To find the reasonable length-to-width ratio and form of binary end plates of a model and reduce the influence of these parameters on the sectional model wind tunnel test for bridges, the sectional models of the main girder with streamlined cross section and blunt cross section were prepared,respectively.Inside the wind tunnel lab,force and pressure tests were done to the sec-tional models,and the influence of changes of these parameters on the three-component force coef-ficient was analyzed.The results of the tests show that the suggested length-to-width ratio of the sectional model is to be above 2:1,but less than 4:1,tending to ensure the stability and reliabil-ity of the three-component force coefficient and make the sectional model have good spanwise cor-relation.It is better to choose big binary end plates,and w hen limited by the condition,the ratio of the width of the binary end plate and the main girder width should be above 1.4,to make sure that the end of the model can better realize binary mobility and reduce the influence of the three-component force coefficient.The main girder sectional model with streamlined cross section is more sensitive to the form of the binary end plates than that with the blunt cross section.The three-component force coefficient is more sensitive to the length-to-width ratio of the sectional model than to the binary end plates.%为寻求合理的模型长宽比、二元端板形式,减小这些参数对桥梁节段模型风洞试验的影响,制作流线型与钝体2种断面主梁节段模型,在风洞实验室对节段模型进行测力与测压试验,分析这些参数变化对三分力系数等结果的影响.试验结果表明:建议节段模型的长宽比大于2:1且小于4:1,以保证三分力系数的稳定性和可靠性,同时使节段模型具有较好的展向相关性;尽可能选择较大的二元端板,条件受限时二元端板的宽度与主梁宽度之比大于1.4,以使模型端部较好地实现二元流动特性,降低其对三分力系数的影响;流线型断面主梁节段模型较钝体断面的易受二元端板形式的影响;三分力系数对二元端板的敏感程度明显小于对节段模型长宽比的敏感程度.
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