engleski

Shake table testing of RC column with different size of foundation

Dynamic interaction of column–foundation–soil coupled system occurs in earthquake action. Among other factors, the layout size of foundation probably has a great effect on the behaviour of concrete columns and whole buildings during the earthquake. As the authors of this paper know, this problem has not been experimentally confirmed yet. In this paper, testing of cantilever reinforced concrete columns in earthquake conditions was experimentally performed on a shake table. The column height was 1.4 m (λ = 75), with square cross section of 0.1m × 0.1m, i.e. 1:4 scale model of a real column was considered. Columns were loaded at the top with a concentrated mass of 2000 kg ( ). The layout size of foundation and stiffness of the subsoil were varied. The columns were exposed to a set of transverse horizontal earthquake accelerations, by successively increased maximal earthquake amplitude in each applied excitation. Three types of foundation with different layout dimensions were analyzed: 1.0m × 0.5m, 0.75m × 0.5m and 0.5m × 0.5m. All foundations were 0.3m in height. Two variants of foundation supporting on the shake table were varied. In the first variant the foundation is leaning on a 1 cm thick limestone sand layer and in the second variant on the 10 cm thick limestone sand layer. Cases with different thickness of subsoil and different earthquake accelerations were examined for each considered type of foundation. Horizontal displacements and accelerations of the top of the column and foundation, vertical displacements of the foundation, strain (stress) states of the concrete and reinforcement at the column bottom, as well as cracking states in concrete were monitored for all tested specimens. All major measured values are graphically presented. The main results are briefly discussed. The most important conclusions are given at the end of the paper. It can be concluded that the layout size of foundation has a great effect on the behaviour of column– foundation–subsoil coupled system in earthquake action.

concrete column ; foundation ; shake-table ; earthquake

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