Experimental and numerical assessment of the shear strengthening effectiveness of hybrid composite plates in reinforced concrete beams

Abstract

This paper presents numerical and experimental studies on the performance of Hybrid Composite Plates (HCPs) as a shear strengthening technique for reinforced concrete (RC) beams. A HCP is a thin plate of Strain Hardening Cementitious Composite (SHCC) reinforced with Carbon Fiber Reinforced Polymer (CFRP) laminates applied according to the Near Surface Mounted technique (NSM). Due to the excellent bond conditions between SHCC and CFRP laminates, these reinforcements provide the necessary tensile strength capacity to the HCP. However, the shear behavior of SHCC material has not been yet fully understood due to lack of an appropriate and accurate direct shear test method. To characterize the behavior of SHCCs in shear, the Iosipescu shear test setup was used to test several specimens, in which the loads were applied in an antisymmetric four point bending configuration to assure a pure shear section. A special geometry for the specimens was chosen to assure a uniform shear stress distribution in the pure shear section. A numerical model is presented for predicting the strengthening effectiveness of HCPs in reinforced concrete beams. The numerical simulations were performed on FEMIX, a computer program that includes a shear crack softening law to simulate the stress transfer mechanism at the shear crack as the crack widens. The values of the parameters that define the shear crack softening law were derived based on simulations of Iosipescu shear tests performed as part of this study. The results of the numerical models for the reinforced concrete beams strengthened with HCPs are compared with the experimental data obtained for this beams. It is demonstrated that the numerical model can predict fairly well the behavior of reinforced concrete beams strengthened with HCPs.