Analysis On Stress Condition Of Whole Bridge And Orthotropic Slab Locality For A Big Span Steel Truss Railway Bridge

Shanxi Central-south Channel Yellow River Bridge is a128-m simply supported ballast track two-line railway bridge which is of plate truss composite structure. This acrticle used spacial finite element analysis method for the whole bridge and fine finite element analysis method for the local section of the bridge deck, systematically analysed the mechanical behaviors of this bridge. The major work and results were as follows:1.The spacial plate-beam method was used to establish a special FEA model for the whole bridge of Shanxi Central-south Channel Yellow River Bridge, the mechanical characteristics and force performances of the bridge under dead load、worst-case load、temperature load and combination of main loads were analysed.The main analysis results showed:the whole bridge had a reasonable bearing structure,the rigidity and strength satisfied requirements.2、The1.5section under weak stressing condition of the bridge deck was chosed to establish a fine FEA locality model with spacial plate and shell elements, the stress where the vertical beams and ribs met the crossgirder web under dead load、worst-case load、temperature load and combination of main loads was analysed.The results showed:the stress of most area was not huge, but the stress of the crossgirder-web’s hole edge where the stiffening ribs went through E2joint crossgirder was coMParatively huge,Mises equivalent stress reached356MPa, which was above allowable stress.3、Three improvement proposals were made based on the original program to improve the orthotropic plate joint stress condition of Shanxi Central-south Channel Yellow River Bridge:the crossgirder web was changed to seal type; the height of the vertical beams was reduced from500mm to700mm; the thickness of the crossgirder end was rised from16mm to24mm. The stress of the above three improved structures under dead load、worst-case load、temperature load and combination of main loads was analysed.4、The results of the three improvement proposals were coMParatively analysed.All of them could improve the local tress condition of the orthotropic plate joint to some degrees.However, reducing the height of vertical beams and rising the thickness of the crossgirder webs could improve the local stress condition of the orthotropic plate joint more effectively, so the later two proposals were recommended.The results of this article provide design basis for Shanxi Central-south Channel Yellow River Bridge, and are of reference value to other similar bridges.