Out-of-plane Response of Clay Brick Unreinforced and Strengthened Masonry Walls Under Explosive-induced Air-blast Loading

Abstract

In recent years, structural engineers and designers are showing their concern about the increasing occurrence of accidental explosions and subversive blasts. Such events induce impulsive loads of abnormal intensity on adjoining buildings leading to the failure of their load-bearing components which may result even in their progressive collapse. Civilian buildings such as universities, schools, and hospitals have been targeted in recent years. Performance of masonry walls being the primary components of the load-bearing structure is of paramount importance under such extreme loadings. In framed structures, generally, panel walls are of unreinforced masonry (URM) and are capable of resisting low-magnitude out-of-plane loads caused by wind and earthquake; however, they are vulnerable to high air pressure generated by explosive-induced detonation. In this study, the out-of-plane behavior of clay brick unreinforced masonry walls under air-blast loading has been investigated using commercial software, Abaqus/CAE 2017. Finite element (FE) models of a single-story dwelling house, consisting of 230 mm thick load-bearing masonry walls and a conventional singly reinforced concrete slab with M20 concrete grade and Fe500 steel, have been developed for this purpose. FE models are subjected to experimental blast peak overpressures available in the literature. For the accuracy of the results, only the target wall has been modeled using a detailed micro-modeling strategy; however, macro-modeling has been opted for other walls to optimize the computational running time. To improve the blast resistance of the wall, analyzes have been extended by strengthening the walls with the reinforced concrete horizontal bands as per IS 4326 (1993) after every three, four, and five courses in different FE models. Concrete-damaged plasticity (CDP) model for concrete and masonry has been utilized for the damage assessment of the walls. Based on the results obtained, this study recommends the provisions for improving the performance of the load-bearing masonry walls under explosive-induced air-blast loading.