Key Design Techniques for Long-span Open Web Arch-stiffened Girder Rigid-frame Bridge
To overcome the disadvantages of using continuous rigid-frame bridge in selecting bridge type for mountainous bridges with a main span larger than 200 m,and the limitations of using reinforced concrete deck arch bridge due to the applicable conditions,a novel open web arch-stiffened girder rigid-frame bridge is proposed,which combining the conventional continuous rigid-frame bridge and deck arch bridge in the structural system.The structural system and mechanical characteristics of the bridge type are analysed by using finite element analysis to study the key design technologies such as main structural parameters,reasonable bridge state,construction of arch-girder confluence section,construction of inverted triangle area of girder-arch,and reasonable timing of removal of temporary buckling cable,etc.The result shows that the open web arch-stiffened girder rigid-frame bridge uses the lower chord arch to assist the main girders and form a self-balancing force system,which significantly reduces the length of mid-span and side-span of main girders,and optimizes the structural,mechanical properties with the advantages of large vertical stiffness and good control effect on long-term deflection and deformation.When the strength,stiffness,and linearity calculation indicators of critical control points of structure meet the target range,a reasonable bridge completion state can be achieved.The convergence of top slab of lower chord arch and the bottom slab of upper chord girder is constructed in the form of A-shaped structure,which is simple and effective in force transmission,and easy to control the construction quality.This type of bridge is suitable for balanced cantilever section construction.The upper chord girder and lower chord arch in the inverted triangle section of beam arch need to use temporary cables to assist the structural stress.During the dismantling phase,the lower chord arch temporary cables should be removed in batches after the formation of girder arch combined section,and the mid-span span conventional girder section before the closure,while the upper chord girder temporary buckle cables should be removed after the main bridge closure.The study describes the engineering practice of Chongqing Lijia Jialing River Bridge,the key design techniques for long-span arch-stiffened girder rigid-frame bridge can provide a valuable reference for the construction of similar bridges.
NETL
NSTL
万方数据
