Research On The Causes Of Cracks And Reasonable Structure About Highway T-beam Birdge

For medium and small span bridges, reinforced concrete T-beam and prestressedconcrete T-beam is one of most widely used structural forms in modern engineering. Ithas many advantages,but a lot of builted simply supported T-beam bridge have beenfounded different degrees of various types of disease generally.And among these disease,a large number of vertical cracks occured in T-beam web plate and diaphragms are themost common. The disease of simply supported T-beam bridge is the result of variousaspects of unfavorable factors, including construction quality defects, poor quality ofmaterials, natural disasters effect and ineffective maintenance, and of course containingsome design deficiencies, such as unreasonable structural arrangement, low invertedcamber, unreasonable cross section shape and unreasonable girder space and thediaphragm space.Using mechanical plane calculation and FEM numerical simulationanalysed a specific engineering diseases instance which’s disease feature was that therewas a large number of vertical cracks on the web plate but no transverse crack on theend of beam,and founded that such disease is not because of the bending crackgenerated by structural insufficient bearing capacity, and is not due to the non-structuralcracks caused by shrinkage and creep of concrete also, it’s real reason should be astructural crack leaded to side bend effect produced by insufficient transverse rigidity ofweb plate. If gave not enough attention, it will be a hidden danger.Side bend effect isdue to large girder space, weak horizontal contact, thin and high web, and smalltransverse rigidity.Whereas,the general design of the T-beam bridge mainly consider themid-span moment of single beam in the vertical plane relyed on transverse distributioncoefficient which is used to transform space problem into plane problem, ignoring thisside bend effect.In order to control this side bend effect and compensate for the insufficient ofgeneral T beam bridge design from the structural construction, author analysed thespace behavior subject to force of T-beam bridge by ABAQUS which is a large finiteelement software firstly; And then compared side bend effect of three different bridgespan in the same girder space, and discussed the reasonable value of the girderspace;Finally,analyzed the relationship between the girder space and the diaphragm space and discussed the appropriate diaphragm distance. The study of above problemshas important research value and guiding significance for the design of T-beam bridge,preventing disease, improving the structure stress and structural durability.