Research On Construction Alignment Prediction Of Segmental Precast Assembled Girder Bridge Based On Response Surface Method

Compared with traditional construction methods such as support construction and cantilever symmetrical casting,this method has the advantages of saving investment,shortening construction period,less interference to the surrounding environment,low pollution,and not taking up the site under the bridge.However,during the construction of the assembled girder bridge,due to many factors that may have an important effect on the bridge alignment,some Bridges have different degrees of buckling and collapse,which poses a serious threat to the normal use of the bridge and the safety of the bridge structure.Therefore,it is of great significance for the construction control and safety of the bridge in the later stage to carry out the research on the prediction of the construction alignment of segmental precast assembled girder bridge and predict the bridge alignment under the influence of different conditions.Based on the prediction of the construction alignment of precast assembled girder bridge in the south fourth link section of Zhengzhou City,Henan Province,the research results are as follows:(1)Taking the prefabricated and assembled typical 3×40m continuous beam bridge of the South Fourth Ring Viaduct segment as the research object,Midas Civil and Midas FEA were used to establish a finite element model to analyze the stress and displacement changes during the bridge construction period.,The results show that during the cantilever assembly process of the mid-span during construction,the maximum displacement appears at the end of the cantilever,and the maximum and middle stress appears at the root of the cantilever,and with the application of the segments,the maximum displacement and stress of the T structure also follow.Increase;during the construction of the side span full hall,the maximum displacement occurs at the cantilever end of the mid-span,and the maximum pressure value is located at the pier of the first T structure,while the cantilever root of the side span is compressed and the cantilever end is tensioned;the deflection of the mid-span after the beam section is closed Ascending,the compressive stress is reduced;after the support is removed and the construction is completed,the side span loses its supporting force,the deflection of the side span is significantly reduced,the compressive stress rises,and the tensile stress decreases.(2)Considering the changes in factors such as the weight of the beam bridge,effective prestress,age,temperature,glue joint volume,and glue joint width,Midas Civil was used to establish a spatial link model,and the weight,prestress,and age of the beam bridge were calculated and analyzed.The effect of time and temperature on the bridge,Midas FEA was used to establish a solid element model,and the volume of glued joints and the influence of glued joint width on the bridge were calculated and analyzed.The displacement and stress of the main girder section were used as indicators to develop single-factor sensitivity.Parameter analysis.The results show that the main parameters that affect the state of the bridge structure during construction are deadweight,prestress,age,glue joint volume,glue joint width,and the secondary parameter is temperature.The result of parameter sensitivity analysis is used in the next step.In the linear forecast.(3)Considering the influence of five sensitive factors,such as dead weight,prestress,age,volume of rubber joint and width of rubber joint,the prediction model of segment prefabricated girder bridge line was built by using the Design Expert software based on the response surface method.By substituting the required sample points into the finite element model for calculation,the sample values of the parameters in the sample space and the output response values are obtained.Then,by substituting the obtained sample data,the response surface model function between the parameters and the displacement was fitted,and the correlation function was obtained.Finally,the construction displacement of the bridge under the influence of the corresponding parameters can be predicted by using the response surface model and substituting the specific parameters.The comparison between the predicted value and the measured result shows that the relative error between the predicted value and the measured displacement is maintained at 0.5%—6.90%.It is worth noting that the relative error in block0 and block 1 is relatively large,which is about 5%—7%.The relative error of other areas is basically maintained at 0%-4%,and the maximum displacement difference is 1.21 mm,which appears in the middle of the side span,and the relative error is 3.91%.This shows that the response surface method prediction model meets the requirements of construction accuracy,can well complete the displacement prediction of the bridge,and can be used to guide the linear construction of the bridge.