Researches On Wind-sand Load Of Low-rise Building And Wind Load Factor Of Long-span Structures

Statistics show that both at home and abroad, and in all the natural disasters, wind damage and loss at the biggest disaster of all. Wind damage can be divided into three categories, the first is the hurricane disaster; the second is the storm disaster; the third is high winds disaster caused by the thunderstorm weather and tornadoes. With the evolution of human, the impact of man’s activities on the global climate is increasing, and wind damage have had a trend of increase whether occurrence frequency or strength. Therefore, in this paper, the problems of wind-sand load and wind load factor for a long-span roof structures were studied.At present, the phenomenon and movement of wind-sand has carried out some research, and obtained a series of research result, found that wind-sand load is greater than the effect of wind load for buildings. However, the main research method is numerical simulation, and there are few experimental study on wind-sand load.Through wind tunnel force balance tests, this paper studied wind-sand flow impacting on overall forces of low-rise building under the conditions of different sand concentration and the wind speed. The results show that compared to the net wind conditions, wind-sand flow has a great influence on the overall forces of low-rise building. The increase of wind-sand flow on the basal mean shear coefficient of low-rise building has obvious effect, and the effect is more and more obvious accompany with sand concentration increase.For the basal fluctuation shear coefficient, in addition to related to sand concentration, also related to indicating wind speed.When the wind speed is small, wind-sand flow increased the fluctuation effect of the test model,and when the wind speed is large, wind-sand flow reduced the fluctuation effect of the test model.Based on the rigid model wind tunnel test data of a gymnasium roof, the authors calculated the wind-induced vibration response and the wind load factor of this gymnasium. And then the authors researched the influence of involving calculated mode number on wind-induced vibration response and wind load factor, also comparatively analyzed the result of CQC method which takes into account the cross part of each mode and SRSS method which takes no account of the cross part of each mode and multi-modal force method. Finally the authors found that whether considering high-order modes or not has a certain influence on the calculated result of wind-induced vibration response and wind load factor of gymnasium roof structure, while the influence of the cross part of each mode also cannot be ignored. Therefore, this article puts forward the correction method of the multi-modal force method which takes into account the cross part of each mode,and good results were obtained.