Abstract
This paper presents results of an analysis of ultimate behavior of tubular beam-columns based on statistical data for cold-formed circular tubes under combined bending and axial loads. The conclusions drawn are summarized as follows : (1) The hardening exponent included in a stress-strain model for tubular sections after cold-forming was found to be represented by a simple function of yield ratio. Statistics of the yield ratio were determined by using statistical data on compressive yield stresses and ultimate tensile strengths. (2) Mean values and coefficients of variation of the column buckling strengths were obtained by using a semi-probabilistic numerical approach. These values were found to agree well with exact values. (3) A simple theoretical approach based on a proposed stress-strain model was found to be capable of interpreting ultimate strengths of tubular beam-columns in the existing data base. Numerical analysis according to the first order probabilistic approximation was carried out to determine mean values and coefficients of variation of resistances. of tubular beam-columns. (4) On the basis of these numerical results, recommendations were given for the design of tubular beamcolumns.
