| In order to study and control the changes of main girder alignment and internal force in each construction stage of prestressed concrete continuous girder bridge,and meet the design requirements and ensure the construction quality.In this thesis,the(60+100+100+60)m continuous beam of Chunhe Road Bridge is studied and the construction controlling practice is carried out.In practice,Midas Civil and FEA NX are used to carry out finite element simulation of the main beam structure in combination with the requirements of the design specifications,and the changes of the linear and internal forces are analyzed.At the same time,the sensitivity analysis of the linear parameters,the temperature field and stress field analysis of the No.0block are carried out.Combined with the results of finite element analysis,the measured values of floor elevation and stress temperature are calculated and compared and fed back to the construction link for control,so that the geometric alignment and internal force state of the continuous beam bridge meet the requirements of the specification and ensure the smooth closure of the main beam.The main research work is as follows:(1)Considering the relevant technical parameters such as design specifications,Midas Civil software is used to establish the finite element model of the main beam,analyze the deflection and stress changes of the main beam during the construction stage,and check and calculate the pre-camber of the main beam.The results show that the deformation and stress of the main beam in each construction stage meet the requirements of the specification.(2)Combined with the finite element analysis results of the main beam,the corresponding continuous beam alignment and stress monitoring scheme are studied and implemented.The research and practice show that the alignment and stress of the main beam meet the requirements of the specification,and the main beam construction can be successfully completed on schedule.(3)Based on the reasonable range of design specifications,the sensitivity of concrete material properties,prestress,settlement and other parameters to the linear deflection of continuous beams is analyzed.Among the parameters,the settlement of the pier foundation has the greatest influence on the linear deflection of the main beam,followed by the concrete bulk density and elastic modulus,prestressed tension value and environmental relative humidity,and the ambient temperature and concrete age have the least influence on the linear deflection of the main beam.(4)In order to prevent the crack damage caused by the influence of hydration heat during the concrete pouring of No.0 block,after calculating the thermodynamic parameters of concrete in combination with the specification,Midas FEA NX was used to establish the concrete pouring of different cement mixing and ordinary cement pouring.The temperature field model of No.0 block with cold water pipe was analyzed.By comparing the hydration heat control schemes of each pouring concrete and combining with the actual construction,the low-heat Portland cement sub-roof with small hydration heat temperature and stress and the horizontal double-layer pouring concrete scheme at other positions are selected to construct Block 0.The measured data show that the scheme has a good control effect on the hydration heat of No.0 block,and the temperature and stress meet the requirements of the specification.(5)The stress of the No.0 block of the main girder is more complicated.In order to study its stress,Midas FEA NX is used to establish the stress field model of the No.0 block,and the stress distribution state of the maximum cantilever and the bridge stage is analyzed.The results show that the simulated stress of the stress field is in good agreement with the measured stress of the sensor,and the tensile and compressive stresses meet the requirements of the specification. |
