大型户外单立柱三面广告牌风荷载的试验研究

Experimental study of wind load effects on large outdoor single-column-supported three-plate billboard

近年来户外大型广告牌发展迅速,但其强风下的风致损坏也时有发生。作为一类典型的风易损性结构,现有的大型单立柱多面广告牌的风荷载计算方法亟需进一步完善。文中以典型的三面广告牌结构作为试验对象,通过面板的测压试验,分析上部面板结构的水平和扭转风力系数随风向角变化规律,针对最不利工况,给出面板水平风力及扭矩荷载的取值;提出顺风向和扭矩风荷载谱的建议公式;进一步,通过整体结构的气弹性模型的响应测力试验,研究三面柔性广告牌的基底风振响应随风向角变化规律和特征。综合静力刚性测压和动力气弹测力两阶段试验结果,给出双面广告牌顺风向和扭转风振响应的理论计算方法。该研究为完善大型广告牌结构的抗风设计,提供了风洞试压的基础数据和风荷载计算的理论方法。

During recent years, the outdoor large single-column-supported billboards develop rapidly, however, their wind-induced damage are reported occasionally and are known as typical wind vulnerability structures. For billboards, the existing calculation method for wind load effects are not satisfied the current requirements and need to be improved immediately. In this paper, a series of wind tunnel experiments on a typical three-plate billboard were conducted. Based on the synchronous pressure measurement test results, the structural overall horizontal and torque wind load coefficients in different wind directions were investigated, and the analytical power spectrum densities of along-wind and torsional wind load in most unfavorable wind direction were given. Furthermore, according to the aero-elastic model test by utilizing the high frequency force balance, the characteristics of the wind-induced internal force responses at the basement of the single column were analyzed. The theoretical calculation methods of the along-wind and torsional wind-induced dynamic response of the three-plate billboard were proposed by combining these wind tunnel testing results. The study can provide the data support and theoretical approach for prediction of the wind load effects of large single-column-supported three-plate billboard.