| As a traditional and classic bridge type,prestressed continuous rigid frame bridge are widely used.At the same time,the problems of cracks and mid-span deflection of the main girder have become increasingly prominent.The main reasons are the excessive weight of the structure and the high shrinkage and creep of the concrete.The appearance and development of Ultra-high Performance concrete(UHPC)provides a feasible method to solve these problems.As a new type of lightweight,high-strength,high-toughness,good durability,ultra-low shrinkage and creep concrete material.How to apply it to long-span bridges to lighten the superstructure of bridges and improve the midspan deflection and box girder cracking of rigid frame bridges is worth studying-At present,the research and practice of UHPC in bridge engineering is developing rapidly,but the research on structural calculation theory and engineering application of long-span UHPC bridges is relatively lacking.Based on the existing research theory and construction design,combined with the actual engineering background,this paper draws up the design scheme of the main girder of the prestressing UHPC continuous rigid frame bridge with 232m main span,and carries out the calculation of its local and overall forces.Discussed the reasonable value of some design parameters of the UHPC rigid frame bridge.The main work and conclusions of this paper are as follows:(1)Based on the engineering background design calculation parameters,the main girder design scheme of UHPC continuous rigid frame bridge is proposed.The material parameters,section size parameters,prestress parameters,beam bottom curve and construction scheme are trial designed.The local stability of thin-walled UHPC box girder is analyzed by static method and the results meet the local stability requirements.The ANSYS is used to establish the solid model of part of mid-span beam section and analyze the local force of bridge deck under vehicle load.The finite element calculation model of UHPC continuous rigid frame bridge is established by Midas Civil software.Analysis of the whole force and the checking calculation is carried out according to the standard requirements,and its feasibility was demonstrated.Compared with the original C55 girder scheme,the results show that the UHPC girder can reduce 50%of the structural self-weight and improve 4.3%of the structural effectiveness.(2)According to the test design parameters,the solid model of the UHPC continuous rigid frame bridge zero block is established by ANSYS.Study on the spatial stress distribution of thin-walled UHPC zero block under the construction of maximum cantilever and completion of bridge and analyze the stress conditions at the top,bottom,web and diaphragm.The results show that the thin-walled box girder and thin diaphragm meet the design requirements.(3)The research on height-span ratio of the UHPC continuous rigid frame bridge has been launched.Summarized and analyzed the value range and characteristics of high-span ratio of continuous rigid frame bridges at home and abroad.5 calculation models with different height-span ratio in pier' s top section,togethter with another 3 calculation models with different height-span ratio in middle section,were built by Midas Civil software.On the basis of different finite element models,results about change rules of stress and deformation under dead-weight,moving load and combined load in given sections of main girder were analyzed.(4)The research on power number of beam bottom curve of the UHPC continuous rigid frame bridge has been launched.6 calculation models which have different power number of beam bottom curve were built by Midas Civil software.On the basis of different finite element models,results about change rules of stress and deformation under dead-weight,moving load and combined load in given sections of main girder were analyzed. |
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