Macro synthetic fibers as reinforcement for deep beams with discontinuity regions: Experimental investigation

Abstract

Macro synthetic fibers enhance the response of concrete in tension, ultimately improving its structural behavior, which leads to fully or partially replacing the conventional reinforcements in structural members. However, their applicability in shear predominant critical structural members that have complex stress fields and congested reinforcements have not been investigated. The objective of this paper is to evaluate the performance of macro synthetic fibers in critical structural applications with plausibly reduced conventional reinforcements by comparing the structural response of macro-synthetic-fiber reinforcement with that of conventional reinforcement and steel-fiber-reinforcement from available literature in order to gain perspicacity on different fiber types, fiber dosages, and congestion of reinforcements. An experimental program was conducted on three quarter-scale deep beams with discontinuity regions having reduced reinforcements. Macro-synthetic fibers were added at volume fractions (Vf) of 1% and 2%, and their performance was compared with that of the specimen without fibers. The applied load versus deflection of the beams, failure modes, cracking patterns, and strain in reinforcements were monitored during the tests until failure. The experimental results revealed that the inclusion of 2% Vf of macro synthetic fibers significantly increased the ultimate strength and post-cracking resistance of deep beams.