Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

Efficient shear strengthening techniques for thick concrete slabs were studied at Université Laval over the last decade. The strengthening techniques consist of adding drilled-in vertical reinforcing bars and to anchor the bars with bolted plates or expansion anchorage at the bar extremities (i.e. the bars are unbonded to the concrete), or to bond the bars to the concrete with high strength epoxy adhesive (no mechanical anchorage). For concrete members with unbonded bars, experimental loading tests and numerical analysis showed that large diagonal shear cracks are required to activate the shear reinforcement and therefore, the shear behaviour of the members is largely influenced by the stiffness of the strengthening. For specimens with epoxy bonded bars, results showed that the development length of the bars is determined by the locations of the shear cracks and thus, bars may debond before reaching their yielding strength. The efficiency of the shear strengthening techniques is therefore largely influenced by the bars spacing and the stiffness of unbonded shear reinforcement.