Effect of vehicle weight on natural frequencies of bridges measured from traffic-induced vibration
Recently, ambient vibration test (AVT) is widely used to estimate dynamic characteristics of large civil structures. Dynamic characteristics can be affected by various environmental factors such as humidity, intensity of wind, and temperature. Besides these environmental conditions, the mass of vehicles may change the measured values when traffic-induced vibration is used as a source of AVT for bridges. The effect of vehicle mass on dynamic characteristics is investigated through traffic-induced vibration tests on three bridges; (1) three-span suspension bridge (128m +404m + 128m), (2) five-span continuous steel box girder bridge (59m + 3@95m + 59m), (3) simply supported plate girder bridge (46m). Acceleration histories of each measurement location under normal traffic are recorded for 30 minutes at field. These recorded histories are divided into individual vibrations and are combined into two groups according to the level of vibration ; one by heavy vehicles such as trucks and buses and the other by light vehicles such as passenger cars. Separate processing of the two groups of signals shows that, for the middle and long-span bridges, the difference can be hardly detected, but, for the short span bridges whose mass is relatively small, the measured natural frequencies can change up to 5.4%.
Keywordsambient vibration test traffic induced vibration vehicle mass suspension bridge short-span bridge dynamic characteristics natural frequency
Unable to display preview. Download preview PDF.
- Askegaard V and Mossing P (1988), “Long Term Observation of RC-bridge Using Change in Natural Frequency,”Nordic Concrete Publ., (7).Google Scholar
- Bendat JS and Piersol AG (1986),Random Data: Analysis and Measurement Procedures, 2nd Edition, John Wiley & Sons.Google Scholar
- Cioara TG and Alampalli S (2000), “Signal Processing Methods for Bridge Monitoring Systems,”Proc. of the IMAC-XVIII: A Conference on Structural Dynamics, San Antonio, Texas; 1334–1340.Google Scholar
- Felber AJ, (1993), “Development of a Hybrid Bridge Evaluation System,”Ph. D. Thesis, Dept. of Civil Engineering, University of British Columbia, Vancouver, Canada.Google Scholar
- Felber AJ and Cantieni R (1996), “Introduction of a New Ambient Vibration Testing System 3 Description of System and Seven Bridge Tests,”Report No. 156 521,EMPA, Switzerland.Google Scholar
- Gentile C and Saisi A (2000), “Accuracy Assessment of Bridge Modal Parameters Estimated from Ambient Vibration Measurements,”Proc. of the IMACXVIII: A Conference on Structural Dynamics, San Antonio, Texas; 1320–1326.Google Scholar
- Kim CY, Kim NS, Yoon JG and Jung DS (2000), “Monitoring System and Ambient Vibration Test of the Namhae Suspension Bridge,”Proceedings of SPIE, California, U.S.A. : 324–332.Google Scholar
- Yang YB, Liao SS and Lin BH (1995), “Impact Formulas for Vehicles Moving over Simple and Continuous Beams,”Journal of Structural Engineering, ASCE, 121(11).Google Scholar