Quantifying the Importance of Social Infrastructure in Community Resilience using Social Capital

Abstract

Social capital is the networks of relationships between people of a specific area that provide them with access to resources and power. Social capital has been shown to have numerous benefits in a community during times of typical functioning through developing and providing a sense of community to the population, and post-disaster through people utilizing that sense of community through providing aid and resources to other community members. Social capital is often grown, and its benefits are often facilitated, through social infrastructure. Examples of social infrastructure include churches, libraries, museums, parks, and many more, all of which are often used to build networks and relationships, and to connect people. Social capital is a critical piece of what makes a community resilient to disasters. However, social capital is typically omitted from quantitative realizations of community resilience. This study provides a method of quantifying social capital as it is provided by social infrastructure and affiliated social organizations through the development of three indices which measure the importance of (1) the organization (Organization Social Capital Index), (2) the physical structure housing the organization (Building Social Capital Index), and (3) the interdependencies between the social organization with critical facilities (Critical Infrastructure Interdependency Index). Calculation and analysis of the three indices allow for prioritization of social infrastructure within a community, whether in typical functioning or the post-disaster setting. Equations are developed initially, then adapted to fit three different phases of a hazard scenario, namely the pre-disaster conditions, the hazard event, and long-term community recovery. The indices are further exemplified to provide a method of measuring social capital facilitated through any type of community building (e.g. restaurant, police station, house). Prioritizing social infrastructure can be examined through post-disaster resource allocation, or through pre-disaster mitigation. The latter is exemplified here through the performance-based seismic design of a two-story church building archetype. The archetype was designed using cross-laminated timber (CLT) panels as the lateral force resisting system following the Simplified Direct Displacement Design methodology and setting immediate occupancy as the performance objective for a maximum considered earthquake (MCE) in San Francisco, California. This thesis demonstrates that designing social infrastructure to higher levels can preserve on average 45% of social capital generated by the organization and 60% of the building’s social capital during an MCE hazard scenario. These findings should be considered by decision makers at the local level, and national level for improved prioritization of recovery resource allocation, and in the consideration of redefining the risk categories for social infrastructure buildings.