A risk de-aggregation framework that relates community resilience goals to building performance objectivess

Abstract

Resilience is often regarded as an attribute of communities rather than of individual buildings, bridges, and other civil infrastructure facilities. Previous research to support development of resilient infrastructure has considered, for the most part, actions and policies to achieve resilience objectives at the community level. While it is clear that a community cannot be resilient without resilient individual facilities, few attempts have been made to relate the performance criteria for individual facilities to community resilience goals in a quantitative manner. This paper presents a method for relating risk-informed performance criteria for individual buildings exposed to extreme hazards to broader community resilience objectives and illustrates the application of the method to two residential building inventories. The paper demonstrates the feasibility of de-aggregating community resilience goals to obtain design performance objectives for individual facilities and thereby relating community goals to requirements in codes and standards that govern design of buildings and other structures.

Keywords:

• Buildings (codes)
• civil infrastructure
• community resilience
• natural hazards
• performance-based engineering
• risk assessment
• structural engineering

Acknowledgments

The research reported herein was supported, in part, by the National Science Foundation under grant number CMMI-1452708 and, in part, by the Center for Risk-Based Community Resilience Planning, supported by the National Institute of Standards and Technology (NIST). This support is gratefully acknowledged. Any opinions, findings and conclusions, or recommendations expressed in this paper are those of the authors and do not necessarily reflect the views of the National Science Foundation or NIST.

Notes

¹ We confine our critical appraisal in this section to buildings, which are the main thrust of this paper. Many of these comments also apply to other civil infrastructure, the performance requirements of which may be different from those for buildings.

² The probabilities of severe damage or incipient collapse in a 50-year period embedded in the ASCE 7 (ASCE, 2010) load provisions are higher for earthquake and tsunami effects than for hurricane winds. The impact of such differences on the resilience of existing communities is unknown.

³ Positive quadrant dependence, of which correlation is the linear and simplest form, invariably causes the losses to be underestimated; see, e.g. Vitoontus and Ellingwood (2013) for a discussion of its impact on the determination of probable maximum losses due to earthquake.

⁴ Numerous metrics for community resilience have been proposed recently. The ability to shelter in place, job loss and population dislocation are common metrics in these studies and all are integrally related to building performance.

⁵ As an example, inter-storey drift is a common measure of structural response in earthquake engineering. In a well-engineered modern building, inter-storey drift ratios between .0025 and .005 might correspond to slight damage.

⁶ For example, ASCE 7 (ASCE, 2010) is based on an earthquake (MCE) with a return period of 2475 years (2%/50 years). For Memphis, TN, for example, the dominant contributors to this return period hazard come from two faults that are 35 and 65 km from Memphis (Reelfoot Fault System), either of which are capable of generating scenario earthquakes of this magnitude.

⁷ This model is relatively simple in comparison with more recent NGA ground motion models (Campbell & Bozorgnia, 2008), but is able to capture the spatial variability in seismic demand adequately for purposes of this community resilience illustration.

⁸ Since Zone II buildings are more vulnerable than Zone I buildings, the option of retrofitting type I building to high-code level and retrofitting type II building to moderate-code level is not considered. Therefore, the following results only consider three alternatives.