混凝土结构抗震非线性分析模型、方法及算例

结构在大震作用下会进入非线性并产生损伤,准确预测地震荷载下钢筋混凝土结构的非线性行为,对评估混凝土结构的抗震安全性具有重要意义。清华大学土木工程系近年来开发的适用于钢筋混凝土杆系结构的纤维模型THUFIBER程序,适用于预应力混凝土杆系结构的纤维模型NAT-PPC程序,以及适用于剪力墙结构的分层壳墙元模型的非线性分析程序。这些程序可以直接将构件的非线性节点力(轴力、剪力和弯矩)、节点变形(平动和转动)和材料的非线性应力-应变行为联系起来,可以模拟各种复杂受力构件的滞回行为和轴力-双向弯曲-剪切耦合行为,借助通用有限元程序方便的前后处理功能和非线性计算功能,该程序可以准确模拟地震作用下结构的三维非线性地震响应,也可模拟爆炸、倒塌等极端非线性行为,通过一系列的数值分析与试验结果的对比和工程应用算例,说明所研发程序的精度和计算能力。

NONLINEAR ANALYTICAL MODELS, METHODS AND EXAMPLES FOR CONCRETE STRUCTURES SUBJECT TO EARTHQUAKE LOADING

Structures may enter nonlinear stage in strong earthquake, precise prediction for the nonlinear behavior of reinforced concrete (RC) structures in earthquake is important to assess the earthquake resistant safety of the structures. This paper presents the programs recently developed by the Civil Engineering Department of Tsinghua University, which include the fiber model THUFIBER for RC frames, the program NAT-PPC for prestressed concrete (PC) frames, and the multi-layer shell element based shear wall program. These programs can connect the nonlinear nodal force/nodal displacement relationship of elements directly with the nonlinear stress/strain relationship of materials. Complicated cyclic behaviors and coupled axial force-biaixal bending-shear behaviors of RC structures can be correctly simulated. And furthermore, with the convenient pre/post processing and the nonlinear capacity of general finite element software, these programs not only can precisely simulate nonlinear seismic response of spatial strutures, but also can simulate some extreme nonlinear problems such as blast or collapse. The precision and the capacity of the programs are illustrated in this paper with a series of applications.