Shear strengthening of reinforced concrete beams with hybrid composite plates

Abstract

The effectiveness of Hybrid Composite Plates (HCPs) for the shear strengthening of the Reinforced Concrete (RC) beams was assessed by an experimental program. HCP is a thin plate of Strain Hardening Cementitious Composite (SHCC) reinforced with Carbon Fiber Reinforced Polymer (CFRP) laminates. Due to the excellent bond conditions between SHCC and CFRP laminates, these reinforcements provide the necessary tensile strength capacity to the HCP. Two HCPs with different inclination of CFRP laminates (45º and 90º) were adopted for the shear strengthening of RC beams by bonding these HCPs to the lateral faces of the beam with an epoxy adhesive. The results showed that these HCPs have assured a significant increase in terms of load carrying capacity, mainly those with inclined laminates. The SHCC surrounding the CFRP laminates in the HCP has offered effective resistance to the degeneration of micro-cracks on macro-cracks, which has avoided the occurrence of premature mixed shallow semi-pyramid-plus-debonding failure modes registered currently when using the NSM-CFRP technique. Advanced numerical simulations were performed by using a FEM-based computer program, whose predictive performance was demonstrated by simulating the experimental tests carried out. In this context a parametric study was executed to evaluate the shear strengthening efficiency of the arrangement and percentage of CFRP laminates in HCPs, as well as the influence of using mechanical anchors to avoid premature detachment of the HCPs.