Structure Analysis And Construction Control For Cast-in-place Prestressed Concrete Continuous Box Girder

The highway bridge, highway transportation infrastructure, plays an important role in road transportation system. The cast-in-place continuous box girder bridge was widely used in highway and urban bridges owing to its many advantages, but the accidents of it occur. The accidents, some bridges have been ahead of the end of the life before the fixed number of year of the design, cause a huge impact to people’s life and property safety. Therefore, it has become a pressing problem that structure analysis and construction control for cast-in-place prestressed concrete continuous box girder.The experts and scholars of our and foreign country carried out a large number of model test and structure theory research of cast-in-place prestressed concrete continuous box girder. But the structural analysis of single box multi cell chamber asymmetric and widen the overall continuous box girder and the research about beams and piers of cast-in-place continuous box girder are relatively few, especially the stage structure analysis of the bridge pier construction and the tracking test of the cast-in-site segments stress of pre-tensile and tensile.Based on one bridge, the superstructure(2×30+40+2×30)m into five span of cast-in-place prestressed concrete single box multi cell chamber asymmetric and widen the overall continuous box girder, the space finite element model was established to analyze. The main contents of this dissertation are described as follows:(1) This dissertation introduces the mechanical characteristics of cast-in-place prestressed concrete continuous box girder. And this dissertation presentations and both at home and abroad research status of structure calculation analysis and construction monitoring of cast-in-place prestressed concrete continuous box girder.(2) Based on one bridge, the superstructure(2×30+40+2×30)m into five span of cast-in-place prestressed concrete single box multi cell chamber asymmetric and widen the overall continuous box girder, the space finite element model by Midas Civil was established to analyze the main beam. The results show that girder of bearing capacity, crack resistance, deflection, persistent state and construction ofgirder under the transient state of stress can meet the specification requirements.(3) Based on one bridge, the superstructure(2×30+40+2×30)m into five span of cast-in-place prestressed concrete single box multi cell chamber asymmetric and widen the overall continuous box girder, the space finite element model by Midas Civil was established to analyze. The main contents of this research and analysis include end floor beam, middle cross beam and counter-force of bearing. The results show that the bearing capacity of the beams, end floor beam of 57, 62 # pier and middle cross beam of 58-61 # pier, can meet the specification requirements. The counter-force of bearing can satisfy the design requirements.(4) Combined with engineering field box girder cracks, the pre-tensile measure of cast-in-place prestressed concrete continuous box girder has been put forward. The test, tracking test of the destroyed cross-section of cast-in-site segments stress of pre-tensile and tensile, study box girder stress change process. The results show that the stress of pre-tensile and tensile showed a trend of decrease from the end to mid-span beam. In the process of pre-tensile, there are not any new cracks in box girder.