IIT Madras develops framework to protect critical infrastructure against ballistic missiles

Chennai: Researchers at the prestigious Indian Institute of Technology Madras (IIT-M) have developed a framework to protect the country's critical infrastructure like military bunkers, nuclear power buildings, bridges, and airport runways against the threat of ballistic missiles. 

Ballistic missiles, which are rocket-powered weapons that follow an arched trajectory to deliver a warhead to a target, can be launched from aircraft, ships, and submarines. The distance that the missiles cover depends on the power of their rockets and the weight of their payloads.

The research by Dr Alagappan Ponnalagu, Assistant Professor, Department of Civil Engineering, IIT-M and Roouf Un Nabi Dar, a research scholar, studied the impact of missiles on Reinforced concrete (RC), which is the main material used to construct vital structures, using computational simulations. 

The framework will improve the resistance of reinforced concrete (RC) panels in the critical infrastructure. 

Dr Ponnalagu said they will extend the study to develop much needed lightweight, cost-effective and sustainable blast and ballistic resistant modular panels that can be used in the construction of bunkers along the borders and highly inaccessible areas for the Indian Army.

Since structures like military bunkers are of strategic importance to countries, it becomes imperative to protect them against projectile and debris impact, which can result in localised damage or even the collapse of the entire structure.

The researchers focused on the development of the novel performance-based design framework based on ‘Depth of Penetration’ (DOP) and Crater Damage Area in the RC panels. In addition to that, a probabilistic formula for estimating the crater diameter in RC panels is proposed.

Peer-reviewed in Reliability Engineering & System Safety journal, the study is helpful not only in terms of providing the ballistic design framework and probabilistic crater quantification formula but also in understanding the ballistic behaviour of RC panels, the IIT-M said. 

With the advent of performance-based design, ballistic design of concrete structures lacks a comprehensive design philosophy and moreover, while quantifying damage parameters, incorrect and inconsistent results were obtained by using deterministic empirical formulations. 

“We have now provided a reliable design formula for estimating crater diameter in addition to the development of a novel performance-based ballistic design framework for RC panels,” Dr Ponnalagu said. 

The study said a novel performance-based design framework was proposed for RC panels based on damage states, namely DOP and crater diameter. “Hence, the framework is a novel design philosophy ensuring resilience against projectile penetration and crater formation of RC panels. On the other hand, the local damage response in terms of crater formation in RC panels was studied under projectile impact,” the study added. 

Roouf Un Nabi Dar said a probabilistic approach was 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.

“The probabilistic model proposed by IIT Madras Researchers 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,” Dar added.