龙潭长江大桥主塔结构设计与计算
张庆开1,2，左英1，胡川开1,2，郑华凯3
1.华设设计集团股份有限公司，江苏 南京 210001；2.江苏华通工程技术有限公司，江苏 南京 210001;
3.江苏省交通工程建设局，江苏 南京 210004
摘要：为提高大跨径悬索桥主塔设计的安全性、稳定性和经济性，以龙潭长江大桥（主跨1 560 m）为工程依托，分析主塔结构设计与计算的理论要点，考虑汽车荷载、温度、风载、地震等基本作用，并考虑大桥结构几何非线性竖向荷载-侧向位移效应、混凝土材料弹塑性等；根据总体计算选取不利截面，在各不利工况荷载组合下确定构件计算长度系数；采用变厚度设计横向、纵向主塔塔壁，随塔柱高度变化调整；对选取截面进行双向压弯静力分析和弹塑性分析，分析大桥整体的稳定性。计算结果表明：采用沿高度3次变截面设计塔壁厚度能满足结构受力要求；经稳定性计算，取消中横梁能保证主塔的安全性，提高大桥的经济性与景观效果，可为同类长细比较大的桥梁主塔结构设计与计算提供依据及借鉴。
关键词：大跨径悬索桥；计算长度系数；几何非线性；弹塑性分析；双向压弯；长细比
Design and calculation of the main tower structure of the Longtan Yangtze River Bridge
ZHANG Qingkai1,2,ZUO Ying1, HU Chuankai1,2, ZHENG Huakai3
1. China Design Group Co., Ltd., Nanjing 210001, China;
2. Jiangsu Huatong Engineering Technology Co., Ltd., Nanjing 210001, China;
3.Jiangsu Transportation Engineering Construction Burea, Nanjing 210004, China
Abstract: To improve the safety, stability, and economy of the main tower design of long span suspension bridges, this study takes the Longtan Yangtze River Bridge (with a main span of 1 560 m) as the engineering reference. It analyzes the theoretical key points of the design and calculation of the main tower structure, considering basic actions such as vehicle loads, temperature, wind loads, and earthquakes. Additionally, it takes into account the geometric nonlinearity of the bridge structure, vertical load-lateral displacement effects, and the elastic-plastic behavior of concrete materials. Based on comprehensive calculations, adverse sections are selected, and the calculated length coefficients of components are determined under various adverse load combinations. A variable thickness design is adopted for the transverse and longitudinal main tower walls, adjusting the thickness according to the height of the tower columns. A bi-directional compression-bending static analysis and elastic-plastic analysis are conducted on the selected sections to assess the overall stability of the bridge. The calculation results indicate that using a cubic variable cross-section design for the tower wall thickness along the height can meet the structural stress requirements. Stability calculations show that eliminating the middle crossbeam can ensure the safety of the main tower while enhancing the economic viability and aesthetic effect of the bridge. This can provide a basis and reference for the design and calculation of main tower structures of larger slenderness ratio bridges.
Keywords: long span suspension bridge; calculated length coefficient; geometric nonlinearity; elasto-plastic analysis; bidirectional bending；slenderness ratio
