Inverse analysis method to determine the tensile properties of cement composite laminates reinforced with polypropylene fibers and GFRP rebar

The innovative use of precast laminated cementitious composite (PLCC) incorporating glass fiber-reinforced polymer (GFRP) bars on the undersides of reinforced concrete beams significantly improves their flexural strength. Unlike conventional steel reinforcements, GFRP bars offer resistance to corrosion and ensure prolonged durability in harsh environments. The integration of fibers into cementitious matrices shows potential for enhancing the bond strength between polymer bars and cement composites. Polypropylene fibers (PPFs) are lightweight and resistant to corrosion. This study, following the ASTM C۱۶۰۹ procedure, examines the flexural behavior of PLCC specimens (۵۰۰×۱۲۵×۲۵ mm) under a four-point loading setup. Parameters such as the first crack occurrence, maximum post-cracking strength, deflection, toughness, and failure modes are evaluated. The experimental analysis assesses the effects of PPF inclusion and the number of GFRP rebars used. Both monotonic and ultra-low cycle fatigue (ULCF) loading conditions are applied. The results highlight a significant improvement in the resistance, strength, and ductility of GFRP-reinforced cementitious composite laminates with the addition of PPFs. Specifically, when PLCCs with one and two GFRP bars are subjected to a ۲۰ mm displacement under monotonic loading, the energy absorption increases by ۴۷۰% and ۶۹۰%, respectively. Similar increases of ۴۳۷% and ۵۵۲% are noted under cyclic loading conditions. Additionally, comparing the maximum post-cracking strength to the initial cracking strength indicates a deflection softening behavior in GFRP-reinforced laminates without PPFs. Conversely, displacement hardening is observed after incorporating PPFs into PLCCs. Subsequently, a numerical study investigated the tensile properties of PPF-reinforced cementitious composites using inverse analysis with ABAQUS finite element software. The inverse analysis results align well with the experimental findings.

کلیدواژه ها:

inverse analysis ، laminated cementitious composite ، energy absorption capacity ، cracking ، flexural strength