大跨度铁路悬索桥结构刚度敏感性研究

Study on the Sensitivity of the Structural Stiffness of Long-Span Railway Suspension Bridge

桥梁刚度参数的确定在大跨度桥梁总体设计中非常重要,结合某大跨度铁路专用悬索桥方案,从结构动力特性、车辆走行性和风致抖振响应3个方面,分析梁、塔、索等构件刚度对桥梁性能的影响,并对大跨度铁路悬索桥刚度评价指标进行研究,结果表明：桁宽的增大能够较显著地增大桥梁横弯基频,桁宽过小时桥梁会产生横向周期性振动,宽跨比限值建议取为1/20~1/35;随着桁高减小,车辆竖向加速度显著增加,高跨比限值建议取为1/70~1/100;主缆刚度增大会使桥梁扭转和竖向基频明显提高;桥塔刚度及恒载的影响有限。

The determination of structural stiffness parameters is very important in the overall design of long-span bridges.Taking a long-span railway dedicated suspension bridge as an engineering example,the effect of the stiffness of girder,tower and cable on the performances of bridge was analyzed from the aspects of the structural dynamic characteristics,train running performance and wind induced buffeting response.The stiffness assessment index for long-span railway suspension bridge was studied.Results indicate that the increase of the truss width can notably raise the transverse bending fundamental frequency of the bridge.The transverse periodic vibration of bridge would occur on condition that the truss width is too small,and the proposed limit value of the width-span ratio is 1/20~1/35.The vertical acceleration of train can be remarkably increased with the decrease of truss depth,and the proposed limit value of the depth-span ratio is 1/70~1/100.The increase of main cable stiffness can obviously improve the torsional and vertical fundamental frequency of the bridge.In addition,the effect of tower stiffness and dead load is limited.