半刚性钢框架实用非线性分析

介绍了在钢框架分析中考虑连接柔性的方法以及常用的连接M–θr模型,建立了能够同时考虑几何、材料和连接非线性的精细塑性铰法三维梁柱单元。单元采用稳定函数考虑二阶效应和剪切变形,采用切线模量和抛物线函数考虑沿单元长度和截面的逐渐屈服,采用Kishi-Chen幂函数模型和修正梁单元方法模拟半刚性连接的非线性行为。利用ANSYS软件的用户可编程特性(UPFs)编写了单元程序,并将用户单元添加至ANSYS软件单元库中。半刚性框架算例分析表明:用户单元分析的荷载-位移曲线与试验结果吻合较好,与采用COMBIN 39单元模拟连接所分析的结果非常接近。

PRACTICAL NONLINEAR ANALYSIS FOR SEMI-RIGID STEEL FRAMES

Methods for taking into account semi-rigid connection effects in steel frame analysis, and practical models of connection moment versus rotation curve are introduced. A three-dimensional beam-column element, based on refined plastic hinge model, is developed to represent the combined nonlinear effects of geometry, material and connection on the behavior of semi-rigid frames. Second-order effects and shear deformation of the frame are captured through stability functions. Tangent modulus and a parabolic function are used to account for the gradual yielding along the length and across the section. Kishi-Chen power model and the modified beam element method are used to describe the nonlinear behavior of semi-rigid connections. Using the User Programmable Features (UPFs) of ANSYS program, the element routines have been developed and successfully incorporated into ANSYS program. Comparing with experimental results, the proposed element can give reasonably good prediction of the load-displacement behaviour of semi-rigid frames. The analytical results are in accordance with those obtained when connections are modeled by COMBIN39 element.