An Investigation of Crack Propagation in Steel Fiber-Reinforced Composite Beams

This paper investigates the cracking phenomena of fiber-reinforced concrete in steel and concrete composite beam systems. Various parameters contribute to the crack development and weakening of the composite system, while the concrete slab is bonded to the steel beam. The weakening can result from the longitudinal shear stress that causes cracking from shear connectors, cracking from tensile forces, crushing due to compressive forces and also cracking from concrete shrinkage. These cracks can contribute to premature failure of the composite beam. This paper investigates fiber reinforcement as a solution to decrease the amount of cracking in composite beams. The presented methodology includes experimental studies to evaluate cracking characteristics and strength of fiber-reinforced composite beams. Parameters of the study included spacing between studs, application of welded wire reinforcement, and fiber reinforcement. Results indicate the effectiveness of fiber-reinforcement in reducing crack widths and number of cracks, even though, spacing between studs and presence of welded wire were essential in crack control. Further, fiber-reinforced specimens showed higher compressive and tensile strength by 30% and 70% respectively. The deflection at the peak load also showed a 23% decrease for the specimen with hybrid fiber-wire reinforcement in comparison with the specimen reinforced with welded wire only.