波浪腹板连接的双核防屈曲支撑承载力及滞回性能研究

Load-carrying capacity and hysteretic performance of corrugated web connected BRB

提出一种用波浪腹板连接的双内核防屈曲支撑(简称CW-BRB)。CW-BRB由浪腹板连接两个内置一字板内核的全钢约束矩形钢管组成,且两个一字板内核在伸出外围约束构件端头前后均通过肋板加强形成H形截面,整体外围约束的抗弯刚度及内核端部强度均获得极大改善,承载力设计效益显著提高。首先,简要介绍波浪腹板剪切变形对CW-BRB弹性屈曲荷载的影响,为计算其约束比或正则化长细比提供依据。其次,重点研究CW-BRB受力性能,通过建立CW-BRB的壳单元模型,分析其单调加载承载力与反复拉压荷载作用下的滞回性能,研究约束比变化对其受力性能与破坏机理的影响。最后,设计了1根单波浪腹板和1根双波浪腹板连接的CW-BRB进行反复加载滞回性能试验研究,并采用壳单元及壳单元位移耦合技术建立CW-BRB试验试件的精细化有限元模型,进行反复拉压荷载作用下的滞回性能数值模拟分析。试验结果与有限元计算结果吻合较好。

In this work, a new type of core-separated BRBs named corrugated-web-connected buckling-restrained braces （CW-BRB） is presented. The external restraining system of the CW-BRB is composed of two steel external tubes with rectangular hollow sections, which are connected by either single or double sinusoidal corrugated webs. Two cores of the CW-BRB at its ends extending outside the external tube are connected by a core stiffener to form a strong H-shaped core section, so that the overall flexural stiffness of the external restraining system and the core projections at each end of the CW-BRB can be greatly improved, and the design benefit from the load-carrying capacity of the CW-BRB can be remarkably increased. Firstly, the elastic buckling load of the CW-BRB is introduced by considering the shear deformation of the corrugated webs in the external restraining system, forming the basis for calculating restraining ratio or normalized slenderness ratio of the CS-BRB. Secondly, for the double sinusoidal corrugated web connected BRBs, the ultimate load-carrying capacity under monotonic axial compression and the hysteretic performance under repeated compressive-tensile cyclic loads are investigated respectively by using the refined finite element models based on shell element and the shell element-displacement coupling techniques. Moreover, the effects of the restraining ratio or normalized slenderness ratio on the mechanical performance and failure mode of the CW-BRB are studied. Finally, experimental studies on two specimens of CW-BRBs （one specimen with a single sinusoidal corrugated web and one specimen with double sinusoidal corrugated webs ） have been conducted respectively to investigate their hysteretic performances and corresponding failure modes. Additionally, a refined FE model with shell elements is established for the simulation and comparison purpose with the experimental loading processes of two specimens. The numerical results obtained from the FE analyses agree well with the experimental results.