New method for prediction of punching resistance of flat slabs with shear reinforcement and its comparison with recently proposed code provisions

Abstract

The use of flat slabs in constructions is wide-spread due to its many functional and economic advantages. Behavior of flat slabs in shear and flexure is a complex problem and over the last decades several buildings have collapsed due to the failure of the punching shear strength, resulting in loss of lives and financial damages. These disasters revealed gaps in the current (or former) design codes and recommendations. A new method for predicting the punching shear strength of flat slabs with shear reinforcement has been developed. This method incorporates a simple system of struts and ties within the shear crack region while utilizing the current Eurocode 2 model for predicting the punching shear strength without shear reinforcement. The accuracy and safety of predictions of the newly developed method were evaluated against some of the major design codes and standards. Specifically, it was compared with the current Eurocode EN 1992, with the final proposition of the newly proposed Eurocode FprEN 1992, and with the method presented in Model Code 2020. This comparison was carried out using experimental data from load tests on flat slab specimens with shear reinforcement that were published in the scientific literature over the last half of a century. The newly developed method achieved the lowest coefficient of variation among all the compared methods while also obtaining the fewest prediction results that could be deemed unsafe due to overestimation of punching shear resistance.The use of flat slabs in constructions is wide-spread due to its many functional and economic advantages. Behavior of flat slabs in shear and flexure is a complex problem and over the last decades several buildings have collapsed due to the failure of the punching shear strength, resulting in loss of lives and financial damages. These disasters revealed gaps in the current (or former) design codes and recommendations. A new method for predicting the punching shear strength of flat slabs with shear reinforcement has been developed. This method incorporates a simple system of struts and ties within the shear crack region while utilizing the current Eurocode 2 model for predicting the punching shear strength without shear reinforcement. The accuracy and safety of predictions of the newly developed method were evaluated against some of the major design codes and standards. Specifically, it was compared with the current Eurocode EN 1992, with the final proposition of the newly proposed Eurocode FprEN 1992, and with the method presented in Model Code 2020. This comparison was carried out using experimental data from load tests on flat slab specimens with shear reinforcement that were published in the scientific literature over the last half of a century. The newly developed method achieved the lowest coefficient of variation among all the compared methods while also obtaining the fewest prediction results that could be deemed unsafe due to overestimation of punching shear resistance.