Bending behaviour of reinforced concrete/engineered cementitious composite beams

Engineered cementitious composites (ECCs) are fibre-reinforced cementitious composite materials with ultra-high ductility. Their excellent tensile properties can make up for the defects of the poor tensile properties and easy cracking of concrete materials. ECCs can thus be used to replace concrete material in the tensile regions of structural components, and the high tensile strength of ECCs can be utilised to form ECC–reinforced concrete (RC) composite beams with good crack controllability. In the work reported in this paper, six ECC–RC composite beams with different ECC cross-section replacement ratios (0, 0·2, 0·4, 0·6, 0·8 and 1·0) were tested to examine the effects of the ECC cross-section replacement ratio on the flexural capacity, deformation and cracking of the composite beams. The experiments showed that the plane section assumption is valid for ECC–RC composite beams in the elastic stage. Compared with an ordinary RC beam, the bearing capacity and ductility of the composite beams were significantly improved and the crack width was reduced. It was found that there is an optimal replacement interval for the ECC cross-section replacement ratio, from which a balance between excellent mechanical properties and economic use of ECC materials may be obtained.