Experimental Study of Perforated Infill Panels for Retrofitting Flat Plates

Lightweight pumice stone concrete (LWPSC) infill panels were investigated as a retrofit alternative for flat-plate buildings. Four 4/10-scale slab-column subassemblies were designed based on ACI 318-63 and current performance-based testing requirements. The specimens were retrofitted with prefabricated LWPSC units and subjected to quasi-static loading conforming to FEMA 273. Among the variables considered were connections between the slab and infill wall and the addition of uniformly distributed perforations (circular holes and rectangular openings). The experimental results indicate that all of the retrofitted specimens significantly improved strength and stiffness compared with the bare frame; however, because of its ductility and energy dissipation mechanism, the most promising infill panel configuration contains rectangular perforations. Two different reinforcement patterns were tested using rectangular openings. The addition of diagonal reinforcement between openings has the effect of increasing the yield strength of the wall as well as better maintaining postyield deterioration.