楼板对钢筋混凝土柱-钢梁空间组合体抗震性能影响研究

Seismic performance of reinforced concrete column-steel beam subassemblies considering effect of RC slab

楼板在地震作用下对钢筋混凝土柱-钢梁组合体抗震性能的影响是建立地震作用下节点计算模型的基础,也是准确评价组合结构体系抗震性能的关键问题之一。为此,完成了3个钢筋混凝土柱-钢梁(RCS)空间组合体试件在考虑不同楼板宽度情况下的抗震性能试验,分析整个受力过程中楼板受力性态对组合构件受力特征、破坏模式等抗震性能的影响。各试验模型在加载过程中均产生梁铰破坏,并表现出较好的延性和耗能能力,最终因节点区钢梁屈曲、扁钢箍开裂和柱端混凝土压碎而丧失承载力。分析表明,楼板裂缝以横向裂缝为主,随着楼板宽度增加,次生斜裂缝增多,板底混凝土压碎区域增大;混凝土楼板与钢梁组合体对节点核心区的约束作用较明显地改善了空间组合体受力性能。对楼板混凝土和板内纵筋在受力过程中的应变进行分析,结果表明,随着楼板宽度的增加,楼板对RCS空间组合体刚度、承载力的贡献值有限。对现浇板受拉有效翼缘宽度进行分析,结果表明考虑钢-混凝土组合梁翼缘有效宽度对梁端受弯承载力、惯性矩影响较大。

The effect of RC slab on the seismic performance of reinforced concrete column-steel beam composite subassemblies under reversed cyclic loading is of fundamental importance in developing and validating nonlinear analysis models and conducting performance simulations. In this study,three specimens of the subassemblies between reinforced concrete column and steel beam subassemblies with different widths of the RC slabs were tested under reversed cyclic loading to investigate the influence of different RC slabs on the seismic performance of the mechanical behavior and the characters of failure model. All specimens with excellent ductility and energy dissipation exhibit the first plastic hinge at the bottom of steel beam in the loading process,and eventually fail due to the buckling of steel beam,the weld failure of steel band plate and the crushing of column concrete in the composite connections. Experimental results show that the flexural cracks become the main features in slab concrete. With the increase of the widths of the slab,the number of diagonal and horizontal shear cracks increases. The region of concrete crushed near the corner of slab is gradually enlarging. Additionally,results from this research present that the effect of the RC slab and steel beam composite which constrained the core concrete of the joint may obviously improve the seismic performance of threedimensional composite subassemblies. Based on analysis of the strains of the slab concrete and the inner longitudinal rebars,the results prove that with the increase of the width of RC slab,the RC slab makes a limited contribution to the strength and stiffness of the composite subassemblies. By analyzing the mechanical behavior of reinforced concrete beamcolumn-slab subassemblies,the effective flange width for the steel-concrete composite beams is evaluated,which has a significant effect on the moment capacity of beam ends and the equivalent elastic moment of inertia values.