A Pragmatic Framework for Cost-Benefit Analysis of Liquefaction Mitigation Applicable to Lightweight Residential Structures on Shallow Foundations

Abstract

Liquefaction hazards are often not assessed or mitigated for lightweight residences on shallow foundations despite their comprising 90% of the US building stock. This study demonstrates a pragmatic approach to performing cost benefit analyses of liquefaction mitigation for such structures using a performance-based framework to predict the benefits of mitigation over an investment time-horizon. These analyses can be used to inform decisions about whether and how liquefaction is mitigated, to quantify the value of ground-improvement, or to demonstrate the economic feasibility of a new intervention strategy. Cost-benefit analyses are demonstrated for numerous US cities using fragility and vulnerability models newly trained on data from New Zealand. To increase their applicability and practicality, these models are developed as extensions to liquefaction analytics already in popular use. It is shown that mitigation economics depend on the interactions of many region-, site-, and asset-specific variables, making it difficult to accurately supplant detailed analyses with general principles or simplifications. The cost-benefit analyses demonstrated herein allow for these variables to be studied in a consistent, rational, transparent, and practical manner. The adoption and improvement of such analyses could increase the use of ground improvements and lead to more efficient management of liquefaction risks worldwide.