Sustained and Cyclic Loading of Concrete Columns

by Jostein Hellesland, Post-Doctoral Fellow; Dept. of Civ. Engrg., The Univ. of Waterloo, Waterloo, Ontario, Canada,
Roger Green, (A.M.ASCE), Assoc. Prof.; Dept. of Civ. Engrg., The Univ. of Waterloo, Waterloo, Ontario, Canada,

Serial Information: Journal of the Structural Division, 1971, Vol. 97, Issue 4, Pg. 1113-1128

Document Type: Journal Paper


An experimental and analytical study was undertaken to determine the influence of sustained and cyclic loading on the load capacity and on the stiffness and deformational characteristics of eccentrically loaded, reinforced concrete columns. The experimental loading history consisted of a short time loading to a service load value, a sustained service load of approximately 4 months, a period of cyclic loading at various load ranges above service load, and then loading to failure. The short time load capacity of a column, and the load capacity following the sustained load period were obtained from a theoretical analysis. Changes in member-stiffness at service load level were recorded both during the sustained and the cyclic loading period. The conclusion is that a sustained service load does not significantly influence the load capacity for the columns tested. Cyclic loading above a load of about 90-95% of the load capacity just prior to cycling may induce incremental collapse. Cyclic loading below this value does not appear to influence the load capacity significantly.

Subject Headings: Load bearing capacity | Cyclic loads | Service loads | Failure loads | Load history | Concrete columns | Reinforced concrete

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