Research On Reinforcement Technology Of Reinforced Concrete T-Beam With Steel Plate Conversion Box Girde

Due to the simple structure and convenient construction of T-type bridges,a large number of T-type bridges are distributed all over China.The design standard of T-girder built in early years is low.With the increasing traffic volume and vehicle load,and the maintenance and defect treatment of bridges are not timely,a large number of old T-girder bridges need to be strengthened or even improved load grade.Aiming at the causes and defects of reinforced concrete T-girder bridge,it is suggested strengthen the reinforced concrete T-girder by steel plate bonding to change the cross-section from T-shape to a box.On the basis of the existing calculation methods of reinforced concrete structures and bonding steel method,the reinforcement technology is theoretically analyzed and the optimization design of reinforcement is put forward.In this paper,the optimization design of reinforcement is carried out from the aspects of compartment division optimization,unloading reinforcement and reinforcing steel plate,and the influence of the thickness and length of reinforcing steel plate on the bearing capacity of the reinforced structure is analyzed.The main work and achievements of this paper are as follows:(1)In this paper,the failure modes of reinforced structures are analyzed theoretically,the limits of corresponding failure modes are given,and the formulas for calculating the ultimate bearing capacity of different failure modes are given.(2)Through detailed comparative analysis of the ultimate flexural bearing capacity,deformation,concrete strain,steel bar stress and steel plate stress of the reinforced structure,it is proved that the strengthening method to change the cross-section from T-shape to a box by bonded steel plate has obvious advantages in improving the flexural bearing capacity of the girder.(3)With the help of finite element software,the torsion resistance of the structure strengthened by T-beam bonded steel plate converted into box girder is analyzed,and it is proved that this strengthening method can obviously improve the torsion resistance of the structure.The effective width of reinforced steel plate is analyzed,and compared with the calculated value in the code.Suggestions on the effective width coefficient of reinforced steel plate are given,and the revised formula of flexural bearing capacity of the box girder after reinforcement is put forward.(4)The non-linear analysis of the beam before and after reinforcement is carried out with the help of finite element software..The analysis shows that the larger the thickness of steel plate used in the reinforcement of T-beam,the larger the ultimate bearing capacity of the structure,the smaller the mid-span deflection and the smaller the crack distribution area of the structure under the same load.(5)The nearer the distance between the edge of reinforced steel plate and the suppor,the more obvious the effect of restricting the development of inclined cracks is.Therefore,the bearing capacity of the structure can be effectively improved by approaching the support as close as possible under permissible conditions.(6)The finite element analysis proves that unloading reinforcement is effective in the reinforcement method of T-beam bonded steel plate transfer box girder.The influence of structural deflection,bending moment and structural integrity of T-beam bonded steel plate box girder after optimization of box chamber division is compared and analyzed,and the superiority of sub-box reinforcement is proved.(7)According to the actual project,the construction steps,matters needing attention and construction requirements of T-beam bonded steel plate transfer box girder are given.