摘要:预应力混凝土连续箱梁桥，以其整体性好、结构刚度大、抗扭刚度大、变形小、抗震性能强、主梁变形挠曲线平缓、伸缩缝少和行车舒适等突出优点得到了迅速的发展，并在量大面广的中小跨径及一般大跨径桥梁工程中占有主导地位。6883
本设计根据任务书要求设计一座三跨连续梁桥,经过严格的方案比选从三个备选方案中选择预应力连续箱梁桥作为设计方案。桥梁采用变截面，单箱双室，采用悬臂浇筑法施工。
    首先进行初步设计，即拟定所选方案桥型的具体尺寸以及相关参数。主桥为40+60+40的三跨预应力梁桥。截面尺寸是根据设计任务书要求，参照规范和相关的参考资料来拟定的。第二步就要进行结构计算，这其中最为关键的便是建模，最后的计算是否正确，在很大程度上取决于模型建得是否正确。本设计利用MIDAS软件，可计算出结构各控制截面的内力。
完成上述工作后，便要进行结构验算。MIDAS完成后便进行运行分析，可在“结果”菜单内查看荷载组合。荷载组合有承载能力极限状态组合、短期组合和长期组合等。根据荷载组合的结果验算截面强度，并进行截面抗裂验算等等来验证结果。
对于施工方法，本桥采用的是悬臂施工法，分不同施工阶段，每阶段分步施工。挂篮沿轨道行走，通过悬挂在已完成的悬臂梁段上进行下一梁段的施工。梁段的模板架设、混凝土浇筑、预加应力等均在挂篮上进行。
通过本次设计来总结大学中的学习成果，并对未来的发展作了简要的展望。本文在最后附加了CAD图纸用以对整个结构的尺寸、平立剖面、钢束布置形状作进一步的说明与补充。
关键词： 连续梁桥；预应力；箱形变截面；结构分析
Design of a prestressed concrete box girder bridge across the river
Summary: With outstanding advantages such as better entirety, bigger structure stiffness and torsional stiffness , smaller deformation, stronger seismic performance , more gentle deformation of main girder flexural , less expansion joints and better driving comfort , prestressed concrete continuous box girder bridge got rapid development, and had a dominant position in large amount of bridge engineering with small and medium-span and common long-span.
This design according to specification requirement to design a three span continuous girder bridge, through strict than choose from three options, select the prestressed concrete continuous box girder bridge as a design solution, with variable cross section, single box double room, using the cantilever construction method.
First deciding the size for the selected scheme of bridge and the related parameters as the preliminary design. Main part of the bridge is a 40 + 60 + 40 three span prestressed concrete girder bridge. Section size is according to the design specification requirements, the reference specifications and related references to the proposed. The second step is to structure calculation. Modeling which is one of the most critical things, largely determines the validity of the computation of the final. This structure internal force of each control section can calculated by using MIDAS software.
After finishing the above work, it must carry on the structure calculation. Running the analysis after MIDAS is completed, and the load combination can be checked in the "results" menu. Load combinations have a carrying capacity limit state combination, combination of short-term and long-term combination, etc. According to the result of load combination calculation strength of cross section,section crack resistance calculation can verify the results.
The construction method of the bridge adopts is the cantilever construction method, each different construction stage is done step by step. Finishing the next girder construction by hanging baskets on the cantilever beam section which has been completed. Beam section of the template construction, concrete pouring, prestressing are conducted on the hanging basket. MIDAS跨江预应力箱梁桥设计计算书+CAD图纸:http://www.youerw.com/gongcheng/lunwen_4465.html