Shear behaviours of hybrid continuous deep beams strengthened with carbon fibre reinforced polymer

Abstract

This paper investigates the shear strength characteristics of reinforced concrete continuous deep beams (RCCDB) consisting of homogenous versus hybrid concrete, and further looks at the effect of Carbon Fibre Reinforced Polymer (CFRP) on the shear strength of hybrid RCCDBs. The experimental work included testing ten specimens of RCCDB under two-point loads. The effects of high strength concrete (HSC) layer thickness and CFRP on the strength of RCCDB were thus studied. The experimental results showed that the strengthening of RCCDB by an HSC layer at the top is better than that from one at the bottom, as the increments in ultimate load strength were 17 and 34% for top strengthening and 8 and 26% for bottom strengthening for 25 and 50% thickness of total depth of beam, respectively. The optimal strengthening of RCCDB using an HSC layer at the top was at 50%. Shear strengthening using 5 cm width CFRP strips for hybrid RCCDBs increased the ultimate shear strength by 69% and 49% for strengthening with inclined and straight shapes, respectively, where such strengthening was applied near to the centre of the specimens.