| As a typical vulnerability structure of wind disaster,the wind-induced damages of large outdoor billboard structures are often occurred,which has a huge potential safety hazard.The existing codes at home and abroad only provide the wind-resistant design method of single-side billboard,which is no longer applicable to the multi-sided billboards with various forms and aerodynamic shapes.Therefore,more attention should be paid to strengthen the research on the mechanism of wind damage and wind-resistant design method of large outdoor billboard.In this paper,the main content is as follows:(1)Based on synchronous pressure measurement wind tunnel test,the wind pressure coefficient and force coefficient of two-sided and three-sided single column billboards were analyzed.And aimed at three typical wind failure modes of single column billboard structure,the local wind pressure coefficient on plates,the wind pressure coefficient of plates and the force coefficient of the whole structure were investigated respectively.The wind load coefficient of billboards in Chinese and American codes was studied and compared with the results of wind tunnel test.For the wind-resistant design method of plate connection,plate support system and the supporting column of single column billboard structure,the advised value of local wind pressure coefficient on plates,wind pressure coefficient of plates and force coefficient of the whole structure were provided.(2)According to the special aerodynamic shape of single column billboard,the theoretical formulas of along-wind vibration factor and equivalent static wind load were derived in light of regular high-rise structure.Furthermore,considering the stress characteristics of “head heavy and feet light’’,the single column billboard structure can be simplified as a single freedom system.And a simplified and practical calculation method of wind vibration factor was proposed.(3)Based on aero-elastic model wind tunnel test,the base shear or torque responses of two-sided and three-sided single column billboard were analyzed,and the wind vibration factor of along-wind base shear response at the most unfavorable wind direction was obtained.The calculation method of the along-wind vibration factor of billboards in Chinese and American codes was studied.Combined with the wind tunnel test results,theoretical analysis and relative code methods,the along-wind vibration factor and equivalent wind load of single column billboard structure were compared and analyzed.And the suggestive calculation method of wind vibration factor was proposed for the wind-resistant design of supporting column(4)Based on the analysis above,this paper further studied the equivalent wind load of roof attached billboard and wall attached billboard.The theoretical formula and simplified calculation method of the background component factor in the wind vibration factor were derived in detail。The study above not only provides detailed test data for improving the wind-resistant reliability of large billboard structure in China,but also provides an important reference for the revision of relevant wind load codes. |
