Research On Wind Load Characteristics Of Wavy Platform Canopy

With the rapid development of high-speed railroad passenger station construction,platform canopy as an important part of the railroad passenger station,plays an irreplaceable role in the process of passenger station operation and maintenance.At present,the platform canopy of high-speed railroad passenger station,the main structure system mostly adopts light steel frame,and the roof form adopts light roofing.Platform canopy has the characteristics of large coverage area,open on all sides,light self-weight,small damping and flexibility.Compared with the station house,its wind resistance is weaker and it is a wind load sensitive structure.This paper takes Qingdao West Station platform canopy as the research object,which is the only one known station canopy with wavy longitudinal form in China.The wind load distribution on the surface of the canopy is complex,and the average wind pressure and body coefficient are unknown.The wind pressure distribution of the platform canopy was studied through wind tunnel test and the body coefficients of windward and windward surfaces were determined;CFD numerical simulation method was used to consider the interference effect of surrounding buildings on the canopy wind load body coefficients,and the distribution law of the canopy body coefficients after interference was studied to provide technical support for the wind resistance design of the platform canopy.The main research contents and conclusions are as follows:The average pressure coefficients,zonal average pressure coefficients and zonal body coefficients of canopies under 36 wind angles were obtained through wind tunnel tests.The distribution law of the average pressure coefficient is: when the incoming flow is parallel to the canopy,the surface of the canopy is mainly positive pressure;when the incoming flow is perpendicular to the canopy,the surface of the canopy is all negative pressure.The wind pressure at the trough of the canopy is higher than that at the crest of the wave.The wind pressure at the front edge of the canopy surface is mainly negative pressure,and the net pressure coefficient is-0.8;the wind pressure in the middle area is about the same after 270°;the wind pressure in the tail area is positive pressure distribution under the local wind angle,and the wind pressure increases first and then decreases after 240°.The distribution pattern of the body shape coefficient is: the body shape coefficient of the leeward side of the front edge of the canopy is mainly negative,distributed between-0.4～0.0;the difference is the smallest when the incoming wind acts in parallel,and the difference of the body shape coefficient of the windward side of the front edge of the canopy is the largest.In the middle region,the body shape coefficient of the leeward side remains constant between 0°and 90°,and the distribution is between 0.0 and 0.1;the distribution of the body shape coefficient of the windward side is about the same when the incoming wind acts in parallel.The windward side of the tail area remains unchanged before 90°,and the distribution is between-0.03 and 0.0;the windward side is basically the same when the wind effect on the canopy is parallel to the incoming current,and the difference of the body coefficient is larger when the incoming current turns to act on the canopy from the oblique direction to the vertical direction.CFD numerical simulation was used to firstly verify the reliability of CFD numerical simulation method.Then,the average wind pressure distribution,zonal body shape coefficient and interference effect of the disturbed canopy are studied by setting the disturbed buildings on both sides of the station canopy and by adjusting the interference factors(including the height of the building,the distance between the building and the canopy and the change of the directional angle).When the incoming flow is at 230° and 320°,the disturbance effect on the canopy caused by the interfering building with a height of 40 m is the largest,and the body coefficient of the canopy after the interference is the largest-0.77,which is 3.7 times of no interference,and the interference effect caused by the height of 10 m is the smallest;when the distance between the interfering building and the canopy is 20 m,the body coefficient is the largest-0.69,which is 3.5 times of no interference,and when the distance between the interfering building exceeds 60 m,the interference to the canopy is the smallest.