The Effect of Eaves Types to Wind Pressures on 45° Pitched Gable Roofs

Abstract

In this study, flow field around a low-rise building model with 45º pitched gable roof having different eave types has been investigated experimentally in order to search the wind loads that can damage the building roofs.  The experiments were carried out in an atmospheric boundary layer that is modeled in the wind tunnel. Atmospheric boundary layer was simulated with combination of barrier, elliptic vortex generators and elements of roughness and a 150 mm height boundary layer was formed at 15 m/s wind velocity. The mean and fluctuating surface pressures were measured on the roofs having different eave types in detail for various wind directions to observe critical suction zones on the roof surfaces. It is seen that eaves increase suction loads on the roof corners. Usage of a special eave causes more critical peak pressures on the roof corners compared with normal eave and without eave cases. 

Keywords

• Atmospheric boundary layer; Gable roof; Normal eave; Special eave; Pressure coefficient; Suction loads

FARKLI SAÇAK TİPLERİNE SAHİP 45° EĞİMLİ BEŞİK ÇATILI BİNA MODELLERİ ÜZERİNDE RÜZGAR BASINÇLARI

Abstract

Bu çalışmada, bina çatılarını hasara uğratabilen rüzgar yüklerinin araştırılması amacıyla, farklı saçak tiplerine sahip 45° eğimli beşik çatılı bina modelleri yüzeylerindeki basınç dağılımları deneysel olarak incelenmiştir. Deneyler rüzgar tünelinde modellenen atmosferik sınır tabaka akışında gerçekleştirilmiştir. Akışın modellenmesinde bariyer, eliptik girdap üreticiler ve pürüzlülük elemanları kombinasyonu kullanılmış ve 15 m/s’lik serbest akış hızında, 150 mm yüksekliğinde bir sınır tabaka oluşturulmuştur. Yüzey basınçlarının ortalama ve çalkantı değerlerinin ölçümü, sınır tabaka içerisine yerleştirilmiş, saçaksız, normal saçaklı ve yelkıran saçaklı bina modelleri üzerinde farklı rüzgar geliş açılarına göre göre ayrıntılı bir şekilde gerçekleştirilerek emme etkilerinin kritik olduğu bölgeler belirlenmiştir. Saçakların çatı köşesindeki emme yükünü arttırdığı; yelkıran saçağın normal saçağa göre %30, saçaksız duruma göre %70 daha kritik pik basınçlar oluşturduğu görülmüştür.

Keywords

• Atmosferik sınır tabaka, Beşik çatı, Normal saçak, Yelkıran saçak, Basınç katsayısı, Emme yükü

References

1. Bitsuamlak, G.T., Warsido, W., Ledesma, E., Chowdhury, A.G. (2013) Aerodynamic Mitigation of Roof and Wall Corner Suctions Using Simple Architectural Elements, Journal of Engineering Mechanics, 139, 396-408. doi: 10.1061/(ASCE)EM.1943-7889.0000505.
2. Case, P.C., Isyumov, N. (1998) Wind Loads on Low Buildings with 4:12 Gable Roofs in Open Country and Suburban Exposures, Journal of Wind Engineering and Industrial Aerodynamics, 77-78, 107-118. doi: 10.1016/S0167-6105(98)00136-6.
3. Davenport, A.G., Surry, D.J. (1974) The Pressures on Low Rise Structures in Turbulent Wind, Canadian Structural Engineering Conference, Ottowa, 1-39.
4. Ham, H.J., Bienkiewicz, B. (1998) Wind Tunnel Simulation of TTU Flow and Building Roof Pressure, Journal of Wind Engineering and Industrial Aerodynamics, 77-78, 119-133. doi: 10.1016/S0167-6105(98)00137-8.
5. Holman, J.P. (1994) Experimental Methods for Engineers, McGraw-Hill Book Company, NewYork.
6. Hoxey, R.P., Reynolds, A.M., Richardson, G.M., Robertson, A.P., Short, J.L. (1998) Observations of Reynolds Number Sensitivity in the Separated Flow Region on a Bluff Body, Journal of Wind Engineering and Industrial Aerodynamics, 73, 231-249. doi: 10.1016/S0167-6105(97)00287-0.
7. Gavanski, E., Kordi, B., Kopp, G.A., Vickery, P.J. (2013) Wind Loads on Roof Sheathing of Houses, J. Wind Eng. Ind. Aerodyn., 114, 106–121. doi: 10.1016/j.jweia.2012.12.011.
8. Ginger, J.D., Reardon, G.F., Whitbread, B.J. (2000) Wind Load Effects and Equivalent Pressures on Low-Rise House Roofs, Engineering Structures, 22, 638-646. doi: 10.1016/S0141-0296(99)00015-2.

