FEMA 320

FEMA 320
Title	FEMA 320
Author	Federal Emergency Management Agency
Country	United States
Language	English
Subject	Seismic rehabilitation guidelines for buildings
Release date	1998
Pages	240 (approx.)

FEMA 320 FEMA 320 is a technical guideline published by the Federal Emergency Management Agency providing methodologies for seismic rehabilitation of wood-frame and unreinforced masonry structures. The document synthesizes engineering practices, regulatory precedents, and post-earthquake observations to offer procedures for assessing seismic vulnerability and prescribing retrofit measures.

Overview

FEMA 320 addresses retrofit strategies for residential and small commercial structures commonly found in urban and suburban settings, drawing on empirical findings from events such as the Northridge earthquake and the Loma Prieta earthquake, and aligning with criteria used by institutions like the American Society of Civil Engineers and the National Institute of Standards and Technology. It integrates concepts from standards promulgated by the International Conference of Building Officials, the Uniform Code for Building Conservation era, and related guidance issued by agencies including the U.S. Geological Survey and the Department of Housing and Urban Development. The guideline references damage patterns documented in studies by organizations such as the Earthquake Engineering Research Institute and the California Seismic Safety Commission.

Purpose and Scope

The primary purpose is to provide practicable, standardized procedures for evaluating and retrofitting existing low-rise structures to reduce collapse risk consistent with objectives of regulatory frameworks like the National Earthquake Hazards Reduction Program and to complement model codes from bodies including the International Code Council and the American Concrete Institute. The scope encompasses seismic assessment methodologies, selection of retrofit measures, and prioritization criteria used by local authorities such as the San Francisco Department of Building Inspection and the Los Angeles Department of Building and Safety. It is intended for use by professionals affiliated with firms and institutions like the American Institute of Architects, consulting practices active in post-disaster recovery, and researchers at universities such as Stanford University and the University of California, Berkeley.

Seismic Design Provisions

FEMA 320 prescribes specific provisions for diaphragm anchorage, shear wall enhancement, and foundation connections informed by investigations that included observations from the 1994 Northridge earthquake and analyses comparable to those in reports by the Applied Technology Council and the Multidisciplinary Center for Earthquake Engineering Research. The guideline details load paths, connection detailing, and acceptable retrofit components drawn from precedents in documents issued by the American Wood Council, the National Arbor Day Foundation (in the context of wood material standards), and engineering research at centers like the Pacific Earthquake Engineering Research Center. Design procedures reference seismic parameters used by the United States Geological Survey seismic hazard maps and align with performance goals discussed in publications by the Federal Highway Administration and the National Science Foundation.

Implementation and Use

Implementers include licensed professionals collaborating with municipal permitting entities such as the San Jose Building Department and nonprofit partners like the Red Cross in post-earthquake mitigation programs. FEMA 320 has been applied in retrofit campaigns in regions governed by building departments of cities such as Seattle, Portland, Oregon, and San Diego, and adopted in guidelines used by state agencies like the California Governor's Office of Emergency Services. Training and dissemination have involved organizations like the National Fire Protection Association and continuing education providers connected to registries at institutions like the California State University system. The guideline’s measures have been integrated into grant-funded mitigation projects administered through programs connected to the Federal Emergency Management Agency hazard mitigation assistance initiatives.

Development and Revisions

The original development drew on post-event reconnaissance coordinated with groups such as the Earthquake Engineering Research Institute and the Applied Technology Council, and technical inputs from academics at Massachusetts Institute of Technology, University of Washington, and University of Southern California. Revisions and related companion documents have been influenced by evolving model codes from the International Code Council, research outputs from the National Institute of Standards and Technology, and lessons from later events including the Northridge and Kobe earthquake studies. Stakeholder review included city officials, professional societies like the Structural Engineers Association of California, and federal program managers associated with the National Earthquake Hazards Reduction Program.

Criticisms and Limitations

Critiques center on applicability limits noted by practitioners at organizations such as the American Society of Civil Engineers and researchers at the Pacific Earthquake Engineering Research Center who observed that prescriptive measures may not capture complex performance objectives explored in studies by the National Institute of Standards and Technology and the Earthquake Engineering Research Institute. Additional limitations cited by municipal officials in Los Angeles and policy analysts at the RAND Corporation include varying enforcement across jurisdictions like Alameda County and uncertainties when reconciling FEMA 320 guidance with newer model codes from the International Code Council and research advances from institutions such as Carnegie Mellon University and the University of California, San Diego.

Category:Seismic safety