Action Plan for Performance Based Seismic Design (FEMA 349) - Federal Emergency Management Agency - Bog

Recent decades have seen a dramatic earthquake related losses. In the past ten years estimated losses were twenty times larger than in the previous 30 years combined. FEMAs expenditures related to earthquake losses have become an increasing percentage of its disaster assistance budget. Predictions are that future single earthquakes, which will inevitably occur, may result in losses of $50-100 billion each. Losses are rising due to several factors. These include: a denser population of buildings being located in seismically active regions. an aging building stock and the increasing cost of business interruption. Nonstructural and contents damage are also large contributors to loss, especially in regions with high-technology manufacturing and health-care industries. It is this increase in losses from all hazards that has led FEMA to support actions to reduce future losses. One of these is Project Impact, an initiative to encourage loss reduction activities through partnerships at the local community level. One of the key components of Project Impact is the community's adoption and enforcement of an adequate building code. Performance Based Seismic Design (PBSD) is a methodology that provides a means to more reliably predict seismic risk in all buildings in terms more useful to building users. PBSD will benefit nearly all building users. The PBSD methodology will be used by code writers to develop building codes that more accurately and consistently reflect the minimum standards desired by the community. A performance based design option in the code will facilitate design of buildings to higher standards and will allow rapid implementation of innovative technology. When performance levels are tied to probable losses in a reliability framework, the building design process can be tied into owner's long-term capital planning strategies, as well as numerical life cycle cost models. PBSD is not limited to the design of new buildings. With it, existing facilities can be evaluated and/or retrofitted to reliable performance objectives. Sharing the common framework of PBSD, existing buildings and new buildings can be compared equitably. It is expected that a rating system will develop to replace the currently used Probable Maximum Loss (PML) system. Such a system is highly desirable to owners, tenants, insurers, lenders, and others involved with building financial transactions. Despite its inconsistency and lack of transparency, the PML system is widely used and a poor rating often creates the financial incentive needed for retrofit decisions. This Action Plan presents a rational and cost effective approach by which building stakeholders: owners, financial institutions, engineers, architects, contractors, researchers, the public and governing agencies, will be able to move to a performance based design and evaluation system. The Plan recognizes that there is a strong demand from stakeholder groups for more reliable, quantifiable and practical means to control building damage. It also recognizes that there is not a focused understanding among these groups as to how these goals can be obtained. This Plan describes how performance based seismic design guidelines can be developed and used to achieve these goals. It will be a vehicle to bring together the diverse sets of demands from within the stakeholder groups and distill them into cohesive and practical guidelines. It engages each of the groups in the development these guidelines, by which future building design will become more efficient and reliable.