基于五参数统一强度理论的刚构桥地震损伤分析

混凝土五参数统一强度理论在主应力空间偏平面上的边界线为十二边形,可通过调整中间主应力的影响系数消除角点的奇异性,以单位体积材料当前塑性耗能及其断裂能的比值定义损伤变量,根据相关流动准则推导混凝土的弹塑性损伤本构关系。该模型可同时考虑混凝土材料中间主应力的影响、高应力状态下的静水应力效应、拉压异性和随动强化效应等,不考虑循环荷载下的刚度折减。由图形回归法给出应力更新的数值方法,编写了相应的Fortran语言程序,并将其用于大跨度连续刚构桥地震损伤的模拟,计算结果验证了所用模型的预测能力。

Plastic Seismic Damage of Concrete Structure Based on Five-Parameter Unified Strength Theory

Trace of five-parameter unified-strength theory in the deviatoric plane becomes dodecagon in the Haigh-Westgaard coordinate system.The singularity at the corners is eliminated by adjusting the coefficient of medium principal stresses.Damage variable is supplied by the ratio of plastic dissipation energy and the fracture energy in unit volume of the concrete.Elastoplastic damage constitutive formulations are deduced based on the associated flow rule.This model enables to consider systematically the effect of intermediate principal stress,quadratic meridian in high confined stress space,different behavior in tension and compression as well as kinematic hardening response corresponding to the post yielding ignoring the stiffness degradation caused by cyclic loading.The stress update with mapping return method is presented and the corresponding program is coded to simulate the nonlinear damage evolution of the structure during earthquake.