基于双质点模型斜拉桥纵向一阶自振周期计算

Calculation of First-Order Longitudinal Natural Vibration Periods of Cable-Stayed Bridges Based on Double-Mass-Point Models

斜拉桥纵向一阶自振周期简化计算对结构方案比选和抗震验算均具有重要的意义,为提高斜拉桥纵向一阶自振周期简化计算的可靠性,根据斜拉桥纵向水平地震惯性力传递路径,建立了全飘浮体系斜拉桥反向双质点简化分析模型和纵向固定铰接体系斜拉桥双质点简化分析模型,分别采用刚度法和柔度法推导了2种体系斜拉桥纵向一阶自振周期的计算公式,并与10座已建斜拉桥的有限元计算结果进行了对比验证。结果表明:基于双质点模型的斜拉桥纵向一阶自振周期简化计算公式的计算结果与有限元计算结果吻合良好,2种简化分析模型均具有较高的计算精度,可用于斜拉桥纵向一阶自振周期的简化计算,可为斜拉桥的初步设计和方案比选提供参考。

The simplified calculation of the first-order longitudinal natural vibration period of a cable-stayed bridge is of important significance to the structural scheme comparison and seismic resistance checking of the bridge.To improve the reliability of the simplified calculation,the reverse double-mass-point simplified analysis model for the full floating system cable-stayed bridge and the double-mass-point simplified analysis model for the longitudinal fixed hinge system cable-stayed bridge were established in accordance with the transmission paths of the longitudinal horizontal seismic inertia forces of the cable-stayed bridges.The stiffness method and flexibility method were respectively used to derive the calculation formulae of the first-order longitudinal natural vibration periods of the bridges of the two systems and the calculations were compared to the finite element calculations of the 10 built bridges of the similar structural type.The results show that the calculations according to the simplified calculation formulae of the first-order longitudinal natural vibration periods of the cable-stayed bridges based on the double-mass-point models are well agreeable with the calculations of the finite element.The 2kinds of the models all have high calculation accuracy,can be used for the simplified calculation of the natural vibration periods of the cablestayed bridges and can provide reference for the preliminary design and scheme comparison of the bridges.