Experimental Study On Punching Shear Failure Of Reinforced Concrete Slabs-column Connection

As society progressed, people began to put forward higher requirements on the interior space, traditional structure has been unable to satisfy people need. Flat slab structure provides people with more possibility, but as the force transmission path and stress state are different from the traditional structure, it is very necessary to study the failure patterns again. Many researchers investigated the parameters of shear resistance of slab-column joint, but they had not agreement on the effect of reinforcement and concrete strength on shear resistance of slab-column connections, especially with the broadest application of high strength concrete, many design methods cannot well reflect the effects of these parameters on slab-column connections punching capacity.Therefore, many researchers proposed various types’ mechanism models, for example, the rigid-plastic model, the critical shear crack theory, strain-based strength model and Carl Erik Broms model, and so on. Due to above models are all based on different assumptions, calculation methods are also different. Many scholars still can not propose a unified analysis method, so most national design criterions are based on empirical equations, which leads the result dispersion. Based on this, a total of 5 two-way slabs are tested, testing failure state, crack state, load-deflection curves and load-strain curves, and the similar 4 test slabs are quoted to compare failure patterns in different concrete strength(C30,C50,C70), longitudinal steel ratio(0.86%,1.28%,1.73%), especially for the high strength concrete slabs.In this article, the punching shear capacity of 5 test slabs and another 4 test slabs are calculated by simplified rigid-plastic model, the critical shear crack theory, strain-based strength model and Carl Erik Broms model, compared to the test results. Besides, the punching shear capacity of 9 test slabs are also computed with Tian, Yi,and H.M. Elsanadedy formula, ACI318-11, Euro Code2-2004, fib Model Code 2010 and GB50010-2010. At last, selecting 52 test slabs which are similar to this test in size, steel ratio and concrete strength, and the punching shear capacity of them are calculated to evaluate the accuracy and dispersion by above methods.