Stress Analysis Of .140 M, Steel Box Tied Stacked Arch

The tied-arch bridge with steel box has the advantages of a large spanning capacity, low construction height, and the beautiful appearance. It has been widely used in countries which have already built high-speed railway. But such bridges are still rare in the high-speed railway line in China. The Xinkaihe Bridge, which is on construction in Ha-Da passenger line, is a 140m span through tied-arch stack with steel box. The upper and lower arches are made of parallel steel box with the same section of two-ribs; the tied beam is made of constant width, variable height steel box section; The deck is a combination of vertical and horizontal steel beam and concrete slab. This bridge is a key project in the construction of Ha-Da passenger line.In this paper, mechanical characteristics of Xinkaihe Bridge were systematicly analyzed with finite element method. The following works were completed:1. Finite element models of this bridge were established both by package ANSYS and MIDAS. Then the stiffness and strength of the bridge are analyzed. Under the combined action of variably loads, the displacement of the tied beam, girder 1, and girder 2 is 10.1cm,10.5cm, and 10.6cm; The stresses of hangers are a little bigger, which reach 227.9MPa, the stress of the other part of the bridge is small than 150MPa.The results show that:the bridge is in reasonable condition, and the stiffness and strength meet design requirements.2. The stability of the bridge was calculated. The overall stability was calculated by MIDAS, while the local stability was calculated by ANSYS. The results show that:The stability factor of the bridge is big, the overall stability factors are bigger than 10.0, the local stability factors are bigger than 8.08.3. The role of resistance provided by concrete bridge deck to the deformation and stress state of the bridge in a variety of loads was studied. The results showed that:When the resistance provided by concrete bridge deck is not considered, in the combined action of dead load & ZK worst two-lane live load & swing power, the vertical displacement of the bridge increased a little; The stress of cross beam increased by 30%, that the maximum stress reached 96.4MPa, the increase of stress of the other parts are less than 5%.4. The role of secondary beam to the deformation and stress state of the bridge in a variety of loads was studied. The results show that:While there is no secondary beam, in the combined action of dead load & ZK worst two-lane live load, only the stress of the first internodes increased by about 20%. The maximum increase of the stress of concrete deck reached 1MPa while the maximum increase of stress of the girder and cross beam reached 15MPa.The stress and stiffness of the other parts are basically unchanged.The results of this study provide references for the design of Xinkaihe bridge. Furthermore, the basic idea and method can also be a reference for the design or research of mechanical characteristics of other tied-arch bridge.