2017 Annual Stability Conference Presentation

Session SS2B – Technical Presentations: Stability at Elevated Temperatures
Tuesday, March 21, 2017
3:15 pm

Stability Analysis of Steel Columns under Cascading-Hazard of Earthquake and Fire

In this study, a nonlinear finite element formulation is developed and utilized to perform stability analysis of W-shape steel columns subjected to non-uniform longitudinal temperature profiles in the absence or presence of inter-story drift, representing residual drift following an earthquake. This formulation takes into account the residual stress distribution in steel hot-rolled W-shape sections, initial geometric imperfections in the steel columns, non-uniform longitudinal temperature distribution, and temperature-dependent material properties. The results indicate an excellent agreement with available strength design equations of steel columns at ambient and elevated temperatures. A set of equations is then proposed to predict the critical buckling stress in steel columns under fire and fire following earthquake considering residual drifts and non-uniform longitudinal temperature distributions. The proposed equations can be implemented to investigate the performance of steel structures under fire and fire following earthquake considering stability as engineering demand parameter.

Mehrdad Memari and Hussam Mahmoud, Colorado State University, Fort Collins, CO

2017 Annual Stability Conference Presentation

Session S9 – Stability of Shells
Thursday, March 23, 2017
4:15 pm

On the Investigation of the Most Critical Shape Imperfections for Wind Turbine Tower Shell Structures

Among the many technical goals of today’s wind energy industry is to develop solutions for taller wind turbine towers. The increase in height of wind turbine towers is imperative to achieve goals of efficiency and competitiveness, as the wind profile is stronger at higher heights. However, making higher wind turbine tower structures poses numerous challenges to structural engineers. One of the biggest challenges for thin cylindrical shells, such as tall wind turbine structures is their high sensitivity to geometric imperfections. It is expected that the capacity of this type of shells can drop significantly in the presence of geometric imperfections. This paper is studying this sensitivity by investigating the worst shape imperfection for a specific wind turbine tower geometry. For this investigation, the elastic modes of the structure are utilized either as individual shapes or as the basis for shape combinations, in order to find the worst initial geometric imperfection shape.

Kshitij Kumar Yadav and Simos Gerasimidis, University of Massachusetts, Amherst, MA;  Jens Lycke Wind, Vestas Wind Systems A/S, Aarhus, Denmark