Experimental and numerical study on shear performance of externally prestressed precast UHPC segmental beams without stirrups

Abstract

Externally prestressed precast ultra-high performance concrete (UHPC) segmental beams without stirrups (EP-WS-PUSBs), a bridge system fabricated by the novel material UHPC, have been widely concerned by scholars. However, the lacking of relevant research on shear behaviors impedes the application of EP-WS-PUSBs. In this paper, seven segmental beams and one monolithic beam were fabricated and tested for failure. This research focused on the influences of experimental parameters, including span-to-depth ratios (1.5, 2.0, and 2.5), the content of steel fibers (0 %, 1.5 %, and 2.0 %), and stirrup spacings (75 mm and 150 mm). A finite element model (FEM) by ABAQUS 6.14 was established to further explore the shear behavior of EP-WS-PUSBs. The numerical analysis containing span-to-depth ratio (1.25, 1.75, and 2.25), joint location (200 mm, 300 mm, and 400 mm), and joint number (2 and 4) were performed. The tiny and dense cracks were observed in UHPC beams with steel fibers, the existence of steel fibers effectively restrained the cracks. The higher shear and cracking strength could be achieved by the increasing content of steel fibers. The shear strength of EP-WS-PUSBs with 2.0% steel fibers volume in fraction increased by 2.65 % and 25.82% than those with 1.5% and 0% steel fibers, respectively. The stirrups could comparably increase the shear strength, as well as improved the stiffness. The results from modified France (Code NF P 18–710 formula) for calculating the shear strength of EP-WS-PUSBs which considered the reduction factor of 0.85 could relatively accurately predict the experimental values, inferred from an average ratio of the predicted values to the experimental results of 0.88, with the standard deviation of 0.14.