Research And Practice Of Construction Control Of Continuous Beam Bridge In Ningyan Uplink Liaison Line (72+120+72)m

With the increasing perfection of bridge design theory,the optimisation of construction materials and the improvement of construction technology,continuous girder bridges have become one of the most common bridge types with their good overall performance and structural stiffness,playing a more important role in the construction of highways and railways in China.In order to ensure the accuracy and quality of the bridge,the continuous girder bridge constructed by cantilever casting method needs to control its alignment and stress.In this thesis,the research and construction monitoring practice of the(72+120+72)m continuous girder bridge on the Ningyan upstream liaison line of the Lianzhen Railway is carried out,with the following main work:(1)Use Midas Civil to build a finite element model of the main beam and carry out construction phase simulation analysis to obtain the deflection and stress values of the main beam under different construction phases,the stress variation of the main beam section and the calculated pre-arch of the main beam to provide a theoretical basis for the implementation of construction monitoring.(2)The simulation results were combined to formulate the alignment and stress monitoring scheme;the pre-pressure test of the hanging basket was introduced in detail,and the linear relationship between load and elastic deformation of the hanging basket was obtained based on the measured data on site;the measured data and the theoretical calculation data were compared and analysed in conjunction with the construction situation on site to guide the construction on site.The monitoring results show that the main girder line is smooth and the stresses are reasonable in the bridge-forming state,and the bridge construction control has achieved good results.(3)During construction monitoring,sensitivity analysis was carried out on parameters affecting the actual state of the main beam,such as the modulus of elasticity of concrete,weight capacity and prestressing steel bundles tension,and the least squares method was used to identify parameters with a greater degree of influence,and the model was adjusted using the corrected parameters;actual pipe friction coefficients,deviation coefficients and friction losses at anchorage were obtained through field tests.(4)Midas FEA was used to build a solid model of block 0 of the main girder and to analyse the stress distribution of block 0 in the maximum moment state during the construction phase,the maximum cantilever state,the bridge state and the most unfavourable moment effect combination state during the service phase.The results show that Block 0 is in a pressurised state under all working conditions and the tensile stresses are mainly concentrated in the part of the cross partition and base plate.