Flexural behavior of preflex sfrc-encased steel joist composite beams

This research investigates the behavior of encased steel composite beams within steel fiber reinforced concrete (SFRC) in straight and preflex beams, using nonlinear analysis. ABAQUS FEA software has been adopted. Composite steel beams encased in fiber reinforced concrete are analyzed and a comparison is made with available experimental results. Good agreement with the experimental results is observed. Upwards camber of the steel section is introduced on the steel joist. It’s found that the preflex section can increase the ultimate load capacity by 10% and decrease midspan displacement by 13% of the same beams without the preflex steel section. Steel fiber dosages, compressive strength, modulus of rupture are examined. The effect of cambering and mesh refinement is also investigated. The physical properties of SFRC are calculated through testing at the UTA Civil Engineering Laboratory Building. In total, nine (4″ x 8″) cylindrical specimens, nine (6″ x 12″) cylindrical specimens, and nine (6″ x 6″ x 20″) beam specimens were produced and tested for their compressive strength, tensile strength, and modulus of rupture after 28 days of curing. The addition of steel fiber will lead to a significant increase in tensile strength and modulus of rupture of concrete. Adding 1% steel fibers by volume can increase the load capacity by 33% and decrease the midspan displacement by 70% in comparison to the same beam using plain concrete. The increase in steel fibers and cambering shows an improvement to the flexural capacity and cracking point of the beam, which can provide mo re strength to structures such as long-span bridges.