Numerical Investigation on Blast Response of Masonry Wall Panel and Development of its Protection Systems

Abstract

Due to di erent accidental or intentional events, the behavior of structural components subjected to blast loading has been the subject of research in recent past. Normally, conventional structures are not required to be designed for blast loads because blast is a low probability event. Therefore, conventional structures are susceptible to damage varied from moderate to severe. There are already many unreinforced masonry buildings in existence, and some of them are possess historical importance. Such buildings are not expected to perform well under blast loading. Apart most human habitat are made up of Reinforced Cement Concrete (RCC) frame building. In recent years, it has been seen that such structures has been targeted by many terrorist attacks. Therefore, understanding the blast response of buildings made up of either masonry or RCC frame become very important. Some experimental work on mitigating blast e ect on URM walls has been done in recent years; however, experimentation usually cost a signi cant amount of time and funds. Hence, numerical simulation is only way forward to study the behavior of di erent types of structures. The aim of the present study is to understand the e ect of internal and external blast loading on masonry wall panel and RCC frame building and towards development of mitigating protective systems using Finite Element Method (FEM). The study assumes that the explosion occured due to LPG cylinder of 6.85 kg TNT, accidentally, at a stand-o distance of 500 mm. Numerical solution is achieved for above state problem using FE modelling through ANSYS and explicit dynamic analysis is carried out in AUTODYN. The modelling and analysis takes into consideration reinforcement details together and material performance under higher strain rates. A coupled numerical approach using Lagrangian and Eulerian methods is adopted for the incorporation of the essential processes, such as explosion, shock wave propagation, shock wave-structure interaction and structural response, in the model. Blast response of structures are evaluated in terms of Pressure-Impulse diagram related blast load parameters and damages of structures. Mitigation of structure providing protective system is explored. various protective systems alternatives are attempted like Prestressing of Masonry Wall Panel, Externally Bonded Glass Fiber Reinforced Polymer (GFRP) on Masonry Wall Panel and Prismatic Tube Core Sandwich Panel. It is found that (1) the wall experiences maximum acceleration is 0.83g and 1.2g for ground blast and air-blast, respectively; (2) the masonry in lls shows extensive damage. A parametric results shows Remapping analogy of blast and Strain Erosion value of 0.1 provides better estimate of dynamic response; and (3) Tube core is found to absorb 83% energy of total energy, energy absorbed by top plate is 17% of total energy absorbed by tube core sandwich panel and less reaction force is transferred to the bottom plate. Numerical results generated can be used to identify relationships such as Pressure-Impulse diagram between the blast load parameters and the masonry wall panel damage.