特大跨径地锚式悬索桥静力稳定性分析

为了解悬索桥在不同简化模型下的静力稳定性,全面分析其整体失稳过程及最终失稳模态,基于地锚式悬索桥主塔失稳导致全桥失稳的受力特点,以在建的南京仙新路长江大桥为工程背景,采用大型有限元分析软件ABAQUS建立了全桥多尺度模型和独塔实体模型,分析对比了线性稳定系数、双重非线性荷载系数、线性失稳模态以及最终破坏形态.分析结果表明:双重非线性稳定安全系数相比于线性有较大降低,非线性稳定计算对于特大跨径地锚式悬索桥应成为必需；全桥多尺度模型的线性稳定系数略大于独塔模型,而全桥多尺度模型的非线性荷载系数则反之,简化的独塔模型仅能在一定程度上代表全桥结构计算结果；主塔发生非线性失稳时塔底附近的混凝土主压应力和钢筋应力均达到抗压强度标准值,材料发生屈服导致结构发生失稳；背风侧主塔下塔柱失稳破坏时呈现出典型的压弯破坏形态,迎风侧塔柱失稳破坏时呈现出混凝土压碎区交叉的压弯扭复合受力破坏形态,随着结构薄壁化趋势的发展,工程设计在满足强度要求的同时应更关注稳定性要求.研究结果可为未来特大跨径地锚式悬索桥的设计计算以及简化模型的选取提供参考.

Static stability analysis of long-span earth-anchored suspension bridge

To study the static stability of suspension bridges under different simplified models and comprehensively analyze the entire instability process and failure modes, based on the mechanical characteristic that the instability of main tower results in the instability of the entire bridge, a full-bridge multiscale model and a single-tower solid model were established by ABAQUS, taking Nanjing Xianxin Road Yangtze River Bridge under construction as the project background. Linear stability coefficients, double nonlinear load coefficients, linear buckling modes, and failure modes were analyzed and compared. Results show that the double nonlinear stability safety coefficients were greatly reduced compared with the linear stability coefficients, and nonlinear stability calculation should be necessary for long-span earth-anchored suspension bridges. The linear stability coefficients of the full-bridge multiscale model were slightly larger than those of the single-tower solid model, while it was opposite for the nonlinear load coefficients. The stability results of the simplified single-tower model could not fully represent the real situation. The concrete principal compressive stress and reinforcement stress near the bottom of the tower both reached standard strength values when the main tower experienced nonlinear instability, indicating that the material yield led to the structural instability. The tower leg on the leeward side failed in the typical compression-flexural failure mode, while that on the windward side failed in the compressive-flexural-torsional failure mode. With the development of the thin-walled structure, more attention should be paid to stability when the strength requirements are met. The research can provide reference for the design and model simplification of long-span earth-anchored suspension bridges.