Experimental Study On The Shear Performance Of ECC/RC Composite Beams With Web Reinforcement

Engineered cementitious composites(ECC)is a kind of fiber reinforced cementitious composite material,which exhibits ultra-high toughness and superior crack control ability.The shear properties and ductility of ECC are also much better than those of concrete,which could effectively improve brittleness of the concrete structures.Based on the structural theory of ordinary reinforced concrete beams,two kinds of high performance materials including high-strength steel bar and ECC are used to form ECC/RC composite beams with high-strength reinforcement.Static load tests were carried out on to investigate the shear performance of the ECC/RC composite beams,The main research contents of this paper is as follows:(1)Analysed failure mechanism and the development of cracks of the shear performance of ECC/RC composite beams with web reinforcement.The results show that shear span ratio is the main factors influencing the failure pattern of composite beams.ECC material has excellent crack control ability.(2)Analysed the variation of steel strain and concrete strain of ECC/RC composite beams.The results show that,ECC material can bear tension with steel,which can reduce the strain of stirrups and longitudinal reinforcement in composite beams.(3)Sudied the effects of different stirrup ratios,treatment methids of interface,thickesses of ECC layer,shear span ratios and concrete strengths on the oblique cracking load,mid-span deflection and shear bearing capacity of specimens.The results show that,composite beams have higher bearing capacity and deformation capacity.(4)Based on the test data,selecting fc1/2 as strength index,the calculation formula for the shear capacity of ECC/RC composite beams with web reinforcement was proposed.It can provide a reference for future adoption of ECC/RC composite beams in civil engineering fields.