Characteristics Of Wind Load On Long-Span Cylindr Roofed Structures

As a kind of typical curved roof, cylindrical roofs are increasingly used in the morden built environment especially in the large-span structures, because they offer aerodynamically effient shapes and provide beautiful architectural appearance to architects and designers. Recently, most researches are carried out for some typical engineering projests, and they are not enough for a broader range of cylindrical roofs. So to conduct more in-depth studies on the characteristics of wind load on cylindrical roofs has certain value in engineering design as well as theoretical research.Based on the wind tunnel data of a series of cylindrical roofs model with different rise-span ratios and height-span ratios, systematic studies have been carried out on the wind load characteristics on cylindrical roofs, mainly including characteristics of mean and fluctuating wind pressure distribution, non-Gaussian feature and spectral characteristics of fluctuating wind pressure on cylindrical roofs. These studies lead to an general description of wind load.The conclusion of this paper could be used as reference in design of cylindr roofed buildings, such as the determination of wind load for main structure, estimation of extreme wind pressure for envelop enclosure, fatigue-resistant design and analysis of wind-induced response. These can provides reference for further theoretical studies as well as structural design of wind-resistance theory of long-span space structures. The main contents in this paper are shown as following:(1) A series of wind tunnel tests of cylindrical roofs with rigid model were designed and accomplished in four different types, with rise-span ratios of 1/2, 1/3, 1/6 and height-span ratios of 1/2, 1/5, 1/10. There are 18 load cases in total.(2) Firstly, based on the rigid model wind tunnel test results, the effects of wind attack angle, rise-span ratio, height-span ratio and different terrain types on the mean wind pressure coefficients are investigated, and the most unfavorable attack angle is determined. In the typical engineering wind attack angle (flow perpendicular to the ridge), the local shape coefficients of building is compared with the values in loading code, and a more accurate computational model of mean wind pressure is proposed for the engineering design of such kinds of roofs(3) Secondly, the effects of building geometric parameters and different terrain types on the fluctuating wind pressure distribution are investigated as well. The signature turbulence features such as separation and reattachment on the roof are also identified with contour maps of wind pressure coefficient on roof surfaces. Meanwhile, non-Gaussian feature of fluctuating wind pressure on cylindrical roofs is discussed, and the criterion to divide Gaussian / non-Gaussian regions on cylindrical roofs is presented in this paper.(4) Rise-span ratio is the most important factor for the wind characteristics of cylinderical roofs. So for the flow perpendicular to the ridge, the auto-spectrum properties characteristics of wind pressure on cylinderical roofs with different rise-span ratios are discussed meticulously. And then, the model of auto-spectrum is proposed based on spectral analysis; meanwhile the spatial correlation between different taps along the span are discussed on the cylinderical roofs surface with different rise-span ratios, and the model of cross-spectrum is established consequently, providing reference for further analysis of wind-induced response, estimation of extreme wind pressure and fatigue-resistant design.