Seismic Vibration Control of Frame Structure Using Shape Memory Alloy by Md. Golam Rashed MASTER OF SCIENCE IN CIVIL ENGINEERING (STRUCTURAL) Department of Civil Engineering BANGLADESH UNIVERSITY OF ENGINEERING AND TECHNOLOGY February, 2013 Seismic Vibration Control of Frame Structure Using Shape Memory Alloy by Md. Golam Rashed A thesis submitted to the Department of Civil Engineering of Bangladesh University of Engineering and Technology, Dhaka, in partial fulfilment of the requirements for the degree of MASTER OF SCIENCE IN CIVIL ENGINEERING (STRUCTURAL) February, 2013 The thesis titled “Seismic Vibration Control of Frame Structure Using Shape Memory Alloy” submitted by Md. Golam Rashed, Roll No.: 0411042321, Session: April 2011 has been accepted as satisfactory in partial fulfilment of the requirement for the degree of M.Sc. Engineering (Civil and Structural) on 25th February, 2013. BOARD OF EXAMINERS ______________________________________ Dr. Raquib Ahsan Chairman Professor (Supervisor) Department of Civil Engineering BUET, Dhaka. ______________________________________ Dr. Md. Mujibur Rahman Member Professor and Head (Ex-officio) Department of Civil Engineering BUET, Dhaka. ______________________________________ Dr. Tahsin Reza Hossain Member Professor Department of Civil Engineering BUET, Dhaka. ______________________________________ Dr. Sharmin Reza Chowdhury Member Associate Professor (External) Department of Civil Engineering AUST, Dhaka. ii D ECLARATION It is hereby declared that this thesis or any part of it has not been submitted elsewhere for the award of any degree or diploma. _________________________________ Md. Golam Rashed iii D EDICATION To my wife, for being patient and understanding. iv A CKNOWLEDGEMENT At first I would like to express my whole hearted gratitude to Almighty Allah for each and every achievement of my life. I would like to express my great respect and gratitude to my thesis supervisor, Dr. Raquib Ahsan, Professor, Department of Civil Engineering, BUET for providing me continuous support and guideline to perform this research work and to prepare this concerted dissertation. His contribution to me can only be acknowledged but never be compensated. His consistent inspiration helped me to work diligently throughout the completion of this research work and also contributed to my ability to approach and solve a problem. It was not easy to complete this work successfully without his invaluable suggestions and continuous help and encouragement. Despite many difficulties and limitations he tried his best to support the author in every field related to this study. I would like to express my deepest gratitude to the Department of Civil Engineering, BUET, The Head of the Department of Civil Engineering and all the members of BPGS committee to give me such a great opportunity of doing my M.Sc. and this contemporary research work on structural application of Shape Memory Alloy (SMA). I would like to render sincere gratitude to Dr. Toby Kim Parnell, USA and Dr. Furo Jumbo, UK for providing useful knowledge on SMA simulation and advanced FEA. I am grateful to Dr. Rafiqul A. Tarefder, UNM, USA for providing the experimental test data and to Dr. Mehedi Ahmed Ansary, BUET, for providing required computational facilities. I would like to convey my gratefulness and thanks to my family, their undying love, encouragement and support throughout my life and education. Without their blessings, achieving this goal would have been impossible. At last I would like to thank my respected supervisor Dr. Raquib Ahsan once again for giving me such an opportunity, which has obviously enhanced my knowledge and skills as a structural engineer to a great extent. v A BSTRACT The use of Shape Memory Alloy (SMA) in mitigating the seismic vibration response of civil infrastructure is gaining momentum. The name “Shape Memory” implies that it remembers its original formed shape. SMA has two basic properties, Super- Elasticity and Shape Memory Effect (SME). The “Super-Elastic” behaviour exhibited by SMA materials, permits a full recovery of strains up to 8% from large cyclic deformations, while developing a hysteretic loop. SME