梁桥非线性随机地震响应的概率特性

Probability characteristics of non-linear random seismic responses on continuous girder bridges

为了分析随机地震作用下桥梁结构非线性响应的概率特性,采用Monte-Carlo数值模拟的方法,并利用弹塑性纤维梁柱单元模型模拟梁单元的非线性行为,对连续梁桥在不同地震峰值加速度作用下的非线性位移及内力时程响应进行了研究。得到了:墩顶位移非线性包络响应服从对数正态分布;桥墩轴力非线性包络响应的概率分布介于对数正态分布和极值I型分布之间;墩底剪力和弯矩非线性包络响应近似服从正态分布;墩底曲率非线性包络反应服从对数正态分布。研究表明:在相同场地条件下,地震峰值加速度的变化不影响结构非线性响应的分布类型,但对非线性响应的变异性影响较大。

Based on Monte-Carlo simulation method, the probability characteristics of non-linear seismic response of continuous girder bridges, with structural randomicity and ground motions randomicity being considered, were studied. The elastic-plastic behavior of RC girder-column element was modeled by fiber elastic-plastic element, Results show that lognormal distribution can be used to model non-linear displace- ments at the top of piers and non-linear curvature at the bottom of piers, that lognormal or Gumbel distri- bution can be used to model non-linear axial forces of piers, and that normal distribution can be used to model non-linear shear forces and moments at the bottom of piers. It can also be seen from the results that variance of peak seismic acceleration does not affect the distribution types of non-linear responses, but does affect the variability of non-linear responses.