Stability Performance Evaluation of Long-span Steel Arch Bridge with Truss Girder Based on Double Nonlinearity
In order to evaluate the stability behavior of a steel arch bridge with truss girder and optimize the structural configuration,Qijiang River Bridge was used as the background.The effects of geometric and material nonlinearity were considered,and elastic-plastic calculation models of the steel arch bridge with truss girder was established.The influence of the rise-to-span ratio(f/L),width-to-span ratio(W/L),initial crookedness,and yield strength of the steel on the stability of the steel arch bridge with truss girder was studied.Additionally,improvements in lateral bracing types,lateral bracing numbers,and bending rigidity of lateral bracing and floor beams on structural stability were explored.The results show that when f/L is between 0.20 and 0.25,the stability of the steel arch bridge with truss girder is relatively superior.Increasing W/L while keeping the bridge span unchanged can significantly improve the structural stability.Increasing W/L from 1/8 to 1/4 results in a 1-time increase in the stability coefficient.The initial crookedness can reduce the structural stability.When the initial crookedness is controlled at l/3 000 to l/1 000,the stability coefficient decreases by 5%.Furthermore,the stability coefficient decreases by up to 18%when the deformation exceeds l/1 000.The yield strength of the steel has little effect on stability.The stability coefficient difference under five yield strengths(250MPa to 350MPa)is less than 7%.Among the current bracing types,the double-star-shaped bracing has the best stability,followed by star-shaped bracing,X-shaped bracing,double-K-shaped bracing,and K-shaped bracing.Under the same steel consumption,the star-shaped bracing is more reasonable than the K-shaped bracing.The stability of the steel arch bridge with truss girder can be enhanced by increasing the lateral bracing numbers or the bending rigidity of cross beams and lateral bracing.
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