Experimental Studies on Blast Performance of Unreinforced Masonry Walls: A state-of-the-art review

A large proportion of India’s residential buildings is of unreinforced masonry (URM) and falls under the category of non-engineered structures. URM walls in the residential buildings, customarily constructed from clay bricks or concrete blocks and cut stones, are found to be braced and therefore able to carry some out-of-plane loads produced by wind and earthquake, and survive. However, they are found to be more vulnerable to high air-pressure generated by explosive-induced detonations. Sufficient amount of investigations has been made by engineers to study the effect of brick strength, mortar strength, boundary conditions, wall thickness, and Young’s modulus of masonry on the blast performance of the URM walls. In this paper, available experimental studies on clay-brick and concrete block URM walls subjected to explosive-induced blast loading are briefly reviewed and summarized in tabular form. Studies conducted to improve the blast resistance of the walls using GFRP strips, GFRP rods, and Polyurea coating, and their effect on mid-span deflection, damage, and cracks have also been reviewed. It has been observed that the effect of brick strength and mortar strength on maximum mid-span deflection and damage resistance of the walls is insignificant under higher peak reflected blast pressures (> 2 MPa). Besides, the walls strengthened with the GFRP strips or Polyurea coating performed better with regards to mid-span deflection, damage, and cracking. The influence of Young’s modulus of masonry on the blast response of the walls is found to be more effective in reducing the maximum mid-span deflection. Also, the failure mechanism of the walls is found to be highly dependent upon the peak overpressure, duration of the blast, and support conditions.