Engineering Guideline for Incremental Seismic Rehabilitation (FEMA P-420 / May 2009)

Initial cost and loss of normal building use have been cited as major obstacles to implementation of seismic rehabilitation. The Federal Emergency Management Agency (FEMA) has published a series of occupancy-specific manuals for building owners that presents incremental strengthening of buildings in discrete stages as a way of managing costs and minimizing disruption associated with seismic rehabilitation projects. Incremental strengthening was initially conceptualized for school buildings under a grant from the National Science Foundation to Building Technology Incorporated. The FEMA manuals are the result of a series of projects funded by FEMA and others dating back to the 1980s, which investigated financial incentives for seismic rehabilitation of existing hazardous buildings, physical seismic rehabilitation potential, and institutional capacity for mitigation investment. Work was conducted by a team of consultants led by the World Institute for Disaster Risk Management in association with Virginia Polytechnic Institute and State University, Building Technology Incorporated, Melvyn Green Associates, EQE Incorporated, and George Washington University. Early on, these projects concluded that a strategy for integrating the planning and implementation of seismic strengthening into the overall facility maintenance and capital improvement process was needed. The strategy was referred to as incremental seismic rehabilitation, and the resulting manuals present seismic rehabilitation within the context of the specific facility management, risk management, and financial management needs and practices of building owners. The technical feasibility and economic viability of incremental seismic rehabilitation has been studied and validated. This Engineering Guideline for Incremental Seismic Rehabilitation is intended as a technical resource for design professionals who are implementing incremental seismic rehabilitation on their projects or advocating the use of an incremental approach to seismic rehabilitation in practice. It explains the concept of incremental seismic rehabilitation as a strategy, discusses owner maintenance, capital improvement and decision-making processes as a basis for communicating with decision-makers on seismic rehabilitation opportunities, summarizes available engineering resource documents, and outlines the overall engineering process for incremental seismic rehabilitation of buildings.