Influence of steel fibers on design stress-strain curve for high-strength concrete

To quantify the effect of steel fibers on the stress-strain curve for high-strength concrete under compression, results of compression tests performed in the Magnel Laboratory, were used. Several series of concrete cylinders with and without steel fibers were loaded in axial compression. The available stress-strain curves for design are discussed and the way in which the parabola-rectangle diagram used in most European countries is related to the real diagram, which shows a softening branch, is investigated. A new proposal for the realistic stress-strain curve for high-strength fiber concrete is presented and a proposal to take into account the effect of steel fibers on the design stress-strain curve for the design of high-strength concrete under compression is given. In addition, a comparison is made between high-strength fiber concrete and confined high-strength concrete.