装配式结构新旧混凝土新型接缝力学性能试验

EXPERIMENTAL RESEARCH ON MECHANICAL PROPERTIES OF NEW AND OLD CONCRETE JOINTS OF PREFABRICATED STRUCTURE

装配式桥梁结构中,由于既有的预制桥墩与承台间的承插式连接方式,接缝界面无钢筋穿过,存在黏结性能不足的问题。为此,提出一种新型界面连接形式,即界面预埋分布式钢纤维的连接技术。为研究此新型接缝对新旧混凝土界面黏结性能的影响,分别设计双面剪切试验和轴心拉伸试验,制定6种试验工况,包括素混凝土整体浇筑、钢筋混凝土整体浇筑、C40-C40界面凿毛连接、UHPC-C40界面凿毛连接、UHPCC40界面预埋波浪型或端钩型钢纤维连接,测试界面的抗剪、抗拉承载力。结果表明:界面预埋钢纤维连接试件的抗剪承载力较凿毛处理和素混凝土整体浇筑有显著提高,最高达到钢筋混凝土整体浇筑的86.5%;预埋钢纤维连接试件的抗拉承载力也明显提高,试件受拉破坏时UHPC-C40界面没有开裂。所得结果初步验证了超高性能混凝土-普通混凝土(UHPC-NC)新旧界面预埋分布式钢纤维工艺可行,并且可有效提高接缝的抗剪强度和抗拉强度。

In the prefabricated bridge structure,the existing socket connection between the prefabricated pier and the bearing platform has no reinforcement passing through the joint interface,which has the problem of insufficient bond performance.In the paper,a new type of interface connection was proposed,namely the interface embedded distributed steel fiber connection technique.In order to study the influence of this new type of joint on the bond performance of new and old concrete interface,double-sided shear test and axial tensile test were designed respectively,and six test conditions were formulated,including integral pouring of plain concrete,integral pouring of reinforced concrete,chiseled connection of C40-C40 interface,chiseled connection of UHPC-C40 interface,embedded wave-shaped/endhook-shaped steel fiber connection of UHPC-C40 interface,and the shear and tensile capacity of the interface were tested.The results showed that the shear bearing capacity of the steel fiber connection specimen was significantly higher than that of the chiseling treatment and the whole pouring of plain concrete,which is up to 86.5% of the whole pouring of reinforced concrete;the tensile bearing capacity of the steel fiber connection specimen was also significantly improved,and the UHPC-C40 interface was not cracked when the specimen was broken.In this paper,the feasibility of embedded distributed steel fiber technique for UHPC-NC new and old interface was preliminarily verified,and the shear strength and tensile strength of the joint could be effectively improved.