A novel ductile lightweight fiber-reinforced concrete (DLFC) infill for seismic-prone zones : experimental and numerical investigations

In urban construction, reinforced concrete (RC) with masonry infill predominates, though traditional masonry's brittle nature poses significant seismic vulnerabilities. This study introduces a novel approach using Ductile Lightweight Fiber-Reinforced Concrete (DLFC) as an infill to address these challenges. Composed of cement, water, expanded polystyrene (EPS), ultra-fine filler, and combined polyvinyl alcohol (PVA) and polypropylene (PPF) fibers, DLFC aims to enhance ductility, minimize damage, and amplify energy absorption in seismic events. Three RC frames, with height-to-span ratios of 0.77, 1.00, and 1.28, were designed and experimentally tested under simultaneous vertical and lateral cyclic loading to evaluate DLFC's seismic response. Results illustrated that DLFC-infilled RC frames boast impressive ductility, an 8% drift at complete failure, minimal out-of-plane behavior, and elevated damping ratios. Remarkably, DLFC's low in-plane stiffness led to reduced frame stiff- ness compared to traditional masonry. An empirical equation, closely aligning with experimental outcomes, was formulated to estimate the lateral strength of the infill wall, and a comparison with the bare frame was made, though it necessitates additional validation through further testing.