Akarsu Köprü Temellerindeki Oyulma Riskinin Değerlendirilmesi

Abstract

Akarsu köprüleri, yapı-akım etkileşimi nedeniyle altından akım geçmeyen köprülere oranla genellikle daha fazla olumsuz koşullara maruz kalırlar. Bu nedenle, köprü yıkılma riskini oluşturan bileşenlerden önemli bir tanesi de anılan etkileşimden kaynaklanan risktir. Bu çalışmada orta ayaklar etrafındaki oyulma olayını etkileyen değişkenlerde rastlanan belirsizlikler, tanımlanan olasılık yoğunluk fonksiyonlarıyla irdelenmektedir. Analizlerde genel taban oyulması ve daralma oyulması etkileri ihmal edilerek zamana bağlı bir temiz su oyulması yönteminin içerdiği belirsizlikler kullanılmış ve Monte Carlo benzeşimleriyle risk hesaplanmıştır. Oluşturulan modelde belirli akım, ayak geometrisi ve taban malzemesi özelliklerinde köprünün maruz kalacağı oyulma riski saptanmaktadır. Geliştirilen model örnek bir uygulama ile sunulmaktadır.

Keywords

• Köprü,oyulma,belirsizlik,risk,emniyet faktörü

Evaluation of Scour Risk at Foundations of River Bridges

Abstract

River bridges are exposed to more inconvenient conditions due to the structure-flow interaction compared to bridges having no contact with flow. Therefore, one of the most important components of the bridge failure risk is the risk induced by soil-flow interaction. In this study, the uncertainties of the hydrological and hydraulic parameters affecting the scouring around bridge piers are examined using appropriate probability density functions. In the analyses, the uncertainties involved in the temporal variation of clear water scouring mechanism are considered. Influences of general bed degradation of the main channel and the contraction scour are ignored. The risk associated with the scouring around piers is estimated using Monte Carlo simulations. In the model, the scouring risk of the bridge pier is determined for the given flow, pier geometry and bed material characteristics. The developed model is presented with an application.

Keywords

• Bridge,scour,uncertainty,risk,safety factor

References

1. Johnson, P.A., Reliability-based Pier Scour Engineering, ASCE Journal of Hydraulic Engineering, 118(10), 1344-1358, 1992.
2. Johnson, P.A., Fault Tree Analysis of Bridge Failure Due to Scour and Channel Instability, ASCE Journal of Infrastructure Systems, 5(1), 35-41, 1999.
3. Johnson, P.A. ve Ayyub, B.M., Assessing Time-variant Bridge Reliability due to Pier Scour, ASCE Journal of Hydraulic Engineering, 118(6), 887-903, 1992a.
4. Johnson, P.A. ve Ayyub, B.M., Probability of Bridge Failure due to Pier Scour, Proceedings of the Water Resources Sessions at Water Forum 1992, ASCE, Baltimore, MD, 1992b.
5. Johnson, P.A. ve Simon, A., Reliability of Bridge Foundations in Modified Channels, ASCE Journal of Hydraulic Engineering, 123(7), 648-651, 1997.
6. Johnson, P.A. ve Ayyub, B.M., Modelling Uncertainty in Prediction of Pier Scour, ASCE Journal of Hydraulic Engineering, 122(2), 66-72, 1996.
7. Yanmaz, A.M., Uncertainty of Local Scouring Parameters around Bridge Piers, Turk. J. Engin. Environ. Sci.25, 127 – 137, 2001.
8. Yanmaz, A.M. ve Çiçekdağ, Ö., Composite Reliability Model for Local Scour Around Cylindrical Bridge Piers, Canadian Journal of Civil Engineering, 28, 3, 520-535, 2001.

