考虑轴力弯矩耦合的截面随动强化恢复力模型

截面层次的恢复力模型能兼顾计算精度与计算效率,为此在梁-柱单元中得到了广泛的应用。但目前给定＂轴力-弯矩-曲率＂的截面恢复力模型无法灵活考虑轴力与弯矩的耦合作用;采用屈服面的截面恢复力模型尚未考虑截面强化效应。提出了基于屈服面的截面随动强化恢复力模型及其积分方法,首先依据截面屈服面建立了截面随动强化恢复力模型,然后依托塑性理论,进行截面状态确定和本构关系积分。最后利用所提出的恢复力模型进行了悬臂柱的静力往复分析。结果表明：（1）所选用的截面恢复力模型能很好考虑轴力存在对弯矩的影响;（2）该模型具有随动强化的特性;（3）在精度上接近纤维截面所用的单轴材料随动强化模型。

Sectional Kinematic-strengthening Restoring Force Model Considering Axial Force and Bending Moment Coupling

Restoring force models（RFM） in sectional level can meet both computational accuracy and efficiency, it is extensively applied to beam column element. However, the current sectional RFM, which is specified by ＇axial force-bending moment-curvature＇ cannot account for axial force and bending moment （AFBM） coupling flexibly, other RFMs based on yield surfaee（YS） did not consider strengthening effect. In this paper, the sectional kinematic-strengthening restoring force model considering AFBM coupling and its integration method is proposed. Firstly, the sectional kinematic-strengthening restoring force model is built based on YS. Secondly, the state of the section is determinated and the constitution relation is integrated according to plastic theory. Finally, the static cycle analysis of a cantilever column was implemented. The results show that： （1） the proposed RFM can well account for AFBM interaction, （2） the RFM based on extending YS is charaeterized by kinematic strengthening. （3） the computational accuracy of the proposed RFM is close to that of the fiber model with uniaxial material constitutive relation.