Arch Rib Distance Optimization Of Rigid Frame Arch Bridge And Strengthening Techniques For Nodes

Rigid frame arch bridge has the virtue of light deadweight, little material, attractive appearance, high extent of assembly and so on, so it had been widely used in our country. However, with the continuous increasing of the vehicle load, series of diseases have commonly emerged in rigid-frame arch bridge such as cracking of the major node, cracking at the tension zone of real abdomen section midspan, cracking at the bottom of arch leg, cracking, fracture even falling off of the transverse strut, cracking of the slight bending slab, cracking of the bridge deck, etc. These proved that there is some deficiency in design and operation of this bridge type. This paper is base on design data and investigation of the rigid frame arch bridge in service, using numerical simulation technology, analysing the disease mechanism,optimal design and anti-cracking of the node about rigid-frame arch bridge. The major theoretical and research contents are mainly summarized as follows:1.System analysis of typical disease mechanism of the rigid-frame arch bridge, using numerical simulation technology, analysing typical disease of 25m,35m,45m rigid-frame arch bridge such as midspan, major and minor nodes, primary and secondary arch legs. The results show that, the principal tensile stress introduced by the major node and primary arch leg exceed the tensile strength standard value of C30 concrete, the principal tensile stress of midspan, secondary arch leg and minor node is also significant, considering the large traffic flow and overloaded vehicles on the bridge in service, plus the deficiency in bridge design, construction, maintenance and so on, it is unavoidable that these section emerge diseases.2.Based on the design data of rigid-frame arch bridge in service, using the finite element analysis software, establish the whole modeling of 25m,35m and 45m rigid-frame arch bridges. Tentatively formulating the thickness of bridge deck as 20cm,25cm,30cm. by adding a frame arch piece, calculating transverse load distribution coefficient in midspan, control internal force and deflection before and after adding the frame arch piece. The results show that, on the base of no significant increase in the amount of concrete and reinforcement, after adding a frame arch piece, the transverse load distribution coefficient in midspan of each arch rib especially the edge arch rib is reduced significantly, mid-span moment, deflection and the thrust of primary and secondary arch legs are also reduced, this method can improve the bearing capacity and stiffness of the rigid-frame arch bridge's superstructure.3.Study on the strengthening technology about anti-cracking of node of rigid frame arch bridge. The major nodes of 25m,35m,45m rigid-frame arch bridge are taken as research objects, sticking and embedding the steel plates with different thickness of 2mm,4mm,6mm, 8mm,10mm,12mm, study the influence of the maximum tensile stress on major node by sticked and embedded the steel plates with different thickness, and contrasting the effectiveness of strengthening technology about major node by sticked and embedded steel plates.