Torsion in Base‐Isolated Structures with Elastomeric Isolation Systems
Publication: Journal of Structural Engineering
Volume 119, Issue 10
Abstract
Torsion in base‐isolated structures with inelastic elastomeric isolation systems due to bidirectional lateral ground motion is studied. In a companion paper by the writers, torsional coupling in sliding base‐isolated structures was investigated. In this paper, which is the second part of the sequence, torsional coupling in elastomeric base‐isolated structures is investigated. Various multistoried structural systems with elastomeric isolation systems are investigated, with the objective of studying the influence of: (1) The flexibility of the superstructure; (2) the ratio of uncoupled torsional to lateral frequencies; (3) stiffness eccentricity in the superstructure; (4) eccentricity in the isolation system; (5) higher mode effects; and (6) number of bearings in the isolation system. Response to different ground motions is also studied. The results are used to explain: (1) The behavior of actual buildings; and (2) some inconsistencies in the conclusions of previous studies. It is shown that, although the total superstructure response is reduced significantly due to the effects of elastomeric base isolation, torsional amplification can be significant depending on the isolation and superstructure eccentricity and the lateral and torsional flexibility.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Buckle, I. G., and Mayes, R. L. (1990). “Seismic isolation: history, application, and performance—A world overview.” Earthquake Spectra, 6(2), 161–202.
2.
Eisenberger, M., and Rutenberg, A. (1986). “Seismic base isolation of asymmetric shear buildings.” Engrg. Struct., 8(1), 2–8.
3.
Goel, R. K., and Chopra, A. K. (1990). “Inelastic response of one‐storey asymmetric plan systems: effects of stiffness and strength distribution.” Earthquake Engrg. Struct. Dyn., 19(3), 949–970.
4.
Hart, G. C., DiJulio, R. M., and Lew, M. (1975). “Torsional response of high‐rise buildings.” J. Struct. Div., ASCE, 101(2), 397–416.
5.
Kan, C. L., and Chopra, A. K. (1981). “Torsional coupling and earthquake response of simple elastic and inelastic systems.” J. Struct. Div., ASCE, 107, 1569–1588.
6.
Kelly, J. M. (1986). “Aseismic base isolation: review and bibliography.” Soil Dyn. and Earthquake Engrg., 5(4), 202–217.
7.
Lee, D. M. (1980). “Base isolation for torsion reduction in asymmetric structures under earthquake loading.” Earthquake Engrg. Struct. Dyn., 8(3), 349–359.
8.
Nagarajaiah, S., Reinhorn, A. M., and Constantinou, M. C. (1991). “Nonlinear dynamic analysis of 3D‐base isolated structures.” J. Struct. Div., ASCE, 117(7), 2035–2054.
9.
Nagarajaiah, S., Reinhorn, A. M., and Constantinou, M. C. (1993). “Torsional coupling in sliding isolated structures.” J. Struct. Div., ASCE, 119(1), 130–149.
10.
Nakamura, T., Suzuki, T., Okada, H., and Takeda, T. (1988). “Study on base isolation for torsional response in asymmetric structures under earthquake motion.” Proc. Ninth World Conf. on Earthquake Engrg., Int. Assoc. of Earthquake Engrg., Tokyo, Japan, V, 675–680.
11.
Pan, T. C., and Kelly, J. M. (1983). “Seismic response of torsionally coupled base isolated structures.” Earthquake Engrg. Struct. Dyn., 11(6), 749–770.
12.
Papageorgiou, A. S., and Lin, B. C. (1989). “Study of the earthquake response of the base‐isolated law and justice center in Rancho Cucamonga.” Earthquake Engrg. Struct. Dyn., 18(4), 1189–1200.
13.
Park, Y. J., Wen, Y. K., and Ang, A. H. S. (1986). “Random vibration of hysteretic systems under bidirectional ground motions.” Earthquake Engrg. Struct. Dyn., 14(4), 543–557.
14.
Reinhorn, A. M., Rutenberg, A., and Gluck, J. (1977). “Dynamic torsional coupling in asymmetric building structures.” Build. and Envir., 12(4), 251–261.
15.
Roeder, C. W., and Stanton, J. F. (1983). “Elastomeric bearings: a state of the art.” J. Struct. Div., ASCE, 109(12), 2853–2871.
16.
Sadek, A. W., and Tso, W. K. (1988). “Strength eccentricity concept for inelastic analysis of asymmetric structures.” Proc. Ninth World Conf. on Earthquake Engrg., Tokyo, Japan, V, 91–96.
17.
Shepherd, R., and Donald, R. A. H. (1967). “Seismic response of torsionally unbalanced buildings.” J. Sound and Vibration, 6(1), 20–37.
18.
Tarics, A. G., Way, D., and Kelly, J. M. (1984). “The implementation of base isolation for the foothill communities law and justice center.” Rep. to the National Science Foundation.
19.
Uniform building code, earthquake regulations for seismic isolated structures. (1991). Int. Conf. of Build. Officials, Whittier, Calif.
20.
Wilson, E. L., Kiureghian, A. D., and Bayo, E. P. (1981). “A replacement for the SRSS method in seismic analysis.” Earthquake Engrg. Struct. Dyn., 9(1), 187–194.
21.
Yasaka, A., Mizukoshi, K., Iizuka, M., Takenaka, Y., Masada, S., and Fujimoto, N. (1988a). “Biaxial hysteresis model for base isolation devices.” Summaries of technical papers of annual meeting, Architectural Institute of Japan, Tokyo, Japan, 1, 395–400.
22.
Yasaka, A., Koshida, H., and Iizuka, M. (1988b). “Base isolation system for earthquake protection and vibration isolation of structures.” Proc. Ninth World Conf. on Earthquake Engrg., Int. Assoc. of Earthquake Engrg., Tokyo, Japan, V, 699–704.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 119 • Issue 10 • October 1993
Pages: 2932 - 2951
Copyright
Copyright © 1993 American Society of Civil Engineers.
History
Received: Aug 7, 1992
Published online: Oct 1, 1993
Published in print: Oct 1993
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.