基于结构损伤的在役钢框架地震易损性研究

摘要

The seismic performance of structures at different ages is necessary to be evaluated because the corrosion of steel may lead structure to earlier failure.A double parameters model for component damage based on the first super deformation and cumulative plastic corner was put forward to establish the overall structure damage model considering the weight coefficients for the component and layer,4 kinds of damage states of the structure were defined.By introducing the parameter of time,the conventional rule for steel corrosion was used to establish the age constitutive and whole-life seismic vulnerability model of the steel frame.Taking a 9 floors frame with beam-column welded steel structure as an example.20 seismic waves meeting the site conditions were selected to get the relationship between the overall damage index of structure and the peak ground acceleration (PGA)by using IDA analysis of steel frame at different ages (0 years,25 years,50 years,75 and 100)in order to obtain the structure fragility curves of 5 instars and 4 performance levels.The relationships between the PGA mean value and age,as well as the PGA logarithmic standard deviation and age getting by quadratic curve regression analysis were used to obtain the continuous probability function of structural failure with the change of age.%针对钢材锈蚀会致结构过早失效、需对不同龄期结构进行抗震性能评估问题，提出基于首超变形及累积塑性转角的双参数构件损伤模型；考虑构件与层权重系数建立结构整体损伤模型，定义结构4种破坏状态。通过已有钢材锈蚀规律引入时间参数，建立钢材多龄期本构与钢框架全寿命地震易损性模型，以9层梁柱焊接钢框架为例，选20条满足场地条件的地震波，对不同龄期（0年、25年、50年、75年、100年）钢框架分别进行动力增量（IDA）分析，所得不同龄期结构整体损伤指数与地震动参数（峰值加速度）之间满足指数关系，给出5个龄期、4种性能水平下结构易损性曲线。通过二次曲线回归拟合不同性态水平下结构破坏时峰值加速度（PGA ）平均值及对数标准差与龄期关系，建立结构随龄期变化的连续失效概率函数，获得结构失效概率随龄期变化规律。