缆-梁加劲联合体系悬索桥结构受力机理分析

Analysis on the Mechanism of the Suspension Bridge with Combined Cable-beam Stiffening System

西部山区高烈度地震区铁路桥梁跨越峡谷时,由于抗震要求,需要修建对大位移适应能力强的大跨度悬索桥。针对深切峡谷地形陡峻不利于建造桥塔且无法设置外伸边跨的一种地形,提出一种缆-梁加劲联合体系悬索桥结构体系,用于提高结构的整体刚度并减小活载作用下梁端的转角。以某桥位的设计方案为研究对象,比较分析常规悬索桥方案、满布桁杆方案及拉压杆-拉索缆-梁联合体系3种悬索桥结构方案在列车活载和铁路横风荷载作用下的结构竖向、横向刚度特征。结果表明,增加加劲梁与主缆之间连接,可明显提高结构整体刚度;拉压杆-拉索方案使索夹下滑力降幅约为50%;增加斜杆对数对结构整体刚度提升明显,可以有效减小索夹下滑力。

Railway bridges spanning canyons in the western mountainous area of high-intensity earthquake have to be long-span suspension bridges with strong adaptability to earthquake-induced large displacement.Aiming at a terrain where the steep terrain of deep-cut canyons is not conducive to the construction of bridge towers and cannot be set up with overhanging side spans,a suspension bridge structural system of cable-beam stiffening combination is proposed to improve the overall stiffness of the structure and reduce the impact of live loads.With reference to the design scheme of a certain bridge,the vertical and lateral structural stiffness characteristics of three kinds of suspension bridge structural schemes,namely the conventional suspension bridge scheme,the full inclined rod scheme and the tension-compression rod-stay-cable-beam combined system,are compared and analyzed under the action of train live load and railway cross-wind load.The results show that increasing the connection between the stiffening beam and the main cable can significantly improve the overall stiffness of the structure;the tension and compression rod-stay cable scheme reduces the sliding force of the cable clip by about 50%;increasing the number of diagonal rod pairs significantly improves the overall stiffness of the structure,which can effectively reduce the sliding force of the cable clamp.