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

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.