双向加载路径下型钢-混凝土组合柱抗震性能试验研究

通过8根型钢-混凝土组合柱在低周往复荷载作用下的加载试验，研究配钢形式、加载路径对该类组合柱破坏过程、滞回性能、刚度退化、延性性能及累积耗能的影响，分析纵筋及型钢的应变发展。结果表明：在相同含钢率下，配置方钢管的型钢混凝土柱的变形能力比十字形截面型钢的型钢混凝土柱的大，破坏位移角增大了约24%；加载路径对组合柱滞回特性影响显著，在非对称路径加载下，滞回特性亦表现出明显的非对称性；与单向循环加载组合柱相比，双向循环加载组合柱的峰值荷载小、刚度退化快、屈服位移小、延性差、破坏位移角小，但其累积滞回耗能明显大于单向循环加载时的情况；纵筋屈服发生在峰值荷载前，而型钢一般在达到峰值荷载时才屈服；在位移加载后期，双向循环加载组合柱纵筋及型钢应变增长明显较单向加载组合柱的快。因此，双向加载路径对型钢-混凝土组合柱承载能力、变形性能及累积耗能等抗震性能的影响显著，在设计时应予以考虑。

Experimental study on seismic behavior of steel-concrete composite columns under bidirectional loading paths

The behavior of 8 steel-concrete composite columns was investigated experimentally under low cyclic loading. The effects of the steel configuration and loading path on the failure process, hysteretic characteristics, stiffness degradation, ductility and cumulative energy dissipation were studied, as well as the stress level of the longitudinal reinforcing bars and steel. The research results indicate that at the same steel ratio the deformation capacity of square steel tube reinforced concrete columns is better than that of cross steel reinforced concrete columns, and the ultimate failure drift ratio is increased by 24% approximately. Loading paths can affect hysteretic characteristics of the specimens significantly. Under asymmetrical loading path, hysteretic characteristics of the specimens are also asymmetry. Compared with specimens under unidirectional cyclic loading, specimens subjected to bidirectional cyclic loading have small peak load, fast stiffness degradation, small yielding displacement, poor ductility and small ultimate failure drift ratio. However, cumulative energy dissipation of specimens under bidirectional cyclic loading is larger than those under unidirectional cyclic loading. Longitudinal reinforcement yielding occurs before the peak load, while steel yielding occurs at the peak load. During late displacement loading, strain of longitudinal reinforcing bars and steel of bidirectional loading specimens increase faster than those of specimens subjected to unidirectional loading. Therefore, the bidirectional loading path has great influence on the seismic performance such as load carrying capacity, deformation performance and cumulative energy dissipation, which should be considered in the design.