SHEAR BEHAVIOR OF FIBROUS REINFORCED CONCRETE WIDE BEAMS

Abstract

When a reinforced concrete beam does not have enough shear strength and / or little amount of secondary rebar are reinforced, the "shear failure" is possible. Such type of failure is not acceptable in civil engineering due it does not indicate any prior notice before the complete failure of the intended structural member. One of the most popular solutions to overcome such shortcoming is the addition of steel fibers due to the ability for enhancing mechanical properties and ductility. Wide beams are such beams that have high width if compared with its thickness, such structural members are frequent in many reinforced concrete building systems and may also face "shear failure" during its service life. The current study investigates the structural behavior of the Steel Fiber Reinforced Concrete Wide Beams by proposing an experimental program comprising casting and testing of twenty beams specimen. The effective shear spans to depth ratio ratios were 2.5 and 3.5, respectively. Two nominal strength levels 30 MPa "Normal strength concrete" and 60 MPa "High strength concrete are also included. The types of steel fibers used are the "End Hocked" as well as the "Staggered" in 0.5% and 1.5% volume fractions for each one. The results showed that the addition of steel fibers enhances the consequent mechanical properties and the relevant structural behavior of wide beams to a serious concern. Furthermore, the addition of steel fibers modified the shear failure mode to "flexural". The first cracking load increased in "Normal strength" from 21.95% to 73.73% by adding "End Hocked" and from 12.19% to 45.45% by adding "Staggered" while such range reported 15.95% to 45.76% for "End Hocked" and 7.25% to 28.81% for "Staggered" in "High strength". Additionally, the ultimate load increased in "Normal strength" from 19.75% to 65.98% by adding "End Hocked" and from 10.52% to 43.81% by adding "Staggered" while such range reported 13.5% to43.57 % for "End Hocked" and 7.25% 29.29to % for "Staggered" in "High strength".