大跨径组合梁斜拉桥经济性能研究

Study of Economic Performance of Long-Span Composite Girder Cable-Stayed Bridge

为推动组合梁斜拉桥向更大跨径发展,以常规两塔斜拉桥为例,开展大跨径组合梁斜拉桥经济性能研究。将斜拉桥分为斜拉索、桥塔、主梁、基础等部分,利用"平均索法"计算各部件轴力,根据轴力大小分别推导得到其材料用量的计算公式,引入材料单价系数,得到单位桥面面积造价,进而计算组合梁斜拉桥各部件的造价与跨径的关系,并与同等跨径的钢箱梁斜拉桥的经济性能进行对比分析。结果表明:与钢箱梁相比,组合梁斜拉桥充分利用混凝土材料抗压性能性价比高的特点,减小了斜拉桥体系中造价占比较大的主梁费用;组合梁斜拉桥主梁自重较大,斜拉索、桥塔、基础等造价相对较高;在一般地质(桩长约50m)、较小场地风速条件下,组合梁斜拉桥的经济跨径界限可达900m。

To promote the development of composite girder cable-stayed bridge towards longer spans,the conventional two-pylon cable-stayed bridge is cited as an example to study the economic performance of the long-span composite girder cable-stayed bridge.The cable-stayed bridge consists of the essential components of stay cables,pylons,main girder and foundation.The average cable force method was used to calculate the axial forces of each component,based on which the calculation formulas for the material amounts used to the components were deduced.And the unit material price coefficient was introduced to obtain the unit bridge deck cost.The results indicate that compared to the steel box girder,the composite girder cable-stayed bridge makes the full use of the compressive property of the concrete,and reduce the costs of the main girder which accounts for a larger proportion in the whole cost of a cable-stayed bridge.The main girder of the composite girder cable-stayed bridge has big self weight,therefore,costs of stay cables,pylons and foundation are relatively high.Under the common geological condition（with pile length of 50 m）and small site wind speed,the economic span length of the composite cable-stayed bridge can reach up to 900 m.