On the distribution of shear forces in non-axisymmetric slab-column connections

Abstract

The majority of punching tests, based on which the provisions for slab-column connections in design codes are developed, were performed on symmetric test specimens where the support reaction was centric with respect to the supported area. However, most slab-column connections in practice are subjected to asymmetric loading. This may lead to non-uniform distribution of bending moments, deformations and shear forces on a control perimeter around the column or transfer of bending moments between the slab and the column. A non-linear finite element approach was developed in this research to investigate the distribution of internal forces around the columns in non-axisymmetric connections. The focus of this paper is on analyzing the interaction between redistributions of bending moments and shear forces while maintaining the equilibrium of internal forces in the slab. Selected test specimens from the literature were modelled with different types of asymmetric loading. The modelling results show that shear redistribution along the perimeter of the connection, which would lead to a more uniform shear distribution, is possible only in certain cases depending on the bending moments and flexural capacity of the slab. It is also shown that uneven distribution of shear forces can also occur in connections with no eccentricity, being related to the non-linear flexural behavior of the slab. The results obtained from the analyses are compared to the approaches suggested in the design codes or by other authors.