| Stiffened steel truss bridge combines the advantages of parallel chord continuous steel truss bridge and curved chord continuous steel truss bridge,and has been applied in the construction of large-span double deck continuous steel truss bridge.Taking X Bridge,the first arch stiffened steel truss bridge in China,as the research background,this paper analyzed the spatial mechanical behaviors of arch stiffened steel truss bridge,compared the differences in mechanical properties between arch stiffened steel truss bridge and suspension stiffened steel truss bridge,and proposed the method of design parameters analysis and optimization of stiffened steel truss bridge.The main work and conclusions are as follows:(1)Based on the spatial finite element model of the X Bridge,the spatial mechanical behaviors of arch stiffened steel truss bridge were analyzed.The analysis results show that the arch stiffening chords reduce the force of parallel chord truss members in the positive and negative bending region and increase the bending stiffness of truss.(2)Based on the spatial finite element model of the X Bridge,the efficiency coefficient of truss members,the stability of the stiffening vertical braces,and the natural vibration characteristics of the X Bridge under two stiffening forms were analyzed.The average efficiency coefficient of the truss members was proposed as the comprehensive evaluation index of the stiffened steel truss bridge,s key sections,and the X Bridge under two stiffening forms was compared.The longitudinal stability calculation length coefficient of the X River Bridge stiffening vertical braces using suspension stiffening chords is 0.517,which is smaller than the longitudinal stability calculation length coefficient of the X River Bridge stiffening vertical braces using arch stiffening chords.The natural vibration characteristics of the stiffened steel truss bridge are influenced by stiffening forms,and the overall stiffness of the X Bridge with arch stiffening chords is greater than that of the X Bridge with suspension stiffening chords.(3)Based on the plane truss finite element models of the stiffened steel truss bridge,the single factor analysis method was used to analyze the influence of single design parameter change on the mechanical properties.Stiffening range,height span ratio of stiffening chord and height of parallel chord truss are the key design parameters,which have great influence on mechanical properties of the stiffened steel truss bridge.(4)The sensitivity of the key design parameters was analyzed based on the orthogonal test.The stiffening range has the greatest impact on the optimization design indicators of the stiffened steel truss bridge.The affiliation method was used to screen the optimal design parameters combination for the stiffened steel truss bridge,and the optimal design parameters combination for the X Bridge was determined: the stiffening range was 17 nodes,the height to span ratio of the stiffening chord was 0.127,and the height of the parallel chord truss was14 meters. |
