Axial tests on concrete wall boundary elements reinforced with FeSMA and GFRP

Abstract

This study investigates the seismic performance of reinforced concrete (RC) wall boundary elements using unconventional reinforcement materials—Iron-Based Shape Memory Alloy (FeSMA) and Glass Fibre Reinforced Polymer (GFRP) rebars—compared to conventional steel reinforcement. The aim is to enhance seismic design by minimizing residual displacements and improving long-term durability. Experimental tests on RC prisms were conducted to assess deformation behavior and failure modes under cyclic tensile-compressive loading. The rebars in some of the specimens were partially or completely debonded. Joule heating successfully activated the FeSMA rebars, prestressing them beyond 300 MPa and effectively applying axial load ratios of 13% to 30%, depending on the specimen’s rebar diameter. Results showed that GFRP-reinforced specimens had over 80% less residual axial deformation than steel-reinforced specimens after reaching an average tensile-axial strain of 1%. Despite larger material strains at failure, the axial displacement capacity of the FeSMA specimens was only slightly greater than that of the GFRP specimens—ranging from 32 to 40 mm (depending on rebar diameter) compared to 24 to 29 mm (depending on the bonding mechanism). Based on extrapolation to an idealized ten-story RC wall, all specimens suggest drift capacities exceeding 2%,. Additionally, debonded rebars were found to reduce strain concentrations, limit out-of-plane deformation, and enhance axial displacement capacity. All test data are available in an openly accessible online repository at https://doi.org/10.14428/DVN/67YZ3R.