Department of

Civil and Environmental Engineering



Kavanagh Lecture - Abstract

April 1, 2004

Stability Lessons from Experiments and Structural Failures


Dr. Joseph A. Yura
Cockrell Family Regents Chair in Engineering
University of Texas at Austin


Stability problems have a reputation of being difficult to solve and to even understand. A theoretical evaluation of stability requires a second order structural analysis, i.e. equilibrium is established for the deflected position of the structure, not a typical first order analysis. Since most undergraduate and graduate structural courses focus on the use of first order analysis, many practitioners have had little structural training in stability issues. Usually, formulas in design specifications for column, beam and plate buckling and for bracing requirements provide the only means of checking stability. The simplicity and format (stress rather than load, for example) of these formulas can mask important assumptions and approximations used in their derivations. With these circumstances, experiments and simple models can be used to convey stability principles in an effective manner.

A variety of structural models will be described that illustrate the following stability principles:

  1. loss of stiffness as the buckling load is approached
  2. inelastic column buckling
  3. importance of end connection details in built-up columns
  4. stiffness and strength required for braces
  5. lean-on bracing systems
  6. torsional buckling