CALCULATED ASSESSMENT OF THE FUNCTIONAL SUITABILITY OF MODULAR-TYPE PROTECTIVE STRUCTURES (SHELTERS) DURING THE USE OF ENEMY AIR ATTACK WEAPONS

Abstract

Introduction. An important factor determining the effectiveness of protective structures in urban construction projects is the ability of their enclosing elements to maintain their protective functions under combat conditions, block the impact of damaging factors caused by air, missile, and artillery strikes, and protect people from debris and fragments of building structures. A pressing issue today, in the context of a full-scale invasion by an aggressor country, is the protection of critical infrastructure, particularly energy facilities and energy communications. To provide such protection, specially equipped protective structures are used, primarily constructed from reinforced concrete monolithic enclosing elements. 
Research Objective. To justify a general computational and theoretical approach to methods for calculating the protective capacity of modular shelters in accordance with the standards in force in Ukraine, specifically DBN V.2.2-5:2023 “Civil Defence Structures. Buildings and Structures,” under the impact of an explosive shock wave. 
Research Methods. The analysis of structural destruction was performed with consideration of relevant plasticity and strength theories. Modern computational technologies, utilizing advanced software and numerical algorithms, were employed for the calculations. Computational procedures were based on the explicit integration method for dynamic equations over time, the finite element method, and the description of contact interactions using the penalty function method. Mathematical models of materials under high-speed deformation were applied, accounting for their nonlinear properties and failure criteria in accordance with the relevant strength theories. 
Research Results. Patterns of correlation between explosion parameters and the stability of structural elements, in particular walls made of concrete lightweight blocks, have been established, which is important for assessing their residual protective capacity. 
The use of modern numerical modeling methods—including the finite element method, explicit integration of dynamic equations, contact interaction models, and nonlinear material models—enabled insight into the mechanisms of destruction and indicators of loss of integrity of protective structures as a result of explosions. This analysis included the most critical combination of explosion parameters, with a TNT equivalent charge of m (TNT) = 718.2 kg. 
The mechanisms of destruction or integrity loss in shelter structures were investigated, and their relationship to the performance of protective functions under an explosion with a TNT equivalent charge of m (TNT) = 30 kg and a minimum distance from the epicenter to the shelter surface of L = 0.5 m. Distributions of plate deformations were obtained for blast wave pressure applied to the shelter structure from the side, the end (closer to the door), and above the upper horizontal surface in the middle.