Investigation of Stability of Through CFST Arch Bridges

Backgrounded by a through concrete-filled steel tube(CFST) arch bridge,the structural stability of the type of the bridges under the action of self weight at completion stage is investigated.In the linear elastic stability analysis,four kinds of methods are used to simulate the structural rigidity of the arch ribs of the bridges.The obtained stability coefficients vary with the calculated rigidity of the ribs and the variation range is considerably great.It is therefore proposed that the instability analysis should be made in consideration of the deformation calculation and the smaller stability coefficients should be selected for the sake of safety concern.In the nonlinear stability analysis,the unified theory of the CFST is used to take into account of the nonlinearity of materials of the ribs and the influences of the geometric defect are introduced.The dual-nonlinear analysis reveals that the geometric nonlinear effect of the ribs is slight and the principal factor that will cause the instability of the structures is the nonlinearity of materials.