高温后套筒灌浆连接大变形反复拉压力学性能研究

STUDY ON MECHANICAL BEHAVIORS OF POST-FIRE GROUTED SLEEVE CONNECTIONS UNDER LARGE STRAIN OF CYCLIC LOADING

套筒灌浆连接是预制混凝土结构当前钢筋连接的主要方式之一。基于套筒受力状态不明的问题,考虑高温作用的影响以及抗震需要,开展高温后(最高温度600℃)套筒灌浆连接试件的大变形反复拉压试验研究,探讨套筒应力分布与连接力学性能发展规律。当套筒灌浆料抗压强度为61.3 MPa时,试验结果表明:套筒环向处于弹性状态,但其中部的纵向将进入弹塑性受力状态;套筒灌浆连接试件失效模式由套筒外钢筋断裂转向钢筋与套筒灌浆料界面粘结滑移失效的关键温度为400℃;相对常温值,高温后试件的峰值载荷与峰值位移分别下降约为12%与17%。

Grouted sleeve connection is one of the main measures for steel rebar splicing of precast concrete structures at present.Aimed to figure out the stress state of sleeve,a post-fire grouted sleeve connection experiment with 12 specimens under large strain of cyclic loading was exerted to investigate the stress distribution development of sleeve and mechanical behaviors of the specimens by taking the elevated temperature and earthquake into account.There were lots of findings when the compressive strength of grout was 61.3 MPa as follows:the sleeve is in elastic state in the circumferential direction and elastic-plastic state in the longitudinal direction in the middle of the sleeve;the crucial temperature is 400℃ when the failure pattern of post-fire specimens changes from rebar fracture outside the sleeve to the bond slip failure between grout and steel rebar;compared to the values at ambient temperature,the peak load and peak displacement of the post-fire specimens decrease about 12% and 17% respectively.