Experimental investigations on the shear bearing behavior of prestressed ultra-high performance fiber-reinforced concrete beams with compact cross-section

Abstract

For ultra-high performance fiber-reinforced concrete (UHPFRC) beams subjected to shear the bearing mechanisms differ significantly depending on the type of cross-section. For I-shaped cross-section, existing models superimposing the contribution of concrete, prestressing, stirrups, and fibers were found to predict the shear bearing capacity appropriately. These models may, however, not be generally applicable. The aim of the present study is to investigate the shear bearing mechanisms for UHPFRC beams with compact cross-section and, in particular, the influences of fiber volume fraction and prestressing on the development of the critical shear crack and the shear bearing capacity. This paper presents the experimental results of 22 three-point test on 11 beams with varying fiber volume fraction and prestressing. It was found that increasing the fiber volume fraction increases the shear bearing capacity, but however, the benefit was less than proportional to the residual flexural tensile strength of UHPFRC. As expected, prestressing also affects the bearing capacity favorably.