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通过7个配置HRB500钢筋和3个配置HRB400钢筋Z形试件的推剪试验,得到了新旧混凝土结合面的荷载-滑移曲线和荷载-钢筋应变曲线,分析了结合面处理方法、抗剪钢筋强度及其配筋率对结合面受剪承载力的影响,并对比了按各国规范公式的计算值与试验值。试验研究结果表明:在直剪作用下,试件出现了结合面剪切破坏和试件侧边混凝土冲切破坏两种破坏形态;达到第一峰值荷载时,结合面的滑移量均小于1 mm且抗剪钢筋应变均大于2.0×10-3,而当结合面滑移量达到2.0 mm时,HRB500钢筋均能屈服;键槽面试件的受剪承载力高于粗糙面试件;对结合面剪切破坏的试件,结合面的受剪承载力随结合面配筋率的增大而增大;假定HRB500钢筋屈服,按规程JGJ 1—2014公式计算的受剪承载力均明显小于试验值。利用试验数据,在规程JGJ 1—2014计算公式的基础上,提出了考虑粗糙面有利影响的修正建议。
The load-slip curve and load-strain curve of the old-new concrete joint surface were obtained by the shear test of 7 HRB500 steel bars and 3 HRB400 steel bars. The effects of the joint surface treatment method, shear reinforcement Strength and reinforcement ratio on the shear capacity of the joint surface, and compared the calculated values and test values according to the national standard formula. The experimental results show that under the action of direct shear, the test specimens have two failure modes, shear failure on the bond surface and blank punching failure on the specimen side. When the first peak load is reached, the slip of the bond surface is less than 1 mm and the shear strains of rebar are both greater than 2.0 × 10-3. When the joint slip reaches 2.0 mm, the HRB500 rebar can yield. The shear strength of the keyway specimen is higher than that of the rough specimen. Shear test specimens, the shear bearing capacity of the joint surface increases with the reinforcement ratio of the joint surface; Assuming HRB500 steel yielding, the shear capacity calculated according to the formula JGJ 1-2014 formula are significantly smaller than the experimental value. Based on the calculation formula of JGJ 1-2014 according to the test data, a correction proposal considering the favorable influence of rough surface is proposed.