不同加载速率下CFRP加固混凝土梁动态力学性能试验研究

混凝土动态力学行为具有明显的率相关性,为此对CFRP加固混凝土梁试件开展了4种加载速率(0. 1、0. 01、0. 001 mm/s和0. 000 5 mm/s)下的力学性能试验,通过位移控制的单调加载方式研究不同加载速率对CFRP加固混凝土梁试件的破坏过程、荷载-裂缝张口位移曲线、断裂能和延性指数的影响。基于实时、动态的声发射无损检测技术,对不同加载速率下CFRP加固混凝土梁断裂过程中的声发射参量进行识别和采集,从声发射角度分析了CFRP加固混凝土梁的受力特性。结果表明:低加载速率下,试件侧面预制缝附近伴有其他裂缝产生,且加载速率越低,其裂缝越明显;CFRP加固混凝土梁的开裂、极限、破坏荷载随加载速率的提高而增大;随着加载速率的提高,CFRP加固混凝土梁的断裂能和延性指数均明显增大;声发射累积振铃计数随加载速率的提高而增大。

Experimental study on dynamic mechanical properties of concrete beams strengthened with CFRP at different loading rates

The dynamic mechanical behavior of concrete has obvious rate dependence. In this paper, the mechanical properties of CFRP-strengthened concrete beam specimens under four loading rates (0.1、0.01、0.001mm/s and 0.0005mm/s) were tested. The influence of different loading rates on the failure process, load-crack opening displacement curve, fracture energy and ductility index of CFRP-strengthened concrete beam specimens were analyzed by means of monotonic loading under displacement control. Based on the real-time and dynamic acoustic emission （AE）nondestructive testing technology, the AE parameters of concrete beams strengthened with CFRP at different loading rates were identified and collected, and the mechanical properties of the strengthened beams were analyzed from the perspective of AE. The conclusions can be drawn that, under low loading rates, there are other cracks near the side prefabricated joints, and the lower the loading rate, the more obvious the crack width. The cracking, ultimate load and failure load of CFRP-strengthened concrete beams increase with the loading rate. The fracture energy and ductility index of CFRP-strengthened concrete beams increase obviously with the loading rate. The cumulative count of acoustic emission increases with the loading rate.