This paper presents a finite element formulation for the modeling of the behavior of partially prestressed steel fiber concrete beams in shear. Based on a secant modulus approach, the formulation treats steel fiber concrete as an orthotropic material, characterized by appropriate constitutive relations in the principal compressive and tensile directions. An experimental program with the partial prestressing ratio, the shear span:effective depth ratio, and the volume fraction of steel fibers as test variables was carried out and the deflections of the beam, concrete, and steel strains were monitored and compared with the results of the finite element analysis. The finite element formulation was found to predict the deformational characteristics and the ultimate load of the test beams well. Steel fibers were observed to improve the beam stiffness after the occurrence of first shear crack and to enhance the shear strength of partially prestressed concrete beams significantly. ADVANCED CE-MENT BASED MATERIALS 1995, 2, 231-239 KEY WORDS: Beams, Finite element analysis, Partial prestressing, Shear strength, Steel fiber concrete, Steel fibers any studies have been carried out on the use of steel fibers in reinforced concrete beams as shear reinforcement. There is a general consensus that the steel fibers are efficient in taking up shear, which may lead to a change of the mode of failure of beams from shear to flexure . Recent studies on reinforced steel fiber concrete (SFC) beams [7] also suggested that, in addition to the increase in the ultimate shear capacity, there is a reduction in strains in the steel reinforcement and concrete by the addition of steel fibers.
There have been a limited number of studies that reported on the use of steel fibers in partially prestressed concrete beams. One of the earlier studies in this area was reported by Balaguru et al.