Structures Under Blast Loads from Academic Research into Engineering Applications: Advances and Limitations

Recent increases in terrorist activities and accidental explosions, e.g., the 2020 Beirut blast or gas explosion event in the North-eastern city of Shenyang, China in 2021, have caused devastating consequences and imposed significant threats to public safety and economic development. Together with direct primary effects from explosive events, i.e., primary shock pressure and/or secondary fragments, the indirect secondary effects caused by blast events such as the progressive collapse of structures are also critical when resulting in more widespread significant losses. Therefore, critical infrastructure, e.g., government buildings, public transport infrastructure, petrochemical, and hazardous material storage facilities, need to be carefully considered under these extreme loading events in their design and operations. In current engineering practices, Single-Degree-of-Freedom (SDOF) is typically utilised to design structures under far-field blast events, whilst finite element (FE) analysis is adopted when considering close-in or contact blast scenarios. With the recent developments of material models under high loading rates, e.g., K&C concrete material release III or Continuous Surface Cap concrete model (CSCM), and fluid-structure interaction simulation technique, e.g., Arbitrary Lagrangian-Eulerian (ALE), the capability and application of FE analysis in the blast effect analysis of structures under close-in blast events have increased considerably. Although FE and SDOF analyses developed in previous studies contribute to providing reasonable predictions on the blast performance of structures, there are several limitations that need to be resolved in order to increase the reliability of the analysis techniques employed to ensure accurate prediction of structural behaviour to these complex response modes. Typical studies normally focus on the structural member responses, i.e., flexural or shear responses, while connection forces between structural members have not been fully investigated. The accuracy of the FE model and SDOF in predicting the reaction at structural supports is still unknown. Moreover, the failure of concrete structures under close-in blast events, e.g., concrete spalling and breaching or fragment velocity, is not considered to be accurately predicted by the abovementioned methods. Advances and limitations of those analysis methodologies are to be discussed in this study.