【作者】 赵国辉；

【导师】 刘健新；

【作者基本信息】 长安大学 ， 桥梁与隧道工程， 2013， 博士

【摘要】 桥梁是救灾生命线上的咽喉，其抗震性能和震后应急保通能力对抗震救灾和灾后重建都起着至关重要的作用。桥梁减隔震设计利用减隔震装置通过延长周期和增加阻尼的方式将结构与地震能量集中的频段隔离并降低结构地震响应。与抗震研究先进国家相比，我国桥梁抗震规范在减隔震装置的力学模型及参数研究方面存在着较大的差距。本文以铅芯橡胶支座和液体黏滞阻尼器为对象，系统研究其力学模型及关键参数对减隔震效果的影响。论文首先对汶川地震中典型桥梁震害进行了简要分析。主要从断层破裂带南北两段运动方式差异性出发，分析了地震断层南北两段不同区域内典型桥梁震害的不同特征。研究发现：断层破裂带南段脆性逆冲运动显著，桥梁震害以极震区次生灾害滑坡冲击破坏和强度型破坏为主。断层破裂带北段韧性走滑运动显著，桥梁震害以梁式结构落梁、双曲拱桥垮塌等位移型震害为主。铅芯橡胶支座力学参数研究方面，采用纤维截面分析方法，研究不同配铅率及支座剪切应变条件下，铅芯橡胶支座力学参数的变化规律。并通过算例分析了不同配铅率和不同地震动峰值加速度条件下，考虑和不考虑支座剪切应变对结构和支座自身地震响应的差异。研究发现：（1）铅芯橡胶支座力学参数并不恒定，受配铅率及剪切应变的影响显著。如屈服力、屈服后刚度、屈服前后刚度比及阻尼比等参数随支座剪切应变变化显著。随着配铅率的增加，剪切应变对支座力学参数的影响愈加明显。（2）地震动峰值加速度较低（小于0.2g）时，对于低配铅率（小于5%），考虑和不考虑剪切应变影响的支座力学模型对梁端位移和支座剪切应变响应的影响普遍较小。但当地震动峰值加速度较高（大于0.2g）时，对于高配铅率（大于5%），考虑和不考虑剪切应变影响的力学模型对梁端位移和支座剪切应变响应的显著。在所有配铅率条件下，不考虑支座的剪切应变的支座力学参数对桥墩内力响应的影响较为显著，误差在10～25%左右。液体黏滞阻尼器阻尼参数研究方面，基于随机振动理论，推导了液体黏滞阻尼器的最优阻尼比及其对应的最优阻尼系数计算公式。分别利用单自由度体系和实桥算例验证了线性液体黏滞阻尼器最优阻尼系数计算公式的正确性。研究发现：（1）与建筑结构不同，在桥梁上安装的液体黏滞阻尼器存在理论上的最优阻尼比及其对应的最优阻尼系数，使阻尼器的效率达到最大值。该最优阻尼系数仅与主梁质量和振动频率有关，且与两者成正比。（2）当阻尼比在0.4～0.6之间时，液体黏滞阻尼器的减震效率与最优阻尼比基本相当。综合考虑地震动强度、伸缩装置的伸缩量及阻尼器的造价等工程因素，液体黏滞阻尼器最优阻尼系数可以在该阻尼比范围内适当调整。更多还原

【Abstract】 Bridge is the key project on the disaster relief lifeline. The aseismic performance andserviceability of bridge during and after earthquake play a very important role in earthquakerelief and post-disaster reconstruction. Isolation design isolates the bridge from earthquake bylengthening the fundamental period of the structure and increasing the damping with the helpof anti-seismic devices. Compared with advanced countries in seismic research, Chineseguidelines for seismic of highway bridges is relatively backward in research of mechanicalmodel and parameters of anti-seismic devices. In this paper, lead rubber bearing and fluidviscous damper are taken as objects, the mechanical model and key parameters of them andthe isolation performance are systematically studied.Typical earthquake damages of highway bridges in Wenchuan Earthquake are analyzedin this paper. Based on the movement difference of south and north part of the fault fracturedzone, different characteristics of earthquake damages of highway bridges in south and northpart of the fault fractured zone are analyzed. It is shown that brittle thrust plays a major rolein the south part of the fault fractured zone, and the earthquake damages of bridges aremainly secondary disasters of landslide impact damages and strength failure. While in thenorth part of the fault fractured zone, the toughly slip plays a major role, and the earthquakedamages of bridges are mainly displacement failure such as unseating of beams and collapseof double curvature arch bridges.Fiber section method is used to study the mechanical parameters of lead rubber bearing.Change law of mechanical parameters under different lead rates and shear strains is studied.Example bridge analysis is carried out with different lead rates and different peak groundaccelerations. Difference of earthquake responses of bridge and the lead rubber bearing isanalyzed by using different mechanical parameters considering shear strain or not. The studyfound as follows:1. Lead rate and shear strain significantly affect the mechanical parameters of leadrubber bearing. The yield force, post-yield stiffness, rate of pre-yield and post-yield stiffnessand the damping ratio of lead rubber bearing are not constant and vary significantly withshear strain. The effect of shear strain on mechanical parameters increases with increasing of lead rate.2. When the peak ground acceleration and lead rate are low, there is little difference inearthquake responses of bridge and the lead rubber bearing by using different mechanicalparameters considering shear strain or not. While, When the peak ground acceleration andlead rate are high, there is considerable difference in displacement of superstructure and thebearing by using different mechanical parameters considering shear strain or not. Whether thelead rate is high or not, there is a considerable difference in earthquake response of the forcein piers of the bridge by using different mechanical parameters considering shear strain or not.The difference is about10~25%.The closed form expression of optimum damping ratio and the corresponding optimumdamping coefficient of linear fluid viscous damper for bridges is derived by stochasticvibration method. Single degree of freedom system and an example suspension bridge areused to verify the validity of the closed form expression of optimum damping coefficient oflinear fluid viscous damper. The study found as follows:1. There is a theoretical optimum damping ratio and the corresponding optimumdamping coefficient of linear fluid viscous damper for bridges. The efficiency of the fluidviscous damper reaches maximum with the optimum damping coefficient. The optimumdamping coefficient only depends on the modal participation mass and the frequency, and isin direct proportion to them.2. The efficiency of the fluid viscous damper is roughly equivalent to that of optimumdamping ratio when the damping ratio is0.4to0.6.Thus the practical optimum dampingcoefficient can be adjusted in this range according to some factors such as the earthquakeintensity，capacity of joints and the cost.更多还原