Effectiveness of a Novel Technique in Strengthening Web-Shear Capacity of Prestressed Hollow Core Slabs Using Externally Bonded FRP Sheets

Abstract

Precast, prestressed hollow-core (PHC) slabs are widely used in floor and roof decks because of their economic benefits. Because no shear reinforcement can be provided because of fabrication restraints, designers have to opt for deeper profile or filling PHC slab cores with concrete when the load demand exceeds the limited concrete shear capacity of PHC slabs. This research project is exploring an innovative technique for strengthening the web-shear capacity of PHC slabs by bonding external fiber-reinforced polymer (FRP) sheets along the internal perimeter of the slab voids. Experimental testing and numerical simulation on full-scale single web, I-shaped beam specimens cut out longitudinally from full-width hollow-core slabs have been performed during the first phase of this research to investigate the feasibility and effectiveness of this new technique. The influence of several design parameters, including the length and the width of the strengthened zone, the thickness of applied FRP sheets, and the prestressing level of PHC, have been investigated. Results show that once the minimum required strengthened zone length and FRP sheet thickness are satisfied, the proposed novel shear strengthening technique would provide a considerable enhancement on the shear capacity and ductility to the strengthened specimens.