千米级斜拉桥在各类环境荷载作用下的梁端变位特征

The Displacement Characteristics of the Beam End of the Kilometer Cable-Stayed Bridge under Various Environmental Loads

摘要: 以沪苏通长江公铁大桥为背景，通过数值计算方法对比分析了各类环境荷载作用下的梁端变位特征。研究表明：梁端纵向位移主要受主梁温度变化与顺桥向风荷载影响，位移幅值与温度正相关，对伸缩装置等结构性能提出更高要求；横向位移同样以温度为主要影响因素，且随离梁端中心点距离增大而增大；竖向位移主要由基础不均匀沉降引起，其他环境因素影响很小；梁端扭转角与竖向转角对环境荷载响应均不显著，变化幅度极小。研究进一步指出，基础不均匀沉降是导致梁端横向转角增大的关键因素，当不均匀沉降量超过10 cm时，横向转角将超过1.0‰ rad的限值，严重影响梁端处轮轨接触关系与高速列车经过梁端的安全性。因此，在桥梁运维中应重点加强梁端结构的维护与不均匀沉降的监测控制，以保障轨道平顺性与行车安全。

Abstract: Based on the background of Shanghai-Suzhou-Nantong Yangtze River Bridge, the displacement characteristics of beam end under various environmental loads are compared and analyzed by numerical calculation method. The research shows that the longitudinal displacement of the beam end is mainly affected by the temperature change of the main beam and the wind load along the bridge, and the displacement amplitude is positively correlated with the temperature, which puts forward higher requirements for the structural performance of the expansion device. The transverse displacement also takes temperature as the main influencing factor, and increases with the increase of the distance from the center point of the beam end. The vertical displacement is mainly caused by the uneven settlement of the foundation, and other environmental factors have little effect. The response of torsion angle and vertical rotation angle of beam end to environmental load is not significant, and the change range is very small. The study further points out that the uneven settlement of the foundation is the key factor leading to the increase of the lateral rotation angle at the beam end. When the uneven settlement exceeds 10 cm, the lateral rotation angle will exceed the limit value of 1.0‰ rad, which seriously affects the wheel-rail contact relationship at the beam end and the safety of the high-speed train passing through the beam end. Therefore, in the operation and maintenance of the bridge, the maintenance of the beam end structure and the monitoring and control of the uneven settlement should be strengthened to ensure the track smoothness and driving safety.