高温下铝合金板式节点平面外受弯承载力试验研究

Experimental investigation on out-of-plane flexural capacity of aluminum alloy gusset joints under elevated temperatures

为研究铝合金板式节点的高温承载性能,采用特制的异型高温试验炉,完成了3组共计9个铝合金板式节点的高温下平面外受弯承载力试验。试验中采用恒温加载方案,在杆件上施加横向荷载以对节点施加平面外弯矩。通过试验得到了铝合金板式节点在不同温度下的破坏模式、极限荷载和弯矩-转角曲线。试验结果表明：铝合金板式节点在高温下的破坏模式与常温下一致;对于薄板节点,其破坏模式为节点板块状拉剪破坏和受压局部屈曲破坏;对于厚板节点,其破坏模式为杆件弯扭失稳。基于试验结果,得到了铝合金板式节点高温下的极限荷载的折减系数,以及高温下的初始刚度折减系数。采用ABAQUS有限元软件对试件进行了数值模拟,并与试验结果进行对比,验证了有限元模型的可靠性。研究结果表明,当节点板厚度较大时,节点域在300℃以下不会发生破坏。在300℃以下时,铝合金板式节点的块状拉剪破坏和中心区屈曲承载力折减系数可取铝合金材料名义屈服强度的高温折减系数;铝合金板式节点的初始刚度可偏安全取为常温初始刚度。

In order to investigate the out-of-plane flexural behavior of aluminum alloy gusset （AAG） joints, groups of AAG joint specimens （ nine in total） were tested under various temperatures using a special-shaped three oven. Steady state test scheme was adopted, and the out-of-plane bending moment was applied to the joint by applying lateral force on the members. The failure modes, ultimate loads and moment-rotation curves were obtained. The test results reveal that under elevated temperatures, the failure modes of AAG joints remain the same as those under ambient temperature. For thin gusset plate joint specimens, the failure modes are block tearing rupture and local buckling of the gusset plate; for thick gusset plate joint specimens, the failure mode is flexural-torsional buckling failure of the beam. Based on the analysis of the test results, the reduction factors at elevated temperatures of the ultimate moment and the initial stiffness were derived. The specimens were simulated using ABAQUS software, and the FE models were verified through comparison between the FE and experimental results. The research resuhs reveal that the joint zone can remain safe at temperatures under 300 ~C if the gusset plate is thick enough. At temperatures under 300 ℃, the reduction factor of block tearing capacity and local buckling capacity can be taken as the elevated-temperature reduction factor of the nominal yield strength of aluminum alloy, and the initial stiffness of the AAG joint can be conservatively taken as that of the joint under room temperature.