9. Yanmaz, A.M. ve Üstün, İ., Generalized Reliability Model for Local Scour around Bridge Piers of Various Shapes, Turkish J. Eng. Env. Sci., 25, 687-698, 2001.
10. Yanmaz, A.M., Dynamic Reliability in Bridge Pier Scouring, Turkish J. Eng. Env. Sci., 26, 367-376, 2002a.
11. Yanmaz, A.M. ve Çelebi, T., A Reliability Model for Bridge Abutment Scour, Turkish J. Eng. Env. Sci., 28, 67-83, 2004.
12. Köse, Ö. ve Yanmaz, A.M., Scouring Reliability of Bridge Abutments, Digest, Teknik Dergi, 1387-1402, 2010.
13. Mays, L., Water Resources Engineering, McGraw-Hill, New York, 2010.
14. Yanmaz, A.M., Köprü Hidroliği, ODTÜ Yayıncılık, Ankara, 2002b.
15. Lagasse, P.F., Ghosn, M., Johnson, P.A., Zevenbergen, L.W. ve Clopper, P.P., Risk Based for Bridge Scour Prediction, Final Report, National Cooperative Highway Research Program, Transportation Research Board, National Research Council, Washington, D.C., 2013.
16. Yanmaz, A.M. ve Çam, U.E., Bridge Scour Countermeasure Design: A Case Study”, Tenth International Congress on Advances in Civil Engineering", 1, 11-20, 2012.
17. Yıldırım, M.S. ve Yanmaz, A.M., Köprü Ayakları Etrafındaki Koruyucu Kaplamanın Bilgisayar Destekli Tasarımı, Teknik Dergi, Cilt 25, 6757-6774, 2014.
18. Yanmaz, A.M. ve Apaydın, M., A Study on Bridge Scour Risk Assessment and Countermeasure Design, ASCE Journal of Performance of Constructed Facilities, 26, 499-506, 2012.
19. Yanmaz, A.M., Caner, A. ve Berk, A., Renovation of a Safety-Inspection Methodology for River Bridges, ASCE Journal of Performance of Constructed Facilities, 21, 382-389, 2007.
20. Caner, A., Yanmaz, A.M., Yakut, A., Avşar, Ö. ve Yılmaz, T., Service Life Assessment of Existing Highway Bridges with no Planned Regular Inspections, ASCE Journal of Performance of Constructed Facilities, 22, 108-114, 2008.
21. Cardoso, A.H. ve Bettess, R., Effects of time and channel geometry on scour at bridge abutments, ASCE Journal of Hydraulic Engineering, 125(4),388–399, 1999.
22. Melville, B.W. ve Chiew, Y., Time scale for local scour at bridge piers, ASCE Journal of Hydraulic Engineering, 125(1), 59–65, 1999.
23. Simarro-Grande, G. ve Martín-Vide, J. P., Exponential expression for time evolution in local scour, Journal of Hydraulic Research, 42(6), 663–665, 2004.
24. Grimaldi, C., Gaudio, R., Cardoso, A.H. ve Calomino, F., Local scouring at bridge piers and abutments: Time evolution and equilibrium, Proc., 3rd Int. Conf. on Fluvial Hydraulics, 1657–1664, 2006.
25. Fael, C.M.S., Simarro-Grande, G., Martín-Vide, J.P. ve Cardoso, A.H., Local scour at vertical-wall abutments under clearwater flow conditions, Water Resources Research, 42(1), 388–399, 2006.
26. Setia, B., 3rd IASME / WSEAS Int. Conf. on Water Resources, Hydraulics and Hydrology (WHH '08), University of Cambridge, UK, Feb. 23-25, 2008.
27. Yanmaz, A.M. ve Altınbilek, H.D., Study of Time Dependent Local Scour Around Bridge Piers, ASCE Journal of Hydraulic Engineering, 117, 1247-1268, 1991.
28. Yanmaz, A.M., Temporal Variation of Clear Water Scour at Cylindrical Bridge Piers, Canadian Journal of Civil Engineering, 33, 1098-1102, 2006.
29. Yanmaz, A.M. ve Köse, Ö., A Semi-Empirical Model for Clear Water Scour Evolution at Bridge Abutments, Journal of Hydraulic Research, 47, 110-118, 2009.
30. Yanmaz, A.M., Time-Dependent Analysis of Clear Water Scour Around Bridge Piers, Doktora Tezi, Orta Doğu Teknik Üniversitesi, Ankara, 1989.
31. Johnson, P.A., Uncertainty of Hydraulic Parameters, ASCE Journal of Hydraulic Engineering, 122 (2), 112-114, 1996.
32. Yanmaz, A.M., Overtopping Risk Assessment in River Diversion Facility Design, Canadian J. Civil Engineering, 27, 319-326, 2000.
33. Muzzammil, M., Siddiqui, N.A. ve Siddiqui, A.F., Reliability Considerations in Bridge Pier Scouring, Journal of Structural Engineering and Mechanics, 28(1), 1-18, 2008.