Floor response spectra of buildings with uncertain structural properties

Conference · Wed Jan 01 04:00:00 EST 1975

OSTI ID:4077253

Chen, P C

All Category I equipment, such as reactors, vessels, and major piping systems of nuclear power plants, is required to withstand earthquake loadings in order to minimize risk of seismic damage. The equipment is designed by using response spectra of the floor on which the equipment is mounted. The floor response spectra are constructed usually from the floor response time histories which are obtained through a deterministic dynamic analysis. This analysis assumes that all structural parameters, such as mass, stiffness, and damping have been calculated precisely, and that the earthquakes are known. However, structural parameters are usually difficult to determine precisely if the structures are massive and/or irregular, such as nuclear containments and its internal structures with foundation soil incorporated into the analysis. Faced with these uncertainties, it has been the practice to broaden the floor response spectra peaks by +-10 percent of the peak frequencies on the basis of conservatism. This approach is based on engineering judgement and does not have an analytical basis to provide a sufficient level of confidence in using these spectra for equipment design. To insure reliable design, it is necessary to know structural response variations due to variations in structural properties. This consideration leads to the treatment of structural properties as random variables and the use of probabilistic methods to predict structural response more accurately. New results on floor response spectra of buildings with uncertain structural properties obtained by determining the probabilistic dynamic response from the deterministic dynamic response and its standard deviation are presented. The resulting probabilistic floor response spectra are compared with those obtained deterministically, and are shown to provide a more reliable method for determining seismic forces. (auth)

• Research Organization: Bechtel Corp., San Francisco
• NSA Number: NSA-33-016456
• OSTI ID: 4077253
• Country of Publication: United States
• Language: English

Related Subjects

*NUCLEAR POWER PLANTS-- SEISMIC EFFECTS
220900* --Nuclear Reactor Technology--Reactor Safety
BUILDINGS
FLOORS
MECHANICAL VIBRATIONS
N77900* --Reactors--Reactor Safety & Environmental Aspects
PROBABILITY
REACTOR COMPONENTS
RESPONSE FUNCTIONS
STATISTICS