Wind and Structures

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Bi-modal spectral method for evaluation of along-wind induced fatigue damage

  • Gomathinayagam, S. (Structural Engineering Research Centre, CSIR) ;
  • Harikrishna, P. (Structural Engineering Research Centre, CSIR) ;
  • Abraham, A. (Structural Engineering Research Centre, CSIR) ;
  • Lakshmanan, N. (Structural Engineering Research Centre, CSIR)
  • Received : 2005.01.01
  • Accepted : 2005.06.27
  • Published : 2006.08.25
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Abstract

Several analytical procedures available in literature, for the evaluation of wind induced fatigue damage of structures, either assume the wide band random stress variations as narrow band random process or use correction factors along with narrow band assumption. This paper compares the correction factors obtained using the Rainflow Cycle (RFC) counting of the measured stress time histories on a lamp mast and a lattice tower, with those evaluated using different frequency domain methods available in literature. A Bi-modal spectral method has been formulated by idealising the single spectral moment method into two modes of background and resonant components, as considered in the gust response factor, for the evaluation of fatigue of slender structures subjected to "along-wind vibrations". A closed form approximation for the effective frequency of the background component has been developed. The simplicity and the accuracy of the new method have been illustrated through a case study by simulating stress time histories at the base of an urban light pole for different mean wind speeds. The correction factors obtained by the Bi-modal spectral method have been compared with those obtained from the simulated stress time histories using RFC counting method. The developed Bi-modal method is observed to be a simple and easy to use alternative to detailed time and frequency domain fatigue analyses without considerable computational and experimental efforts.

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References

  1. Cook, N.J. (1984), The Designer'S Guide to Wind Loading of Building Structures - Part 1, Butterworths, London, UK
  2. Dionne, M. and Davenport, A.G. (1988), 'A simple relationship between the gust response factor and fatigue damage', J. Wind Eng. Ind. Aerodyn., 30, 45-54 https://doi.org/10.1016/0167-6105(88)90070-0
  3. Gilani, A. and Whittaker, A. (2000), 'Fatigue-life evaluation of steel post structures, Part-I: Background and analysis', J. Struct. Eng., 126, 322-329 https://doi.org/10.1061/(ASCE)0733-9445(2000)126:3(322)
  4. Gilani, A. and Whittaker, A. (2000a), 'Fatigue-life evaluation of steel post structures, Part-II: Experimentation', J. Struct. Eng., 126, 331-340 https://doi.org/10.1061/(ASCE)0733-9445(2000)126:3(331)
  5. Gomathinayagam, S., Dharanieepathy, M.V., and Keshava Rao, M.N. (1990), 'The influence of wave-current sea states on the reliability estimates of offshore towers', Ocean Eng., 17, 105-124 https://doi.org/10.1016/0029-8018(90)90017-Z
  6. Harikrishna, P., Shanmugasundaram, J., Gomathinayagam, S., and Lakshmanan, N. (1999), 'Analytical and experimental studies on the gust response of a 52 m tall steel lattice tower under wind loading', Comput. Struct., 70, 149-160 https://doi.org/10.1016/S0045-7949(98)00156-4
  7. Holmes, J.D. (2002), 'Fatigue life under along-wind loading-closed form solutions', Eng. Struct., 24, 109-114
  8. Jiao, G. and Moan, T. (1990), 'Probabilistic analysis of fatigue due to Gaussian load process', Probabilistic Eng. Mech., 5, 76-83 https://doi.org/10.1016/0266-8920(90)90010-H
  9. Kumar, K.S. (2000), 'Random number sensitivity in simulation of wind loads', Wind and Struct., 3(1), 1-10 https://doi.org/10.12989/was.2000.3.1.001
  10. Kumar, S., Browne, M., and Stoyanoff, S. (2003), 'A comparative study of cycle counting methods with application to wind-induced fatigue', Proceedings of 11th International Conference on Wind Engineering, Lubbock (USA)
  11. Lakshmanan, N., Gomathinayagam, S., Harikrishna, P., Annadurai, A., and Mohamed, S. (2003), 'Measured wind induced response and fatigue of steel lamp mast', Proceedings of 11th International Conference on Wind Engineering, Lubbock (USA).
  12. Lutes, L.D. and Larsen, C.E. (1990), 'Improved spectral method for variable amplitude fatigue prediction', J. Struct. Div., ASCE, 116(4), 1149-1164 https://doi.org/10.1061/(ASCE)0733-9445(1990)116:4(1149)
  13. Lutes, L.D., Corazao, M., Hu, S.J., and Zimmerman, J. (1984), 'Stochastic fatigue damage accumulation', J. Struct. Eng., 110, 2585-2601 https://doi.org/10.1061/(ASCE)0733-9445(1984)110:11(2585)
  14. Matsuishi, M. and Endo, T. (1968), 'Fatigue of metals subjected to varying stresses', Japan Society of Mechanical Engineering, Japan, March
  15. Ortiz, K. and Chen, N.K. (1987), 'Fatigue damage prediction for stationary wideband processes', Proceedings of Fifth International Conference on Application of Statistics and Probability in Soil and Structural Engineering
  16. Peil, U. and Behrens, M. (2002), 'Fatigue of tubular steel lighting columns under wind load', Wind and Struct., 5, 463-478 https://doi.org/10.12989/was.2002.5.5.463
  17. Repetto, M.P. and Solari, G. (2001), 'Dynamic along-wind fatigue of slender vertical structures', Eng. Struct., 23, 1622-1633 https://doi.org/10.1016/S0141-0296(01)00021-9
  18. Robertson, A.P., Holmes, J.D., and Smith, B.W. (2004), 'Verification of closed-form solutions of fatigue life under along-wind loading', Eng. Struct., 26, 1381-1387 https://doi.org/10.1016/j.engstruct.2004.05.004
  19. Robertson, A.P., Hoxey, R.P., Short, J.L., and Burgess, L.R. (1999), 'Wind-induced fatigue loading of tubular steel lighting columns', Proceedings of loth International Conference on Wind Engineering, Copenhagen, Denmark
  20. Solari, G. (1993), 'Gust buffeting. I: Peak wind velocity and equivalent pressure', J. Struct. Eng., ASCE, 119, 365-382 https://doi.org/10.1061/(ASCE)0733-9445(1993)119:2(365)
  21. Solari, G. and Repetto, M.P. (2004), 'Wind-induced response and fatigue of structures', Proceedings of 1st International Symposium on Wind Effects on Buildings and Urban Environments, Tokyo, Japan
  22. Wirsching, P.H. and Light, M.C. (1980), 'Fatigue under wide band random stresses', J. Struct. Div., 106, 1597-1607
  23. Wirsching, P.H. (1984), 'Fatigue reliability for offshore structures', J. Struct. Eng., ASCE, 110, 2340-2356 https://doi.org/10.1061/(ASCE)0733-9445(1984)110:10(2340)
  24. Wyatt, T.A. (1984), 'An assessment of sensitivity of lattice towers to fatigue induced by wind gusts', Eng. Struct., 6, 262-267 https://doi.org/10.1016/0141-0296(84)90022-1