Distribution Characteristics Of Average Wind Speed In Typical Valley And Aerostatic Stability Analysis Of Cross-valley Pipeline Suspension Bridge

The construction of mountain transportation requires numerous cross-valley bridges.For wind-resistant design of cross-valley bridge,it is necessary to study the characteristics of wind speed and its influence on wind resistance of bridge.In this thesis,the numerical simulation of valley wind field is carried out by computational fluid dynamics.By building different kinds of simple valley model,thesis analyzes the distribution characteristics of average wind speed in valley,and has summarized "effect of narrow" in valley about the variation of wind speed in horizontal direction,vertical direction and the direction along valley.According to the measurement of valley wind field and the velocity distribution of channel flow,thesis examine the wind speed distribution in valley.The aerostatic stability is very important in wind-resistant design of suspension bridge.Basing on the research of valley wind field,thesis sets up distribution curves of average wind speed along bridge in valley,and analyzes the aerostatic stability of a pipeline suspension bridge by uneven wind speed.As a result,research shows the influence of different wind speed distributions on aerostatic stability of pipeline suspension bridge.Simultaneously,thesis shows the influence of wind cable on aerostatic stability of pipeline suspension bridge.As a result,the middle of valley will emerge a wind speed amplification phenomenon.In horizontal direction,wind speed will increase with friction weakening from the side to the middle in valley.Then wind speed will reach a maximum value.At last,wind speed becomes moderate.In height direction,wind speed will increase from the bottom of valley and reach a maximum value in 2/3 valley height.And then wind speed decreased.Along valley,speed amplification phenomenon will weaken gradually and tend to be gentle.When wind enters into the bend section of valley,the change of terrain will force airflow to change,and unevenness of wind speed will increase in transverse direction.For aerostatic stability of bridge,critical wind speed of pipeline suspension bridge will change by using different wind speed distribution.When average value of wind speed is identical along bridge,distribution of the middle wind speed greater than the both side is more likely to lead structure to be unstable.Result also shows that wind cable can effectively reduce the displacement of pipeline suspension bridge and greatly improve its aerostatic stability.