钢-混凝土组合框架结构抗震非线性弱形式求积元时程分析

Steel-concrete composite (SCC) frame structures have many advantages such as high strength, light weight, faster optimized construction processes, etc. With the increased utilization of SCC frame structures, its seismic performance has gradually attracted people's attention. Efficient and accurate nonlinear time history analysis is very important for the seismic analysis and design of the SCC frame structures. Unfortunately, the 1D low-order finite element models of SCC beams experience the so-called “slip locking” phenomenon for large values of the shear connection stiffness, whereas the application of 1D high-order finite element model, shell finite element model, solid finite element model will significantly increase the number of degrees- of-freedom especially for the whole SCC frame structure. The weak form quadrature element method is a new highly efficient numerical tool which is characterized by conceptual simplicity, straightforward implementation and easy upfront preparation and post-processing. The weak form quadrature element method will be applied to seismic nonlinear analysis of the SCC frame structures in this project. The influences of geometric nonlinear effect, stiffness of the shear connector, semi-rigid joint on seismic.characteristics and responses of the SCC frame structures will be discussed. The primary aim of the present project is to improve the adaptability of the weak form quadrature element method in engineering applications and offer an effective and accurate numerical method for the seismic analysis and design of the SCC frame structures.

由钢-混凝土组合梁与型钢柱或钢管混凝土柱构成的钢-混凝土组合框架结构，近年来在国内外得到了广泛的应用，其抗震性能也逐渐引起人们的重视。非线性时程分析是组合框架结构抗震设计和性能评价的重要工具，而基于有限元方法构造的一维低阶组合梁单元存在“滑移闭锁”问题，若采用一维高阶组合梁单元、壳单元或实体单元则会增加问题的自由度，进而降低组合框架结构整体迭代计算的效率。弱形式求积元法是一种新兴的数值计算方法，具有准确高效、概念简单，实施步骤直接、前后处理过程简便等诸多优点。本课题将弱形式求积元法应用于组合框架结构抗震材料几何双重非线性时程分析，着重讨论几何非线性效应、剪力连接件的布置与性能、梁柱节点连接性能、组合梁截面参数对其抗震性能和设计的影响，为钢-混凝土组合框架结构的抗震分析和设计提供有力的计算手段。

由钢-混凝土组合梁与型钢柱或钢管混凝土柱构成的钢-混凝土组合框架结构近年来在国内外得到了广泛应用，其抗震性能也逐渐引起人们的重视。非线性时程分析是结构抗震设计和性能评价的重要工具。弱形式求积元法作为一种新兴的数值计算方法，具有准确高效、实施步骤直接、前后处理过程简便等诸多优点。本项目将该方法应用于钢-混凝土组合框架结构的抗震非线性时程分析，主要工作及结论如下：.（1）分别基于Euler梁理论和几何精确梁理论建立了组合梁的求积元几何非线性分析格式，挠度不超过正常使用极限状态条件时，两种几何非线性格式计算所得钢-混凝土组合梁挠度差异不超过5%，且基于Euler梁的几何非线性格式单元自由度较少，计算成本较低。.（2）为使程序易于扩展，采用将普通组合梁单元位移向量数目（自由度）加以缩减及在其内部组装柔性弹簧单元的方式，可方便地构造出可以考虑组合框架结构中组合梁边界处滑移约束及梁柱节点半刚性（柔性）连接的组合梁单元。.（3）建立了剪力连接件一维滞回本构模型，该模型由带有下降段的骨架曲线与滞回规则组成，通过与相关试验结果的比较表明该材料模型具有准确性及有效性。.（4）系统开展了钢-混凝土组合框架结构非线性时程分析。组合框架梁柱节点半刚性连接对结构地震响应影响较大，组合梁边界滑移约束条件及几何非线性效应的影响相对较小。在分析实际工程结构时，需合理建立结构的计算分析模型。.（5）编制了钢-混凝土组合框架结构抗震非线性时程分析通用程序。. 上述工作表明，将求积元方法运用于钢-混凝土组合框架的抗震非线性时程分析是可行和成功的，相关结论可为该结构的抗震分析和设计提供高效的计算手段和参考依据。