Research On Design Method About Supported Effects Of Double Bearing Bridge Transforming From Simply-supported Into Continuous Girder

The rapid development of the highway makes a significant increase in the number of bridges, Among the high-grade roads and bridges the multi-span and medium span (span of 16 to 25 meters) bridge account for a large proportion. People have always hoped to combine the batch of pre-cast of production of simply supported beam with the advantages of continuous beams, and to use methods of manufacturing a batch of pre-cast beams or plate to speed up the construction of the speed of continuous beam to eliminate the cumbersome process, which resulted in the method of prefabrication entire span beam, casting concrete at the end of the beam and prestressed tension after the beams were erection on spot (a state of simply supported beam) in order to make them continuously, then the structure was called "transforming from simply-supported into continuous structure system". During the formation of transforming from simply-supporting into continuous girders, in order to ensure a multi-span bridge continuous, conversion of support is a key step. are referred to as "simply supported structure system after the row". We hope that not only the we are be able to transform simply supported system into continuous system, but also can we avoid the troublesome of conversion process. Then the idea of a new structure system that "dead load, simply supported, live load, continuous, with no need to convert the support" called "double bearing transforming form simply-supported into continuous girder bridge" emerged Two-bearing system bridge has been apply to many successful construction, of which the key is to ensure that in any dual-bearing can not be separated from an empty seat, Effect can be seen supporting the importance of this system.This paper is based on the theory of force method of structural mechanics, deduced theoretical formula for calculating moment and reaction of a two-span beam bridge which was setting up elastic support.When using double-bearing, the double bearing effect is related to the flexibility and the distant between the two supports. As a theoretical study, this paper discussed the spacing of two supports, which range from 20 to 100 (cm), of two girder bridges, which have the same span. Respectively consider the only effect of their dead load, the only effect of live load and the combination effect of dead load, live load and construction load, when the two-span continuous girder bridges respectively adopt a flexible double-bearing system, the regulation of variation of the internal force and reactions of structure which changes with the support stiffness between 50 and 2500(10~3kN /m ).Finally, compared the test result of 312 National Highway Weihe Xianyang Bridge,which was built with double-bearing system, and the theoretical calculation, the feasibility of double-bearing system in actual bridge was verified.