防屈曲可更换伸臂桁架弦杆抗震性能试验研究

EXPERIMENTAL RESEARCH ON SEISMIC PERFORMANCE OF BUCKLING RESTRAINED REPLACEABLE CHORD IN OUTRIGGER

为提高伸臂桁架弦杆的延性变形能力和震后可修复能力,提出了一种防屈曲可更换伸臂桁架弦杆。为研究上述新型弦杆的可行性和可靠性,采用1∶3的缩尺比例,设计制作了1个传统削弱式截面(reduced beam section,RBS)弦杆和2不同构造形式的新型防屈曲可更换弦杆,开展了拟静力低周往复加载实验。对新型弦杆的变形能力、承载力、刚度、耗能能力等进行了分析,结果表明:传统RBS弦杆在轴压的作用下,屈曲后承载力和刚度退化快;新型弦杆通过外置RBS板材实现了损伤集中控制,通过防屈曲盖板有效抑制RBS板材的屈曲行为,避免了传统RBS弦杆的屈曲现象,其平均延性系数约为传统RBS弦杆的2倍,满足了新型弦杆在压-弯-剪耦合作用下的延性变形需求。该研究成果可为高性能伸臂桁架的发展完善提供参考。

To improve the ductility and post-earthquake repair capacity of the chord in outriggers,a buckling restrained replaceable chord was proposed.To validate the feasibility and reliability of this new chord,three types of 1/3 scaled chords,including one conventional chord with reduced beam section(RBS)and two new buckling restrained replaceable chords with different construction details,were tested through pseudo-static experiments.The corresponding deformation,strength,stiffness and energy dissipation capacities were compared and analyzed.The results indicate that conventional chord exhibits a severe degradation of strength and stiffness after buckling under the axial compressive load.As for the proposed chords,the damage is successfully controlled and concentrates in the external RBS plates,and the buckling of RBS plates is effectively prevented by the buckling restrained plates,thus avoiding the buckling of flanges in the chord.The average ductility coefficient reaches twice of that of conventional chord,which satisfies the ductility demand under the compression-bending-shear interaction.The research outcome can provide a reference for the development of high-performance outrigger.