As primary load-bearing members of masonry buildings, the strength and behavior of masonry brick walls are the most important factors affecting the structural performance for the loads the building is exposed to during its life span. The current paper therefore experimentally examines a structural strengthening method to improve the performance and behavior of masonry brick walls. Masonry walls were strengthened with expanded steel plates of different thicknesses attached to the walls using different numbers of bolts. Five wall specimens were examined under a diagonal static compression test. For strengthening, expanded steel plates were anchored to both sides of un-plastered walls using bolts and were then plastered. The thickness of the steel plates and the number of bolts were examined as experimental variables. The results showed that the strengthened wall specimens using expanded steel plates of different thicknesses and different numbers of bolts increased an average of 45-94% ultimate strength at 245mm displacement, the ductility of all strengthened specimens increased by 114%-180% and an average increment of 280-480% higher energy dissipation capacities compared to the reference specimen. The result shows that strengthening masonry brick walls provides 2 to 3 times higher energy dissipation capacity for the energy generated by seismic effects compared to the reference specimen. The research then indicated the expanded plate thickness in strengthening walls has a direct relation with load-bearing capacity of brick masonry walls. An increase of 33% and 100% in plate thickness resulted to increase in load bearing capacity by 2% and 11.5%, respectively. It has also been observed that specimens did not experience a sudden drop in load carrying capacity. They maintained their stability until the end of the tests and changed their stiffness and ductility.