装配式高架桥结合面抗剪性能试验研究

Experimental Research on Shear Performance of Joint Interface in Prefabricated Viaducts

采用湿接缝连接的分节段施工是解决大体积预制混凝土高架桥构件运输、安装困难问题的最有效方法之一。为研究湿接缝处结合面的抗剪性能,考虑结合面连接筋、混凝土强度等级、结合面处理工艺等因素的影响,设计了4组12个试件进行双剪试验,并采用最小二乘法对扩展剪切摩擦理论公式中的结合面处理工艺机械咬合力系数c进行了拟合。研究结果表明:结合面的处理工艺对试件的抗剪承载能力有较大影响,露骨料组试件、止浆带组试件和凿毛组试件的承载力分别约为整浇组试件的92.7%~94.1%、82.7%~86.7%和66.7%~71.1%;结合面连接筋可以显著提高试件的延性、抗剪承载力和抗裂性,承载力提升幅度约为47.3%~65.0%;当试件达到极限状态时,结合面连接筋应变分布不均匀,所有连接筋的平均应变约为屈服应变的50%;各国规范的抗剪极限承载力计算值均远低于本次试验值,具有较高的富余度;所拟合的相关参数,可为工程应用提供参考。

The segmented construction with wet joints is one of the most effective methods to solve the transportation and installation difficulties of large prefabricated concrete viaduct components.To study the shear performance of the joint surface at the wet joint,four groups of 12 specimens were designed for double shear tests,taking into account the effects of reinforcement,concrete strength grade,joint surface roughing process,and other factors.The mechanical bite force coefficient c of the joint interface roughing process in the extended shear friction theory formula was fitted by using the least squares method.The research results showed that the joint surface roughing process had a significant influence on the shear bearing capacity of the specimens.The bearing capacity of the specimens with exposed aggregate,plastering strip,and chiseling surface roughing treatment were approximately 92.7%to 94.1%,82.7%to 86.7%,and 66.7%to 71.1%of that of the monolithic specimens,respectively.The connecting rebars of joint surface could significantly improve the ductility,shear bearing capacity,and crack resistance of the specimens,and the increase in bearing capacity was about 47.3%to 65.0%.When the specimens reached the ultimate state,the strain distribution of the connecting rebars of joint surface was uneven,and the average strain of all the rebars was about 50%of the yield strain.The calculated values of the shear bearing capacity of various country codes were much lower than the test values,indicating a high safety margin.The fitted parameters could provide a reference for engineering applications.