Title: Behavior of Fiber-Reinforced Prestressed and Reinforced High-Strength Concrete Beams Subjected to Shear

Author(s): S. K. Padmarajaiah and Ananth Ramaswamy

Publication: Structural Journal

Volume: 98

Issue: 5

Appears on pages(s): 752-761

Keywords: beams; concrete; fiber; fiber-reinforced concrete; reinforcement; shear strength; steel.

DOI: 10.14359/10629

Date: 9/1/2001

Abstract:
This paper presents experimental and analytical results of 13 fully/partially prestressed high-strength concrete (plain concrete strength of 65 MPa) beams having fibers, under four points loading. The behavior of prestressed beams, which were designed to be shear dominant in the absence of fibers, has been discussed and the influence of fiber content and fiber location on the shear behavior of the beams has been examined. The levels of prestressing force, fiber volume fraction (0, 0.5, 1.0, and 1.5%), fiber location (full length, and shear span only), the presence/absence of stirrups in the shear span, and the shear span-depth ratio were the variables considered in the experimental program. A rigorous analytical model is proposed to predict the shear strength of prestressed high-strength concrete beams containing steel fibers. Effects of fiber content, level of the prestressing force, shear span-depth ratio, aggregate size, and the compressive and tensile strength of the plain concrete are accounted for in the model. Test results of this study and those reported in the literature were used for the verification of the proposed model. For beams designed to be shear predominant, a significant conclusion emerging from this study is that the beams having fibers located only within the shear span over the full cross section had load deformational response and peak load values that were comparable to the response of beams having fibers over the entire beam. Fibers in the shear span altered the failure mode from one of brittle shear to one of ductile flexure. This study also indicates that stirrups may be replaced by an equivalent amount of fibers without compromising the overall structural performance. A nominal minimum shear reinforcement may be provided with fibers for safety.