The Stress And Cable-girder Anchorage Local Stress Analysis For The Large Span PC Extradossed Cable-stayed Bridge Box Girder

Extradosed cable-stayed bridge because of its beautiful appearance, the main girdersstiffness, strong spanning ability can be used in the construction of railway Bridges. Theupcoming construction of the Chengdu-Kunming railway expansion renovation project ofJinsha River prestressed concrete extradosed cable-stayed bridge as the background, some keyproblems of prestressed concrete extradosed cable-stayed bridge are carried out numericalsimulation analysis, the main work and conclusions are as follows:1.Based on the APDL language of extradosed cable-stayed bridge cable forceoptimization for parametric analysis. Stay cables play an important role in ExtradossedBridge, cable-girder anchorage make the main girder similar to more elastic supportcontinuous beam. When the load is determined, through the adjustment of cable force canchange the stress distribution of the structure which reflect the various performance indicatorsto achieve the optimal structure. Extradosed cable-stayed bridge as a three-dimensional spacestructure, to optimize the cable force calculation need to establish space finite elementanalysis model,This article chooses the principle of minimum bending energy, getting into aset of values under the action of dead load from the ANSYS parametric design languageAPDL cable force optimization program. In this paper, the cable force optimization modelaccurately simulate the change of the main girder section in height and width, to make up forthe deficiencies of the main girder simulation when using ANSYS modeling in the past.Practice shows that the program calculation accuracy is higher, using convenience,converging fast, has the very high application value.2. Prestressed concrete extradosed cable-stayed bridge upper structure set up by adoptingthe ANSYS12.1three dimensional space finite element model. Calculation and analysis showthat the main girder under dead load and prestressed load lines smooth, uniform stress, thecross section in compression state, the maximum compressive stress is far less than thecompressive strength of concrete limit. The girder under the dead load and prestressed loadand the joint action of the most unfavorable live load the deflection and longitudinal stressesare within a reasonable range. Under the influence of live load (partial load), got the maingirder of each control section left, middle and right longitudinal stress distributioncharacteristics of the web. The results show that the position of the downward deflection ofthe drastic changes of the girder，the longitudinal stress under the partial load side webs is lessthan the other side webs from the live load, therefore the position of the girder is the mostunfavorable areas, such as in the middle span section and in side span section. While otherparts of the partial load below the main girder side webs longitudinal stress is bigger than the other side webs from live load, for the whole cross section of the girder under pressure, thestress distribution to make such a structure with a certain security reserves. This paper firstexplores the main girder of prestressed concrete extradosed cable-stayed single box doubleroom left, middle and right three longitudinal stress distribution characteristics of web,received good results, can provide reference for the same type bridge design.3.Using ANSYS12.1to a variety of new cable-girder anchorage ways to carry on thenumerical analysis. The results show that: in the case of a single steel plate anchored,although the vast majority of the regional stress of the girder concrete in anchoring sectionwithin the allowable range, the steel’s local stress is too large, so the anchor way is notsuitable for use through the analysis.Using double plates anchored, the vast majority of theregional stress of the girder concrete in anchoring section and steel anchor plate structurewithin the allowable range, a large part of the local stress can take appropriate reinforcementmeasures to meet force structure requirements. In general use of steel anchor plate anchorage,novel structure, beautiful style, but the power transmission of anchored structure is complex,the connection between steel and concrete is bad, need to consume a large amount of steel, thecost is higher. When using concrete blocks anchored, must be appropriate to join the prestresscan meet the requirements of the structural force. Numerical calculation of the round angleand wedge angle anchoring, show that the wedge angle anchoring beams and the most ofanchor block in the state of compression, the individual regions found that tensile stress, thevalue of the maximum tensile stress is smaller than the round angle anchorage of stress, andstress concentration in the area is very small. Most of the wedge angle in compression, wherethe position of the maximum tensile stress occurs on cross-sectional what structure of amutation, the local stress concentration phenomenon,a small concentrated stress value,small-scale, if use the rounded transition, can meet the requirement of the structure force.Different cable-girder anchorage ways, the force beam segment of anchorage zone is morecomplex, influenced by many factors, through the calculate analysis of four differentanchorage types, can provide a reference for beam of extradosed cable-stayed bridge design.