Risk-Based Approach – Damage Criteria

This paper compiles human vulnerability and structural damage criteria from well-known literature references for explosions, fires and dispersion analysis.

In the first section, the manuscript addresses human vulnerability from explosions. Based on the contents described below, three parameters should be considered when evaluating human vulnerability due to overpressure: (1) overpressure, (2) impulse and (3) probit analysis. However, it is important to mention that dedicated criteria for human vulnerability based on the Department of Defense (DoD) is addressed in the following reference: [1] “Facility Siting Addressing Explosions Impacting Process Plant Permanent and Portable Buildings, Combining Exceedance Curves, Structural Response and Human Vulnerability Criteria,” After addressing human vulnerability the following section presents several well-known overpressure thresholds for domino effect and escalation analysis. It is important to note that even though the impulse has a potential effect on escalation triggered by explosions, it is normal to only use overpressure. Additionally, the following two references address the domino effect and escalation triggered by explosions phenomena, based on only thresholds and based on the Single Degree of Freedom (SDOF) approach: [2] “Domino Effect and Escalation Triggered by Explosions – Combining Exceedance Curves and Overpressure Threshold Criteria;” and [3] “Domino Effect and Escalation Triggered by Explosions – Combining Exceedance Curves, Single Degree of Freedom and Pressure-Impulse Diagrams.”

The second section addresses the human vulnerability, domino effect and escalation from fires. With regards to human vulnerability, three parameters need to be considered: (1) thermal flux, (2) thermal dose and (3) probit analysis. The following reference is developed with the aim to address building occupant human vulnerability through a detailed risk-based approach using Heat Flux Exceedance Curves (HFECs) as addressed in reference [4] “Facility Siting Addressing Fires Impacting Process Plant Permanent and Portable Buildings, Combining Exceedance Curves and Human Vulnerability Criteria.”

Similarly to explosions, domino effect and escalation triggered by fires is also briefly explained in this manuscript. The following references further address this phenomenon and include a case study based on well-known thresholds approach and the Dynamic Thermal Stress Analysis (DTSA) approach: [5] “Domino Effect and Escalation Triggered by Fires – Combining Exceedance Curves and Time to Failure Simplified Methodologies;” and [6] “Domino Effect and Escalation Triggered by Fires – Combining Dynamic Thermal Stress Analysis and Wall Segmentation Approach.”

Finally, in the third section only human vulnerability due to toxic dispersions is addressed; i.e., there is no potential for domino effect triggered by toxic clouds. When addressing human Risk-Based Approach – Damage Criteria 2 vulnerability due to toxic dispersions, the damage criteria is based on: (1) probit analysis and (2) exposure thresholds limits or doses. When it is desired to evaluate flammable dispersions, the vulnerability is based only on exposure thresholds as illustrated in the fires damage criteria. Similar to explosions and fires, a dedicated reference is developed to specifically address facility siting for toxic dispersions: [7] “Facility Siting Addressing Hazardous Vapor Cloud Dispersions Impacting Process Plant Permanent and Portable Buildings, Combining Exceedance Curves and Human Vulnerability Criteria.”

As a summary, the present manuscript collects several criteria, well-known thresholds and data for addressing human vulnerability regarding the three hazards used in a risk-based approach assessment or Quantitative Risk Assessment (QRA): overpressure, thermal radiation and toxicity. Furthermore, for both explosions and fires, domino effect and escalation phenomena are addressed.

Figure 02: Exposure and Damage Criteria to Vapor Cloud Explosion

Table 07: A Response of Structural Elements to the Different Levels of Overpressure