PEC柱-型钢梁框架中节点抗震性能试验研究

为研究部分包裹混凝土(PEC)柱-型钢梁框架中节点的抗震性能,以端板厚度、柱翼缘宽厚比以及是否增设背垫板为参数,对4榀焊接H形钢部分包裹混凝土柱-型钢梁框架中节点进行低周反复荷载试验,分析其破坏模式、承载力、滞回性能及延性等。并以此为基础,建立有限元拓展模型。试验和有限元结果表明:各节点滞回曲线均为饱满的梭形;节点处梁翼缘、腹板变形明显,节点域出现塑性铰;端板厚度由18 mm增加到24 mm,节点承载力提升7.1%;柱翼缘宽厚比由8减小到6,节点承载力提升17.3%;增设背垫板后,节点承载力提升14.2%;加载过程中节点刚度退化稳定,屈服后承载力退化系数约为0.9;节点位移延性系数介于3.72～5.34之间,等效黏滞阻尼系数介于0.537～0.619之间;节点破坏时,层间位移角介于1/26～1/24之间,变形性能满足抗倒塌设计要求。基于节点受力分析,建立节点域抗剪计算模型,提出PEC柱-型钢梁框架中节点受剪承载力计算公式,计算结果与试验值及有限元模拟结果较为吻合。

Experimental research on seismic performance of PEC column-steel beam frame interior joints

To investigate the seismic behavior of partially encased concrete （PEC） column-steel beam frame interior joints and analyze its seismic performance such as failure mode, bearing capacity, hysteresis performance and ductility, low-cycle reversed loading tests were conducted on four specimens. The end-plate thickness, width-thickness ratio of column flange, and backing plate were the design parameters. Based on the test, the finite element spreading model was established. The test and FEA results indicate that the hysteresis curves of joints all have a full shuttle type. At the joint, the flange and the web of the beam have obvious deformation, and the plastic hinge occurs at the beam end. As the end-plate thickness increases from 18mm to 24mm, the ultimate bearing capacity of the joint rises by 7.1%. When the width-thickness ratio of the column flange is reduced from 8 to 6, the ultimate bearing capacity of the joint is increased by 17.3%. By adding the backing plate, the ultimate bearing capacity of the joint rises by 14.2%. During the loading process, stiffness degradation of the specimen is stable, and the bearing capacity degradation coefficient after yielding is about 0.9. The displacement ductility ratios of joints are between 3.72 and 5.34, and the equivalent viscous damping coefficients are between 0.537 and 0.619.When the specimen is damaged, the inter-story drift ratio is between 1/26 and 1/24, and the deformation performance meets the requirements of anti-collapse design. Based on the force analysis of the joints, the joint region shear calculation model was established, and the calculation formula for the shear capacity of the PEC column-steel beam frame interior joints was proposed.The calculated results are in good agreement with experimental values and finite element simulation results.