apractical soft story earthquake isolation system PDF
Preview apractical soft story earthquake isolation system
.' t ., PB 276 814\ I i REPORT NO. UCB/EERC-77/27 EARTHQUAKE ENGINEERING RESEARCH CENTER NOVEMBER 1977 APRACTICAL SOFT STORY EARTHQUAKE ISOLATION SYSTEM by JAMES M. KELLY JOHN M. EIDINGER and C. J. DERHAM A report on research conducted under GrantENV76-04262 from the National Science Foundation. .•A i •.a a ii lJ·· Y ~. REPRODUCEDBY NATIONAL TECHNICAL INFORMATION SERV~CE u.S.DEPARTMENTOFCOMMERCE r, ------------ SPRINGFIELD,VA. 22161 COllEGE OF ENGINEERING UNIVERSITY OF CALIFORNIA . Berkeley, California BIBLIOGRAPHIC DATA 1. Report No. UCB/EERC-n/27 SHEET \ 4. Title and Subtitle 5. Report Date A Practical Soft Story Earthquake Isolation System November 1977 6. 7. Aurhor(s) 8. Performing Organization Rept. J. H. Kelly, J. M. Eidinger and C. J. Derham No. 77-27 9. Performing Organization Name and Address 10. Project/Task/Work Unit No. Earthquake Engineering Research Center, University of California, Berkeley 11. Contract/Grant No. 47th Street and Hoffman Blvd. ENV76-04262 Richmond, California 94804 12. Sponsoring Organization Name and Address 13. Type of Report & Period Covered National Science Foundation 1800 G Street, N.W. Washington, D.C. 20550 14. 15. Supplementary Notes 16. Abstracts Th' . . d . ~s report descrlbes the experlmental an analytlcal results of a practical earthquake isolation system. The experimental work was carried out using a 20 ton three-story single-bay moment-resistant steel frame structure on the 20 by 20 foot shaking table at the Earthquake Engineering Research Center at the University of California, Berkeley. The soft story isolation system is composed of elastic natural rubber bearings and a highly nonlinear energy-absorbing device, all placed beneath the base floor of the model structure. The bearings allow for lateral movement of the base of the model and are designed so that no adverse column P-6 effects can occur. The energy-absorbing devices act as highly efficient dampers, and are based upon the two way plastic torsion of steel bars. For smaller earthquakes, the structure behaves as with a rigid foundation. For large earthquakes, the structure's first mode period increases from 0.6 to 1.0 seconds, and equivalent first .mode damping is between 30% and 35%.. Thus, fordestruc tive earthquakes, the use of the isolation system typically reduces the structure's response by over 50% of that of a conventional rigid foundation structure. An inelastic time history analysis gives good correlation with experimental test data. A simple design procedure based upon elastic response spectra is suggested. A full scale structure located in a seismic zone and built with such an isola tion system achieves two major cost benefits over a conventional structure: (1) Lower initial construction,costs due to reduced lateral load requirements; (2) Lower earthquake-caused repair costs, due to decreased structural and non-structural damage. 17b~ Identifiers/Open-Ended Terms 17c. COSATI FieId/Group 18. Availability Statement 19•.Security Class (This 21.·No. of Pages Report) 150 'UNCIASSIFIED Release Unlimited 2U. Security Class (This 22. Price Page IItIJ 7-- R ¢ I UNCLASSIFIED FOR'" NTIS-35 (REV. 10'73) ENDORSED BY ANSI AND UNESCO. THIS FORMMAY BE REPRODUCED USCOMM·DC 8265·P74 APRACTICAL SOFT STORY EARTHQUAKE ISOLATION SYSTEM by James M. Kelly, Professor of Civil Engineering and John M. Eidinger, Graduate Student University of California, Berkeley and C. J. Derham, Principal Physicist Malaysian Rubber Producers' Research Association Brickendonbury, England Report to National Science Foundation Report No. UCB/EERC..77/27 Earthquake Engineering Research Center College of Engineering University of California Berkeley, California November 1977 ABSTRACT This report describes the experimental and analytical results of a practical earthquake isolation system. The experimental work was carried out using a 20 ton three-story single-bay moment-resistant steel frame structure on the 20 by 20 foot shaking table at the Earthquake Engineering Research Center at the University of California, Berkeley. The soft story isolation system is composed of elastic natural rubber bearings and a highly nonlinear energy-absorbing device, all placed beneath the base floor of the model structure. The bearings allow for lateral move ment of the base of the model and are designed so that no adverse column p-~ effects can occur. The energy-absorbing devices act as highly efficient dampers, and are based upon the two-way plastic torsion of steel bars. For small earthquakes, the structure behaves as with a rigid foundation. For large earthquakes, the structure's first mode period increases from 0.6 to 1.0 seconds, and equivalent first mode damping is between 30% and 35%. Thus, for destructive earthquakes, the use of the isolation system typically reduces the structure's response by over 50% of that of a conventional rigid foundation structure. An inelastic time history analysis gives good correlation with experi mental test data. A simple design procedure based upon elastic response spectra is suggested. Afull scale structure located in a seismic zone and built with such an isolation system achieves two major cost benefits over a conventional structure: (1) Lower initial construction costs due to reduced lateral load requirements; (2) Lower earthquake-caused repair costs, due to decreased structural and non-structural damage. ACKNOWLEDGMENTS The authors wish to express their appreciation to the National Science Foundation, R.A.N.N. Division, for their support through Grant No. ENV76-04262, and to the Malaysian Rubber Producers' Research Association. Anumber of people's contributions made this project possible. Many thanks are due to Messrs. David Steere, Ivo Van Austen, Steve Miller and John McNab for their electronic, machine shop and laboratory work. Graduate students Dan Chttty and Robert Turner helped perform the tests and reduce part of the data. i i
Description:The list of books you might like
