楊永斌臺灣大學：土木工程學研究所林正偉Lin, Cheng-WeiCheng-WeiLin2007-11-252018-07-092007-11-252018-07-092004http://ntur.lib.ntu.edu.tw//handle/246246/50364橋梁振動頻率，不論是對於系統參數的識別或是橋樑安全檢測的工作都是非常基本而且重要的指標。傳統量測橋梁振動頻率的方法，往往需要將量測儀器裝置在待測的橋體上，不僅需要花費釵h人力，對於需要重複或長期監測的橋梁而言，固定安裝在橋梁主體的量測儀器更是一項成本上的負擔。本文提出以一移動的量測車輛通過橋梁，由車輛的振動反應中，萃取出橋梁振動頻率的內涵之方法，除了可以有效並正確量測除橋梁的頻率，所獲得的橋梁動力參數更可以提供工程師或橋梁管理單位做初步且快速的診斷工作。 本研究由車-橋互制系統方程式出發，針對兩個振動子系統分別以古典積分方法求出振動反應之解析解，由解析解中我們並觀察出主要控制參數，從而瞭解引起此一互制系統之共振條件與振動反應中之頻率內涵。對於橋梁的振動反應而言，其反應歷時主要由兩種振動頻率所組成，也就是外力作用頻率與橋梁振動頻率，針對外力作用頻率的特性，我們可以運用在作為識別之車輛通過速度之工具。另一方面，車輛通過橋梁之振動反應中，本研究發現，其頻率內涵包含三種頻率成分，也就是外力作用頻率、車輛自然振動頻率以及受頻率平移後之橋梁振動頻率；本研究中以解析的方式將車輛振動反應中橋梁振動頻率分量所顯現的都卜勒效應量化出其頻率平移的大小。 由基本理論的研究，我們可以明確地肯定，由通過橋梁之車輛振動反應中，可以萃取出橋梁的振動頻率，本研究亦針對一座新完工之橋梁，實際以商用貨車拖曳一符合單自由度振動系統模型之量測車輛，進行本研究提出方法之現地量測驗證工作，由實驗所得到之結果，可以清楚地歸結出本研究所建立之橋梁振動頻率量測方法，是一可行並具有效率之量測方式，未來將可成它a運用在目前大量橋梁振動頻率量測方面的需求上。The frequencies of vibration of bridges represent a kind of information that is most useful for many purposes. Traditional vibration tests aimed at measuring the bridge frequencies often require on-site installation of the measurement equipment. The idea of using a moving vehicle over a bridge as a message carrier of the bridge is explored theoretically in this study. Employing a simple model from scratch for simulating the vehicle-bridge interaction response, with which approximate, but reasonably accurate, solutions for both the bridge and the vehicle are presented in closed-forms. The key parameters dominating the vehicle-bridge response are identified. The dynamic responses of the bridge are governed at different extents by two frequency sets pertaining to the driving frequency resulting from the vehicle passing and natural frequencies of the bridge. On the other hand, the vehicle responses are governed by five distinct frequencies that appear as driving frequencies, vehicle frequency, and bridge frequencies with shift. In this study, the frequencies of vibration of a bridge also have been measured from the dynamic response of a two-wheel cart hauled by a light truck moving over the bridge. The front truck can be regarded as the exciter to the bridge, and the towed cart serves as a receiver of the bridge vibrations. By fast Fourier transform to the measured vehicle dynamic responses, the frequencies of the bridge can then be extracted successfully. The feasibility of the present approach for indirectly measuring the bridge frequencies from the vehicle response was discussed theoretically and confirmed by the field tests. The methodology developed herein is simple and efficient, which can be readily applied to a wide range of practical problems.TABLE OF CONTENTS Acknowledgement (Chinese) i Abstract (Chinese) iii Abstract v Table of Contents vii List of Tables x List of Figures xi Chapter 1 Introduction 1.1 Background 1 1.2 Objectives 3 1.3 Arrangement of the Dissertation 5 Chapter 2 Literature Review 2.1 Introduction 7 2.2 Vehicle-Bridge Interaction Problem 8 2.3 On-Site Bridge Experiments 13 2.4 Relationship between Bridge Damage and Natural Frequencies 18 2.5 Concluding Remarks 21 Chapter 3 Vehicle-Bridge Interaction System Formulation 3.1 Introduction 23 3.2 Mathematical Formulation for VBI Problem 24 3.3 Single-Mode Analytical Solution 25 3.4 Conditions of Resonance 29 3.5 Simulation by Finite Element Method 30 3.6 Verification of Accuracy of Analytical Solutions 34 3.7 Extraction of Fundamental Frequency of Bridge 35 3.7.1 Effect of moving speed of the vehicle 36 3.7.2 Condition of resonance 36 3.7.3 Effect of damping of the bridge 37 3.7.4 Effect of vehicle traveling over a stiffer bridge 38 3.8 Concluding Remarks 38 Chapter 4 Evaluation of Numerical Example Results 4.1 Introduction 57 4.2 Physical Modeling and Formulation 58 4.3 Dynamic Responses of the Bridge 63 4.3.1 Bridge response to a single moving vehicle 65 4.3.2 Bridge response to five moving vehicles 66 4.4 Dynamic Response of the Vehicle 67 4.5 Numerical Verification 70 4.6 Concluding Remarks 72 Chapter 5 Parametric Study 5.1 Introduction 87 5.2 Effect of Initial Vibrations on Test Vehicle 87 5.3 Effect of Initial Vibrations on Bridge 91 5.4 Effect of Different Patterns of Traffic Flow 92 5.5 Effect of Damping Properties of the System 93 5.5.1 Bridge Damping Effect 95 5.5.2 Vehicle Damping Effect 96 5.6 Three-Span Continuous Bridge 96 5.7 Effect of Signal Pollution 97 5.8 Effect of Road Surface Roughness 98 5.9 Effect of Vehicle to Bridge Frequency Ratio 100 5.10 Effect of Bridge Boundary Conditions 101 5.11 Concluding Remarks 102 Chapter 6 Experimental Validation and Results 6.1 Introduction 141 6.2 Objectives 141 6.3 Description of the Bridge 142 6.4 Description of Test Vehicles 142 6.5 Instrumentation 143 6.6 Plan of Testing 144 6.7 Eigenvalue Analysis Result 145 6.8 Experimental Results 145 6.8.1 Ambient vibration test 145 6.8.2 Vehicle characteristics test 146 6.8.3 Bridge response due to moving heavy truck 146 6.8.4 Stationary trailer on bridge excited by a moving heavy truck 147 6.8.5 A trailer hauled by a moving light truck 148 6.8.6 A trailer hauled by a light truck plus a moving heavy truck 149 6.9 Comparison of Measured Results with Numerical Results 150 6.10 Concluding Remarks 151 Chapter 7 Conclusions And Further Studies 7.1 Conclusions 183 7.2 Further Studies 185 References 187 Appendix 1993777822 bytesapplication/pdfen-US萃取頻率量測車輛振動橋梁振動頻率Frequency MeasurementExtractingVehicle VibrationBridge frequenciesthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/50364/1/ntu-93-D87521007-1.pdf