Analytical investigation of seismic performance of masonry walls strengthened with strain hardening fiber reinforced geopolymer matrix

Strain hardening fiber reinforced geopolymer matrix, termed here as strain hardening material, is being proposed as a new seismic retrofitting material. Seismic behavior of the masonry walls with and without the strain hardening material was evaluated through finite element simulations in this paper. The finite element simulation was conducted on a masonry wall model with smeared crack material properties. The effectiveness of the strain hardening material for enhancing the seismic capacity of the masonry wall was evaluated through pushover analyses. Several parameters are considered in the pushover analysis including thickness and mechanical properties of the strain hardening material, wall geometries and loading directions. The force-displacement response obtained from the pushover analysis was used to develop a simplified multi-degree spring model. Nonlinear dynamic time history analyses were conducted using the spring model to evaluate the seismic demand of masonry structures strengthened with the strain hardening material. From the simulation results, it has been found that the strain hardening material can significantly improve the strength and ductility of the masonry wall under earthquakes. Design recommendations are made for retrofitting masonry structures using the proposed strain hardening material.