This paper presents the identification of the instantaneous modal properties and the experimental response of a full-scale, five-story base-isolated RC building tested on a shake table. A suite of earthquake motions of various intensities was applied to the building to progressively increase the seismic demand. The deterministic-stochastic subspace identification method is employed to estimate the variations of the modal properties of the building by employing a short-time windowing approach. The changes of the modal parameters during the seismic motions are tracked and analyzed. Observed and measured responses of the structure are analyzed and correlated with the variation of the identified modal parameters. The nonlinear behavior of the isolators generates the variation of the identified natural frequencies and equivalent damping ratios of the building, which change in agreement with the input motion intensity. A high correlation between the effective stiffness of the isolators and the instantaneous frequency of the first mode is found. The effective damping ratio of the isolation system and the instantaneous damping ratio of the fundamental mode of the building are highly correlated.
Get full access to this article
View all access options for this article.
References
1.
AllemangR. J., BrownD. L., 1982.
A correlation coefficient for modal vector analysis,
inProceedings, 1st International Modal Analysis Conference (IMAC I) ,
8–10 November 1982,
FL.
2.
AriasA., 1970.
A measure of earthquake intensity,
inSeismic design for nuclear power plants (
HansenR., ed.),
MIT Press,
Cambridge, MA,
438–
483.
3.
American Society of Civil Engineers (ASCE), 2010.
Minimum Design Loads for Buildings and Other Structures ,
ASCE/SEI 7-10 ,
Reston, VA.
4.
AstrozaR., 2015.
Vibration-Based Health Monitoring and Mechanics-Based Nonlinear Finite Element Model Updating of Civil Structures ,
Ph.D. dissertation, University of California, San Diego.
5.
AstrozaR., EbrahimianH., ConteJ. P., RestrepoJ. I., HutchinsonT. C., 2016.
System identification of a full-scale five-story reinforced concrete building tested on the NEES-UCSD shake table,
Structural Control and Health Monitoring23, ,
535–
559.
6.
CelebiM., 1996.
Successful performance of a base-isolated hospital building during the 17 January 1994 Northridge earthquake,
The Structural Design of Tall Buildings5, ,
95–
109.
7.
ChenM. C., PantoliE., WangX., AstrozaR., EbrahimianH., HutchinsonT. C., ConteJ. P., RestrepoJ. I., MarinC., WalshK., BachmanR., HoehlerM., EnglekirkR., FaghihiM., 2016.
Full-scale structural and nonstructural building system performance during earthquakes: Part I – Specimen description, test protocol, and structural response,
Earthquake Spectra32, ,
737–
770.
8.
ChenM. C., AstrozaR., RestrepoJ. I., ConteJ. P., HutchinsonT. C., BockY., 2017.
Predominant period and equivalent viscous damping ratio identification on a full-scale building shake table test,
Earthquake Engineering & Structural Dynamics46, ,
2459–
2477.
9.
FurukawaT., ItoM., IzawaK., NooriM., 2005.
System identification of base-isolated building using seismic response data,
ASCE Journal of Engineering Mechanics131, ,
268–
275.
10.
FurukawaS., SatoE., ShiY., BeckerT. C., NakashimaM., 2013.
Full-scale shaking table test of a base-isolated medical facility subjected to vertical motions,
Earthquake Engineering & Structural Dynamics42, ,
1931–
1949.
11.
GengJ., MelgarD., BockY., PantoliE., RestrepoJ. I., 2013.
Recovering coseismic point ground tilts from collocated high-rate GPS and accelerometers,
Geophysical Research Letters40, ,
5095–
5100.
12.
GutiérrezG., 2016.
Linear Time-Variant and Linear Time-Invariant Modal Properties of a Full-Scale Five-Story Building Tested on a Shake Table ,
Civil Engineering Thesis, Universidad de los Andes, Chile.
13.
HousnerG., BergmanL. A., CaugheyT. K., ChassiakosA. G., 1997.
Structural control: Past, present, and future,
ASCE Journal of Engineering Mechanics123, ,
897–
971.
14.
ImregunM., EwinsD.J., 1993.
