循环荷载作用下不锈钢T形件螺栓连接滞回性能试验研究

Cyclic loading tests on hysteretic behavior of stainless steel bolted T-stub connections

为研究不锈钢T形件螺栓连接的滞回性能,分别参照JGJ/T 101—2015《建筑抗震试验规程》和FEMA 461设计了两种不同的循环加载制度,开展16个不锈钢(奥氏体型S30408、双相型S22253)T形件和4个普通钢(Q345B)T形件螺栓连接试件的低周循环加载试验,获得了T形件的滞回曲线和破坏形态,得到了T形件在循环荷载作用下的循环硬化、强度退化特性和耗能能力。研究结果表明:不锈钢T形件的滞回性能明显优于普通钢T形件的,前者耗能平均为后者的2.07倍;循环荷载作用下T形件的破坏形态主要包括螺栓断裂和翼缘板靠近焊趾处断裂两类,与T形件的单调加载破坏模式和加载制度有关;两种牌号不锈钢T形件在循环荷载作用下均表现出较为明显的循环硬化特性,试验后期则由于裂纹的萌生和发展呈现出强度退化;相对于FEMA 461的加载制度,采用JGJ/T 101—2015的循环加载制度得到的T形件的加载圈数和总耗能能力均较大。

By referring to the two different loading protocols from JGJ/T 101—2015 and FEMA 461,cyclic loading tests on a total of 16 stainless steel(austenitic S30408 and duplex S22253)and four carbon steel(Q345B)bolted T-stub connections were carried out to investigate the hysteretic behavior.The hysteretic curves and the failure modes of the tested T-stubs were obtained,together with the cyclic hardening,strength degradation behavior and the energy dissipation capacity.It is revealed that the stainless steel T-stubs exhibit much more favorable hysteretic behavior than the carbon steel counterparts,and the energy dissipation of the tested stainless steel T-stubs is about 2.07 times that of the carbon steel ones.Two typical failure modes including the bolt fracture and the flange fracture adjacent to the weld toe are displayed,which are dependent on the corresponding static failure mode and the loading protocol.The T-stubs in both stainless steel grades exhibit considerable cyclic hardening behavior under cyclic loading,and display strength degradation during later stages of tests due to the occurrence and development of cracks.Moreover,the obtained number of load cycles and the energy dissipation capacity from the JGJ/T 101—2015 loading protocol are both higher than those from the FEMA 461 loading protocol for the tested T-stubs.