斜拉桥V塔与基座钢-混结合部施工极端工况下强化设计

Reinforcement Design of Steel-Concrete Joint at V Tower-Base of a Cable-stayed Bridge

某跨河人行景观采用异形斜拉桥,主塔底部为非对称V形钢结构,下与混凝土基座相连,钢-混结合部构造形式、受力状况及传力机理均十分复杂,施工阶段V形平面内最大弯矩相比使用荷载下的峰值多出近2倍而且反号。为了验算施工极端荷载下钢-混结合部的安全性,采用ABAQUS软件对其建立了两种非线性有限元模型,其中对钢塔壁板分别采用壳单元和实体单元,发现后者对局部应力状态的模拟结果更为精细。鉴于多处应力计算结果严重超出相应规范限值,提出了增大壁板厚度及强度等两种局部加强措施,从中优选出在斜板外侧底部加焊系列三角形和矩形竖板的设计方案,极大缓解了锐角处的应力集中,既安全可靠,又经济适用,对类似工程具有参考价值。

A cross-river pedestrian landscape adopts a special-shaped cable-stayed bridge.The bottom of the main tower is an asymmetric V-shaped steel structure,which is connected to the concrete base.The structural form,stress state and force transmission mechanism of the steel-concrete joint are very complicated.The maximum bending moment in the V-shaped plane during the construction stage is nearly twice as much as the peak value under the service load and the opposite sign.In order to check the safety of the steel-concrete joint under the extreme load of construction,two nonlinear finite element models were established by ABAQUS software.Shell element and solid element were used for the steel tower wall plate respectively.It was found that the latter had more detailed simulation results for the local stress state.In view of the fact that the calculation results of multiple stress seriously exceed the corresponding limits of the code,two local strengthening measures,such as increasing the thickness and strength of the wall plate are proposed.The design scheme of welding a series of triangular and rectangular vertical plates at the outer bottom of the inclined plate is selected,which greatly alleviates the stress concentration at the acute angle.It is safe,reliable and economical,and has reference value for similar projects.