风雨耦合作用下桥梁主梁静力三分力系数研究

Study on Static Three Component Force Coefficients of Bridge Main Girder Under Coupling Effect of Rain and Wind

针对风雨耦合作用下桥梁主梁的静力三分力变化问题,首先对降雨特性做了简要介绍,然后对降雨引起的空气密度改变、降雨对结构的冲击力及简化计算模型、结构表面积水厚度进行了分析。最后以4类典型主梁断面为例,进行了不同雨强下节段模型静力三分力测试。结果表明:降雨引起空气密度改变很小,即使雨强达到300mm·h-1,改变量不超过1%;雨强达到上述超强暴雨时,结构竖向冲击力仅为0.67Pa,同样雨强且风速为50m·s-1时,水平冲击力约为100Pa,占同等风速下纯风作用力的6.5%,而且其随风速的增长率要远小于风作用力的增长率;随着雨强的增大,主梁升力系数明显减小,小风时可达到无雨时的数倍,扭矩系数无规律变化,阻力系数有所增大但比例十分有限;随着风速增大,降雨的影响会相对弱化;试验结果验证了通过质量加权平均简化后的雨滴冲击力计算公式的正确性。

Aiming at the problem that bridge girder＇s static three component force coefficients change during wind driving rain,the authors firstly made a brief introduction about the characteristics of rainfall.Then the change of air density,the impact of rainfall on the structure and its simplified calculation mode,the surface water thickness were discussed.Finally,according to the wind tunnel tests of four typical main girder sections,the three component force tests of segmental model under different rain intensities were implemented.The results show that rain causes a small change in air density,even if the intensity of the rain is 300 mm·h^-1,the amount of change is not more than 1%.When the rain intensity reaches the above super heavy rain,the vertical impact force of the structure is only 0.67 Pa,when the wind speed is 50 m·s^-1,and under the same rain intensity,the horizontal impact force is about 100 Pa,it is6.5% of the wind force,and its increase rate with the wind speed is far less than that of wind force.The lift coefficient decreases with the increase of rainfall intensity,it can be several timesthan the values without rainfall in weak wind,change of torque coefficient is not regular,the resistance coefficient is increased but the proportion is very limited,accompany with the wind velocity＇s increasing,rainfall influence will relatively die down composed with the wind load.In addition,test results verify the correctness of impact force calculation method simplified by mass weighting method.