Analysis And Optimization On The Stress Performance Of The Qiu Puhe Low Tower Cable-stayed Bridge

As a new type of bridge structure, the low tower-cable-stayed bridge was not acontinuous beam bridge nor a traditional cable-stayed bridge. This type of bridgehad both the characteristics of the continuous girder bridge and common cable-stayed bridge, the stress on the structure was complex and the inhomogeneousphenomenon of normal stress at cross section was very serious. The phenomenon ofshear lag was more serious along with the enlargement of width-span ratio andwidth-height ratio. Existing research results showed that the internal force of girdercross section and the influence of shear lag on the structure were larger in thecourse of construction than completed bridge, so the internal force became thecontrol value of section design in the construction stage. In addition, the girder oflow tower cable-stayed bridge was the main bearing component which occupied animportant position in the whole bridge. However, the design was based on theexperiences of designers to draw up initial cross section forms, and the structureforms which met the condition were determined after several times trials. The mainthing of this design was that the cross section of forms just met the specificationrequirements, but not was the most reasonable one, in addition to the large amountof calculations. Therefore, this text conducted the following research based onQiupuhe super-large bridge which was being built: As a foundation of constructionmonitoring and control project work, element model of whole bridge wasestablished by a professional software named MIDAS/CIVIL2010at first and thestress on the girder was analyzed during the completed bridge phase. The analysisresults showed the rationality and feasibility of the design; Secondly, Qiupuhe wasa typical short tower cable-stayed bridge with single cable planes and wide boxgirders. A element model of part segment space including the first pair cablenamely J1cable was established by ANSYS and the characteristics of stress on thewide girder section and the shear lag were analyzed under the tesion duringconstruction. The results were consistent with the actual monitoring data preferablyso that verified the correctness and reliability of the theoretical calculation. Theresults had a certain reference and guidance significance to the same kind of bridgedesign and construction control. Finally, the stress performances of short towercable-stayed bridge under the cross section form of the design were calculated combining with theoretical calculation data and actual measured data. On the basisof this, optimization measures of the design of the cross section form were putforward. The space force performances before and after cross section optimizationwere compared and analysed. The analysis results verified the rationality andfeasibility of the optimization ideas and could give some reference to the design ofsimilar bridge in the future.