波纹腹板内衬混凝土组合梁高温下抗剪性能研究

Shear Behavior of Concrete-reinforced Web Composite Beams with Corrugated Webs at High Temperature

文中采用有限元软件建立波纹钢腹板组合梁(CBCW)和波纹钢腹板内衬混凝土组合梁(CBCWC)在火灾下的数值模型,研究组合梁高温下主应力、剪应力演化和组合梁截面各部件的承剪比.结果表明:在高温条件下,内衬混凝土中温度梯度改变了内衬混凝土的承剪能力和传力路径,进而影响CBCWC的剪力分配机制.相对于CBCW,高温下CBCWC中波纹钢腹板的抗剪性能得到显著提升.在临界状态时,CBCW的失效机理为波纹钢腹板发生严重的剪切屈曲,CBCWC的抗剪机理可等效为力学“桁架”模型,失效机理为等效拉杆和等效压杆丧失承载能力.CBCWC中布置的内衬混凝土抑制了波纹钢腹板的高温剪切屈曲,显著提高了组合梁高温下的耐火极限.

The numerical models of corrugated steel web composite beam(CBCW)and corrugated steel web-lined concrete composite beam(CBCWC)under fire were established by using finite element software,and the evolution of principal stress and shear stress of composite beams at high temperature and the bearing-shear ratio of each component of composite beam section were studied.The results show that the temperature gradient in the lining concrete changes the bearing capacity and force transmission path of the lining concrete at high temperature,and then affects the shear distribution mechanism of CBCWC.Compared with CBCW,the shear performance of corrugated steel webs in CBCWC is significantly improved at high temperature.In the critical state,the failure mechanism of CBCW is severe shear buckling of corrugated steel webs,and the shear mechanism of CBCWC can be equivalent to a mechanical“truss”model,and the failure mechanism is the loss of bearing capacity of equivalent tie bars and equivalent compression bars.Compared with CBCW,the lining concrete arranged in CBCWC inhibits the high-temperature shear buckling of corrugated steel webs and significantly improves the fire resistance of composite beams at high temperatures.