Keywords: structural stability, residual stiffness, columns, braces, dual structural systems, structural engineering, steel structures, buckling, horizontal forces, bending moments, steel beams, horizontal load
Residual stiffness assuring stability of steel structures
Through revisiting the classic problems of elastic and elastic-plastic buckling of frames, elastic-plastic stability of beam-columns, buckling of column braced at mid-span by a horizontal brace and the buckling of dual structural systems, the paper proposed the concept of 'residual stiffness', i.e., the residual part of the total stiffness after deducting the stiffness depleted by horizontal forces and bending moments in the members. Check for stability of members and structures in real steel structures is to assure a minimum residual stiffness of the members and structures to resist against the destabilising effect of gravitational loads. Through analysis of the instability of beam-columns and dual structural systems, it is revealed that in the limit state, the stiffness due to the horizontal load (bending moment) is linearly or more than linearly decreased.