Influences of Tensile Longitudinal Reinforcement Ratio and Ductile Layer Thickness on Flexural Mechanical and Cracking Behavior of UHTCC/RC Layered Composite Beam

Abstract

Ultra high toughness cementitious composite (UHTCC) shows enormous deformation capacity and exceptional ability to control crack under tension loading. With such tensile properties, a layer of UHTCC is considered to replace concrete surrounding the major tensile reinforcements in a concrete beam to produce a UHTCC/RC composite beam with improved cracking and mechanical response. The present investigation was conducted to examine flexural behavior of various UHTCC/RC layered composite beams using four-point bending tests. The tensile longitudinal reinforcement ratio and the thickness of UHTCC layer were two varying parameters. It is shown that the composite beams improved load-deformation and cracking behaviors in RC beam, and that the degree of load-deformation improvement becomes less significant as the reinforcement ratio increases but varies slightly as the thickness of UHTCC layer increases. It is also discovered that, in the composite beam studied, both the tensile longitudinal reinforcement ratio and the thickness of UHTCC layer have little impact on cracking conditions especially the maximum crack width at the height level of tensile longitudinal bar.