截面轴力与弯矩屈服面在钢框架动力弹塑性分析中的应用

为了在现行规范下考虑轴力与弯矩的相互作用，并兼顾计算精度与计算效率，研究了截面屈服面在钢框架动力弹塑性分析中的新应用。首先选用截面组合思想构建轴力与弯矩的屈服面。接着，基于经典塑性理论建立截面恢复力模型，并给出了截面状态确定方法。然后阐述了基于力的梁柱单元状态确定过程及其对截面恢复力模型的调用。最后采用alpha-OS积分算法，对一个四层两跨钢框架开展了动力弹塑性分析。结果表明：截面轴力弯矩屈服面能很好地考虑轴力存在及变化对截面弯矩承载力的影响，基于屈服面的恢复力模型在计算精度上远高于塑性铰模型并逼近纤维模型，在效率上远高于纤维模型，可以用于钢框架的动力结构弹塑性分析。

Application of sectional yield surface of axial force and bending moment to dynamic elastoplastic analyses of steel frame structures

In order to consider axial-flexure interaction under current codes, and to balance computational accuracy and efficiency, a new application of sectional yield surface to dynamic elastoplastic analysis of steel frame structures is studied. First of all, yield surface of section axial force and bending moment was formed by section assemblage concept. Secondly, sectional restoring force model (RFM) was established based on classical plastic theory, and the section state determination was introduced. Thirdly, the element state determination invoking the sectional RFM was illustrated. Finally, dynamic elastoplastic analysis of a 4-storey 2-span steel frame was implemented based on alpha-OS integration method. The results show that the sectional yield surface can well account for the effect of existence and variance of axial force on the sectional bending moment capacity. Besides, it can be concluded that the computational accuracy of proposed sectional RFM is better than plastic hinge model while the efficiency is higher than fiber model.