Torsional behavior model of steel-fiber-reinforced concrete members modifying fixed-angle softened-truss model

Steel-fiber-reinforced concrete (SFRC) is an efficient cement-based composite material that can compensate for the drawbacks of the material properties of conventional concrete and has better structural performances than conventional concrete. It can improve torsional behavior as well as flexural and shear behavior. However, analysis of the torsional behavior of SFRC members is quite complicated because force equilibrium and strain compatibility in a three-dimensional space should be satisfied. Accordingly, many studies proposed empirical evaluation equations for the torsional strength of SFRC members based on experimental results. Therefore, this study derived a constitutive model of SFRC in tension, which greatly influences the torsional behavior of SFRC, based on the test results of SFRC shear panels under biaxial stress, and this tensile behavior model was introduced to a fixed-angle softened-truss model. A theoretical evaluation model based on the modified fixed-angle model for torsional behavior of SFRC was developed, and the performance of the analytical model was also evaluated compared to test results obtained from literature.