Forensic engineering techniques to analyze bombing events

Bombing at Erawan Shrine, Bangkok, Thailand on August 17, 2015 caused a massive damage to both lives and properties killing 20, injuring around 130, damaging vehicles, and other structures in the vicinity. This paper aims to estimate the TNT equivalent charge weight used for this bombing incident using Finite Element Analysis. Only the damage from blast pressure is considered in this paper. Analysis results are compared with onsite damage data obtained from online media. It is shown that an equivalent explosive of 3 kg of TNT bare charge could have been used for the bombing. To provide more insight, possible sizes of the explosive casing, type and weight of cased explosive are estimated. Based on evidences obtained from online media, the length of the pipe is assumed to be 25 cm. Two examples of TNT and C4 pipe bombs with diameter 3, 4 and 5 inch are investigated. The first example of TNT pipe bomb, a 4 or 5 inch pipe bomb could cause the damage in the same level as that observed from the incident. The second example of C4 pipe bomb, a 4 inch pipe bomb is the possible size which could have been used for bombing. The authors further investigate the damage to people resulted from blast pressure. Blast pressure at various distance is calculated using CONWEP code. It is found that the lethal zone is approximately 2 m. A person who stands between 2 m and 3.45 m from the explosion might suffer from lung damage whereas people in the range of 3.45 m to 8.5 m from the explosion might get eardrum rupture. Finally, importance of researches on this matter in order to minimize the risk and improve safety of the community is emphasized.