When Going Beyond Empirical Is Needed, a Real Life Example.

Most facility siting analyses start with a basic, worst-case empirical consequence analysis. And as it turns out, many of those studies quickly demonstrate that the impact to buildings exceeds the acceptable criteria and require further analysis. The next level of analyses includes various techniques to rebalance conservatism and realism including quantitative risk-based studies that produce exceedance curves, etc. However, because the basis of these studies is generally trying to reach the acceptable criteria from the worst-case direction while minimizing the changes to the consequence modelling effort itself—it is not uncommon for these studies to result in design loads that require expensive retrofits to buildings. As a final step, some of these studies will turn to computational fluid dynamics (CFD) to justify avoiding these expensive retrofits. By following this process, the cost of the facility siting study is maximized and there is a higher chance that expensive building retrofits that don’t actually pass a cost-benefit analysis might be forced to move forward.

This paper will demonstrate some of the benefits of using more realistic CFD modelling earlier in the process to more accurately reflect the real extent of potential building damage. When using the right mix of empirical modelling and CFD up-front as part of a risk-based analysis, facility siting studies can more realistically reflect the potential harm and provide greater cost-benefit—i.e., reduce the true overall cost of the study while also being more realistic about when it may be required to retrofit buildings to meet certain design accidental loads. The paper will focus on a real-life example of this application.