Analyse The Space Stress Of Long Span PC Continuous Rigid Frame Bridge

In recent years, lightweight and slender bridge structures are always favored bydesigners, and loads and spans of bridge are also increasing. Continuous rigid frame bridgebecome popular because of the unique advantages in these aspects. However, diseases such asmid-span deflection and cracks of girder appear in later operations with the increasing spans,Therefore, it is particularly important to analyze the space stress of long span PC continuousrigid frame bridge.1）This paper firstly describes the development trend and system characteristics ofcontinuous rigid frame bridge, discusses two problems like mid-span deflection and cracks ofgirder, which is easily occurred in the continuous rigid frame bridge, and puts forward thesignificance and necessity of space stress analysis of long span PC continuous rigid framebridge. This paper Introduces the characteristics of space stress and the analysis method of thebox girder as well as the basic theory and design method of prestressed steel.2）Then take South Channel Bridge,spans of55m+2×100m+55m, as an example, thispaper builds a beam element model which include the whole bridge by the finite elementsoftware Midas/Civil, through the establishment of a variety of load conditions, this paperanalyses the stress state of the whole bridge under different conditions such as dead load,second dead load, creep and shrinkage of concrete, prestressed steel, temperature effect, liveload and so on. Then get the corresponding calculation and analysis data.3）Then simulation for analyzing local spatial entity model of the bridge by using thefinite element software Midas/FEA, This paper selects main pier No.0block, which iscomplex in structure form and stress, and the extened unit as the research object,the spatialeffect of continuous rigid frame bridge prestressed.What is more,it analyses the spatial effectof prestressing force in continuous rigid frame bridge, and compared with beam elementmodel.It concludes that prestress of pre-stressed steel will diffuse in the beam. Therefore,there is a blind spot about prestress in the beam, which can not be seen in the beam elementmodel. 4）Finally, this paper analyse the action of box girder webs under vertical prestressdetailedly,and study the theory and the design method of vertical prestressed reinforcement.And through the comparison analysis of different spacing of vertical prestressedreinforcement, it obtains the reasonable spacing of vertical prestressed reinforcement in theweb,which considers the effect of the diffusion effect of prestress fully.