Reasonable Design Of Curved Steel Continuous Box Girder Bridge And Local Analysis

The curved steel box girder bridge plays an indispensable role in urban traffic construction.In order to obtain the most reasonable design parameters of curved steel box girder bridge,it is necessary to conduct in-depth study on the complex mechanical properties of curved girder and steel box girder.Based on the calculation theory of curved girder bridge and steel box girder bridge,the eccentricity selection of fixed support of middle pier of a 72 m curved girder in Chengpeng high-speed urban section is studied quantitatively by using finite element method.The influence of the thickness of roof and stiffening rib on the stress of roof is analyzed,and some main conclusions are drawn as follows.1.When fixed bearings are arranged at the inner most eccentricity of curved girder bridge,the minimum torsion of main girder can be obtained,and the bending moment is larger;When the fixed support is arranged at the middle pier,the minimum bending moment of the main beam can be obtained,and the torque is greater.When the fixed bearings are arranged in the outermost eccentricity,the bending moment and torsion of the main girder belong to small values.2.In order to obtain the most ideal support reaction,it is better to arrange multiple supports evenly,the fixed supports are suitable to be located in the center of the section,and a certain number of eccentric hinged supports should be set symmetrically on both sides.3.Local analysis of steel box girder shows that increasing the thickness of roof can effectively reduce the stress of roof when the thickness of roof is not too large.When the roof thickness t>28mm,the effect of increasing plate thickness on roof stress is no longer obvious,so the design of roof thickness should not exceed 28 mm.4.Increasing the U rib thickness can not reduce the longitudinal and lateral stresses at the same time,increasing the thickness of the open rib can reduce the longitudinal and lateral stresses caused by the wheel load above the open rib.The increase of stiffener thickness will lead to the increase of the equivalent stress at the joint between the stiffener and the roof,which is not conducive to the strength and fatigue performance of the steel box.Therefore,it is better to reduce the thickness of the stiffener as much as possible under the standard design.