Stability Analysis of Softening Frames
Publication: Journal of Structural Engineering
Volume 114, Issue 5
Abstract
As the design process is refined, second‐order (stability) analysis becomes more important for both steel and concrete structures. Softening in concrete members, defined as the loss of moment capacity at advanced curvatures, is a material instability. The presence of significant axial force in a softening member raises the possibility of double or interactive instability, i.e., instability from large axial forces and instability from softening. Stability functions for members with finite softening lengths are derived. Computer program SOAPS (Second‐Order Analysis with Plasticity and Softening), developed for the stability analysis of plane frames with elastic‐plastic‐softening characteristics, incorporating stability functions and the effect, is used. Three examples are presented to demonstrate the application of program SOAPS. Increasing axial loads reduce the critical softening parameter for any hinge and therefore may also reduce the number of hinges formed before collapse. Consideration of stability effects may lead to a different order of hinge formation and large reductions in collapse load.
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 114 • Issue 5 • May 1988
Pages: 1057 - 1072
Copyright
Copyright © 1988 ASCE.
History
Published online: May 1, 1988
Published in print: May 1988
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