不同加载速率下钢筋混凝土柱受力性能试验研究

Experimental study on mechanical properties of reinforced concrete columns at different loading rates

为了剔除混凝土离散性的影响,利用电液伺服试验系统对同一钢筋混凝土柱进行不同加载速率下的往复加载试验。试验采用位移控制的加载模式,加载速率分别为0.2、40 mm/s。试验结果表明:构件的承载能力、刚度退化、承载力退化和累积耗能等力学性能均与加载速率直接相关。在加载速率为40 mm/s条件下,构件的承载能力、累积耗能均有提高,随着加载幅值的增加,加载速率的影响逐渐降低。刚度退化、承载力退化在快速加载条件下更为显著,随着加载速率的增加,软化台阶缩短,损伤进程加剧,构件延性降低,变形能力下降。在双向加载条件下,两个加载方向的耦联作用加速了构件的破坏进程,混凝土的开裂、钢筋屈服、混凝土脱落、纵筋屈曲均发生在更低的位移水平范围内,随着加载速率的提高,两水平加载方向的耦联作用进一步增强,构件变形能力明显降低。

To eliminate the influence of concrete discreteness, quasi-static test of the same reinforced concrete （RC） column under different loading rates was carried out by the electro-hydraulic servo test system. The displacement- controlled loading, with loading rates of 0.2 mm/s and 40 mm/s, respectively, was adopted. The test results show that the mechanical properties of the specimen, such as the bearing capacity, stiffness degradation, bearing capacity degradation and cumulative energy dissipation, are directly related to the loading rate. The bearing capacity and cumulative energy dissipation of the specimens are improved under the loading rate of 40 mm/s. With the increase of the loading amplitude, the influence of loading rate gradually decreases. Stiffness degradation and bearing capacity degradation of the specimens are more significant under rapid loading. With the increase of loading rate, the softening stage is shortened with more obvious damage process. Besides, the ductility of the specimen and the deformation capacity are decreased. The coupling interaction of bi-direetional loading accelerates the failure process of the specimens. The cracking of the concrete, the buckling of the reinforcement bar, the spalling of the concrete and the yielding of the longitudinal reinforcement bar occur in the range of lower displacement level. With the increase of loading rate, the coupling interaction of bi-directional loading is further strengthened, and the deformation capacity of the specimen is obviously reduced.