NUMERICAL STUDY OF THE PUNCHING SHEAR MECHANISM FOR THIN AND THICK REINFORCED CONCRETE SLABS

Abstract

The assessment of the punching shear capacity for reinforced concrete slabs, carried out according to the regulatory documents of a number of countries, leads to significantly various results. At the same time, the results of the calculated forecast may have great differences from the experimental data. A great influence on the accuracy of the results of the calculated forecast is exerted by the thickness of the examined slabs, as well as the value of longitudinal reinforcement. These parameters determine the features of the mechanisms of destruction of slabs in case of the punching shear mechanism, as indicated by individual interpretations of the results of experimental studies. In order to determine the features of the punching shear mechanism of reinforced concrete slabs of various thicknesses, numerical studies of the process of cracking and destruction of slabs of different thicknesses have been performed. Differences in the mechanism of formation and development of cracks in thin and thick slabs are revealed. The paper shows that the behavior of thin and thick slabs has qualitative distinctions at the initial stages of formation and development of the cracks leading to destruction. The authors have also shown the difference between stress-strain state of thick and thin slabs before destruction. In conclusion, it was established that the influence of longitudinal reinforcement on the strength during punching in thick slabs is much less than in thin ones.When evaluating the punching shear capacity of reinforced concrete slabs, the regulatory documents of different countries give significantly different results. In this case, the calculation results may differ significantly from the experimental data. The deterioration of the thickness of the calculated slabs, as well as the value of the longitudinal reinforcement has a great influence on the accuracy of the calculation results. These parameters determine the features of the destruction mechanisms of slabs under punching. This fact is indicated by some interpretations of the results of experimental studies. In order to establish the peculiarities of the punching shear mechanism of reinforced concrete slabs of different thicknesses, a numerical investigation of the cracking and destruction of slabs of different thicknesses have been performed. Differences in the mechanism of formation and development of cracks in thin and thick slabs have been revealed. The paper shows that the behavior of thin and thick slabs has qualitative differences at the initial stages of the cracks formation and development that leads to destruction. The difference between stress-strain state of thick and thin slabs before breaking have been shown. It was found that the effect of longitudinal reinforcement on the punching shear strength in thick slabs is much less than in thin ones.

Keywords

• modeling, numerical methods, design model, stress-strain state, reinforced concrete structures, punching failure