方案一:主桥采用了钢桁架拱五跨连续钢箱梁,其跨径布置19.74×2+255.74+19.74×2=334.7m。桁架拱高42.7m跨度为297m,矢跨比1/7。钢箱梁在平面上成弧线,以拱为轴左右对称布置,在跨中位置通过一段斜向梁联系。
主拱以上弦杆为主要受力构件,为保证拱平面外的稳定性,截面宽度为4m高1m,通过与其他杆件形成桁架保证拱面内的稳定性。主梁为栓焊流线形扁平钢箱梁,梁高1.8m,宽7m,刚隔板间距1.75m。中心7m宽考虑为人行道,中心3.5m宽考虑紧急时通行车辆。
![broken image](http://user-assets.sxlcdn.com/images/155870/Fo5ndL8O8uDEzHaA2ZPJqOkYNG9A.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/format/png)
![broken image](http://user-assets.sxlcdn.com/images/155870/FhTrBiLZW1T2gxDDUGuYKh8s9Upz.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
结构计算模型
![broken image](http://user-assets.sxlcdn.com/images/155870/FhHLQUbicEDL9nj8NSAP6PqvhQ2r.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/format/png)
基本组合下轴力 (kN)
![broken image](http://user-assets.sxlcdn.com/images/155870/FhDEsnBFAiVBP7k8Nz4NhYoGY7PH.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
基本组合下弯矩My (kN*m)
![broken image](http://user-assets.sxlcdn.com/images/155870/Fi1PbGpfbt72FhNAoVHkRFscSsoq.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
基本组合下弯矩Mz (kN*m)
![broken image](http://user-assets.sxlcdn.com/images/155870/Fu_--ZPc8VovPgdcFtIh6CLIvy95.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
基本组合主要杆件应力 (MPa)
![broken image](http://user-assets.sxlcdn.com/images/155870/FocrsS4zy8kbRnAUq6jSOhBA7JZJ.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/format/png)
人群荷载(车辆荷载)下结构变形,跨中位移最大值354(313mm),挠度=354mm/241m = 1/680
![broken image](http://user-assets.sxlcdn.com/images/155870/FhhImAge0Djwy1hlJTJw-ZtKCJ6h.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
第1屈曲模态(主拱平面内屈曲),线型稳定系数4.8.
![broken image](http://user-assets.sxlcdn.com/images/155870/FgdoGnZE-be2eH7T4Hs30cYpOf3o.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
第2屈曲模态(主拱平面外屈曲),线型稳定系数5.0.
![broken image](http://user-assets.sxlcdn.com/images/155870/FleHMd4mlNyriWR0XRHCteYhw-iw.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
方案二:主桥采用连续双曲面拱壳,板厚900mm,使用高强度混凝土C60。使用抛物线线型控制所有弧线拱线,形成双向曲面。桥墩间距58.4×2=116.8m,壳体主正压应力沿斜向在桥墩间成Z字形分布,主拱(主压应力方向)跨度约88m,壳体向上拱起15.6m,矢跨比1/5.6。
使用板单元模拟壳体,桥墩位置为变截面线单元。二层人行道,对主桥没有刚度拱线,以荷载的形式加载在模型里。局部应力集中的位置,考虑增加密肋粱。
![broken image](http://user-assets.sxlcdn.com/images/155870/FhN9JgoX-3YZ3Yg66TrnI_9we9ji.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/format/png)
![broken image](http://user-assets.sxlcdn.com/images/155870/FvNhhg1HqdaHq3brZ4cBtgGdjuyp.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/format/png)
主压力方向在桥墩间呈Z字形分布(蓝色箭头)
![broken image](http://user-assets.sxlcdn.com/images/155870/FiXS4gRD9JUQvs_W6CR2JfSxQ1Hl.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
结构计算模型
![broken image](http://user-assets.sxlcdn.com/images/155870/FrMH5_MPfeC8z_z1PZgEG4qffNy6.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/format/png)
基本组合下顶板压应力 (MPa)
![broken image](http://user-assets.sxlcdn.com/images/155870/FljMALT03eIzlbCuPX2ZR7pGhuIb.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
基本组合下底板压应力 (MPa)
![broken image](http://user-assets.sxlcdn.com/images/155870/Ft9Pp7rRbzXqYa3dqwzvEgY_DcgN.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
短期组合板顶拉应力 (MPa)
![broken image](http://user-assets.sxlcdn.com/images/155870/Fh_e8VowftbAh88aBbMZT1slwCyK.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
短期组合板底拉应力 (MPa)
![broken image](http://user-assets.sxlcdn.com/images/155870/Fjw2cFlBddvG3veYx_tmCHP5qz20.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
长期组合下结构变形,挠度= 8.02cm/88m = 1/1097
![broken image](http://user-assets.sxlcdn.com/images/155870/FjXRXOmLs-2_VRS1Z5jxnjNuCyJw.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
第1屈曲模态(边跨屈曲),线型稳定系数10.8.
![broken image](http://user-assets.sxlcdn.com/images/155870/Fvi9ffj2Yw74E4f5-kLTst2pumOa.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
第3屈曲模态(主跨屈曲),线型稳定系数12.5.
![broken image](http://user-assets.sxlcdn.com/images/155870/Ft8NJe4T_umo2Szkih44tblNt1GP.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
方案三:主桥采用不对称结构布置形式,一侧通过斜柱连接上下钢梁,形成桁架体系,对侧增加支座减小跨度。跨度为37.375×2+90+37.375×2 = 239.5m 。
![broken image](http://user-assets.sxlcdn.com/images/155870/Fn9MusnvH7oTnWdalIhEepVmjZkD.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/format/png)
结构计算模型
![broken image](http://user-assets.sxlcdn.com/images/155870/FtRTOSrIYSyExaWcHc6Tzo15yqg9.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/format/png)
基本组合下轴力 (kN)
![broken image](http://user-assets.sxlcdn.com/images/155870/FhJJ28Atx9o41N7IVjjU_PPAVlms.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/format/png)
基本组合下弯矩My (kN*m)
![broken image](http://user-assets.sxlcdn.com/images/155870/FqsrOzlmSbxgMLb2l-3OG6yUsMvm.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/format/png)
基本组合杆件应力 (MPa)
![broken image](http://user-assets.sxlcdn.com/images/155870/Ft1LX8P7nv6MBOIsgV6lodqU_L6p.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)
标准下结构变形,跨中位移最大值110mm,挠度=111mm/90m = 1/810
![broken image](http://user-assets.sxlcdn.com/images/155870/FpOJZJ0oLM7kIjZXDua0dzSvDvmo.png?imageMogr2/strip/auto-orient/thumbnail/1200x9000>/quality/90!/format/png)