Strengthening of flat slabs with transverse reinforcement by introduction of steel bolts using different anchorage approaches

The present work reports the experimental research carried out to study a strengthening method for flat slabs under punching by introduction of new shear reinforcement. Eight specimens were strengthened with the introduction of prestressed vertical bolts, using different anchorage approaches: large anchorage on surface, small anchorage on surface and small embedded anchorage. A reference specimen, unstrengthened, was also tested. The experimental punching loads, failure modes and shear reinforcement contribution are compared with the provisions of EC2, ACI 318-11 and MC2010. The tests results show that using small embedded anchorage plates is viable and efficient method for punching capacity improvement. Additionally is a method also with advantages of better aesthetics for the final strengthened structure.

► Eight specimens were strengthened with the introduction of prestressed vertical bolts.
► Large and small anchorages on surface and small embedded anchorages were used.
► The use of embedded anchorages led to a slightly decrease of punching load capacity.
► EC2 and MC2010 provided a good agreement with experimental punching loads.