Jordan Journal of Civil Engineering

Paper Detail

On the Current AISC Approach to Stability Analysis and Design of Steel Structures

Volume 11, No. 4, 2017
Received: 2017/08/27, Accepted:


Osama Mohamed;


In 2005, the American Institute of Steel Construction (AISC) stability analysis and design requirements changed significantly compared to procedures required prior to 2005. The most significant change related to stability analysis and design is the requirement to include geometric imperfections in the calculation of the required strength. Direct Analysis Method (DAM) is currently the recommended code method, while a modified version of the traditional Effectiveness Length Method (ELM) is now referred to as an alternative method of design. The critical changes appeared in the 13th edition (AISC, 2005) and continued to the present 14th edition (AISC, 2011). The objectives of this paper are to: 1) provide an overview of the rationale behind the code change that took place in 2005 and remained in the current specifications and 2) present the current features of ELM and DAM methods. A case study is presented to assess the differences in structural response when DAM and ELM methods are used. It was shown that DAM predicts higher demand on beams and columns of the structural system at the lower levels, but the difference in demand between DAM and ELM methods decreases at the upper levels of the structural system. This is due to the variation of effective length factor required in ELM for compression members, from top levels to bottom levels of the system. DAM, however, permits the use of an effective length factor of 1.0.


AISC approach, Stability analysis and design, Steel structures