顶板短束在城市小半径曲线梁桥中的应用

研究目的:在设计小半径曲线梁桥时,由于周期紧,经常习惯的布置通长预应力钢束,这样虽然可以节省设计时间,但是这种布束方式会造成曲线内外侧受力不均匀,造成材料浪费。本文以北京市广渠路五环立交一半径R=54.5 m的预应力混凝土匝道桥为工程实例,分别按照预应力通长束以及"长束+短束"布置,利用MIDAS/Civil分别对于两种布束方式建立三维杆单元模型,讨论不同布束方式下结构内外侧支座反力、扭矩及扭转应力、有效预应力及结构经济性方面的差异,为设计提供参考。研究结论:通过本文的研究可知,正确的布束方式应该是"长束为主、短束为辅",合理的预应力布束方案可以有效地改善结构的受力情况,减小结构的变形,使曲线内外侧支座反力均匀,降低预应力损失并提高结构的经济性。

Application of Roof Short Prestressed Tendons in Urban Small Radius Curved Girder Bridge

Research purposes: When designing the small radius curved girder bridge,in order to save time,the long prestressed tendons are always arranged because the design time is short.But this arrangement of the prestressed tendons may cause uneven load bearing between the internal curve and external curve and waste of the engineering materials.For a prestressed concrete ramp bridge with radius of 54.5 meters of the 5th ring road overpass at Guangqu Road in Beijing,the long tendons and short tendons + long tendons were respectively arranged,the three-dimension bar element models were established with the MIDAS/Civil for these two types of the arrangement.The discussion was made on the differences of the support reaction between the internal curve and external curve,the torsion and torsional stress,the effective prestress and the structure’s economical efficiency of these arrangements in order to provide the reference to the design. Research conclusions:From the research presented in this paper,it is known the right way to arrange prestressed tendons is the long tendons as the dominant role and the short tendons as the subsidiary role.The reasonable way to arrange prestressed tendons can effectively improve the structures’s load bearing condition,decrease the structure’s deformation,make the support reaction even between the internal curve and external curve,reduce the prestress loss and improve the structure’s economical efficiency.