Stability analysis of steel space frames under large displacement

The incremental application of the small displacement theory is a typical solution for the large displacement problems. Updating of the configuration and load is mean differences between small and large displacement approach. One new approach of load and internal forces updating called null configuration is presented in this paper. The tangent method is necessary to apply this approach. Space frames consists of beams and columns. Each of them is discretized by straight 1D finite element (FE). Updating the large translation displacements in the incremental procedure follows from simple summarising of their vectors from the increment to increment. Updating the large rotations is simplified to rotations of the rigid body. This assumption will be acceptable if the FE length is sufficiently small and the internal forces and hence the stresses within FE are expressed within small displacement of each increment.