9. Ginger, J.D., Holmes J.D. (2003) Effect of Building Length on Wind Loads on Low-Rise Buildings with a Steep Roof Pitch, Journal of Wind Engineering and Industrial Aerodynamics, 91, 1377–1400. doi: 10.1016/j.weia.2003.08.003.
10. Kanda, M., Maruta, E. (1993) Characteristics of Fluctuating Wind Pressure on Long Low-Rise Buildings with Gable Roofs, Journal of Wind Engineering and Industrial Aerodynamics, 50, 173-182. doi: 10.1016/0167-6105(93)90072-V.
11. Kind, R.J. (1988) Worst Suctions Near Edges of Flat Rooftops with Parapets, Journal of Wind Engineering and Industrial Aerodynamics, 31, 251-264. doi: 10.1016/0167-6105(88)90007-4.
12. Meecham, D., Surry, D., Davenport, A.G. (1991) The Magnitude and Distribution of Wind-Induced Pressures on Hip and Gable Roofs, Journal of Wind Engineering and Industrial Aerodynamics, 38, 257-272. doi: 10.1016/0167-6105(91)90046-Y.
13. Parmentier, B., Hoxey, R., Buchlin, J. M., Corieri, P. (2002) The Assessment of Full-Scale Experimental Methods for Measuring Wind Effects on Low-Rise Buildings, COST Action C14, Impact of Wind and Storm on City Life and Built Environment, June 3-4, 2002, Nantes, France.
14. Prasad, D., Uliate, T., Ahmed, M.R. (2009) Wind Loads on Low-Rise Building Models with Different Roof Configurations, Fluid Mechanics Research, 36(3), 231-243.
15. Richardson, G.M., Hoxey, R.P., Robertson, A.P. Short, J.L. (1997) The Silsoe Structures Building: Comparisons of Pressures Measured at Full Scale and in two Wind Tunnels, Journal of Wind Engineering and Industrial Aerodynamics, 72, 187-197. doi: 10.1016/S0167-6105(97)00274-2.
16. Robertson, A.P. (1991) Effect of Eaves Detail on Wind Pressures over an Industrial Building, Journal of Wind Engineering and Industrial Aerodynamics, 38, 325-333. doi: 10.1016/0167-6105(91)90051-W.
17. Savory, E., Dalley, S., Toy, N. (1992) The Effects of Eaves Geometry, Model Scale and Approach Flow Conditions on Portal Frame Building Wind Loads, J. Wind Eng. Ind. Aerodyn., 41-44, 1665-1676.
18. Stathopouos, T. (1984) Wind Loads on Low-Rise Buildings with Various-Sloped Roofs, Engineering Structures, 23, 813-824.
19. Stathopoulos, T., Luchian, H. (1994) Wind-Induced Forces on Eaves of Low Buildings, Journal of Wind Engineering and Industrial Aerodynamics, 52, 249-261. doi: 10.1016/0167-6105(94)90051-5.
20. Uematsu, Y., Isyumov, N. (1999) Wind Pressures Acting on Low-Rise Buildings, J. Wind Eng. Ind. Aerodyn., 82, 1-25. doi: 10.1016/S0167-6105(99)00036-7.
21. Quan, Y., Tamura, Y., Matsui, M. (2007) Mean Wind Pressure Coefficients on Surfaces of Gable-Roofed Low-Rise Buildings, Advances in Structural Engineering, 10(3), 259-272. doi: 10.1260/136943307781422253.