1- Department of Structures, Faculty of Civil Engineering, Iran University of Science and Technology, Tehran, Iran
2- Faculty of passive defense, malek ashtar university of technology, iran ,hoseini@mut.ac.ir
2- Faculty of passive defense, malek ashtar university of technology, iran ,
Abstract: (534 Views)
So far, the performance of masonry walls against in-plane lateral loads such as earthquake loads has been extensively studied, but less attention has been paid to out-of-plane loads such as explosions. Due to their large surface area, walls endure significant forces during explosions, leading to extensive damage and potentially causing severe financial losses and casualties. Given the increase in terrorist and sabotage attacks, reinforcing these structures seems necessary. In recent years, fiber-reinforced polymers (FRP) have been widely and effectively used in the reinforcement and performance improvement of these structures. Their light weight, high stiffness and high strength, and corrosion resistance are among the properties that have attracted researchers to use these materials. Finite element modeling not only provides a basis for better understanding the behavior of masonry walls but also is very useful in predicting the behavior of these members after reinforcement, especially in the absence of experimental results. In this study, using numerical modeling in ABAQUS software, the behavior of masonry walls reinforced with FRP strips against a blast with an explosive charge equivalent to 150 kg of TNT (the weight of explosive likely to be carried in a sabotage attempt via a vehicle) at a distance of 5 meters was investigated. Lagrangian equations were used to model the mechanical behavior of the structure, and the solver used in this research is an explicit solver to account for the time factor in the software’s integration process. The total time considered for the entire explosion process is 1 second, and the explosive load was applied to the studied structure using the Conwep method. The type of fibers, width, thickness, area, and angle of the FRP strips were important and influential parameters that were examined for the efficiency of this reinforcement method. The modeling results indicate that this reinforcement technique is highly effective in strengthening masonry walls against explosions, as it has reduced the deflection of the wall by at least 70% and its energy by up to 90%. It can also be inferred that an arrangement for reinforcing masonry walls with FRP strips is suitable if it covers the areas prone to damage, which in masonry walls are the mortar joints between the bricks. Therefore, the horizontal arrangement shows better performance compared to the vertical and diagonal arrangements. Similarly, reinforcing 100% of the wall area performs much better than reinforcing 50% and 25% of the wall area, but it is not economically acceptable. In general, similar to structural elements, non-structural elements can also exhibit plastic behavior in critical situations, preventing the collapse of these elements due to the absorbed energy. Therefore, walls with higher plastic energy show better behavior against explosive loads. Additionally, based on the hysterical displacement and kinetic energy diagrams of the wall, it can be seen that the behavior of reinforced walls is oscillatory, while the behavior of unreinforced walls is noticeably pulsating. Finally, the optimal arrangement of FRP strips proposed for reinforcing masonry walls against explosions in this study is the use of CFRP strips horizontally, with a thickness of 1 mm, a width of 24 cm, and covering 50% of the surface area; This configuration successfully decreased the deflection of the wall from 63.1 cm to 7.7 cm and damped approximately 13% of the blast wave energy.
Article Type: Original Research |
Subject:
Civil and Structural Engineering
Received: 2024/10/5 | Accepted: 2024/12/17
Received: 2024/10/5 | Accepted: 2024/12/17
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