Analysis of the Structural Alignment during the System Conversion of Continuous Beam Bridges with High Piers, Long Spans and Wide Box Girders

With the rapid development of the worldwide highway transportation industry, continuous box girder bridges have many advantages, such as superior spanning capacity, reasonable force-bearing performance, and low cost, which give them significant strengths in bridge design. However, to ensure that the structural alignment of the girder meets the design and specification requirements, it is necessary to study the laws of alignment changes of cantilever structures during the construction process. This is to reasonably control the alignment of the main girder structure during construction and ensure that the alignment of the completed bridge is consistent with the design alignment. This paper takes a continuous rigid frame bridge on a certain expressway as the engineering basis. Its superstructure is a three-span prestressed concrete continuous box girder with a span of (88 + 160 + 88) m, a bridge width of 16.5 m, and a maximum pier height of 130 m. The paper analyzes the influence of each construction stage on structural deformation during the system conversion construction process of the structural girder. A structural model is established using Midas/Civil, and the laws of structural deformation during the system conversion process as well as the differences in the peak values of structural deformation under different closure sequences are analyzed and summarized. The calculation results show that during the system conversion process of the girder, the structural alignment undergoes different changes, and different closure sequences also have an impact on the peak values of structural deformation. This indicates that it is necessary to monitor the alignment of the girder during construction and determine a reasonable closure sequence, which can provide a reference for the construction procedures and construction monitoring of similar structures under similar conditions.