Researches On Wind Resistance And Wind-sand Resistance Of Structures

The wind load is a very important load for structure,and is indispensable for structural design.With the development of large-span buildings,high-rise buildings,large-span bridges,the wind load plays an more and more important role.Even in some cases,it becomes a kind of control load of the structural design.Now,the reseach of wind load has entered the stage of the practical application,but there are few studies on wind field of wind-sand and structural wind load in desert area.According to the statistics,the direct and indirect annual economic losses caused by wind-sand damage are up to 54 billion yuan.Accordingly,it is of geat urgence and importance to study wind resistance and wind-sand resistance of structures in northwest desert area under the effect of wind-sand.Field measurement is one of the main methods to study wind resistance and wind-sand resistance of structures.Based on the full-scale test room in the desert area of Ningxia,the field measurement base to study wind load and wind-sand load is established,and long term field measurements of wind effects of the test room were carried out under the effect of wind-sand.The test mainly includes two parts,one is to measure the wind-sand wind field within the height range of 10m.The other one is to measure wind pressure on the surface of the test room.Based on the measurement of wind-sand wind field in desert area of Ningxia,some characteristics like the average wind speed,average wind angle and turbulence intensity,gust factor,and turbulence integral scale and so on within the height range of 10m were studied.Among them,results of wind profiles and turbulence profiles and so on are different of the recommended value of China standard,therefore,those results have some reference value for wind load design of building in desert area.Based on the measurement of wind pressure on the surface of the test room,some wind pressure characteristics of measured points like the wind pressure coefficient,fluctuating wind power spectrum and the correlation of fluctuating wind pressure were studied.The wind tunnel test which conforms to the law of wind-sand wind field was carried out.And the wind pressure test results of wind tunnel were compared with the field measurement results.The results show that the wind pressure coefficient on the surface of structural in field test is bigger than that in the wind tunnel test.Especially,the coefficient of fluctuating wind pressure on the windward side of the building increases remarkably with the effect of sand wind.On the whole,the correlation of fluctuating wind pressure on the surface of the test room in field measurement is less than that in the wind tunnel test.The particularity of large-span roof structural style,the large span,and the use of many lightweight materials make its natural frequency get close to the predominant frequency of natural wind and make it become sensitive to wind effect.In this paper,a rigid model wind tunnel test is carried out based on a large-span stadium in Wuhan.The influence of the external platform width on the wind load of the large-span roof is analyzed in detail.The results show that the average wind pressure or pulsating wind pressure are significantly enhanced by external platform,which is unfavorable to the structure,so that designers should pay more attention to it.