A SIMPLE APPROACH FOR PREDICTING CURVATURE IN CONCRETE MEMBERS REINFORCED WITH STEEL FIBERS AND BARS

Abstract

The paper proposes a simple deflection model for concrete bending members reinforced with steel fibers and bars (further denoted as R/SFRC members). Most of the current design approaches for such elements require the knowledge of the residual strength of steel fiber reinforced concrete (SFRC) in tension with the latter characteristic being obtained from standard bending tests. The involvement of extra tests hampers a wider application of R/SFRC structures in practice. The proposed model does not require the characteristic of the residual strength. It was derived using an inverse approach earlier proposed by the authors. The resultant tensile force of SFRC acting in the tension zone of a R/SFRC beam was derived from the experimental moment-curvature diagram. A load level was identified at which the resultant tensile force reached zero, implying that the section stiffness equals to the stiffness of the fully cracked RC section. The proposed model in a simple way expresses curvature via the curvatures at a cracking load and the load corresponding to the stiffness of the fully cracked RC section. The predictions by the proposed model were checked against independent test data.