The In-Plane Ultimate Bearing Capacity Analysis For Arch Rib Of Dumbbell Shaped Concrete Filled Steel Tubular (CFST)

This thesis introduced the finite element method about ultimate bearing capacity of dumbbell-shaped CFST arch rib, especially the double elements model method, Compared with Experiment results, the relative material constitutive relationship were selected. The double elements model method was used in the dual nonlinear analysis of the dumbbell-shaped CFST arch rib, the results show that:For the dumbbell-shaped CFST arch rib, The Impact of the material nonlinearity is much larger than the geometric nonlinearity on the structure. There is a coupling phenomenon between Geometric nonlinearity and material nonlinearity, the dual nonlinearity is not the simple sum of them. Geometric nonlinearity and material nonlinearity should be comprehensive considered during the analysis of Ultimate bearing capacity of the CFST arch rib.The finite element method was used in the parametric analysis of the dumbbell-shaped CFST arch and the single tube CFST arch. Main parameters include the ratio of rise to span, slenderness ratio, steel ratio, loading patterns, section forms of arch rib and arch axis linetype. The effect of different parameters on the nonlinear performance and ultimate bearing capacity of the structure was discussed. The results showed that the variation of load-carrying capacity of dumbbell-shaped CFST arches are similar to those of the single tube CFST arches. Dumbbell-shaped arches have higher load-carrying capacity and better ability to load change.This thesis introduced the equivalent beam-column method. The impact of the ratio of rise to span and the initial imperfection was considered in the Stability factor. Bending moment-Axial force equations of DL/T5085-1999 procedures and CECE28:90 procedures were used in the Calculation. The equivalent beam-column method was used to calculate the arches. The calculated results was compared with the finite element results. The results showed that:The Calculated curve of the equivalent beam-column method and finite element method were in the same direction. But with the change of those parameters. Unsafe situation will be occurred, It should be pay more attention in practice.