冷弯薄壁型钢复合墙体受剪性能数值模拟及简化力学模型研究

Numerical simulation and simplified mechanical model on shear behavior of enhanced cold-formed steel composite wall

冷弯薄壁型钢复合墙体是多层冷弯薄壁型钢房屋建筑结构的主要承重及抗侧力部件。为实现该类复合墙体受剪性能高效模拟与分析,建立了其OpenSees数值计算模型,能够较为准确地模拟同侧双层及其以上墙板覆面的轻钢复合墙体在低周往复荷载作用下的滞回性能,得到的滞回曲线具有明显的捏缩滑移特征,其水平极限荷载模拟结果与试验值的比值在0.90-1.14之间,抗剪刚度预测值整体偏于安全。在此基础上,对复合墙体的墙板上螺钉分布影响进行了分析,结果表明墙板板边螺钉的间距对复合墙体受剪性能影响较大,改变墙板板内螺钉间距对复合墙体受剪性能无明显影响。根据数值分析所获得的复合墙体的墙板处螺钉受力特征,提出改进的墙板螺钉简化力流模型。考虑了墙体边柱螺钉参与水平剪力分配,但不考虑墙板中部的螺钉贡献。简化的力流模型能够较真实地反映螺钉群受力情况,采用该模型预测的复合墙体水平极限荷载与试验结果的比值在0.91-1.18之间。

The cold-formed steel （CFS） composite wall is the major load-bearing and lateral resistance component for mid-rise CFS structures. In order to implement high efficiency simulation and analysis of shear behavior, an OpenSees numerical model of such wall system was built and it can simulate hysteretic behavior of CFS composite walls with at least double layers of sheathings on either side under low cyclic lateral loading. The hysteretic curves have characteristics of pinching and sliding. The ratio of lateral ultimate load of composite wall between simulated and experimental results is about 0.90-1.14 and the predicted shear stiffness tends to be conservative. In addition, the analysis is conducted by changing the arrangement of screws on the CFS composite wall. The results show that the influence of screw spacing along the periphery of sheathing is significant on the shear performance of CFS composite wall and the screw spacing in the field of sheathing has little effect on the shear behavior of composite wall. A simplified mechanical model of sheathing-to-CFS screws is developed and improved by considering the mechanical characteristic of screws on the side studs of composite wall, ignoring the contribution of screws in the field of sheathing. The simplified mechanical model reflects the actual mechanical characteristics of sheathing-to-CFS screws of CFS composite wall. The ratio of the predicted using the simplified mechanical model to the experimental lateral ultimate load of composite wall is about 0. 91-1.18.