Large-span Prestressed Continuous Rigid Frame Bridge Key Issues

In the past twenty years, continuous rigid-frame bridge stands out above the other bridge type and has advanced by leaps and bounds in china according to its cross-ability, the good structural-performance as while as the lower cost. however, as large span continuous rigid-frame bridge optimization design research is rarely and the reference material is not much, design process can be inevitably subjective and blindness. Meanwhile, designers have to endure heavy work, time wasting, and evenscheme mistake. And with the wide application of continuous rigid-frame bridge, some large span continuous rigid-frame bridge has appeared the problem of excessive deflection,which has, to some extent, restricted the continuous rigid-frame bridge further development.According to the problems of engineering design, construction and operation, the paper has done some research in the geometry parameters effect, long-term down deflection, closing segment twice pre-stressed etc., using finite element analysis, based on ELiPo bridge which is included in JiShou-ChaDong highway.(1)The development situation of long span continuous rigid-frame Bridges, development trend, the mechanics characteristics and existing problems are introduced by reference to a lot of documents.(2)Introduced the experience of section parameter values, and with ELiPo bridge for practical engineering background, analyzed the effect of side-main span ratio, beam height curve changes of parameters on the girder.(3)With ELiPo bridge for practical engineering background, the sensitivity of down deflection has been studied with a few parameters including the loading age, environment relative humidity, estimating shortage of prestressed friction loss, loss of prestress, box girder cracking and overweight structure.(4)Discussed the closure section problems including influence of closure sequence, the design of stiff skeleton, the calculation of jacking force, counterweight settings, closure temperature chosen etc..(5)This paper studies the use of "twice pre-stressed"in the E Li Po bridge and proves that it is effective and economic to solve the preblem of web's inclined cracks.