Monitoring And Analysis Of Cast-in-site Continuous Box Girder Used Composite Falsework During Construction Stage

Prestressed continuous box girder bridge has many advantages, such as good overall performance, great structural rigidity, small distortion and good seismic performance. It is widely used in the modern road and railway construction. Cast-in-site construction with falsework is one of the oldest, most mature and most widely used bridge construction methods. Currently composite falsework composed of bailey beams, large diameter steel tube column and cuplock scaffolding is widely used in construction.Due to the search of continuous cast-in-site box girder used composite falsework construction is a not deep enough, quality problems such as cracking of beams, security incidents such as scaffolding collapse occur frequently. Therefore, for security, construction and the security and stability of the composite falsework, it is necessary to search the force and stability of the falsework, components in continuous cast-in-site box girder construction.This paper discusses the combination of composite falsework and the application in construction firstly, and then analysis the cause of scaffolding collapse accident occurred at home and abroad. Secondly introduced the theory of structural stability, and combines the Sui river bridge across State Road 104 (40+56+40m) continuous box girder bridge of Beijing-Shanghai high speed railway, introduced cast-in-site construction technology. Stress monitoring and data analysis of the continuous beam across State Road 104 in different construction stages are completed in this paper.In the paper, the whole finite bridge model established for construction simulation by large finite element software MIDAS/Civil. After comparing the results and monitoring data, they have the similar law.Finite models of bailey beams, large diameter steel tube column and cuplock scaffolding are established by MIDAS/Civil software. Dead load of the continuous box girder in different construction phases is applied to the composite support, and then analysis the components force of composite falsework in different construction stages.Finite element model of large diameter steel tube column and cuplock scaffolding were established. The influence of some important factors on buckling loads of falsework is analysed. These factors include vertical and horizontal distance, horizontal strut, vertical strut and step distance.The results in the paper are valuable for design and force research in the construction by composite falsework. It gives valuable reference for the application of composite falsework in cast-in-site construction, to ensure bridge quality and safe construction.