免拆UHPC模板RC梁受弯性能试验及承载力分析

对4根免拆超高性能混凝土(UHPC)模板钢筋混凝土(RC)梁和2根RC梁进行了受弯性能试验,试件变化参数为配筋率和保护层厚度,重点研究免拆UHPC模板RC梁的受力性能以及模板与后浇混凝土的剥离情况。结果表明:从开始加载到峰值荷载点,免拆UHPC模板与后浇混凝土界面没有发生任何滑移及剥离;峰值荷载后至构件破坏时,预制UHPC模板与后浇混凝土界面出现轻微剥离;免拆UHPC模板RC梁的开裂荷载较普通RC梁提高了近50%,屈服荷载、极限荷载提高约为10%。基于截面平衡条件、平截面假定以及UHPC、混凝土、钢筋的本构关系,建立了免拆UHPC模板RC梁的受弯承载力计算公式,公式计算值与试验值吻合较好。

FLEXURAL BEHAVIOR AND CAPACITY ANALYSIS OF RC BEAMS WITH PERMANENT UHPC FORMWORK

Four reinforced concrete(RC) beams with pre-fabricated permanent ultra-high performance concrete(UHPC) formworks and two RC beams were tested for flexural behavior. The reinforcement ratio and thickness of concrete cover were varied. The mechanical properties of pre-fabricated UHPC formwork RC beams and the interface bonding performance between UHPC formwork and post-cast-in-place concrete were mainly studied. The results show that when the load reached the peak value, no slip was observed on the interface between the prefabricated UHPC formwork and the post-cast-in-place concrete. The interface between the pre-fabricated UHPC formwork and the post-cast-in-situ concrete was slightly debonded after the peak load. Cracking load of prefabricated UHPC formwork RC beams increased by approximately 50%, and the yield load and ultimate load increased by about 10%, compared to that of standard RC beams. A flexural capacity calculation model of the pre-fabricated UHPC formwork RC beams was established based on the section balance condition, the assumption of plane section and the constitutive relation amongst UHPC, plain concrete and the reinforcement. The calculation results of flexural capacity agreed well with the experimental results.