冷弯薄壁型钢组合楼盖面外和面内刚度试验研究及理论分析

EXPERIMENTAL STUDY AND THEORETICAL ANALYSIS OF OUT-OFPLANE AND IN-PLANE STIFFNESS OF COLD-FORMED THIN-WALLED STEEL COMPOSITE FLOOR

冷弯薄壁型钢组合楼盖作为冷弯薄壁型钢结构住宅体系中主要竖向承重和水平传力构件,应具备良好的面外和面内受力性能以推动轻钢结构体系由低层向多高层发展。基于此,对冷弯薄壁型钢组合楼盖分别进行正常使用阶段抗弯刚度试验、抗弯承载力试验以及面内刚度试验,试验结果表明:组合楼盖面外最终破坏模式为C形楼盖梁在最外侧加载点处压屈破坏,面内最终破坏模式为两侧C形楼盖梁与压型钢板间自攻螺钉连接破坏,冷弯薄壁型钢组合楼盖属于部分抗剪连接的组合楼盖。设置楼面板会大幅提高组合楼盖的面内承载力、面内刚度及面内延性,混凝土组合楼盖的抗弯刚度和刚度退化程度优于石膏基自流平砂浆组合楼盖。基于组合楼盖的受力机理和破坏特征,引入C形楼盖梁与组合楼板界面滑移模量,推导了部分抗剪连接T形截面组合梁的等效抗弯刚度公式来计算楼盖的竖向挠度;建立宽翼缘深梁受力分析模型,推导出组合楼盖面内跨中位移计算方法。该文研究成果为完善冷弯薄壁型钢多层住宅体系中组合楼盖的设计计算理论提供了科学依据。

As the main vertical bearing and horizontal force transmission component in cold-formed thin-walled steel structural residential systems,the cold-formed thin-walled steel composite floor should have good out-ofplane and in-plane mechanical properties to promote the development of light steel structural systems from lowrise to multi-storey.Based on this,the bending stiffness test for normal service stage,bending capacity test and inplane stiffness test of cold-formed thin-walled steel composite floor were carried out respectively.The test results show that the final out-of-plane failure mode of the composite floor is the buckling failure of C-shaped floor joists at the outermost loading point.The final in-plane failure mode of the composite floor is the self-tapping screw connection failure between the outside C-shaped floor joists and profiled steel sheet.Moreover,the cold-formed thin-walled steel composite floor is a partial shear connection composite floor.The in-plane bearing capacity,stiffness and ductility of the composite floor can be greatly improved by setting floor panel.The bending stiffness and the degree of stiffness degradation of the concrete composite floor are better than those of the gypsum based self-leveling mortar composite floor.Based on mechanical mechanism and failure characteristics of the composite floor,the equivalent bending stiffness formula of T-shaped partial shear connection composite beams is derived by introducing the interface slip modulus between C-shaped floor joists and composite floor slab to calculate the vertical deflection of composite floor.The mechanical analysis model of wide flange deep beam is established and the calculation method of in-plane midspan displacement of composite floor is deduced.The research results provide scientific bases for improving the design and calculation theory of composite floor in cold-formed thinwalled steel multi-storey residential system.