Comparative Study On Mechanical Properties Of PC Composite Box-girder Bridges With Corrugated Steel Webs

With the widespread use of prestressed concrete box-girder bridges,the structural design theory is increasingly perfect,the construction technology is more mature,and the bridge span is constantly increasing.At the same time,diseases such as the main girder deflection and web cracking of prestressed concrete box-girder bridges in operation have become increasingly prominent and have become urgent problems for bridge engineering.The wrinkle effect of PC composite box-girder bridge with corrugated steel webs can greatly improve the application efficiency of longitudinal prestress and effectively improve the problem of deflection of the main beam.In addition,the use of steel webs fundamentally solves the problem of web cracking.Therefore,it is of great significance for the promotion and application of PC composite box girder bridges with corrugated steel webs to reserch the mechanical properties and compare with prestressed concrete box girder bridge in construction and economy,especially in prestressed application efficiency.Which is an important subject to solve the current development problem of prestressed concrete bridges.The original design of Liangshui Bridge is a pre-stressed concrete continuous rigid frame bridge.The trial design of the PC composite box-girder bridge with corrugated steel webs was carried out.Structural checking and mechanical analysis were performed using Midas Civil software and Midas Civil Designer software.The content and results are as follows:(1)Combined with relevant domestic bridge design specifications and examples of internationally constructed PC composite box-girder bridges with corrugated steel webs,redraft the cross-section form and prestressed reinforcement configuration scheme for Liangshui Bridge.The finite element model of Liangshui Bridge was built with Midas Civil software,and the structural check calculation was assisted by Midas Civil Designer software.A PC composite box-girder bridge with corrugated steel webs in compliance with bridge design standards was designed.(2)According to the Liangshui Bridge design document,a finite element model of prestressed concrete box-girder bridge is established.Compared with PC composite box-girder bridge with corrugated steel webs,the self weight of the girder of the latter is reduced by about 25%.and the internal force of the girder of the latter caused by the dead weight is reduced by about 25%.The overall stiffness of PC composite box-girder bridge with corrugated steel webs is smaller.The latter’s natural frequency is slightly higher,and its frequency spectrum is more intensive.PC composite box-girder bridge with corrugated steel webs has better mechanical and seismic performance than prestressed concrete box girder bridge.(3)The amount of prestressed reinforcement,the internal force of the girder caused by the prestressed load and the application efficiency of unit prestressing force of the two bridge types were compared.Under the prestressed load,the internal force of the girder of PC composite box-girder bridge with corrugated steel webs is about 68%of that of PC box girder bridge,the amount of steel beam is reduced by 29.93%,the efficiency of unit prestress is increased to 1.54～2.23 times,and the prestress is almost entirely borne by the concrete roof and floor.(4)Research the cantilever construction technology,material consumption and cost of PC composite box-girder bridge with corrugated steel webs.Compared with the prestressed concrete box-girder bridge,the construction period of one section of PC composite box-girder bridge with corrugated steel webs is saved by 10% when the form traveler method is adopted.When Rap.con/RW construction method is adopted,the construction period is saved by 25%.When Liangshui Bridge is designed as a PC composite box-girder bridge with corrugated steel webs,the material consumption of the superstructure is saved by about 23%,and the substructure is also more compact.The PC composite box-girder bridge with corrugated steel webs has advantages in construction period and material cost,but has disadvantages in construction difficulty.