Tensile Behavior of Steel-Polypropylene Hybrid Fiber-Reinforced Concrete

The present study deals with the uniaxial tensile behavior of steel-polypropylene hybrid fiber-reinforced concrete (HFRC). The tensile strengths and complete stress-strain responses of HFRC were measured in terms of different volume fraction and aspect ratio. It was observed that the uniaxial tensile behavior of plain concrete can be significantly improved upon with the addition of hybrid fibers. The steel fiber primarily increases the peak tensile strength, while the polypropylene fiber mainly contributes to increasing residual strength in post-peak response. Subsequently, predictive equations for both the tensile strength and complete stress-strain relation of HFRC were developed, and the results were found in satisfactory agreement with experimental results. Furthermore, a simple elliptic-cap model in tension region was also proposed for the tensile meridian of HFRC within the framework of elastoplasticity, representing a three-dimensional scenario of strength criterion capable of predicting the multiaxial stress state of HFRC in tension region.