负弯矩作用下钢-混凝土组合梁受力性能试验研究

通过8根跨度为3.0m和4.2m的钢-混凝土组合梁在负弯矩作用下的受力性能试验，研究了端部弯矩、跨度、H形钢的腹板高厚比、抗剪连接栓钉数量、设置横向加劲肋等因素对组合梁失稳破坏模式、受弯承载力及转动能力的影响。试验结果表明：对两端部作用数值相等的负弯矩工况，组合梁发生畸变失稳，其受弯承载力小于组合梁全截面塑性弯矩，转动能力偏小，而对其他接近实际结构的负弯矩工况，组合梁发生局部失稳或局部与畸变耦合失稳，其受弯承载力大于组合梁全截面塑性弯矩，转动能力较大；随着腹板高厚比减小或者在腹板上设置横向加劲肋，组合梁的受弯承载力和转动能力都有明显提高。

Experimental investigation on mechanical behavior of steel-concretecomposite beams under negative bending

Eight experiments on the mechanical behavior of steel-concrete composite beams with span lengths of 3 m and 4.2 m were carried out under monotonic negative bending moment. The effects of factors such as bending moment at the ends of beam, span length, height-to-thickness ratio of H-section steel web, number of stud shear connector and setup of transverse stiffener on the failure mode, bending capacity and rotational ability of composite beams were investigated.It is found from the experiments that distortional buckling occurs for the cases with the same amplitude of negative bending moment at the two ends of a beam. Their bending capacity is less than cross-sectional plastic moment of composite beam and rotational ability is lower. However, local buckling or coupling of local buckling and distortional buckling takes place for the other cases with the negative bending moment close to actual structures. Their bending capacity is greater than plastic moment and rotational ability is higher. As the height-to-thickness ratio of web is decreased, or when transverse stiffeners are installed on the web, both bending capacity and rotational ability of the composite beams are increased.