简支槽形钢-混凝土组合梁的试验研究

Experimental study of simply supported channel steel-concrete composite beams

槽形钢-混凝土组合梁是近年来提出的一种新型下承式桥梁结构。对截面尺寸几何比例为1∶3、构件长度比例为1∶4的简支单线槽形组合梁模型进行两点对称加载的静力试验。对槽形组合梁的抗弯承载力、刚度、应力和裂缝分布特征等基本受力性能开展研究。试验结果表明,通过栓钉连接,试验模型中钢板与混凝土的协同工作性能良好,最终破坏时,表现出较明显的弯曲破坏形态。梁上翼缘的侧向水平位移整体形态为支座处外张,中部内收,但其最大值远小于梁跨中的竖向挠度,表明该模型截面具有良好的抗扭性能。钢梁底板纵向应力沿板宽的分布表现出一定的剪力滞现象,混凝土底板的剪力滞效应不及前者明显。采用截面分析法对模型梁的承载力和变形进行计算分析,其结果与试验结果吻合良好。此外,通过抗弯承载力分析表明,槽形钢-混凝土组合梁的极限抗弯承载力不能套用全截面应力的矩形图分布模式进行计算,应考虑适当折减。

The channel steel-concrete composite beam is a new type of through girder applicable to railway bridges.A static test of two-point symmetric loading was conducted on a simply supported single-lane channel steel-concrete composite beam model of 1∶3 sectional scale and 1∶4 length scale,to study the bending capacity,stiffness,stress distribution,and crack pattern,etc..Experimental results reveals that steel plates and the concrete integrated through shear stud connectors can work together well.The channel beam model exhibited a bending failure mode.The lateral transversal displacements of the upper beam flange near the beam supports were outwards against the section center,on the contrary,those at the middle part of the beam were inwards,and the transversal displacements were much smaller than the vertical deflections at mid-span,which revealed that the section type of the model performs well in torsion.There were some extent shear lag for the longitudinal stress distribution along the direction of width of the bottom steel plate,while it was not as obvious as the former for the bottom concrete board.The flexural load carrying capacities and deformations of the channel composite beam were also analyzed using the section analysis method,and the results agreed well with the test.In addition,the flexural capacity analysis indicates that it is necessary to consider reduction in the ultimate flexural capacity of the channel steel-concrete composite beam,instead of completely using the rectangular mode of stress distribution for full section.