Study On The Criteria Of The Static Stability Checking Wind Velocity Of Long-span Suspension Bridges

With the application of new materials in long-span bridges and the rapid development of bridge construction technology,the span of suspension bridge is getting longer and longer.Usually these long-span suspension bridges are built in strong wind areas,so the dynamic and static response of these bridges caused by wind load is increasingly obvious,the critical wind velocity of static stability also reduces fast with the span of suspension bridge increasing significantly,the increase of span may change the competitive relationship between the critical wind velocity of flutter and the critical wind velocity of static stability.About the critical wind velocity of static stability safety,factor of 2.0 is used in Wind-resistance Design Specification for Highway Bridges of china,which often leads to the static stability safety of many long-span suspension bridges can’t meet the conditions.As a key problem in the wind-resistant design of long-span suspension bridges,in this paper static stability needs to be further studied.A taut strip model that can eliminate the influence of the bridge tower is fabricated.The model is tested in uniform flow field and four kinds of turbulence wind fields for the investigation of different characteristics of static stability in disparate flow field.The criteria of the static stability checking wind velocity of long-span suspension bridges is put forward on the basis of experimental research.In addition,the wind velocity correction coefficient for static instability inspection is defined.Besides,An ANSYS program based on the iteration of time and wind load which considering the geometric nonlinearity is written to analyze the static stability of long-span suspension bridges.Then,a finite element model of the taut strip model is established to analyze the static stability of model in the uniform flow field.Then,several practical bridges are selected to analyze the critical wind velocity of the static instability to verify the criteria of wind velocity determination based on the test results.The results show that turbulent wind plays an incentive role for the static stability of long-span suspension bridges.The stimulating effect becomes more obvious with the increase of terrain roughness.The correction coefficient of wind velocity for static stability test of long-span suspension bridges is closely related to the selected static analysis method,terrain roughness,and bridge span.