A Framework for the Evaluation of Liquefaction Consequences for Shallow-Founded Structures

Abstract

Performance-based earthquake engineering is increasingly being used to inform decision-making regarding seismic design. Recent research has provided a number of procedures that yield information needed for the development of a performance-based framework for liquefaction engineering. This study proposes a structure for such a framework for application to shallow-founded structures and identifies procedures that are key to its use. Procedures used in such performance-based engineering frameworks must offer a probabilistic estimate of hazard, demand, and/or damage, rather than a simple deterministic estimate. The framework includes analysis of both foundation and structural performance. The foundation may be subject to settlement and residual tilt if subsurface layers of soil liquefy. Although liquefaction generally reduces the acceleration demand on the superstructure, it may still cause significant damage to nonstructural components or lead to casualties. Further, the framework is organized with mitigation decision-making in mind. Mitigation may reduce the impact of foundation damage, but is expected to simultaneously increase the demand on the superstructure. Decisions about whether to mitigate, and how, must consider this tradeoff.