Effect of Cyclonic Load Factor on Monopole Towers

 
 
 
  • Abstract
  • Keywords
  • References
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  • Abstract


    Considering the amount of tropical cyclonic related damages are disproportional to the return period in Indian coastal areas. For better safety of structures, the IS code875 (Part3)2015 presents the cyclonic importance factor (k4 factor) according to the importance level of structure with a maximum value of 1.30 for post cyclonic importance structures category. This factor is recommended in static and dynamic analysis of wind load computations. This is the additional wind speed multiplication factor besides the offshore wind velocity multiplication factor of 1.15 that has been retained in the revised wind code 2015 version for coastal areas up to 200 Km. Monopole towers, which are vulnerable to cyclonic wind speeds, are ideal for use when zoning is difficult in urban areas. The towers with heights 30, 40 and 50m are modelled in STAAD.Pro (V8i) software to evaluate the k4 factor in static and dynamic analysis. The results suggested that when the design wind speed is increased by 30% (1.30) for k4 factor in dynamic analysis contribute the more along wind internal stresses in comparison with static and offshore static analyses. The maximum internal stresses variations are observed in offshore dynamic conditions where k4 factor of 1.30 in association with offshore wind velocity factor of 1.15 is considered. The effectiveness of these factors are reviewed with the cyclonic Gust factor values (Gc).

     


  • Keywords


    IS 875 (Part-3): 2015, k4 factor, Monopole tower, STAAD.Pro (V8i) software, Tropical cyclone.

  • References


      [1] IMD (2013). A Report on Very Severe Cyclonic Storm, PHALIN over the Bay of Bengal (2013). http://www.rsmcnewdelhi.imd.gov.in/images/pdf/publications/preliminary-report/phailin.pdf. Indian Meteorological Department, New Delhi.

      [2] IMD (2014). A Report on Very Severe Cyclonic Storm, HUDHUD over the Bay of Bengal (2014). http://www.rsmcnewdelhi.imd.gov.in/images/pdf/publications/preliminary-report/hud.pdf. Indian Meteorological Department, New Delhi.

      [3] IMD (2017). A Report on Very Severe Cyclonic Storm, VARDHA over the Bay of Bengal (2016). http://www.rsmcnewdelhi.imd.gov.in/images/pdf/publications/preliminary-report/vardha.pdf. Indian Meteorological Department, New Delhi.

      [4] IS 875 (Part3):2015, Indian Standard Code of Practice for Design Loads (Other than Earthquake) for Buildings and Structures, Wind loads, Bureau of Indian standards, New Delhi.

      [5] Brian W, Smith. Communication Structures(2007), Thomas Telford Publishing Ltd, London

      [6] Santhosh Kumar B, Balaji K.V.G.D, Chandan Kumar Patnaikuni, “A study of k4 factor impact on industrial and post-cyclonic importance structures”, International Journal of Civil Engineering and Technology, Vol.8, No.7, (2017), pp.264–273.

      [7] STAAD Pro (V8i) software. 3D Structural Analysis and Design Software.

      [8] Lakshmanan N, Gomathinayagam S, Harikrishna P, Abraham A and Chitra Ganapathi S, “Basic wind speed map of India with long-term hourly wind data”, Current Science, Vol.96, No.7, (2009), pp.911-922.

      [9] Santhosh Kumar B, Balaji K.V.G.D, Chandan Kumar Patnaikuni, “The latency of IS 875 (Part3):2015 provisions on low rise buildings”, Proceedings of Structural Engineering Convention (SEC16), (2016), pp.21-23.

      [10] Pavan Kumar, M. Markendeya Raju. Navya, M. Naidu,GT. “Effect of Wind Speed on Structural Behaviour of Monopole and Self-Support Telecommunication Towers”, Asian Journal of Civil Engineering, (2017), pp. 911-927.

      [11] Celio F, Carril Jr N I., “Experimental study of the wind forces on rectangular latticed communication towers with Antennas”, Wind Engineering and Industrial Aerodynamics, (2003), pp.1007-1022.

      [12] Balagopal, R. Prasad Rao, R. Rokhade, R.P. “Simplified Model to Predict Deflection and Natural Frequency of steel Pole structures”, J.Inst.Eng.India Ser.A(2018) http://doi.org/10.1007/s400030-018-0298-3

      [13] Richa Bhatt, “Influence of modelling in the response of 3D steel frames under wind loading”, M. Tech Thesis, IIT –Roorke (2012)

      [14] IS 875 (Part-3): 1987 (Reaffirmed 1997). Indian Standard Code of Practice for Design Loads (Other than Earthquake) for Buildings and Structures, Part-3, Wind loads, Bureau of Indian standards, New Delhi

      [15] Abraham A, Harikrishna P, Gomathinayagam S, and Lakshmanan N, “Failure investigation of microwave towers during cyclones- A case study”, Journal of Structural Engineering, Vol.32, No.3, (2005), pp.147-157.

      [16] Shanmugasundaram J, Harikrishna P, Gomathinayagam S and Lakshmanan N, “Wind, terrain, structural damping characteristics under tropical cyclone conditions”, Engineering Structures, Vol.21, No.11, (1999), pp. 1006-1014.

      [17] Holmes J.D, “Along-wind response of lattice towers: Part I-derivation of expression for gust response factors”, Engineering Structures, Vol.16, No.4, (1994), pp.287292.

      [18] Holmes J.D, “Along-wind response of lattice towers-II: Aerodynamic damping and deflections”, Engineering Structures, Vol.18, No.7, (1996), pp. 483-488.

      [19] Holmes J.D, “Along-wind response of lattice towers-III. Effective load distributions”, Engineering Structures, Vol.18, No.7, (1996), pp. 489-494.

      [20] Kareem, Asan, “Wind effects on structures: probabilistic point of view”, Probabilistic Engineering Mechanics, Vol.2, No.4, (1987), pp.166-200.

      [21] Venkateswarulu B, Harikrishna P, Selvirajan S, and Satish Ram Kumar M, “Stochastic Gust Response of Microwave Lattice Towers”, Journal of Computers and Structures, Vol.52, No.5, (1994), pp. 1031-1041.

      [22] Celio F, Carril Jr, and Nicholas, “Experimental study of the wind forces on rectangular lattice communication towers with antennas”, Journal of Wind Engineering and Aerodynamics, Vol. 91, No.8, (2003), pp.1007-1022

      [23] IS 800:2007. Indian Standard Code of Practice for Use of Structural Steel, Bureau of Indian standards, New Delhi

      [24] AS 3995-1994, Australian Standard, Design of steel lattice towers and masts.

      [25] IS 1161:1998, Indian Standard, Steel Tubes for structural purposes.

      [26] ANSI/TIA-222-G-2005, Structural Standard for Antenna supporting Structures and Antennas.


 

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Article ID: 21807
 
DOI: 10.14419/ijet.v7i4.17.21807




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