Research On Three Dimensional Prestress Design And Construction Technics Optimization Of Long Span Continuous Beam Bridge

Prestressed continuous beam bridge was widely used in super highway and railway construction considering its good overall performance , its rigid structure , small deformation and excellence seismic repellency . Prestressing was one of the significant components in designing a continuous beam bridge , which would suggest a longer span , great improvement of constructing quality and greatly reduced structure load to ensure neat and lightweight structure and thousand tons of steel and concrete if designed properly , otherwise , a waste of structuring material was a lesser problem , more could be the crack or even the destruction of the concrete box beam . It is in this aspect that the prestressing design became a crucial problem in the engineering field.It is analysed first in this article the stress and strain of the concrete box and also how prestressed bars acted during different phases of bridge construction using MIDAS/CIVLE simulation software , the result could be used to be referenced in designing prestressed rebar when designing a continuous beam bridge.Then a compare of web plate cross-section stress under six different application of prestress in the vertical prestress force and bended prestress force, results come out to suggest that the deploy of longitude bent bars was just to reduce the prime tension stress of the web plate using the sub-prestress of the vertical prestress , which could be replaced by linear longitudal bars and vertical prestressed bars .The linear layout of bars not only simplified the designing and constructing procedure , but also reduced the lose of stress caused by frictional resistance , more than that , the length wise prestress force could easily performed to prominently reduce the stress in the web plate . It was introduced in this article the strength theory of concrete under two dimensional force , a proper way of calculating vertical prestress force was given and a discussion on how to improve the constructioning technics of vertical prestressed bars.A method concerning the calculation of horizontal prestress force was introduced and also the rules as to the laying out those prestressed force . It is from those problem discussed below that the theory was produced to properly design big span three dimensional prestressing concrete continuous beam bridge .