School of Civil and Environmental Engineering

Ph.D. Thesis Defense Announcement

Advanced Design Evaluation of Planar Steel Members and Framing Systems

By

Oguzhan Togay

Advisor:

Dr. Donald W. White (CEE)

Committee Members:

Dr. Barry J. Goodno (CEE), Dr. Dewey Hodges (AE), Dr. Glaucio Paulino (CEE), Dr. Arash Yavari (CEE)

Date & Time: Monday, October 29, 11am

Location: SEB 122

This research provides a comprehensive approach for the design of structural steel members and framing systems via an Inelastic Nonlinear Buckling Analysis (INBA) employing column, beam and beam-column inelastic stiffness reduction factors derived from the ANSI/AISC 360 Specification. The resulting procedure provides a relatively rigorous check of member and frame design resistances accounting for member cross-section double- or single-symmetry, nonprismatic member geometry, 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. 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 pre-buckling displacement effects, to fully satisfy the stability design requirements of the AISC Specification. Member cross-section based strength limit states are checked, given the internal forces calculated using the AISC DM requirements. The key concepts of this advanced design evaluation approach are developed, and a variety of applications of the method are demonstrated. Results from the recommended approach and from routine application of the DM are compared to results from test simulations satisfying the requirements of Appendix 1.3 of the AISC Specification.

In the Inelastic Buckling Analysis, the analysis solution is conducted up to the load level corresponding to the most critical buckling or cross-section strength limit state of the ANSI/AISC 360 Specification. From prior research as well as from the validation studies conducted in this work, it is observed that the Flange Local Buckling (FLB) and Tension Flange Yielding (TFY) limit states in Chapter F of the ANSI/AISC 360 Specification tend to underestimate the true I-section member flexural resistances as the web and/or the compression flange become increasingly slender. This dissertation provides an updated approach for calculation of the resistances corresponding to these limit states, considering the development of the spread of yielding in flexural tension (TFY) using mechanics of materials concepts, and accounting for post-buckling resistance based on the unified effective width approach from Chapter E of the AISC Specification for FLB limit states.