Date of Thesis

5-11-2016

Thesis Type

Honors Thesis

Degree Type

Bachelor of Science in Civil Engineering

Department

Civil Engineering

First Advisor

Ronald D. Ziemian

Second Advisor

Jean C. Batista Abreu

Abstract

Design by advanced second-order elastic analysis (DEA) is based on the premise that reliance on approximate methods to account for parameters in design can be reduced by directly modeling them in the analysis. Current analysis methods often rely on equations based on effective buckling lengths to determine the axial capacity of beam-columns; however, complex systems may not possess clearly defined effective-lengths or the axial force may vary significantly within such lengths. By employing a rigorous second-order (geometric nonlinear) analysis that explicitly models system and member initial geometric imperfections and reduces member stiffness to account for partial yielding within the analysis, it has been established that a simplified form of the axial capacity can be employed in the design process. Instead of using buckling-length-based column strength equations that consider member out-of-straightness imperfections and the effect of residual stresses on partial yielding, the engineer is granted the ability to use the axial cross-sectional strength. Twelve benchmark frames were analyzed using design by advanced second-order elastic analysis and the results were compared to current analysis methods in the 2010 American Institute of Steel Construction's Specification for Structural Steel Buildings. The research described herein and studies performed by other form the basis for the revised Appendix on Design by advanced elastic analysis appearing in the forthcoming 2016 American Institute of Steel Construction's Specification for Structural Steel Buildings. This method effectively removes the need to consider member length when calculating the axial strength of beam-columns.

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