| With the rapid development of China's economy and infrastructure,the construction of highway,railway and municipal roads has made rapid progress,and bridge engineering,as a channel across the obstacles,plays an important role in this process.The early ordinary reinforced concrete beam bridge can not meet the needs of today's large span,durability,economy,safety and so on because of its great limitations,so the prestressed concrete beam with many advantages has been booming.Among them,prestressed concrete continuous beam has many advantages,such as large span,large rigidity,small deformation,beautiful shape,smooth and comfortable vehicle driving,reasonable stress,good wind resistance and seismic performance,and becomes the preferred bridge type in the span range of(40-150)m.The construction method of continuous beam bridge is mainly cantilever casting method.During the cantilever construction,the beam body goes through a complex change process,and the stress state and line shape of the main beam will become more complex.In the construction control of the actual project,some key technologies involved in the cantilever casting construction are found and studied.Although the research on this type of bridge has been very common,it is still meaningful to study and analyze from the perspective of construction.Based on the continuous beam of Pingjiang super large bridge,the main research and analysis contents are as follows:(1)This paper briefly introduces the engineering situation of the example bridge,lists the upper and lower structures as well as the necessary data,and provides the data support for the subsequent analysis.This paper expounds the different types and applicable conditions of the zero block support in the temporary structure,and analyzes the design and calculation of the support in detail to ensure the construction safety of the zero block of the continuous beam.In addition,considering the calculation and analysis of temporary consolidation under the most unfavorable partial load combination,it is necessary to recheck the designed key links before construction.(2)In view of this consolidation mode of the continuous beam,a variety of temporary consolidation simplified models are established,and the internal force and deformation before and after the release are compared and analyzed.It is found that the internal force of the support simulated by "rigid connection + elastic connection general + general support" is the most accurate,while the error of the constraint method directly carrying out the joint "general support" is the largest,which is not recommended.According to the actual project,it is better to build the pier model when modeling the continuous beam,so as to provide more accurate pre camber for cantilever construction.It can provide reference for the construction modeling of the same type of continuous beam bridge.(3)This paper analyzes the problem of balance weight in the construction of unbalanced section of side span,and points out that it is necessary to carry out "balance weight at the same time of construction" in the construction,so as to ensure the safety and reliability of bridge construction and lay the foundation for accurate closure in the later stage.(4)This paper expounds the method and necessity of construction control,establishes a finite element model reflecting the actual construction process,analyzes the actual stress and deflection in each construction stage,and describes the principle of stress test,which is helpful for the judgment of installation and collection time.Finally,the elevation setting of the cantilever casting segment is calculated and analyzed,and the expected goal is achieved.(5)This paper points out the advanced technology used in the construction,aiming at providing reference for the future construction,continuously improving the construction technology level of continuous beam bridge,and building a safe and high-quality project. |
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