摘要: 钢管混凝土下承式简支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出色的优势和很强的推广价值。4851
本设计根据任务书要求设计一座单跨拱桥,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简支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、系杆、横系梁等。下承式简支系杆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24m，矢跨比1/5。最重要的是拱肋的截面尺寸，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。
关键词：简支；下承式；钢管混凝土；系杆；结构分析
Design of a single span simply supported tied-arch
bridge across the river in Jiaxing
Abstract: Steel pipe concrete through simply supported tied-arch bridge is a new bridge-type, because of their trial, economic and other aesthetic aspects of the unique advantages, in recent years in the field of engineering are more widely used, because of the inherent characteristics of the structure to enable it to effective bridge are highly promotional value with the outstanding advantage.
This design according to the specification requirements to design a single span； composite arch bridge, after rigorous project selection from the three options for the selection of through simply supported tied-arch bridge as a design. Mainly in the upper part of the structure of the bridge the main arch, side arch, oblique lateral support and the support, boom, tie beam, horizontal line, beams and columns and so on. Through simply supported tied-arch bridge, beautiful and stress is reasonable, but the bridge design parameters, the parameters are related to design work, brings difficulties.
First, starting preliminary design, namely the elaboration of the selected programmers bridge the specific size and the relevant parameters. The arch ribs’ main hole calculation span is 120 m, calculated vector high is 24 m, rise-span ratio is 1/5. Ultimately to the arch bridge is the main section size, are in accordance with the norms and relevant reference materials to develop.
The second step to carry out structural terms, this is the most crucial modeling, the final calculation is correct, largely depends on the model built in is correct. The design of the "MIDAS" software can calculate the internal structure of the control section. 跨江单跨简支系杆拱桥设计+CAD图纸+模型:http://www.youerw.com/gongcheng/lunwen_1651.html