摘要:下承式钢管混凝土系杆拱桥是一种新桥型，因其实用、经济美观等方面的独特优势，近几年在工程领域中得到较为广泛的应用，更因其结构上的固有特点使其能够有效克服桥梁常见病害具有很强的推广价值。43795

本设计根据任务书要求设计一座下承式拱桥,经过严格的方案比选从三个备选方案中选择下承式钢管混凝土系杆拱桥作为设计方案。桥梁上部结构主要有主拱肋、横向支撑、吊杆、纵梁、横系梁及立柱等。下承式钢管混凝土拱桥美观且受力合理, 但该种桥型设计参数较多, 各参数相互关联, 给设计工作带来了困难。

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。主拱拱肋计算跨径120m，计算矢高30m，矢跨比1/4。最重要的是主拱肋的截面尺寸，都是根据根据规范和相关的参考资料来拟定。

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，对于拱桥最重要的就是要验算拱圈截面承载力与拱圈的整体稳定性。建模完成后便进行运行分析，可在“结果”菜单内查看荷载组合。荷载组合有基本组合、短期组合和长期组合等。对下面的验算来说，若进行承载能力验算，则选用强度包络下的组合；若进行正常使用验算，则选用应力包络下的组合；若进行挠度验算，则选用位移包络下的组合。

对于施工方法，本桥采用的是拼装法施工拱肋，满堂支架施工上部结构。适合平坦的河滩施工。但不足之处是拱肋在空中对接精度较难控制，拱轴线型控制有一定的难度，分段越多，其工期和质量控制的难度就越大，施工费用也越高，在施工中要采用新技术和新工艺。灌注钢管内混凝土采用泵送顶升法。

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。

Jiangsu jingjiang Xia Shi harbor bridge, arch bridge design

Abstract: the concrete-filled concrete arc bridge is a kind of new bridge, because actually use, beautiful and unique advantages in aspects of economic, get more extensive application in the field of engineering in recent years, because of its inherent characteristics make its structure can effectively overcome the bridge common diseases has a strong promotion value.

This design according to the requirements specification to design a concrete-filled steel-tube, after strict scheme is selected from three alternatives to select the concrete-filled concrete arc bridge as a design solution. Bridge upper structure mainly has the main arch rib, horizontal support, derrick, longitudinal beam, transverse beam and column, etc. Concrete-filled steel tube concrete arch bridge is beautiful and reasonable force, but this kind of bridge design parameters is more, the parameters related, brought difficulties to design work.

First carries on the preliminary design, the size for the selected scheme of bridge and the related parameters. Span 120 m, the main arch rib to calculate the vector 30 m high, rise-span ratio 1/4. The most important thing is that the section size of main arch rib, is according to the proposed according to specification and related resources.

The second step is to structure calculation. That is one of the most critical modeling, the final calculation is correct, to a large extent depends on the model built is correct. This design using MIDAS software, can calculate the structure internal force of each control section.

Completion of work, the structure and checking calculation of will, the most important thing is to check for arch bridge bearing capacity of arch ring cross section and the overall stability of arch ring. Modeling is completed after running analysis, can be in the "results" menu to check the load combination. Load combinations have a basic combination, combination of short-term and long-term combination, etc. For the following calculation, if for bearing capacity calculation, choose the combination of the strength envelope under; If normal use and checking, the combination of stress under the envelope; If on the deflection, the combination of displacement under the envelope. MIDAS120跨径下承式钢管混凝土系杆拱桥设计:http://www.751com.cn/gongcheng/lunwen_44815.html