预应力RC-UHPC简支组合箱梁设计

Design of Prestressed RC-UHPC Simple-supported Composite Box Girder

摘要:

为改善混凝土箱梁的受力性能,提出预应力RC-UHPC简支组合箱梁新结构。以实际工程中某现浇预应力单箱双室简支箱梁桥为工程背景,开展设计研究,采用预应力RC-UHPC组合箱梁替代原设计的现浇箱梁,通过理论分析和Midas civil相结合的方式,探讨了此结构的计算方法,并对设计的箱梁进行设计计算,结果表明所设计的新结构的抗弯承载力和最大变形量等均符合现行设计规范的要求。通过对原设计箱梁和新型箱梁的造价、施工便利性、耐久性等方面进行比较,发现所提出的新型箱梁的造价与原设计箱梁较为接近,但其混凝土和预应力筋的用量比原现浇桥减少了49.6%和21.1%,可采用预制吊装方案,施工方便,且腹板采用的UHPC抗裂性、耐久性均得到明显提高,具有广阔的应用前景。

Abstract:

In order to improve the stress performance of concrete box girder, a new structure of prestressed RC-UHPC simple-supported composite box girder is proposed. Taking a cast-in-situ prestressed single-box double-cell simple-supported box girder bridge in a practical project as the engineering background, the design and study are carried out. The prestressed RC-UHPC composite box girder is used to replace the original design of cast-in-situ box girder. The calculation method of this structure is discussed through the combined method of the theoretical analysis and MIDAS CIVIL, and the box girder is designed and calculated. The results show that the flexural capacity and the maximum deformation of the new designed structure conform to the requirements of the current design code. Through the comparison of the cost, construction convenience and durability of the original designed box girder and the new box girder, it is found that the cost of the proposed new box girder is closer to that of the original designed box girder. But the amount of concrete and prestressing tendons is reduced by 49.6% and 21.1% compared with that of the original cast-in-situ bridge. The prefabrication hoisting scheme can also be used, the construction is convenient, and the UHPC crack resistance and durability of the web are also obviously improved, which has a broad application prospect.