Environmental and Economic Assessment of a Reliability-Based Design Model for FRP-Confined Concrete Columns

The recent development of a reliability-based design (RBD) framework for fibre-reinforced polymer (FRP)-confined concrete columns has significantly advanced the safety calibration and efficiency of confinement models through probabilistic formulations of resistance factors. However, the broader implications of such reliability-informed designs on sustainability and cost-effectiveness remain largely unexplored. This study extends the RBD model proposed by Mohammadi et al. (2025) by quantifying its environmental and economic impacts in comparison with the conventional design provisions of fib Bulletin 90 and ACI 440.2R. The analysis integrates life-cycle assessment (LCA) and an initial cost analysis to quantify the environmental and economic impacts. Three representative column geometries (circular, square, and rectangular) are analysed across a range of strength improvement levels ( 0-100% ). Results indicate that the RBD-calibrated model reduces FRP material demand by up to 100 % (where confinement is deemed unnecessary given that the less conservative partial factor provided by this model gives a higher unconfined design concrete strength value compared to other models) and provides consistent savings of over 40 % compared to f ib and ACI provisions for circular sections. It also maintains material efficiency advantages for geometrically challenging rectangular sections at moderate strengthening levels, all while maintaining the target reliability index ( β_T=3.8 ). This translates to significant reductions in embodied carbon emissions and construction costs. The findings emphasise that incorporating reliability-based calibration into design practice not only ensures code-compliant safety margins but also contributes substantially to the environmental and economic sustainability of FRP-based strengthening systems.

Keywords: Reliability-based design, FRP-confined concrete, probabilistic modelling, life-cycle assessment, initial cost analysis, structural reliability, sustainable infrastructure.