When there’s a war, you would need a good, solid bunker for protection from missiles and other threats. You wouldn’t want to be a sitting duck in the line of fire! That’s why the construction of the bunker needs to be solid and strong.
Ballistics is a field of engineering that deals with the launching, flight behaviour, and the impact effects of projectiles such as bullets, bombs, and rockets. This science is used not only for designing bunkers, but also for designing the walls of nuclear power buildings, bridges, and other protective structures.
Due to the strategic importance of these structures, it is necessary to protect them against projectile and debris impact which can result in localised damage or even the collapse of the entire structure.
Reinforced concrete (RC) is one of the main materials used to build protective structures. Concrete structures face highly localised damage such as penetration, perforation, scabbing, spalling, and crushing under projectile impact load.
Usually extensive experimental and numerical studies have been done to investigate concrete panels, resulting in design guidelines for local damage parameters. However, with the advent of performance-based design, the ballistic design of concrete structures lacks a comprehensive design philosophy. Moreover, while quantifying damage parameters, incorrect and inconsistent results are obtained by using deterministic empirical formulations.
In this study, the authors Mr. Roouf Un Nabi Dar and Prof. P. Alagappan from the Department of Civil Engineering, Indian Institute of Technology (IIT) Madras, Chennai, India, have focused on the development of the novel performance based design framework based on the depth of penetration (DOP) and the crater damage area in RC panels. Hence, this framework will help designers come up with innovative solutions for improving the ballistic resistance of RC panels.
Furthermore, a probabilistic approach is taken to formulate a reliable formula for quantifying unexplored crater damage, based on well-established Bayesian methodology for RC panels that takes into account uncertainty. This caters the need to take care of uncertainties that deterministic models do not.
The proposed probabilistic model for estimating crater diameter in RC panels under projectile impact was validated with several experimental test results from the literature. The agreement of the predicted crater diameter with the experimental results ensures its reliability and accuracy.
Thus a reliable design formula for estimating crater diameter is provided in addition to the development a novel performance-based ballistic design framework for RC panels. This study is helpful not only in terms of providing the ballistic design framework and probabilistic crater quantifications formula, but also in understanding the ballistic behaviour of RC panels.
Article by Akshay Anantharaman
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