Safety of the Models for Assessment of Punching Resistance of Flat Slabs with Openings Adjacent to the Columns

Abstract

The paper deals with the quality of the current EC2 (2004) model for predicting punching capacity of flat slabs without transverse reinforcement, supported by elongated columns and weakened by two openings placed adjacent to the column. The ratio column’s section height/effective depth of a slab was six. The reference punching capacities were obtained from non-linear analyses carried out on the flat slab fragments. Five different arrangements of the openings were tested with three models that take into account an effect of the openings on the punching resistance. Based on the investigation performed, it was observed that the length 3d of the effective part of a column perimeter along the column height h with the ratio h/d > 3 is very conservative. The whole control perimeter contributed to the punching capacity for all slab fragments tested. Current design model EC2 (2004) is safe in the case of predicting the punching capacity of flat slabs with openings adjacent to the columns if the standard method of reduction of the control perimeter lengths due to openings is used. The most consistent results provided method that is based on the Augustin's proposal for reduction of the control perimeter length.