Effective Length of Columns in Multi-Storey Steel Building Structures(I):Theoretical Explanation

Firstly,in respect to axially compressed members,the paper expatiated the definitions and relations of important concepts such as Euler critical force,effective length,P-δ effect and the stability coefficient (pillar curve). Then, more attention is specifically paid to the concept of effective length of the frame column by tracing the origination of the formula of the ultimate load capacity of bending-compression members employed in steel structure design code of China (GB 50017). It is then disscussed in the paper the relationship between second order stress analysis considering P-Δ effect and the selection of the column's effective length when checking frame column strength. In the last part of the paper, suggestions are given with respect to the methods of frame column load capacity checking and column's effective length selecting.