Study On Construction Control And Key Problems Of Long-span Continuous Rigid Bridge With High Pier

Because of the topography and geomorphology in the west of China,the high pier and long span continuous rigid frame bridge has gradually become one of the main bridge types in bridge construction.Based on the construction of the Shibao Chuan Bridge of Huanglong to Pucheng Expressway in Shaanxi Province,the construction monitoring and monitoring of the Shibao Chuanhe Bridge are carried out first.Then the thrust value of the bridge is calculated and the influence of the thrust on the structure is analyzed.Finally,the influence of concrete creep on the shear lag effect of the main beam is studied.The main contents of this paper are as follows:(1)According to the construction plan and construction method of Shibao Chuanhe Bridge,the construction control system of Shibao Chuanhe Bridge is established.A simulation model of construction process is established by Midas/Civil finite element software,and the theoretical stress and alignment are obtained,which is used as the control target to guide the field construction.By comparing the measured value with the theoretical value,the results show that the maximum difference between the measured elevation and the theoretical elevation is 9 mm,which is consistent with the design line.The measured stress and theoretical stress after tensioning of prestressed steel bundles of each beam are consistent with the stress characteristics of cantilever construction stage.(2)Midas/Civil finite element software is used to calculate the thrust displacement of Shibao Chuanhe Bridge and to explore the factors affecting the thrust displacement.The relationship between the thrust displacement and the thrust is determined by applying different horizontal thrust at the thrust position of the simulation model,and the thrust force of the Shibao Chuan River Bridge is calculated.Through the influence of the temperature difference on the top thrust,the adjusted thrust value caused by the temperature difference is calculated,and the final thrust is determined by synthesizing the longitudinal horizontal displacement and the temperature difference of the pier top.It provides a reference for the calculation of top thrust of the same type of bridge.(3)The influence of He-Long thrust on the displacement of main pier and internal force of main pier of Shibao Chuanhe Bridge is studied.The vertical horizontal displacement of12#,13#,15#,16# pier is offset by 72.5%,72.1%,65.4%,73.9% respectively,and the 14# pier remains unchanged;The bottom bending moment of 12#,13#,15# and 16# piers was reduced by 39.1%,55.1%,48.7% and 40.6% respectively,and the 14# piers did not change much;The maximum combined stress of 12#,13#,15# and 16# piers was reduced by 33.3%,21.2%,17.1%and 27.6% respectively,and the 14# piers did not change much;The axial force of the bottom of each pier is not greatly affected.This shows the necessity of pushing the dragon.(4)Aiming at the cantilever construction stage of main girder,a ANSYS solid finite element model considering concrete creep and concrete loading age of 7 days and 15 days is established.Life and death unit technology is used to simulate the construction process,and the influence of creep on shear lag effect during cantilever construction is analyzed.In the model,the normal stress of the roof of the cantilever root section is extracted,and the transverse normal stress distribution is drawn.From the overall trend,the distribution of the normal stress of the roof of the cantilever root section is generally consistent with that of the concrete creep.Numerically,when concrete creep is considered,the loading age of concrete increases from 7 days to 15 days,and the normal stress of the roof of cantilever root section increases,the maximum increase is 6.43%;When concrete creep is not taken into account,the maximum increase of normal stress in the roof of cantilever root section is 7.86% compared with that of concrete loading age of 15 days,it can be seen that the normal stress of cantilever root section is larger than that of concrete creep.Without considering concrete creep,at the end of 12# block,the shear hysteresis coefficient is the largest at the junction of web and roof of cantilever root section.Compared with concrete creep(loading age is 7 days),the maximum shear lag coefficient increases 1.4% and the increase is not obvious.