the dynaseis experiment elsa, jrc ispra italy 2003 monitoring of the dynamic behaviour of a building...
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The
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ELSA, JRC Ispra Italy
2003
Monitoring of the dynamic behaviour of a building at
Parque das Nações Lisboa
Instituto Superior de Engenharia de Lisboa
Maria Ana Baptista
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Project funded by the Portuguese Science Foundation (FCT)
DYNASEIS - DYNAMIC BEHAVIOUR OF A RE–INFORCED CONCRETE STRUCTURE UNDER SEIMIC LOAD
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
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The Building ofPortugal Telecom Offices
Located at the newly residential and office area of Lisboa, calledParque das Nações (Expo98)
Built in 1998Area 11 000 m2
TARGET
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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 floors used by Marconi (PT subsidiary) as their head-office.
TARGET
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TARGET
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1. Forced-vibration tests are more difficult to perform and require heavy equipment and logistics;
2. State-of-the-art vibration generators do not have the capability to excite to resonance all significant modes of all structures (Çelebi,2000);
3. Different vibrational modes can be detected from a single measurement;
4. 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).
WHY AMBIENT VIBRATION TEST ?
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The Telecom Tower is located close to the Gare do Oriente railway station (designed by Santiago Calatrava) and is one source of ambient noise).
AMBIENT VIBRATION TEST
Others are urban traffic, wind, etc...
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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
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INSTRUMENTS - SENSORS
Dynamic Range 155 dB
Frequency Band DC to 200 Hz
Scale Amplitude 0,25g a 4,00g
Dynamic Range 140 dB
Frequency Band DC to 200 Hz
Scale Amplitude 0,25g a 4,00g
Uniaxial Acelerometer Episensor FBA ES-U:
Triaxial Acelerometer Episensor FBA ES-T:
1
6
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INSTRUMENTS - ACQUISITION
Dynamic Range > 114 dB
Sampling Rate 20 a 200 Hz
Output 24 bit
Acquisition Mode Contínuous/Trigger
Clock GPS (accuracy 0,5 ms)
Acquisition System: Kinemetrics Altus K2 Digital Recorder:
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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
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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
FIRST TEST
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FIRST TEST
Cables were deployed along the floors ...
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Successive setups (30.12.2002):•Floor_10•Floor_08•Floor_06•Floor_04•Floor_02
FIRST TEST
To maintain a good quality control the sensor layout was kept the same when moving from setup to setup.
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FIRST TEST
Example of event record from setup 6.
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ESD obtained by FFT
Triaxial record on the top floor
y direction
x direction z direction (vertical)
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Event recorded at the 6th floor:
A – transversalB – longitudinalC – longitudinal
ESD obtained by FFT A
B
C
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Successive setups 24.012003:•Floor_11•Floor_07•Floor_05•Floor_03•Floor_01 - closed
FIRST TEST
Field Operations: 24 January 2003
Triaxial: Top Floor (fixed)
Continuous 10 min observations in all uneven floors with the following geometry:
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• 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);
6 HOUR CONTINUOUS ACQUISITION10 February 2003 and 11 February 2003
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• continuous observation can be achieved only in the following places: 11th, 6th, 0th floors
• triaxial accelerometer at floor – 4 (foundation level)
6 HOUR CONTINUOUS ACQUISITION10 February 2003 and 11 February 2003
Data Acquisition – 6 hours Sampling rate 100Hz
Data is stored in a PCMCIA 64 MB
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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
6 HOUR CONTINUOUS ACQUISITION10 February 2003 and 11 February 2003
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• 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
NEXT ACTIVITIES
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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
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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.
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STRUCTURAL RESPONSE
VibrationExcitation
Frequency range
Hz
Displ.range
µm
VelocityRangemm/s
Accel.Range
µg
Traffic: road, rail 1 - 80 1 - 200 0.2 - 50 2 - 100
Wind 0.1 - 10 10 - 105
Earthquakes 0.1 - 30 10 -105 0.2 - 400 2 - 200
Acoustic: traffic and machinery outside
10 - 250 1 - 100 0.2 - 30 2 - 100
Machinery inside 1 - 1000 1 - 100 0.2 - 30 2 - 100
Adapted from ANSI: S247 - 1990