针对现行规范对寒区桥梁减隔震设计中仅考虑橡胶支座力学特性受环境温度作用影响,而忽略桥墩混凝土材料特性受温度影响的不足,以高寒地区一座两联3×30 m混凝土连续梁桥为背景,开展不同环境温度下桥墩混凝土材料抗压性能试验,确定温度对其力学参数的影响,基于试验结果对不同环境温度下的桥墩混凝土力学参数进行修正,从而建立不同环境温度下的全桥精细化非线性有限元模型,并基于增量动力分析(IDA)法探究不同环境温度下该桥的地震易损性.结果表明:极端温度引起桥墩混凝土材料参数和支座刚度的改变,使得该桥自振频率随着温度的升高而降低;地震作用下,极端低温时桥墩墩顶位移较常温增大了 26.8%,而极端高温时支座位移增大了19.4%;根据现行规范计算的极端低温时支座和桥梁系统的损伤概率偏小,极端高温时结构和构件的损伤概率偏大,在设计中应予以重视;极端低温下桥墩、支座及桥梁系统的损伤概率,较常温分别增大45.0%、35.2%和27.5%,对于高寒地区该类桥梁设计时需考虑低温对其抗震性能的影响.
In the isolation design of bridges in cold regions,the current code only considers the in-fluence of ambient temperature on the mechanical properties of rubber bearings.The code,how-ever,overlooks how temperature affects the properties of concrete materials used in piers.This paper focuses on a two-segment,3×30 m continuous concrete girder bridge in the alpine region.The aim was to determine the influence of temperature on the bridge's mechanical parameters by conducting a series of tests on the compressive performance of pier concrete materials at different ambient temperatures.Based on the test results,modifications were made to the mechanical pa-rameters of the concrete used in the piers at different ambient temperatures.This allowed for the creation of refined nonlinear finite element models of the entire bridge at different ambient tem-peratures.Utilizing the incremental dynamic analysis,we discussed the seismic vulnerability of the bridge at different ambient temperatures.The results show that extreme temperature changes the material parameters of pier concrete and the stiffness of bearings,thus causing the natural frequency of the bridge to decrease as temperature increases.In the event of an earthquake,the displacement at the top of the pier top increases by 26.8%at extremely low temperatures.Mean-while,bearing displacement increases by 19.4%at extremely high temperatures compared with that at normal temperatures.According to the current code,the failure probability of bearings and the entire bridge system is relatively low at extremely low temperatures.However,the fail-ure probability of the structure and components is significantly higher at extremely high tempera-tures,a factor that should be closely considered during design.Compared to normal tempera-tures,the failure probability of the pier,bearing,and bridge system at extremely low tempera-tures increases by 45.0%,35.2%,and 27.5%,respectively.Therefore,the influence of low tempera-tures on seismic performance should be considered when designing bridges like this in cold regions.