Assessment of Retrofitting Techniques for a Four-Story Masonry Building to Resist Blast Loading

Abstract

Masonry walls are commonly preferred in the construction of low-rise buildings due to their proven efficiency in resisting gravity loads and their relatively low material and labor costs. However, few studies investigating the behavior of retrofitted buildings under blast loading have been found in the literature. This paper describes the first comprehensive study investigating the efficiency of four retrofitting techniques for a low-rise masonry building under blast loading. The investigated retrofitting materials were textile-reinforced mortar (TRM), carbon-fiber-reinforced polymers (CFRPs), glass-fiber-reinforced polymers (GFRPs), and polypropylene bands (PPBs). Compared with regular reinforcing steel, these materials have light weight, high corrosion resistance, and perfect durability properties, in addition to their ease of application. A three-dimensional applied element model (AEM), which accounts for both geometric and material nonlinearities, was developed and validated to analyze an existing four-story masonry building under blast loading. Material nonlinearity was considered by including nonlinear models for masonry, mortar, TRM, CFRPs, and PPBs. Masonry blocks were modeled using brick elements, while the in-between mortar was modeled using spring elements. Validation of the AEM was by modeling masonry walls taken from the literature and comparing their results with counterparts obtained from experiments from the literature. Cracking pattern, displacements, support rotation, and load capacity for the investigated building with and without retrofitting using the four materials were compared. Costs were compared based on market prices. Retrofitting the case study building with TRM, CFRPs, GFRPs, and PPBs reduced maximum support rotation by 39%–98%, 28%–88%, 33%–92%, and 9%–84%, respectively, and increased blast load capacity by 35%–404%, 48%–91%, 83%–135%, and 26%–46%, respectively. The study revealed that retrofitting the investigated building with TRM provided the optimum behavior in terms of cost, crack propagation, and blast load capacity. Masonry walls are frequently used in low-rise buildings due to their efficiency in resisting gravity loads and having low material and labor costs. This study investigated the efficiency of textile-reinforced mortar (TRM), carbon fiber–reinforced polymers (CFRPs), glass fiber–reinforced polymers (GFRPs), and polypropylene bands (PPBs) to improve the resistance of low-rise buildings to blast loading. The adopted retrofitting materials have light weight, high corrosion resistance, and perfect durability properties. A numerical model analyzed an existing four-story masonry building under blast loading. Cracking, displacements, support rotation, and load capacity with and without retrofitting were compared. Costs were compared based on market prices. Retrofitting the studied building with TRM, CFRPs, GFRPs, and PPBs reduced maximum support rotation by 39%–98%, 28%–88%, 33%–92%, and 9%–84%, respectively, and increased blast load capacity by 35%–404%, 48%–91%, 83%–135%, and 26%–46%, respectively. The study findings recommend TRM in retrofitting masonry buildings to achieve the least cost and the fewest cracks in addition to the highest blast load resistance.