An S-shaped Curve Girder Bridge Radial Deviation Research Based On Long-term Health Monitoring Data

With the rapid development of China’s transportation, curved girder bridge are widely used in city interchange and mountain highway, but because of its mechanical characteristics of "bending and torsion coupling", radial beam deviation diseases are often seen during its operations. In order to ensure safe operation of bridge, radial beam deviation study has a certain theoretical and practical significance.Firstly, this paper summarizes the mechanical characteristics of curve beam bridge, introduces the calculation method and monitoring methods of curved girder bridge deformation. Then, combined with an S-shaped curve girder highway bridge health monitoring project, use an element analysis software, named Midas civil, analyse the factors of plane deformation under different lineshape and supporting forms. The results showed that:(1) structural weight, steel beams prestressed, uniform temperature effects, temperature gradient and vehicle load effect will produce radial displacement, and the smaller the radius of curvature, the greater the impact. Affected by the change of direction of the curve, the radial displacement between two beam of a S-shaped curved bridge is not a true reflection of the its own radial displacement. It is necessary to place enough deformation monitoring points and have a long-term monitoring; gradient temperature effect is the main reason that the beam of curved girder bridge bearing difference force on inner and outer support. Uniform temperature effect is one of the main reason of radial displacement, so the curve girder bridge during construction should be completed in time when the temperature is close to the annual temperature; vehicle load is another major reason of radial displacement, operating units should set some the appropriate speed limit signs to avoid speeding by;(2) when the support is limited to slide, curved girder bridge impacted most greatly under the uniform temperature effect. Bearing friction coefficient increases, support reaction and radial deformation effects have increased with uniform temperature effect. And the supports may damage or overrun under the most unfavorable load. Therefore, we should pay attention on curved girder bridge support conservation;(3) the relative displacement between the bridge linking the test results to verify the results of the element analysis;Radial displacement of a curve girder bridge is a combination of multiple factors and it is cumulatived with long-term effects. In order to ensure safety, curved girder bridge should have a long-term health monitoring and periodic measuring during its operation.