Monitoring of the dynamic behaviour of a building at Parque das Nações Lisboa

1. Monitoring of the dynamic behaviour of a building at Parque das Nações Lisboa Maria Ana Baptista Instituto Superior de Engenharia de Lisboa

2. DYNASEIS - DYNAMIC BEHAVIOUR OF A RE–INFORCEDCONCRETE STRUCTURE UNDER SEIMIC LOAD Project funded by the Portuguese Science Foundation (FCT) • MAIN OBJECTIVES • Study of dynamic response of a re-inforced concrete structure using ambient vibrations (“output only”) • Experimental study of natural frequencies • Implementation of numerical modelling of the structure

3. TARGET The Building of Portugal Telecom Offices Built in 1998 Area 11 000 m2 Located at the newly residential and office area of Lisboa, called Parque das Nações (Expo98)

4. TARGET The Tower has 12 floors above ground and four basement levels, and is responsible for the entire telecommunications network in the “Parque das Nações” complex (Expo ’98). Two floors are entirely occupied by the telecom central, being the remaining floorsused by Marconi (PT subsidiary) as their head-office.

5. TARGET

6. WHY AMBIENT VIBRATION TEST ? • Forced-vibration testsare more difficult to perform and require heavy equipment and logistics; • State-of-the-art vibration generators do not have the capabilityto excite to resonance all significant modes of all structures (Çelebi,2000); • Different vibrational modes can be detected from a single measurement; • Forced vibrations can damage the structure. • However, • 1. Modal characteristics corresponding to low amplitude vibrations may be different from large higher levels of shaking (Ventura & Schuster, 1996).

7. AMBIENT VIBRATION TEST The Telecom Tower is located close to the Gare do Oriente railway station (designed by Santiago Calatrava) and is one source of ambient noise). Others are urban traffic, wind, etc...

8. DYNAMIC MODELLING • Dynamic analysis was performed by the designers of the structure but the information available is scarce. • The building is a reinforced concrete structure consisting of “boat shape” flat plate slabs. • floor slabs are 0.25 m thick (floors 5 to 11), 0.30 m (floors 1 to 4) and 0.40 m (ground floor); • floor slabs are directly support by columns; • analysis were conducted up to 8 modes but only the first 6 were considered relevant; • fundamental frequency: 0.55 Hz; Exterior Support beam For lifts and windows

9. INSTRUMENTS - SENSORS 1 Triaxial Acelerometer Episensor FBA ES-T: 6 Uniaxial Acelerometer Episensor FBA ES-U:

10. INSTRUMENTS - ACQUISITION Acquisition System: Kinemetrics Altus K2 Digital Recorder:

11. FIRST TEST Field Operations: 30 December 2002 Triaxial: Top Floor (fixed) Continuous 10 min observations in all even floors with the following geometry: Reference Sensors Roving Sensors

12. FIRST TEST • Sampling Rate – 250 Hz • Channels • 1,2,3 – (x,y,z) triaxial reference acelerometer • 4 – y direction south tower • 5 – x direction south tower • 7 – x direction north tower • Time base – TU (sinal GPS) • Scale 2,5 V/1g

13. FIRST TEST Cables were deployed along the floors ...

14. FIRST TEST • Successive setups (30.12.2002): • Floor_10 • Floor_08 • Floor_06 • Floor_04 • Floor_02 To maintain a good quality control the sensor layout was kept the same when moving from setup to setup.

15. FIRST TEST Example of event record from setup 6.

16. y direction ESD obtained by FFT Triaxial record on the top floor z direction (vertical) x direction

17. ESD obtained by FFT A Event recorded at the 6th floor: A – transversal B – longitudinal C – longitudinal B C

18. FIRST TEST Field Operations: 24 January 2003 Triaxial: Top Floor (fixed) Continuous 10 min observations in all uneven floors with the following geometry: • Successive setups 24.012003: • Floor_11 • Floor_07 • Floor_05 • Floor_03 • Floor_01 - closed

19. 6 HOUR CONTINUOUS ACQUISITION 10 February 2003 and 11 February 2003 • free-field station: it is impossible to locate a free-field station at a distance greater than 1.5-2 times the height of the nearest/tallest building (Çelebi, 2000);

20. 6 HOUR CONTINUOUS ACQUISITION 10 February 2003 and 11 February 2003 Data Acquisition – 6 hours Sampling rate 100Hz Data is stored in a PCMCIA 64 MB • continuous observation can be achieved only in the following places: 11th, 6th, 0th floors • triaxial accelerometer at floor – 4 (foundation level)

21. 6 HOUR CONTINUOUS ACQUISITION 10 February 2003 and 11 February 2003 Data acquisition system K2 was installed at 6th floor Connection of the transverse and logintudinal sensors to the junction box that is connected to k2 and after that The sensors were oriented parallel to the tranverse (x) and longitudinal (y) axes of the building

22. NEXT ACTIVITIES • Conclusion of the Finite Element Modeling (FEM) of the building – SAP2000 in order to avoid definitive installation at nodal points of the structure; • Experimental data analysis: Modal analysis – ArteMis; • Validation of dynamical analysis • Improvement of the methodology: • - in earthquake prone areas • - different building typology

23. ACKNOWLEDGMENTS The author wish to thank the Portuguese Telecom Board of Administration and LNEC (Laboratório Nacional de Engenharia Civil) for all support. DYNASEIS TEAM: M. A. Baptista, A. Campos Costa, A. Afilhado, C. S. Oliveira, P. Mendes, M. Vasques This project was funded by Portuguese Science Foundation (FCT) project POCTI-36071-ECM

24. REFERENCES Çelebi M.,2000 Seismic Instrumentation of bulidings, USGS OF report 00157 Ventura & Schuster, 1996 d Structural dynamic properties of a re inforced high rise building during construction. Can. J. Civil Eng 23,950-970.

25. STRUCTURAL RESPONSE Adapted from ANSI: S247 - 1990