装配式混凝土框架顶层端节点抗震性能试验

Experimental Investigation on Seismic Performances of Knee Joints for Monolithic Precast Concrete Frame

摘要:

进行了5个配置500 MPa级纵筋框架顶层端节点试件的低周反复加载试验，研究了采用两种新型构造的装配整体式混凝土框架顶层端节点的破坏形态、滞回曲线、骨架曲线和位移延性等抗震性能及承载力，并提出了柱端无上伸节点的斜截面受弯承载力计算方法.结果表明：装配式试件均发生了梁端受弯破坏，且集中在梁端结合面较小范围内，但梁水平叠合面未见开裂；装配式试件的滞回曲线相对现浇试件更为饱满，其位移延性和耗能能力均优于现浇试件；装配式试件的位移延性系数为2.54~3.66，极限位移角为1/29~1/26，且柱端无上伸试件的延性略优于柱端上伸试件；装配式试件的极限承载力比现浇试件平均约低10%，但其极限承载力计算值与试验值之比平均为0.62~0.71，仍具有较高的安全储备.

Abstract:

Five full-scale knee joints of concrete frame with HRB500 reinforcements were designed，and pseudostatic tests were conducted. Seismic performances of two new kinds of precast knee joints were investigated. Failure patterns, hysteretic loops, skeleton curves, displacement ductility, energy dissipation capacity, and ultimate bearing capacity were analyzed. Besides, the calculation method of bending bearing capacity of inclined section in knee joint were proposed. The results indicated that all the precast specimens were subjected to bending failure in the small range of the beam end. There was no crack on the combined interface of frame beams. Compared to the castinsitu joint, the precast joints had a greater displacement ductility coefficient and the hysteretic loops were chubbier. The displacement ductility coefficient and ultimate displacement angle of precast joints were from 2.54 to 3.66 and 1/29 to 1/26 respectively. The ductility of specimens without extended column head were greater than that of specimens with extended column head. The average ultimate bearing capacity of precast specimens was about 10% lower than that of the castinsitu joint, while the ratio of calculation value to experimental value was from 0.62 to 0.71, still having a high safety degree.