Study On The Punching Shear Capacity Of Reinforced Concrete Flat Slab

The flat slab structure is also called as slab-column structure, which have goodeconomic advantage of effectively reduced storey, and can take full use of the clearheight room. However, such a good structure is not widely used in our country. Thereason is that punching failure is more likely to occur in this kind of structure. Becauseof the stress distribution complexity of the slab-column connections, designers do notknow how to avoid punching failure effectively, which restrict the application of flatslab structure in China. At the same time, the calculation method of several nationalbuilding codes is different, the punching failure mechanism is still not clear yet, so thefurther study is necessary.In this dissertation, punching failure is the center of the research, the study ofinfluencing factors and punching failure mechanism of the flat slab is discussed basedon results obtained with comparison of different codes, and elastic-plastic numericalsimulation. A comparison of punching shear capacity calculation methods was studiedbased on code: GB50010-2010, ACI318-08and EN1992-1-1:2004. The effects ofdifferent influencing factors such as the concrete strength, shape of loading area,longitudinal reinforcement ratio, anti-punch reinforcement placing was discussed.According to423international and domestic experimental results, calculation valuesand experimental values of the punching failure capacity were compared and analyzedamong different codes, then, doing the non-linear fitting, obtained the relationshipbetween different influencing factors and capacity. The results indicate that because ofthe consideration of longitudinal reinforcement ratio in Europe code, the calculationcapacity of Europe code is more reasonable, and is the highest one. The lowest one isChina code. Then using ABAQUS software to simulate punching capacity of the concrete slab, from the result of slab surface stress shows that destruction of slab startfrom the bending moment, then the oblique maximum principal tensile stressconcentration area in the slab’s cross section stress cloud illustrates the punching failureis a kind of diagonal tension failure. At the same time, assess the accuracy of calculationmethod of punching failure capacity in2010new China concrete structure design code,and proposing suggestion for modifications. By introducing the rate of longitudinalreinforcement in punching shear capacity calculation method, the distributions ofrevised calculation results become more reasonable, the ratio of calculated results andexperimental values also were improved.