Verification of the Effect of Concrete Overlay for Strengthening Flat Slabs against Punching

Abstract

This article aims to verify the possibility of strengthening existing flat slabs against punching by concrete overlay and the effectiveness of this type of strengthening. The method of strengthening by concrete overlay was verified on a theoretical level using the currently valid Eurocode 2 and other standards. A non-linear analytical model was developed in Atena 3D software, and the results of this model were compared with previous results from calculations according to the valid standards. The article also contains previous research results of Hugo Fernandes, who dealt with a similar type of strengthening method and this research was also based on experimental study. An important aspect is the detailing of the interface between the two concrete layers namely the roughening the existing surface or the use of studs, which ensure a minimum longitudinal displacement of the two layers. Two non-linear model approaches were presented. The results based on nonlinear analysis show that when using a simple model of two macroelements and defining the parameters of one interface, the punching shear resistance is higher than the actual resistance, in this case by of about 13% on the dangerous side.