approved by Hota V. S. GangaRao, PhD, Chair Ruifeng Liang, PhD P V. Vijay, PhD Department of Civil and Environmental Engineering Morgantown, West Virginia 2011 Keywords: Rammed Earth, Hakka, Tulou, Field Testing, Finite Element Modeling, LEED Certification, Green Building ABSTRACT Structural Responses and Finite Element Modeling of Hakka Tulou Rammed Earth Structures Daniel Stanislawski Constructed Facilities Center, West Virginia University Hakka Tulous are rammed earth structures that have survived the effects of aging and natural elements upwards of even over a thousand years. These structures have housed the Hakka people of the Fujian Province, China in natural yet modern housing that has provided benefits over newer building materials. The key building material, rammed earth, which is used for the walls of the Hakka Tulou structures, has provided structural stability along with thermal comfort to the respective inhabitants of the Hakka Tulous. Through material testing and analysis this study has examined how the Tulou structures have maintained their structural stability while also providing thermal comfort. Reports of self healing cracks in the rammed earth walls were also analyzed for their validity in this study. The study has found that although the story of the self healing crack cannot be validated, there is reason to believe that with the existence of lime, some type of autogenous healing could occur on a small scale. The study has also found, through the use of nondestructive testing, that both the internal wooden systems (flooring, roof, and column support) and the rammed earth walls, are still structurally sound. Also, rammed earth’s high thermal mass along with the use of sufficient shading has allowed for a delay release of heat energy from the walls of the Tulous, thus providing thermal comfort that can be felt during both night and day temperatures. The Hakka Tulou structures have been found to resist destruction from natural disasters such as strong earthquakes even when more modern construction has not. Through finite element modeling, this study has shown that the high volume of rammed earth used in the construction of the Hakka Tulous helps dissipate lateral force energy into much lower stresses for the rammed earth wall. This absorption of lateral force energy allows the rammed earth structures to survive even the strongest of earthquakes experienced in the region. The Hakka Tulou, if rated by the LEED green building certification program, would earn the highest certification as this rammed earth construction has offered efficient living for hundreds of years. As historic as these rammed earth structures are, they present an environmentally friendly option to structures of the future. i ACKNOWLEDGEMENTS I would like to thank my advisor, Dr. Hota GangaRao, for the support that he has provided not only during the duration of this project, however also throughout my time as a Masters student at West Virginia University. I would also like to thank Dr. Ruifeng Liang for his direct guidance and assistance throughout this project. Without Dr. Liang’s assistance in the project, which includes but is not limited to translating information from Chinese and overseeing project goals, it would have been much more difficult to complete the research. Additionally, I am grateful to Dr. P. Vijay who I initially worked under when coming to WVU. His guidance during field testing assisted in my acquiring of valuable skills that proved necessary for this project. I am also thankful to Mark Skidmore and Dave Dittenber for their advice and assistance during material testing as well as West Virginia University student, Matt Blandford, for his constructive feedback. I would also like to acknowledge the Xiamen University of China as portions of my research reported in this document are based on a field study that was conducted in the summer of 2009 by WVU-CFC in collaborations with the Xiamen University. Additionally, I would like to thank Minoru Ueda for providing his 7-day thermal data for this study as well as the National Science Foundation for its support. Without NSF support I would not have had the opportunity to study Hakka Tulous. Lastly, I would like to thank my family and friends for their support during the duration of this research and during my stay at West Virginia University. ii TABLE OF CONTENTS ABSTRACT .................................................................................................................................... i ACKNOWLEDGEMENTS ......................................................................................................... ii TABLE OF CONTENTS ............................................................................................................ iii LIST OF FIGURES ..................................................................................................................... vi LIST OF TABLES ........................................................................................................................ x CHAPTER 1 INTRODUCTION ........................................................................................... 1 1.1 Background ..................................................................................................................... 1 1.2 Objectives ......................................................................................................................... 2 1.3 Scope ................................................................................................................................ 3 1.4 Organization of Thesis .................................................................................................... 6 CHAPTER 2 LITERATURE REVIEW ............................................................................... 8 CHAPTER 3 MATERIAL CHARACTERIZATION AND STRUCTURAL EVALUATION OF HISTORIC TULOU STRUCTURES ..................................................... 15 3.1 Introduction ................................................................................................................... 15 3.2 Validating Age of Samples ............................................................................................ 16 3.3 Scanning Electron Microscopy and Energy-dispersive X-ray Spectroscopy Analysis of Tulou Rammed Earth Samples................................................................................................ 17 3.4 Material Tests ................................................................................................................ 24 iii 3.4.1 Xiamen University Data ........................................................................................... 26 3.4.2 West Virginia University Data.................................................................................. 34 3.4.3 Conclusions ............................................................................................................... 46 3.5 NDT, Ultrasonic and Rebound Hammer Tests ............................................................ 51 3.5.1 Ultrasonic Test .......................................................................................................... 52 3.5.2 Rebound Hammer Test ............................................................................................. 55 3.5.3 Conclusions ............................................................................................................... 56 3.6 Load Testing on Floor and Roof Truss Systems .......................................................... 57 3.6.1 Roof Truss System .................................................................................................... 59 3.6.2 Floor System ............................................................................................................. 67 3.6.3 Conclusions ............................................................................................................... 73 CHAPTER 4 FE MODELING EVALUATION ................................................................ 77 4.1 Introduction ................................................................................................................... 77 4.2 Rule of Mixtures ............................................................................................................ 79 4.3 Self Healing Crack? ...................................................................................................... 84 4.3.1 Understanding Why the Crack Developed ............................................................... 84 4.3.2 Possible Mechanisms of Self Healing....................................................................... 93 4.3.3 Conclusions ............................................................................................................. 103 4.4 Earthquake Resistance of the Hakka Tulou .............................................................. 103 4.4.1 Simplified Lateral Force Analysis .......................................................................... 104 iv 4.4.2 Tulou Model Earthquake Response ........................................................................ 108 4.4.3 Conclusions ............................................................................................................