臺灣博碩士論文加值系統

The objective of this research is to examine the seismic behavior of reinforced concrete bridge columns under long duration ground motions. In order to achieve this purpose, two typical reinforced concrete bridge columns designed per current seismic bridge design codes were tested. The first column (called CLC) was tested using the developed loading protocol. This protocol was developed to simulate the effects of long duration ground motions. The second column (called COC) was tested one cycle for each drift to represent short duration ground motions effects and to provide a baseline performance. Test results showed that the column under the long duration loading protocol exhibited significantly greater stiffness and strength degradation than those under the conventional cyclic loading protocol. Based on the test results, relationships between hysteretic parameters, hysteretic energy dissipation and maximum occurred displacement were discussed. The stiffness degradation is related to the hysteretic energy dissipation. The strength degradation is related to the hysteretic energy dissipation and maximum displacement. The pinching is related to maximum displacement.
Furthermore, analytical model was proposed based on test results. This model is capable of considering the effects of hysteretic energy dissipation and maximum occurred displacement on the stiffness degradation, strength degradation and pinching. The model through calibrations can capture the response characteristics of reinforced concrete bridge columns tested under both loading protocols.
Based on the observations of constant-R spectra, if above mentioned effects are not considered properly then ductility demand will be underestimated especially in long duration earthquakes. Note that the underestimation decreased as structural period increased. In addition, ground motion duration was found to be insignificant with respect to ductility demand. According to constant ductility analysis, it is suggested that when a structure is subjected under long duration ground motions, the proposed model is more preferably to be used to predict the response of structure. In contrast, the proposed model may be replaced with the commonly used modified Clough model if the structure is subjected to short duration and not located in short period region.

The objective of this research is to examine the seismic behavior of reinforced concrete bridge columns under long duration ground motions. In order to achieve this purpose, two typical reinforced concrete bridge columns designed per current seismic bridge design codes were tested. The first column (called CLC) was tested using the developed loading protocol. This protocol was developed to simulate the effects of long duration ground motions. The second column (called COC) was tested one cycle for each drift to represent short duration ground motions effects and to provide a baseline performance. Test results showed that the column under the long duration loading protocol exhibited significantly greater stiffness and strength degradation than those under the conventional cyclic loading protocol. Based on the test results, relationships between hysteretic parameters, hysteretic energy dissipation and maximum occurred displacement were discussed. The stiffness degradation is related to the hysteretic energy dissipation. The strength degradation is related to the hysteretic energy dissipation and maximum displacement. The pinching is related to maximum displacement.
Furthermore, analytical model was proposed based on test results. This model is capable of considering the effects of hysteretic energy dissipation and maximum occurred displacement on the stiffness degradation, strength degradation and pinching. The model through calibrations can capture the response characteristics of reinforced concrete bridge columns tested under both loading protocols.
Based on the observations of constant-R spectra, if above mentioned effects are not considered properly then ductility demand will be underestimated especially in long duration earthquakes. Note that the underestimation decreased as structural period increased. In addition, ground motion duration was found to be insignificant with respect to ductility demand. According to constant ductility analysis, it is suggested that when a structure is subjected under long duration ground motions, the proposed model is more preferably to be used to predict the response of structure. In contrast, the proposed model may be replaced with the commonly used modified Clough model if the structure is subjected to short duration and not located in short period region.

ABSTRACT i
ACKNOWLEDGEMENT ii
LIST OF TABLES v
TABLE OF FIGURES vi
1. INTRODUCTION 1
1.1. Background 1
1.2. Motivation of research 3
1.3. Objectives and scopes 3
1.4. Outline 4
2. LITERATURE REVIEW 5
2.1. Bouc-Wen-Baber-Noori hysteresis model (Baber and Noori, 1985) 5
2.1.1. Equation of Motions and Constitutive Relations 5
2.1.2. Hysteretic Shape Properties 7
2.1.3. Degradation Parameters 10
2.2. Modified Clough 11
2.3. Previous Research 13
2.3.1. Ground motion duration effects on nonlinear seismic response (Iervolino et al., 2006) 13
2.3.2. Influence of ground motion duration on degrading SDOF systems (Bojorquez, Iervolino, Manfredi, and Cosenza, 2006) 14
2.3.3. Using spectral matched records to explore the influence of strong-motion duration on inelastic structural response (Hancock and Bommer, 2007) 19
2.3.4. Identification and verification of seismic demand from different hysteretic models (Chung and Loh, 2002) 20
2.3.5. Cumulative seismic damage of reinforced concrete bridge piers (Kunnath, El-Bahy, Taylor, and Stone, 1997) 21
2.4. Effect of Long Duration 23
3. EXPERIMENTAL STUDY 24
3.1. Specimens design 24
3.2. Material of specimens 25
3.3. Test setup and instrumentation 26
3.4. Loading protocol 28
3.4.1. Ground motion selection 28
3.4.2. Rainflow algorithm 29
3.4.3. Loading protocol procedure and applied loading. 32
3.5. Damage observation 35
3.5.1. Damage index 39
3.5.2. Effects of hysteretic energy dissipation 53
3.5.3. Effects of maximum displacement 54
3.5.4. Curvature, shear strain and displacement distribution 54
4. ANALYSIS STUDY 59
4.1. Preliminary modification 59
4.1.1. Strength Degradation Function Modification 59
4.1.2. Pinching function modification 60
4.2. Model calibration 64
4.3. Constant-R analysis 65
4.3.1. Constant R analysis with real ground motions 66
4.3.2. Constant-R analysis with compatible ground motions 68
4.4. Constant ductility analysis 74
5. CONCLUSION AND SUGGESTION 76
5.1. Conclusion 76
5.2. Future works 77
Reference 78
APPENDIX A Ground Motions Characteristics 80

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