大都市的扩展历程与大都市边缘区的城乡一体化问题分析

以一座三塔悬索桥为分析对象，采用SAP2000平台建立该桥空间动力有限元模型并进行非线性动力分析，研究了地震作用下，缆梁间设置中央扣、中塔与主梁间设置弹性索和二者组合使用对于该桥抗震性能的影响。分析结果表明，缆梁间设置中央扣可以显著减小主梁位移和中塔塔底剪力和弯矩，但会使各塔顶主索鞍座水平力和边塔内力增加；选用合理的弹性索刚度，可以有效控制主梁位移，同时使中塔与边塔的受力处于合理范围内；两者组合使用，能够进一步降低主梁位移和均衡中塔与边塔的受力，同时可以减小弹性索索力，更有利于中塔下横梁受力。

An Analysis on Metropolitan Expansion Process and Urban rural Integration in Its Fringe Area

Based on a triple tower suspension bridge, the effect of different longitudinal constrain systems under earthquake are compared by SAP2000. The influence of elastic cables between middle tower and main girder, central buckle between main cable and main girder, and the combination of both on anti seismic performance of this bridge are investigated in detail. The results show that the central buckle can decrease the displacement of girder end and the shear force and moment of middle tower bottom obviously, but increase the internal forces of the side tower bottom and the horizontal force of the main cable saddle. A reasonable stiffness of the elastic cables can limit the longitudinal displacement of main girder efficiently and control the internal forces of middle and side towers. Using the combination of both, the longitudinal displacement of main girder and the internal forces of towers would be under well control, and a smaller cable force can be more conductive to the crossbeam of the middle tower.