Research Spotlight: Comprehensive Stability Design of Steel Members and Systems via Inelastic Buckli

2017 Annual Stability Conference Presentation

Session S4 – Stability of Beam-Columns Wednesday, March 22, 2017 4:30 pm

Comprehensive Stability Design of Steel Members and Systems via Inelastic Buckling Analysis – Beam-Column Validation Studies

This research provides an overview of a comprehensive approach for the design of structural steel members and systems via an Inelastic Nonlinear Buckling Analysis (INBA) that includes appropriate column, beam and beam-column inelastic stiffness reduction factors. The stiffness reduction factors are derived from the ANSI/AISC 360 Specification column, beam and beam-column strength provisions. The resulting procedure provides a relatively rigorous check of member design resistances accounting for continuity effects across braced points, as well as lateral and/or rotational restraint from other framing including a wide range of types and configurations of stability bracing. With this approach, no separate checking of the corresponding Specification member stability design resistance equations is required. The buckling analysis captures these resistances. In addition, no calculation of effective length (K) factors and moment gradient and/or load height (Cb) factors, is necessary. The buckling analysis directly captures the fundamental mechanical responses associated with these design strength factors. This approach is coupled with the AISC Direct Analysis Method (the DM), for calculation of the pre-buckling displacement effects, to fully satisfy the stability design requirements of the AISC Specification. In addition to explaining the method’s key concepts, the research focuses on validation of the method for capture of the lateral-torsional buckling response of general doubly-symmetric I-section beam-columns subjected to major-axis bending. Results from the recommended approach and from routine application of the DM are compared to the results from test simulation per Appendix 1.3 of the AISC Specification.

Oğuzhan Toğay and Donald W. White, Georgia Institute of Technology, Atlanta, GA