预制混凝土叠合板钢筋黏结性能的研究

Study on Bond Behavior of Steel Bar in Precast Concrete Composite Slabs

通过钢筋的拉拔试验研究了预制混凝土叠合板内钢筋的黏结性能。设计30个预制板与后浇混凝土的叠合板试件,主要研究混凝土强度、钢筋锚固长度、钢筋位置、钢筋直径四个因素对黏结性能的影响。并设计12个混凝土现浇试件作为对比,以研究两种试件钢筋与混凝土黏结强度的差异。试验结果表明:叠合试件发生剥离破坏和劈裂-剥离破坏,现浇试件均发生劈裂破坏;叠合试件内钢筋的黏结强度随钢筋直径和锚固长度的减小、混凝土强度和钢筋至预制板距离的增大而增大,并且明显小于现浇试件中钢筋的黏结强度。根据试验结果,统计回归出预制混凝土叠合板钢筋的极限黏结强度计算公式,并由此推出钢筋锚固长度的计算公式以指导工程应用。

This paper investigates the bond behavior of steel bars in precast concrete composite slabs through pull-out tests. A total of 30 specimens representing steel rebars embedded in precast concrete composite slabs were prepared for evaluating the influences of concrete strength, anchorage length, embedded location and rebar diameter on bonding strength of the rebars. For comparison purpose, another 12 specimens of the steel rebars embedded in cast-in-place concrete were also tested. Test results show that the rebars embedded in precast concrete composite slabs either exhibit debonding failures or cause splitting failures in the surrounding concrete while the rebars embedded in cast-in-place concrete consistently failed due to splitting failures of the concrete. Additionally, it is found that bonding strength of the rebars embedded in precast concrete composite slabs increases when the rebar diameter and anchorage length reduce. Moreover, bonding strength of the rebars embedded in precast concrete composite slabs tends to be higher when concrete strength is higher and the distance between steel rebars and precast panels becomes larger. Further, test results reveal that bonding strength of the rebars embedded in precast concrete composite slabs is remarkably lower than that of the rebars embedded in castin-place concrete. Based upon regression analysis of the test data, an analytical model was proposed for calculating bonding strength of the rebars embedded in precast concrete composite slabs. The model can be used to determine the required anchorage length of the rebars embedded in cast-in-place concrete in design.