Experimental research on the axial compressive performance of brick masonry walls strengthened with a steel plate frame considering initial load

Abstract

Initial load means the load, including dead or/and live load, applied on brick masonry walls before being strengthened, which can influence the strengthening effect. However, research on the strengthening of brick masonry walls particularly considering the effect of initial load is insufficient. Steel is widely utilised for brick masonry strengthening because of its simple construction procedure and flexible configuration. Hence, for advancing the application of steel plates in brick masonry strengthening engineering and studying the effect of initial load on strengthening, an experiment was performed to investigate the axial compressive performance of a steel plate frame (SPF) strengthening brick masonry wall considering initial load for various frame configurations. The experiment results indicated that the SPF effectively confined the brick masonry wall, and steel plate columns underwent local buckling failure under axial load; the load-bearing capacity of brick masonry walls increased by at least 10.62 % strengthened with double-sided single-span SPF, and it further improved by 18.75 % strengthened with double-sided double-span SPF when initial load ratio was less than 0.25. Initial load ratio considerably affected the axial collaborative performance of the brick masonry wall and SPF, and increasing initial load ratio resulted in poor axial collaborative performance, following which the load-bearing capacity of the strengthened masonry walls decreased. The load-bearing capacity of the strengthened walls was higher for an initial load ratio less than 0.25. Conversely, a rare strengthening effect was observed when the initial load ratio exceeded 0.7. Based on the simplification of steel plate boundary conditions and the buckling theory of struts, a formula for predicting the load-bearing capacity of brick masonry walls strengthened with an SPF considering initial load was derived, which showed acceptable accuracy in comparison with experimental values.