Post-cracking behavior in tensile for UHPFRC using inverse analysis, fracture energy and finite element method

Resumo

Ultra-high performance fiber reinforced concrete (UHPFRC) is an advanced composite material
characterized by compressive and tensile strengths above 150MPa and 7MPa, respectively. Initially, an
experimental procedure was used to characterize the tensile performance through bending tests, using beams with
1% and 2% content by volume of steel fibers. Three-point bending load arrangement notched prisms were used to
determine the contribution of the fibers to reinforcing a cracked section. With that, the (F vs. ω) experimental
curves were graphed, and from there, the analytic tensile curves (σ vs. ω) was obtained point by point by
application of the inverse analysis procedure proposed by the AFGC. With the analytic curves, the fracture energy
was calculated, following a procedure proposed by RILEM. Subsequently, the crack width was transformed into
strain using a relationship that involves the characteristic length. The resulting analytical behavior law was used
to carry out computational modeling applying the finite element method. Both the finite element method and the
fracture energy were used to validate the procedures, comparing experimental and numerical results. Models and
experiments showed good agreement and finally was determined the constitutive law for the UHPFRC in tension.
It can be concluded from this study, therefore, that the post-cracking tensile behaviour of UHPFRC can be
appropriately evaluated and validated through the applied analysis procedure in this research.