Failure mechanism and resistance predictions for one-way slabs in transition between shear and punching coupling linear elastic finite element analyses with critical shear crack theory-based models

Linear elastic finite element analyses (LEFEAs) have become more frequent in the design and assessment of reinforced concrete slabs under concentrated loads, as they enable low-cost evaluation of the distribution of shear forces over critical sections. However, few publications have addressed the benefits of combining LEFEA with mechanical-based models to predict the most critical shear failure mechanism and the corresponding shear and punching capacities. Notably, most previous studies employed a similar approach for a specific boundary condition or evaluated only the one-way shear capacity of slabs under concentrated loads near line supports. This study investigates the accuracy of the expressions based on the critical shear crack theory (CSCT) combined with LEFEA to assess the shear and punching capacity of one-way slabs under concentrated loads. Since such slabs may develop different failure mechanisms, this study also evaluates the level of accuracy to predict the governing shear failure mechanism identified in the tests, a topic rarely discussed until now. For this purpose, a dataset of 112 experiments was selected, covering different boundary conditions and loading arrangements. LEFEA was used to evaluate the uneven distribution of shear forces and bending moments on the critical shear regions. Some outputs from LEFEA were used in the analytical calculations with the CSCT-based expressions to predict the shear and punching capacity of such tests. The use of LEFEA also aided in understanding the change of shear failure mechanisms according to parameters such as the member width to load size ratio b_slab/l_load and the shear slenderness a_v/d_l. The combination of the CSCT expressions with the LEFEA allows for predicting the governing shear failure mechanism and the shear capacity of the slabs for most tests accurately at a low computation cost. When the governing failure mechanism was not correctly identified, a conservative estimate of the shear capacity was provided, which is desirable in such cases.