Title: Behavior of Steel Fiber-Reinforced Rubcrete Deep Beams under Shear

Author(s): Sandeep M. S., Praveen Nagarajan, and Shashikala A. P.

Publication: Structural Journal

Volume: 119

Issue: 1

Appears on pages(s): 15-25

Keywords: ANSYS; fiber-reinforced rubcrete; numerical analysis; rubberized concrete; rubcrete; steel fiber-reinforced concrete (SFRC); strength reduction factor; strut efficiency factor

DOI: 10.14359/51733003

Date: 1/1/2022

Abstract:
During a calamity like an earthquake, utmost importance should be given to lifeline structures such as bridges and high-rise buildings. Pier caps, transfer girders, pile caps, and so on are some of the structural elements found in flyovers, bridges, and skyscrapers. These elements can usually be considered as deep beams, which are shear-critical members. The shear predominance in deep beams increases the brittleness of the overall structure and results in reducing the seismic resistance. Research shows that the ductile performance of concrete can be improved by adding highly deformable materials such as rubber in the concrete mixture. This paper describes the experimental studies conducted to understand the influence of crumb rubber and steel fiber in enhancing the ductile performance of shear-critical beams. As part of the experimental studies, the load-deflection response including the post-peak behavior was captured and is reported. Results of the study highlight the potential of crumb rubber and steel fiber in improving the ductility of concrete members. It was observed that the addition of 10% pretreated crumb rubber, along with 0.75% steel fiber, is ideal for structural applications. Based on the peak load of deep beams obtained from experimental investigation, the strut efficiency factor (βs) for bottle-shaped struts was calculated. It was observed from the calculated values of the strut efficiency factor that the value of βs recommended by ACI 318-14 is on the conservative side. Hence, new relations were developed to predict the strut efficiency factor for concrete containing rubber and steel fiber.