Realization of complex mode shapes,
inProceedings, 11th International Modal Analysis Conference (IMAC XI) ,
1–4 February 1993,
Kissimmee, FL.
15.
KasaiK., MitaA., KitamuraH., MatsudaK., MorganT. A., TaylorA. W., 2013.
Performance of seismic protection technologies during the 2011 Tohoku-Oki earthquake,
Earthquake Spectra29, ,
S265–
S293.
16.
LohC-H., WengJ-H., ChenC-H., LuK-C., 2013.
System identification of mid-story isolation building using both ambient and earthquake response data,
Structural Control and Health Monitoring20, ,
139–
155.
17.
MoaveniB., AsgariehE., 2012.
Deterministic-stochastic subspace identification method for identification of nonlinear structures as time-varying linear systems,
Mechanical Systems and Signal Processing31, ,
40–
55.
18.
NagarajaiahS., SunX., 2000.
Response of base isolated USC hospital building in Northridge earthquake,
ASCE Journal of Structural Engineering126, ,
1177–
1186.
19.
OgawaN., OhtaniK., KatayamaT., ShibataH., 2001.
Construction of a three-dimensional, large-scale shaking table and development of core technology,
Philosophical Transactions of the Royal Society A359, ,
1725–
1751.
20.
PantoliE., ChenM. C., HutchinsonT. C., AstrozaR., ConteJ. P., EbrahimianH., RestrepoJ. I., WangX., 2016a.
Full-scale structural and nonstructural building system performance during earthquakes: Part II – NCS damage states,
Earthquake Spectra32, ,
771–
794.
21.
PantoliE., ChenM. C., HutchinsonT. C., AstrozaR., ConteJ. P., EbrahimianH., RestrepoJ. I., WangX., 2016b.
Landmark dataset from the building nonstructural components and systems (BNCS) project,
Earthquake Spectra32, ,
1239–
1260.
22.
PeetersB., De RoeckG., 2001.
One-year monitoring of the Z24-bridge: Environmental effects versus damage events,
Earthquake Engineering & Structural Dynamics30, ,
149–
171.
23.
RainieriC., FabbrocinoG., 2014.
Influence of model order and number of block rows on accuracy and precision of modal parameter estimates in stochastic subspace identification,
International Journal of Lifecycle Performance Engineering1, ,
317–
334.
24.
SatoE., FurukawaS., KakehiA., NakashimaM., 2011.
Full shaking table test for examination of safety and functionality of base-isolated medical facilities,
Earthquake Engineering & Structural Dynamics40, ,
1435–
1453.
25.
SiringoringoD., FujinoY., 2014.
Long-term seismic monitoring of base-isolated building with emphasis on serviceability assessment,
Earthquake Engineering & Structural Dynamics44, ,
637–
655.
26.
StewartJ., ConteJ. P., AikenI., 1999.
Observed behavior of seismically isolated buildings,
ASCE Journal of Structural Engineering125, ,
955–
964.
27.
Strong Motion Center, n.d. www.strongmotioncenter.org (last accessed April 2017).
28.
TobitaJ., IzumiM., KatukuraH., 1988.
Identification of vibration systems and nonlinear dynamics characteristics of structures under earthquake excitations,
Proceedings, 9th World Conference on Earthquake Engineering ,
2–9 August 1988,
Tokyo-Kyoto, Japan.
29.
Van Den EindeL., Van Den EindeL., RestrepoJ. I., ConteJ. P., LucoJ. E., SeibleF., FiliatraultA., ClarkA., JohnsonA., GramM., KusnerD., ThoenB., 2004.
Development of the George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES) large high performance outdoor shake table at the University of California, San Diego,
inProceedings, 13th World Conference on Earthquake Engineering ,
1–6 August 2004,
Vancouver, Canada.
30.
Van OverscheeP., De MoorB., 1996.
Subspace Identification for Linear Systems: Theory, Implementation, Applications ,
Kluwer Academic Publishers,
The Netherlands.
31.
ZhongK., ChangC. C., 2016.
Recursive combined subspace identification technique for tracking dynamic characteristics of structures under earthquake excitation,
Journal of Engineering Mechanics142, ,
04016092.
