高强混凝土新旧结合面抗剪性能试验

Experimental Investigation on Interface of High Strength Concretes Cast at Different Times Under Direct Shear

摘要:

进行了11个标号C80和4个标号C40混凝土试件的单调推剪试验，得到了结合面破坏形态、剪力滑移曲线和剪力抗剪钢筋应变曲线，分析了混凝土强度、结合面配筋强度和结合面类型对结合面抗剪性能的影响.收集了32组国外试验数据，对比了高强混凝土结合面受剪承载力试验值与国内外相关标准的计算值.研究结果表明：试件出现了结合面剪切和试件混凝土冲切两种破坏模式；粗糙面C80试件的结合面受剪承载力小于C40试件，键槽面试件的结合面受剪承载力高于粗糙面试件；结合面的受剪承载力与配筋强度成正比；按照我国《装配式混凝土结构技术规程：JGJ 1—2014》公式计算的C80试件受剪承载力与试验值之比在0.33~0.72之间，且相比于国际结构混凝土协会、美国和欧盟规范，我国规程计算公式偏保守.利用试验数据，经回归分析，提出了高强混凝土新旧结合面受剪承载力修正建议计算公式.

关键词:新旧混凝土结合面; 受剪承载力; 推剪试验; 高强混凝土; 高强钢筋

Abstract:

In this paper, the monotonic directshear tests composed of eleven C80 and four C40 concrete pushoff specimens were conducted. The failure patterns of specimens, loadslip relation curves, and loadrebar strain relation curves were obtained. The experimental results were analyzed in terms of concrete strength, interface shear rebar strength, and interface types. Afterwards, 32 sets abroad results of interface shear capacity were compared with calculated values using relevant standards at home and abroad. It is found that two failure patterns occur, specifically the interface shear failure and concrete punch failure. The load of C80 specimens with rough interfaces at their first peaks are lower than those of C40 specimens. Moreover, the load values of specimens with shear keys are larger than those with rough interfaces, and the load increases with interface rebar strength. The ratio of capacity calculated by JGJ 1 and test results is between 0.33 and 0.72. Compared with MC2010, ACI318 and EN1992, JGJ 1 is more conservative. Based on the test results, regression analysis was finished and a modification suggestion calculation formula aimed at interface between high strength concretes was presented.

Key words:interface between concretes cast at different times; shear capacity; pushoff test; high strength concrete; high strength rebar