Aglaia E. Pournara
Graduate Diploma Thesis, February 2011
The main purpose of this study was the investigation of the structural response of high strength steel imperfect tubular beam columns (σy=590MPa) under axial compression and combined loading. Buckling curves (Fig. 1a) and interaction diagrams (Fig. 1b) have been defined through finite element analysis for various cross sections and different cases of imperfections. Moreover, the failure modes of the tubular models have been identified as shown in Fig. 2. The finite element results have been compared with the proposed curves and equations by the current standards such as EN-1993-1-1 (2005), EN-1993-1-6 (2007), API-RP2A (1993), AISC-LRFD (2000) & CIDECT (1992). In these provisions, regular steel is assumed so that cross section classification and slenderness limits are penalized and the proposed structural strength values appear to be rather conservative. In hence, there is limited information for cross sections of high strength steel (over 460 MPa) and the current work aimed at contributing in the enhancement of the current guidelines considering stability curves and interaction diagrams for high strength steel imperfect tubular beam-columns.
Figure 1: (a) FEA stability curves and (b) interaction diagrams in comparison with current provisions.
Figure 2: Failure modes of FE models under (a) axial compression and (b) combined loading.