Performance evaluation of FRP-strengthened self-compacting concrete filled double-steel-plate composite shear walls: Experimental and numerical studies

Concrete-filled double-steel-plate (CFDSP) composite shear walls, known for their efficient structural performance and enhanced seismic resilience, are the focus of this study, which investigates their seismic response under displacement-controlled cyclic loading. Despite the growing use of fiber-reinforced polymer (FRP) in structural retrofitting, its application in enhancing the seismic performance of CFDSP composite shear walls has not been thoroughly explored. The experimental analysis involved testing two CFDSP walls filled with self-compacting concrete (SCC) and strengthened with FRP wraps. Both specimens were identical in shape and configuration, with the variation introduced in the type of FRP material used for strengthening. One specimen was strengthened with carbon fiber-reinforced polymer (CFRP) wraps, while the other was retrofitted with glass fiber-reinforced polymer (GFRP) wraps. Testing continued until ultimate drift ratios of 3.90 % for the GFRP-strengthened specimen and 3.84 % for the CFRP-strengthened specimen were achieved. The performance of the composite shear wall specimens was evaluated by comparing key parameters such as lateral strength, ductility, stiffness, and energy dissipation capacity. Following the experimental tests, numerical analysis was conducted to validate the experimental results. With an acceptable agreement between the experimental and numerical results, a non-retrofitted CFDSP wall was analyzed to further investigate the effect of FRP strengthening on the structural performance of the specimens. Additionally, a numerical parametric study was conducted to assess the effects of different types of FRP wraps, the number of FRP layers, fiber orientation angle, FRP wrap configuration, and the concrete's compressive strength on the lateral strength of CFDSP walls. The results indicate that, in addition to improvements in other structural parameters, the lateral strength of shear walls retrofitted with CFRP and GFRP increased by 49.66 % and 21.80 %, respectively, compared to the non-retrofitted numerical model. On the other hand, the parametric study identified bidirectional CFRP wraps with a 90° fiber orientation as the most effective retrofitting scheme for enhancing the lateral strength of composite shear walls.