Study On A Design Method Of Prestressed Tendon Layout Based On The Reasonable Finished State Of Long-span PC Continuous Rigid Frame Bridges

Long-span prestressed concrete bridges have many advantages such as reasonable structure stress, large span capacity, ease of construction etc. However, currently there are some problems in the application of long-span prestressed concrete bridges. Therefore, it becomes necessary to perform a further study on the design theory of long-span prestressed concrete bridges.Based on the reasonable finished state of long-span prestressed concrete continuous rigid frame bridges and set in an engineering research on a practical continuous rigid frame bridge, this thesis proposes an optimization design method of prestressing tendon layout for long-span continuous rigid frame bridges. More endeavor is made as follows.(1)In this thesis, some research findings of reasonable finished state are collected and concluded. Simultaneously, the damage causes existing in present long-span prestressed concrete continuous rigid frame bridges are analyzed.(2)On the basis of studying the reasonable finished state of long-span bridges, this thesis puts forward three characteristics of the reasonable finished state of prestressed concrete continuous beam bridges according to both construction methods and stress characteristics of prestressed concrete continuous bridges.(3)In accordance with symmetrical internal force distribution principle of reasonable finished state as well as prestressed tendon layout design method of zero bending moment, the range of moment equilibrium coefficient of long-span continuous rigid frame bridges is determined.(4)Based on the cable force adjustment of the reasonable finished state of cable-stayed bridges, a design method is raised that long-span prestressed concrete continuous rigid frame bridges employ the least bending energy method combined with stress balance method to configure prestressed tendons.(5)By simplifying the hypothesis, the practical calculation formula of prestressed tendon layout of prestressed concrete continuous rigid frame bridges which utilize the cantilever construction method is deduced.(6)Based on a practical continuous rigid frame bridge, through building a design calculation model which compares the prestressed tendon layout design of this thesis with that of the original bridge by using Midas/civil finite element software, it is proved that the prestressed tendon layout design referred in this thesis can make the finished state of this bridge more reasonable.