On the basis of the dynamic model of vehicle-bridge coupled vibration,the influencial parameters on the impact factor of each member in butterfly-shaped arch bridge were studied by a self-compiled computing program,such as the velocity of vehicle,distance of eccentric load,structural damping,road roughness,traffic direction,wheelbase, vehicle-to-vehicle distance,vehicle number and structural design parameters.The results show that:as a whole,the impact factors of main cable forces will increase with the increase of vehicle velocity;the impact factor of transverse displacement at the vault of major arch ribs on eccentric side will increase with the increase of the distance of eccentric load,however,the impact factor of vertical displacement will decrease rapidly;the increment of the structure damping will make the impact effect weakened;the impact factor varies along with the grade of road roughness;there is great difference between the impact factors of symmetric members when the driving direction is different;there is an optimum rise/span ratio that minimizes the impact factor of mid-span deflection;the impact factors will be reduced obviously when the Nielsen system is used.%通过建立车桥耦合动力学模型，编写计算程序研究了行车速度、偏载距离、结构阻尼、路面不平度、行车方向、轴距、车间距、车辆数及结构设计参数等对蝶形拱桥各构件动力冲击系数的影响。结果表明：主吊索力的冲击系数整体上随着速度的增大而增大；偏载侧主拱拱顶横向位移的冲击系数随着偏载距离的增大迅速增大，而竖向位移的冲击系数却呈现迅速下降的趋势；阻尼比使得各构件的冲击系数均有所降低；构件的冲击系数随着路面不平度等级的不同而不同；异向行驶时，左右对称的各构件冲击系数差别较大；存在某个矢跨比值使得主梁跨中挠度的冲击系数最小；采用尼尔森体系，各构件的冲击系数明显减小。
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