Punching shear of edge column-slab connection subjected to unbalanced moment

Abstract

Abstract Studying flat slabs subjected to high punching shear stresses at edge columns is crucial due to the extra punching shear stresses caused by the unbalanced moments. This paper endeavors to experimentally study the performance of edge column-slab connections, and then compare obtained experimental results with the values calculated based on six different design codes, as well as two proposed methods by other researchers. This study demonstrates the findings from 7 half-scale RC edge connections. The purpose of the experimental program was to investigate punching shear strength and edge-column slab connection behavior. Three groups of test specimens have been considered to investigate the following parameters: the load eccentricity effect, the change in column dimension (dim.) parallel to the unsupported edge (C 2 ) effect, and the spandrel beam effect. Each group included three specimens. The mean compressive strength of the used concrete was 43 MPa, while the slab had a constant flexural reinforcement ratio of 1.5%, and dim. (1.6 × 1.0 × 0.1 m). All the investigated slabs, with the exception of slab S7 (with a large spandrel beam), exhibited failure in the punching shear mode. The test outcomes show that higher eccentricity lowers the ultimate load of the investigated slabs, while enlarging the column dimension (C 2 ) and adding the spandrel beam enhance both the ultimate load capacity and the stiffness of the connection. Increasing the height of the spandrel beam may change the mode of failure for the edge connection. The FIB-MC-2010 code was found to be the closest to the experimental records, while ACI 318 was the most conservative. Additionally, the ECP 203 simplified method and AS-3600 should have additional limitations in their punching shear capacity equations. However, the BS 8110–1:1997 code requires updating.