Effect of blast load on the concrete and masonry structures

Nowadays, due to the various explosive attacks on buildings and infrastructure facilities, the design of these structures can be seriously modified and eventually secured. These attacks can be voluntary or involuntary. Unfortunately, hostile or voluntary sabotage, explosions, or shock have become part of the normal burden scenarios in which built facilities can be exposed throughout service. The use of bombed vehicles to attack city centers by terrorist organizations around the world has increased considerably in recent years. After a bomb explodes within or near a building, serious damage can occur or the bulb can be completely destroyed.effects, including the severe dynamic loading conditions of the building and / or due to the structure. An explosion is a rapid release of stored energy characterized by a bright flash and an audible blast. Part of the energy is released as thermal radiation (flash); and part is coupled into the air as air blast and into the soil (ground) as ground shock, both as radials expanding shock waves. The rapid expansion of hot gases resulting from the detonation of an explosive charge gives rise to a compression wave called a shock wave, which propagates through the air. The blast wave instantaneously increases to a value of pressure above the ambient atmospheric pressure. This is referred to as the positive phase that decays as the shock wave expands outward from the explosion source. After a short time, the pressure behind the front may drop below the ambient pressure. During such a negative phase, a partial vacuum is created and air is sucked in. This is also accompanied by high suction winds that carry the debris for long distances away from the explosion source. The most common form of damage after explosions is the collapse of the walls, the expansion and bursting of the windows, and the deterioration of the carrying elements. In addition, direct blowout and debris effects, structural collapse, fire and smoke can cause many injuries and deaths. Modeling and numerical analysis of reinforced concrete and masonry buildings, which have been affected by the explosion loads, can be done easily with today's technology and finite element software. This thesis indented to improve the knowledge of reinforced concrete building with infill wall masonry subjected to explosive loading. A further aim is to describe and use the non-linear-finite element method through the study of different parameters (material, numerical and explosions) that can affect the response of reinforced concrete and masonry under explosions. Particular attention will be given to dynamic behaviour since it differs in many aspects from static behaviour. The compressive and tensile strengths increase due to the strain rate effect Initial stiffness increases, and moreover the concrete load carrying capacity is enhanced in dynamic loading. Also, the negative phase of the shock wave which is often neglected in reinforced concrete studies under explosives will be considered in order see its eventual impact on the response. To learn more about the structural behaviour of concrete and masonry buildings subjected to severe loading, a powerful tool is to combine advanced non-linear FE analyses and experiments. A trustworthy model must be able to capture correct results from several experiments. Unfortunately, tests are costly and their reproducibility is not guaranteed, thus recourse to numerical simulations is unavoidable. However, it is necessary to make additional software for such commercial software in case of explosion effect. Or it should be well known how the effect of the explosion will be handled in the analyzes and models to be done with the end-user program. In this thesis study, the buildings were modeled by using the finite element method to investigate the effect of the explosion on reinforced concrete and masonry buildings, and the structural responses of the building were obtained by considering the bomb explosion at different distances from the models. It is therefore aimed to provide a sustainable design in order to ensure sufficient performance throughout the life of the buildings, considering all the possible effects, including the severe dynamic loading conditions and /or due to the structure. The use of Fiber Reinforced Polymer (FRP) is among of the advanced and efficient technologies for structural reinforcement of concrete elements in buildings. In this article the performance of FRP laminate on the lateral facade to strengthening the blast effect on the two storey building is studied. Concept and theory of nonlinear finite element is used. Blast load is simulated by ConWep blast loading model and results are used to comparison and evaluation the retrofitted structures performance against blast loads. Keywords: Blast load, RC buildings, masonry buildings, nonlinear analysis, damage, finite element analysis