Continuous Rigid-frame Box Girder Web Plate Fracture Analysis And Prestress Effect Research

System of continuous rigid frame bridge with its great spanning capacity, reasonableforce, integrity good advantages, in the bridge to get fast development. However, in theprocess of the construction and operation of the bridge box girder web plate are in variousforms of cracks appeared on the different degree. These cracks appear not only affects theintegrity and the durability of the bridge, but also for the safety of the structure has causedsevere damage.In this paper, by studying the vertical prestressed and longitudinal steel beams of boxgirder web cracks, the influence mechanism, analysis the stress of web plate of variousconditions, and proposes the corresponding measures to prevent cracks in web design. Thispaper mainly studies the following aspects of content:First of all, this article summarizes and sums up the main form of box girder web platefracture and cracking, and analyzes the causes of cracks, and influencing factors, and itsworking mechanism; Secondly, based on practical engineering modeling, analyzes thedifferent states of vertical prestressed box girder web plate is under stress, the influence ofmainly includes the vertical prestress loss, the vertical stress of reinforcement spacing, thebias of vertical prestressed and decorate a form, etc., and puts forward the correspondingdesign measures to prevent cracks; Now finally, in view of the prestressed steel beam ofdifferent decorate a form, this paper discusses the longitudinal steel beam to the effect of thebox girder web plate stress, it is concluded that should set the appropriate longitudinalreinforcement under shear, bending beam to collaborative web to prevent cracks.In short, in the design of prestressed concrete continuous rigid frame box girder, satisfythe requirement of stress in box girder section size case, reasonable arrangement of verticalprestressed reinforcement, can effectively control box girder web principal tensile stress andconcrete strength and the shear stress is not the super limit, so as to prevent crack craze. At thesame time, should be set up under the corresponding bending beam, ensure uniform web force,vertical prestressed shearing together together.