设置锚筋的新老混凝土结合面抗剪机理及黏结强度计算  

SHEAR MECHANISM AND BOND STRENGTH CALCULATION OF NEW-TO-OLD CONCRETE INTERFACE WITH ANCHOR BARS

作　　者：林拥军[1] 徐文强 张显昭 刘开齐 LIN Yongjun;XU Wenqiang;ZHANG Xianzhao;LIU Kaiqi(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学土木工程学院,成都610031

出　　处：《工业建筑》2021年第6期72-83,共12页Industrial Construction

基　　金：中国-印尼高铁技术联合研究中心(KY201801005);国家自然科学基金项目(51778532)。

摘　　要：设置锚筋的新老混凝土结合面与不设锚筋的新老混凝土结合面的剪切黏结性能有很大的不同,现有新老混凝土黏结强度计算式大都是基于剪切摩擦理论或者是对试验数据进行拟合得到的,不同国家的混凝土结构设计规范也给出了各自的抗剪强度计算式。基于已有的85组设置锚筋的新老混凝土结合面抗剪试验结果对现有典型算式适用性进行验证,结果表明:采用这些方法要么过于保守,要么会导致结构不安全。根据设置锚筋的新老混凝土结合面的受力特点,建立了结合面剪切受力弹簧-摩擦块模型,结合已有剪切试验荷载-滑移曲线,深入分析了结合面全过程剪力传递机理。分析结果表明:结合面抗剪承载力可分为混凝土结合面胶结力、键槽咬合力、钢筋的销栓作用力及摩擦力四部分。在对这四部分的计算方法进行理论分析的基础上,提出了设置锚筋的新老混凝土结合面的抗剪黏结强度计算式。采用已有的20组试验数据对所提出的结合面抗剪黏结强度计算式的适用性进行了验证,试验值与计算值比值的均值为1.182,标准差为0.305,与已有计算方法的对比分析表明,所提出的算式计算结果与试验结果最为吻合,离散性较低。The shear bond performance of new-to-old concrete interface with anchor bars is different from that of new-to-old concrete interface without anchor bars.The existing calculation equations for the shear strength of new-to-old concrete interface are mostly based on shear friction theory or fitting the test data.The concrete structure design codes for different countries also propose their shear strength calculation formulas.A total of 85 test data of new-to-old concrete interface with anchor bars were used to verify the applicability for the existing typical recipes.The results showed that these methods were either too conservative or lead to structural unsafe.According to the stress characteristics of the new-to-old concrete interface with anchor bars,the spring-friction block model for the shear transfer of new-to-old concrete interface with anchor bars was established.Meanwhile,the mechanism of shear transfer in the whole process of the interface was thoroughly analyzed by combining with the existing shear test load-slip curve.The results indicated that the shear bearing capacity of new-to-old concrete interface with anchor bars could be divided into four parts:the cohesive force of the new-to-old concrete interface,the mechanical occlusal force of groove,the pin bolt force of anchor bars,and the friction force.Based on the theoretical analysis of the calculation methods of four parts,the calculation formula for the shear strength of new-to-old concrete interface with anchor bars was proposed.The applicability of the proposed formula for calculating the shear bond strength of new-to-old concrete interface with anchor bars was verified by using 20 sets of test data.The average value and standard deviation of the ratio of experimental value to the calculated value were 1.182 and 0.305,respectively.Compared with the existing calculation methods,it was shown that the calculated results of the equation proposed in the paper were in the best agreement with the experimental results,and the discreteness was relatively l

关 键 词：新老混凝土结合面 锚筋 弹簧-摩擦块模型 抗剪机理 黏结强度 

分 类 号：TU528[建筑科学—建筑技术科学]