Improved simplified constitutive tensile model for fiber‐reinforced concrete

Abstract

Due to the low strain capacity and the weak crack resistance of concrete, fibers are commonly added to concrete to increase its tensile resistance. The most recent standardized constitutive tensile model is given in the fib Model code 2010, which is based on a simplified stress profile at serviceability limit state (SLS) and ultimate limit state (ULS). However, in current research, an improved stress profile at ULS is proposed. Consequently, three new constitutive tensile models, which are valued for a specific FRC class, are developed. Those models are constructed with the test data of fiber‐reinforced concrete with natural aggregates (FR‐NAC) and three types of recycled aggregates (FR‐RAC). In addition, macro glass fibers and macro polypropylene fibers are used. The test data indicate that the lower concrete Young's modulus of FR‐RAC, as well as the crack growth resistance due to plastic work of the recycled concrete mixtures, result in an increased residual tensile strength at SLS and ULS. The residual tensile strength at 2.5 mm CMOD () of the normal recycled aggregate concrete (nRAC) mixture with 0.75 V% glass fibers is 0.95 MPa, while the FR‐NAC mixture with the same fiber content only indicates a ‐value of 0.43 MPa. Consequently, higher linear postcracking stresses are observed for the FR‐RAC mixtures, especially for the FR‐RAC mixtures with 0.75 V% glass fibers and the lower quality of recycled aggregates.