Research On The Closing Deviation And Forced Closing Effect Of PC Continuous Rigid Frame Bridge

In the actual construction of the prestressed continuous rigid frame bridge,due to the deformation of the hanging basket,the sunshine temperature,the wind load,the loss of the prestress,the shrinkage and creep of the concrete,etc.,the closing end may be displaced.Bridges with excessively large displacements at the closing ends need to take forced closing measures.The forced closing of the bridge will cause secondary internal forces to have an adverse effect on the structure and will exist for a long time.This article mainly studies the three-span prestressed continuous rigid frame bridge cantilever construction in sections.The main span of the bridge has different vertical height differences at the closing end of the bridge and the impact of forced closing on the structure.The following aspects are mainly completed and the corresponding results are obtained.in conclusion:(1)Using the basic principles of structural mechanics,the calculation formula for the additional weight of the three-span continuous rigid frame bridge with constant cross-section and variable cross-section for the vertical forced closing and the calculation formula for the secondary internal force caused by the constant-section beam are derived.And verified by engineering examples;(2)The reason for the displacement of the closing end of the prestressed continuous rigid frame bridge,as well as the function of the counterweight,the calculation method of the counterweight,and the principle of the application of the counterweight are explained in detail;(3)Combining the actual engineering series,using Midas Civil rod system finite element analysis software,using the construction pre-camber in the program,the three-span pre-stressed continuous rigid frame bridge with a main span of 150 m was used to numerically simulate the vertical elevation difference of the closure.The stress and deformation of the main girder after forced closing under the four working conditions of the mid-span applying additional weight phase,the mid-span closing bridge completion phase,the second phase load phase and the three-year shrinkage and creep are analyzed separately.And the law of influence of internal forces;(4)Use Midas Fea solid finite element software to apply additional counterweight to the 150 m main span of the three-span prestressed continuous rigid frame bridge to perform local simulation analysis on one side of block 0,the top plate and diaphragm of block 0 are chamfered,the bottom plate and the diaphragm The chamfering and the position of the manhole are likely to cause stress concentration,so structural measures should be strengthened;after the bridge is forcibly closed,the stress value of the top plate of block 0 on the side of the additional counterweight is applied to reduce the stress value of the top plate,and the stress value of the bottom plate increases;(5)The structural secondary internal force generated after the forced closing of the bridge exists for a long time,and the error of the closing end should be avoided as much as possible in the actual project.Under the action of the 134 mm vertical closing height difference of the bridge,the normal stress of the bottom plate under the maximum negative bending moment at the top of the pier during the operation stage of the bridge exceeds the specification limit,which does not meet the specification requirements.