allows the material to recover the initial shape or position which in turn can be used as re-centering mechanism. The mechanism of shape recovery involves two crystallographic phases, Martensite and Austenite, and the transformations between them. The Austenite phase provides more stiffness than the Martensite phase. Phase transformation occurs between Martensite & Austenite depending upon temperature & stress. These unique properties result in high damping, combined with repeatable re-centering capabilities which can be used to advantage in several civil infrastructure applications, especially in seismic vibration control devices. Super-Elastic response of SMA has historically been the primary mode of interest of civil engineers as it occurs over a wide-range of temperatures; and also because SMA reaches activation temperature and becomes Austenite at the ambient temperature of civil engineering infrastructures. Thus the re-centering capability of SMA by generation of an activation force is not utilized. The use of high temperature SMA has enabled the re-centering mechanism to work. The SMA is heated by electrical current flow and the use of constant current in this purpose will result in greater power consumption which can be reduced significantly by passing pulsed current through the SMA using Pulse Width Modulation (PWM) technique. In this study, both the Super-Elastic and Shape Memory Effect has been taken into account by using SMA with high activation temperature. A Thermo-Mechanical SMA phenomenological constitutive model is used to simulate the SMA behaviour. The dynamic response data of a frame structure has been obtained from FE analysis by using the nonlinear FE software program MSC Marc. Then the frame is braced and reanalyzed; first using standard steel wire and then later using SMA wire, the seismic response of both the braced frames were measured. The SMA bracing is activated by joule-heating due to electrical current flow. The SMA is first activated by constant current, later using pulsed current. In this research work, From the FE solutions, the effectiveness of SMA braces as a seismic vibration control device and guidelines to optimum electrical input, considering appropriate stiffness and damping characteristics; is established. From the simulation result, it is evident that the use of pulsed current resulted in reduced energy consumption by the SMA, as well as mitigating the seismic vibrations on the frame structure. vi C ONTENTS Page No. DECLARATION iii DEDICATION iv ACKNOWLEDGEMENT v ABSTRACT vi LIST OF FIGURES x LIST OF TABLES xvi LIST OF ABBREVIATIONS xvii NOTATIONS xviii CHAPTER 1 INTRODUCTION 1.1 General 19 1.2 Background and Present State of the Problem 20 1.3 Objectives of the Present Study 20 1.4 Scope and Methodology of the Study 21 1.5 Organization of the Thesis 21 CHAPTER 2 LITERATURE REVIEW 2.1 General 23 2.2 Basic Characteristics of SMA’s 25 2.2.1 Shape Memory Effect 27 2.2.2 Pseudo-Elasticity 27 2.2.3 Damping Properties 28 2.3 Constitutive Modeling of Shape Memory Alloys 29 vii 2.3.1 Phenomenological Modeling 29 2.3.2 Thermodynamics-Based Modeling 29 2.4 Structural Applications of SMA in Civil 30 Engineering 2.4.1 SMA in Building Structures 30 2.4.2 SMA in Bridge Structures 32 2.5 Limitations 33 2.6 Concluding Remarks 33 CHAPTER 3 CONSTITUTIVE MODELING 3.1 General 35 3.2 Overview of Constitutive Modeling of Shape 35 Memory Alloys 3.3 Saeedvafa Constitutive Model for Shape 37 Memory Alloy 3.4 Implementation 45 3.5 Concluding Remarks 48 CHAPTER 4 VERIFICATION 4.1 General 49 4.2 Experimental Setup and Geometric Properties 49 4.3 Material Properties 51 4.4 Modeling Assumptions and Analysis Procedure 53 4.5 Verification 58 4.5.1 El Centro Case 59 4.5.2 Northridge Case 61 4.6 Concluding Remarks 63 viii CHAPTER 5 RESULTS AND DISCUSSIONS 5.1 General 64 5.2 Simulation Parameters and Procedures 64 5.3 Unbraced and Steel Braced Frame Parametric 67 Study 5.4 SMA braced Frame Parametric Study 73 5.4.1 Constant Current 74 5.4.2 Pulsed Current 87 CHAPTER 6 CONCLUSIONS AND RECOMMENDATIONS 6.1 Conclusions 104 6.2 Recommendations for Further Studies 105 REFERENCES 106 Appendix - A 112 ix
Description: