Experimental Investigation: New Ductility-Based Force Modification Factor Recommended for Concrete Shear Walls Reinforced with Glass Fiber-Reinforced Polymer Bars

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Title: Experimental Investigation: New Ductility-Based Force Modification Factor Recommended for Concrete Shear Walls Reinforced with Glass Fiber-Reinforced Polymer Bars

Author(s): Ahmed Hassanein, Nayera Mohamed, Ahmed Sabry Farghaly, and Brahim Benmokrane

Publication: Structural Journal

Volume: 116

Issue: 1

Appears on pages(s): 213-224

Keywords: deformation; force modification factor; glass fiber-reinforced polymer; seismic; shear wall

Date: 1/1/2019

Abstract:
Reinforced concrete shear walls are the most common lateral-force-resisting system in reinforced concrete structures. Recent experimental studies have proven the applicability of using glass fiber-reinforced polymer (GFRP) reinforcement in lateral-resisting concrete structural systems (shear walls and columns). In this study, five concrete shear walls reinforced with GFRP bars and spirals were tested under reversed cyclic quasi-static loading and constant axial load. The main difference between the walls was the GFRP reinforcement configuration in the boundary elements. Two shear walls included boundaries reinforced with square GFRP spirals, while the third shear wall had boundaries reinforced with circular GFRP spirals. The remaining two shear walls had higher confinement of boundary elements consisting of square GFRP spiral embedded inside rectangular GFRP spiral in one and rectangular GFRP spiral with two GFRP ties in the other. The main objectives were to assess the impact of increasing the confinement level in the boundaries and the effect on inelastic deformation capacity. The walls with higher confinement clearly achieved higher drift ratios and strength. The envelope curves were bilinearly idealized. The elastic-plastic transition point and the maximum deformation limit were identified based on the seismic performance of the test specimens. The recorded inelastic rotation capacity of the test walls achieved the required level for lateral-resisting systems. Moreover, the ductility-based force modification factor was assessed and a new value of 2.4 was suggested for implementation in FRP design codes.