“Seismic Analysis
 of
Coupled Structural and Piping Systems”
by
Brian Lawton, P.E. and Albert Wong, Ph.D., P.E.
Stone & Webster, Inc.
A Shaw Group Company
Stoughton, MA
 
Abstract
In the design of the main steam piping system of a 1300 MW nuclear power plant, the main steam piping within the turbine building must be anchored to the turbine pedestal columns and the turbine building floors. The turbine pedestal is isolated from the turbine building floors to minimize the effect of machine vibrations on the turbine building. The major seismic loads produced by the piping are due to inertia and relative displacement between the turbine building and the turbine pedestal. The conventional analytical design method assumes that the piping and structural systems can be decoupled and that the inertia and displacement loads from the pipe system are considered additive. This method, though conservative yields excessively large seismic pipe support loads to the supporting structures.

To study the conservatism in the conventional method and to estimate a more realistic load definition of the main steam pipe support loads, a coupled analytical model of the main steam piping, the turbine building and the turbine pedestal was developed and a seismic analysis utilizing GT STRUDL was performed. This was accomplished using response spectrum analytical techniques. The analysis results show that the coupled model predicts a significant reduction in the pipe support loads on the turbine pedestal columns. It also shows that the restraint effect of the piping system excites modes not accounted for in the uncoupled turbine pedestal model.  These results of the coupled model thus provide a more realistic load definition of the main steam piping system to the turbine pedestal and demonstrate the conservatism in the conventional design method. 

Biographical and Educational Data
 
Brian A. Lawton:

B.S., Civil Engineering - University of Massachusetts (Dartmouth) - 1978
Northeastern University - Graduate courses in Structural Engineering

Licenses, Registrations, and Certifications
Professional Engineer - Massachusetts

Professional Affiliations
American Society of Civil Engineers – Member
Structural Engineering Institute – Charter Member

Albert Y. C. Wong, Ph.D., P.E.

Education

Ph.D., in Civil Engineering - University of Illinois at Champaign Urbana - 1973
M.Sc., in Civil Engineering - University of Illinois at Champaign Urbana - 1970
M.S., in Business Administration - Boston College - 1981
B.Sc., (Hon.) in Civil Engineering - University of Hong Kong - 1968
United States Civil Defense Preparedness Agency, Multi-Protection Design 1974
Graduate Courses in Power Plant Design - Northeastern University

Licenses, Registrations, and Certifications
Professional Engineer - Massachusetts, New York, Pennsylvania, Texas, Arizona, Ohio, North Carolina

Professional Affiliations
American Society of Civil Engineers - Member
American Concrete Institute - Member
American Institute of Steel Construction
Institute of Civil Engineers - Graduate Member

Publications
"The Effects of Drying on the Freeze-Thaw Durability of Concrete," University of Illinois Engineering Experiment Station, Bulletin 506 by A. Y. C. Wong, C. L. Anderson, H. K. Hilsdorf

"Effects of Diaphragms on Load Distribution of Continuous Slab Girder Bridges" by A. Y. C. Wong and W. L. Gamble - University of Illinois Structural Research Series, SRS 391

"Probabilistic Prediction of Floor Response Spectra" by Manas K. Chakravorty, A. Y. C. Wong, D. C. Foster - Third Canadian Conference on Earthquake Engineering, June 4-6, 1979, Montreal, Canada

"A Frequency Domain Approach to Seismic Analysis of Multiple Supported Secondary Systems" by Manas K. Chakravorty, A. Y. C. Wong, M. B. Stetson, International Meeting on Fast Reactor Safety Technology, August 19-23, 1979, Seattle, Washington

Report on the Review Team on the Department of Energy Natural Phenomena Hazard Mitigation Order and Standards

 
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Lawton 2002.ppt
Date: 6/21/2002 
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