马鞍山长江公路大桥三塔悬索桥钢箱梁设计特色

马鞍山长江公路大桥左汊主桥为三塔两跨悬索桥,其主梁采用钢箱梁结构.根据结构受力合理、施工方便、节省材料等原则设计了钢箱梁.横隔板采用空腹桁架式结构,既满足结构受力要求,又可减轻结构重量、便于施工；在中塔位置采用下横梁与钢箱梁不等高的固结设计,使下横梁内力及钢箱梁应力满足设计要求；塔梁固结设计增大了钢箱梁的竖向刚度,减小了中塔顶主缆的不平衡水平力；在标准节段与塔梁固结段设置变高段使塔梁固结位置应力传递匀顺；将锚拉板与钢箱梁内纵腹板连为一体并伸出钢箱梁顶板,桥面荷载直接通过纵向腹板及横隔板耳板传给吊索,避免了设置复杂的吊索锚固加劲构造及吊索锚固耳板与桥面板间直接承受拉力的焊缝.

Design Features of Steel Box Girder of Three-Tower Suspension Bridge of Maanshan Changjiang River Highway Bridge

The left main bridge of Maanshan Changjiang River Highway Bridge is a three-tower and two-span suspension bridge.The main girder of the bridge employs the steel box girder that is designed on the principle of more rational structural force conditions,convenient construction and material saving.The diaphragms inside the girder are of the Vierendeel trusses that on the one hand can satisfy the structural force condition requirement and on the other hand can reduce structural weight and is convenient for construction.At the intermediate tower,the rigid fixity of unequal height way of the lower cross beam and the girder is designed,which guarantees the design requirements of the internal force of the cross beam and stress of the girder.The design of the rigid fixity also increases the vertical rigidity of the girder and reduces the unbalanced horizontal force of the main cables atop the intermediate tower.The setting of the variable height section within the range of the typical girder blocks and the rigid fixity of the tower and girder can result in smooth transferring of the stress in the rigid fixity.By connecting the anchor tensile plates with the longitudinal webs in the girder and extending them outside the top plate of the girder,the loads on the deck can transfer to the suspenders directly via the longitudinal webs and the ear plates of the diaphragms,therefore avoiding setting complicated stiffening structures for the suspender anchors and the welding seams that will directly sustain tensile force in between the ear plates of the suspender anchors and the deck plate.