不规则钢筋混凝土梁桥抗震性能评价N2方法

N2 method for seismic performance evaluation of irregular RC bridges

将非线性静力分析(Pushover)和非线性时程分析结合起来,给出了一个用于不规则钢筋混凝土梁桥抗震性能评价的N2方法(名称源于Fajfar).首先对多个代表性桥墩进行非线性静力分析,获得桥墩的"能力"曲线以及不同破损极限状态对应的墩顶位移.不同破损极限状态由钢筋和混凝土的应变以及桥墩截面抗剪能力共同定义,并可由墩底截面弯矩——曲率关系曲线转化为以墩顶位移的表述形式.再通过全桥模型的非线性时程分析获得各个桥墩的地震"需求"位移,最后通过二者比较来评价桥梁的抗震性能.给出了一个曲线连续梁桥计算实例,验证了方法的可行性.

A combined non -linear method by pushover analysis and time history analysis was presented to evaluate the seismic performance of irregular RC bridges, which was named as N2 method firstly developed by Fajfar in structural seismic damage analysis. Firstly, pushover analysis of every typical pier of the bridge was carried out using single pier model, and displacements at top of the pier for different damage limited states and ＂capacity curve＂ of the pier were obtained. Damage limited states, which were represented by displacements at top of the pier by transforming from moment - curvature relationship of the section in plastic hinge zone, were defined by both of the strain of concrete or longitudinal steels in plastic hinge zone and shear strength of the section. Then demanded seismic displacements of the pier were calculated by non - linear time history analysis using the integral bridge model. Moreover, the seismic performance of the bridge was evaluated by means of comparing the capacity of the pier with the seismic demands. Finally a continuous curved bridge was taken as an example to illustrate the application, which proved the feasibility of the method.