大跨径预应力混凝土箱梁桥长期下挠问题的研究现状

State of Art of Long-term Deflection for Long Span Prestressed Concrete Box-girder Bridge

近年来,大跨径预应力混凝土箱梁桥的下挠现象日益威胁结构安全,而导致这一现象的原因仍然没有完全明确。从混凝土的收缩徐变、预应力效应、箱梁开裂的影响、现有计算与防治手段等方面,对国内外在大跨径预应力混凝土箱梁桥下挠问题上的研究现状进行了总结与综合评价分析;对导致下挠问题的主要成因与研究难点在机理上进行了解释。最后,对桥梁设计计算、桥梁混凝土施工及箱梁下挠的防治技术进行论述,并对开展控制结构长期下挠的研究提出了建议。

The long-term deflection of Long Span Prestressed Concrete Box-girder Bridge （LSPCBB） is getting more and more serious in terms of structure safety. And there are still many ambiguous reasons as to the cause of the deflection of LSPCBB. In respect of the causes of long-term deflection, domestic and aboard research literatures on the deflection problem of KSPCBB are reviewed and analyzed from the aspects of concrete creep ＆ shrinkage, prestress effect, box-girder cracking, calculation and retrofit methods.Not only are the cause mechanism and research difficulties of the deflection explained, but also the suggestions about further research of long-term deflection control in design calculation, construcfion and retrofit technologies of KSPCCB are presented.