Shake table testing of reinforced concrete columns with different layout size of foundation

Abstract

The behavior of cantilever reinforced concrete columns with different layout size (length) of the foundation was experimentally investigated. Three different layout sizes of the foundation were adopted, i.e. three different rotational stiffnesses of foundation (high, medium, low). The column parameters (slenderness, material properties, reinforcement, mass at the top, etc.) are equal for all tested structures. The foundation of the columns is placed on a shake table in variants: (i) over a 20 mm thick layer of limestone sand, (ii) over a 100 mm thick layer of limestone sand, (iii) foundations fixed to the shake table. The tested structures were exposed to repeated horizontal base accelerations of an artificial accelerogram. Each structure was tested by a set of artificial accelerograms, with successive increase of accelerations in each applied excitation until structural collapse or loss of stability. Characteristic displacements and accelerations of the structure were measures, as well as concrete and reinforcement strains. It was concluded that the layout size of the foundation has a significant influence on the behavior of the concrete column under earthquake conditions, especially for greater base accelerations.