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Note that P-delta effects increase lateral flexibility for members under compression, but they can also increase the lateral stiffness for members under tension. In some systems the two effects can cancel out, at least for overall system behavior. For example, lateral wind loading on a building already under gravity load may increase the compression on one side of the structure and decrease it on the other side, perhaps even going into tension. Locally, the members under greater compression are more likely to buckle than the members on the windward side, and small P-delta effects could be important. However, the lateral stiffness of the overall building is little changed by the presence of the wind load as the increased flexibility of columns on one side is counteracted by the smaller effect (or even tension stiffening) on the other side.

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List of resources2
drafts-rootP-Delta drafts


  • Powell, G. H. (2010). Modeling for Structural Analysis: Behavior and Basics (1st ed.). Berkeley, CA: Computers and Structures, Inc.
    Available for purchase on the CSI Products >


  • Deierlein, G. G., Reinhorn, A. M., and Willford, M. R. (2010). Nonlinear Structural Analysis For Seismic Design, NEHRP Seismic Design Technical Brief No. 4., NIST GCR 10-917-5. Gaithersburg, MD: National Institute of Standards and Technology.