Preliminary study: Document format for describing risks and vulnerabilities in the event of weapon action in urban environments

Authors:

  • Oskar Paradis
  • Johan Gidholm
  • Jesper Krusell

Publish date: 2024-06-12

Report number: FOI-R--5612--SE

Pages: 18

Written in: Swedish

Keywords:

  • Pressure
  • air blast
  • blast wave
  • weapons effects
  • structural collapse

Abstract

On behalf of Växjö municipality, FOI has carried out a preliminary study to illustrate risk for buildings located near targets exposed to conventional weapons. The models used are based on calculations of pressure loads from detonations and calculation of vulnerability criteria of various facade constructions and windows. The study does not provide site-specific assessments. The data and results given in the report are produced to show which circumstances affect damage to a building. An adversary nation can use different methods and one or several weapon systems to perform an attack. How the attack is carried out can for example depend on the purpose of the attack and what opportunities the adversary has to execute it. In this study, a case has been used to produce illustrative data and describe the circumstances that affect consequences for buildings surrounding the target. The case consists of a guided missile with a warhead of 450 kg striking a target in an urban environment. The missile is assumed to have a surface detonation. When the damage to buildings is described, only the structural strength of the facade is considered. In addition to the facade itself, window damage is also accounted for. The pressure effect from a warhead that detonates on the ground surface will have a hemispherical propagation, starting from the point of impact, and the pressure will decrease with distance. When assessing the damage, the building's orientation in relation to the burst and the placement of the surrounding buildings need to be taken into account. The damage can be significantly increased if there are surrounding buildings. Two different building types are used to visualize the blast effect, a cast-in-situ concrete building with thick walls and a timber frame building. These buildings are subjected to three load cases. Further method development based on the presented work is required to obtain a method that can be used to make proper assessments. The information and results could then be adapted to answer to questions with different needs for details, e.g. rough estimates of risks or site specific assessments. This in order to produce typical cases and results that can be used to support decisions regarding the design and planning of cityscapes and vital societal functions. The results can be adapted for workshops as well as for site-specific assessments.