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Keywords: bridges, structural response, structures dynamic diagnostics, traffic effects on bridges, finite element analysis, bridge dynamic loading tests, natural frequencies and modes.

Summary

Cable-stayed bridges are usually built for long spans and are subject to dead and moving loads, seismic motions of supports, to wind forces, temperature and many other forces. The dynamic study of the suspended and cable-stayed bridges was initiated by collapse of the well-known Tacoma Bridge in the USA. This paper deals with the vibration of suspended bridge subjected to the action of moving loads during the regular dynamic tests of the bridge and to point out the discrepancy that may occur between finite element modelling and on-side strain and displacements and acceleration amplitude measurements. This is based on practical experience from the assessment of the New Bridge crossing the Danube in Bratislava, Slovakia, a 431.8 m long with skew pylon 90 m high. The length of the main span crossing the Danube is 303.0 m and the total width of the bridge deck is 21.0 m. The finite element modelling is described and typical problems are outlined. From the regular tests of the bridge results it follows that the assessment results in the ultimate limit state and especially in the fatigue limit state are very sensitive to precise finite element modelling [1,2,3,4,5,6,7]. The relevant combination of a detailed and comprehensive finite element modelling, sensitivity analysis, on-site measurements and model updating is crucial for the assessment in order to provide a solid decision basis for the necessary actions to be taken. Also, a reliable finite element model is a necessary basis for applying more advanced assessments such as plastic analysis, fracture mechanics, seismic analysis, etc.

The predicted dynamic behavior of the bridge using a simplified finite element analysis calculation was compared with the measured one. Despite both the complex structural layout of the bridge, and simplifying assumptions of the model, results showed good agreement for all identified frequencies in the basic frequency range 0-5 Hz. This computational model will be applied for the bridge fatigue and seismic analysis before starting a decision making process regarding the bridge strengthening.

References

1: J. Bencat, "Report on static and dynamic test results of the New Bridge over the Danube in Bratislava", SvF/08, UZ / Zilina, 2008.
2: J. Bencat, "Report on dynamic monitoring results of the New Bridge over the Danube in Bratislava", SvF/09, UZ / Zilina, 2009.
3: Slovak Standard No.73 6209, "Loading test of bridges".
4: Slovak Standard No.73 6203, "Loading of bridges".
5: M.S. Troitsky, "Cable-stayed bridges", (2nd edition), BSP Professional Books, 1988.
6: J.S. Bendat, A.G. Piersol, "Engineering applications of correlation and spectral analysis", (2nd edition), Wiley Interscience, New York, 1993.
7: E. Ozakan, J. Main, P. Jones, "Long-term measurement on a cable-stayed bridge", Proc. of IMAC XXI - Conference, Orlando, Florida, 2003.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 91 PROCEEDINGS OF THE TWELFTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING Edited by: B.H.V. Topping, L.F. Costa Neves and R.C. Barros Paper 88 Assessment, Measurement and Monitoring of the New Bridge crossing the Danube in Bratislava J. Bencat, Z. Bergerová and D. Papán Department of Structural Mechanics, Faculty of Civil Engineering, University of Zilina, Slovakia doi:10.4203/ccp.91.88 purchase the full-text of this paper Full Bibliographic Reference for this paper , "Assessment, Measurement and Monitoring of the New Bridge crossing the Danube in Bratislava", in B.H.V. Topping, L.F. Costa Neves, R.C. Barros, (Editors), "Proceedings of the Twelfth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 88, 2009. doi:10.4203/ccp.91.88 Keywords: bridges, structural response, structures dynamic diagnostics, traffic effects on bridges, finite element analysis, bridge dynamic loading tests, natural frequencies and modes. Summary Cable-stayed bridges are usually built for long spans and are subject to dead and moving loads, seismic motions of supports, to wind forces, temperature and many other forces. The dynamic study of the suspended and cable-stayed bridges was initiated by collapse of the well-known Tacoma Bridge in the USA. This paper deals with the vibration of suspended bridge subjected to the action of moving loads during the regular dynamic tests of the bridge and to point out the discrepancy that may occur between finite element modelling and on-side strain and displacements and acceleration amplitude measurements. This is based on practical experience from the assessment of the New Bridge crossing the Danube in Bratislava, Slovakia, a 431.8 m long with skew pylon 90 m high. The length of the main span crossing the Danube is 303.0 m and the total width of the bridge deck is 21.0 m. The finite element modelling is described and typical problems are outlined. From the regular tests of the bridge results it follows that the assessment results in the ultimate limit state and especially in the fatigue limit state are very sensitive to precise finite element modelling [1,2,3,4,5,6,7]. The relevant combination of a detailed and comprehensive finite element modelling, sensitivity analysis, on-site measurements and model updating is crucial for the assessment in order to provide a solid decision basis for the necessary actions to be taken. Also, a reliable finite element model is a necessary basis for applying more advanced assessments such as plastic analysis, fracture mechanics, seismic analysis, etc. The predicted dynamic behavior of the bridge using a simplified finite element analysis calculation was compared with the measured one. Despite both the complex structural layout of the bridge, and simplifying assumptions of the model, results showed good agreement for all identified frequencies in the basic frequency range 0-5 Hz. This computational model will be applied for the bridge fatigue and seismic analysis before starting a decision making process regarding the bridge strengthening. References 1 J. Bencat, "Report on static and dynamic test results of the New Bridge over the Danube in Bratislava", SvF/08, UZ / Zilina, 2008. 2 J. Bencat, "Report on dynamic monitoring results of the New Bridge over the Danube in Bratislava", SvF/09, UZ / Zilina, 2009. 3 Slovak Standard No.73 6209, "Loading test of bridges". 4 Slovak Standard No.73 6203, "Loading of bridges". 5 M.S. Troitsky, "Cable-stayed bridges", (2nd edition), BSP Professional Books, 1988. 6 J.S. Bendat, A.G. Piersol, "Engineering applications of correlation and spectral analysis", (2nd edition), Wiley Interscience, New York, 1993. 7 E. Ozakan, J. Main, P. Jones, "Long-term measurement on a cable-stayed bridge", Proc. of IMAC XXI - Conference, Orlando, Florida, 2003. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £140 +P&P)
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