engleski

The study on the effect of longitudinal reinforcement ratio on the behavior of concrete cantilever column on a shake-table

The effect of longitudinal reinforcement ratio on the behavior and ultimate bearing capacity of small-scale concrete cantilever columns is analyzed by using a shake-table. Total amount of the longitudinal reinforcement was varied (1.1%, 2.0% and 3.1% of the concrete cross- section), while all remaining parameters of the columns were fixed. The columns were 1.08 m in height (slenderness approximately 75), with 0.1×0.1 m square cross-section. The columns were constrained in the foundation with length of 1 m, width of 0.5 m and depth of 0.3 m, with possibility of its uplifting from the base. A concrete block with dimension of 1×1×0.8 m was centrally placed at the top of the columns having a total mass of 2 tons. The columns were exposed to horizontal harmonic ground accelerations, with period equal to basic oscillation period of individual column. The acceleration amplitude was successively increased until collapse of the columns. Horizontal displacement and acceleration at the top of the columns, outer vertical concrete strains at the bottom of the columns, and vertical reinforcement strains at the bottom of the columns were measured for each performed test. Only some results are shown, with their brief discussion. It was concluded that vertical reinforcement ratio in the column has a great influence on its behavior and ultimate bearing capacity during an earthquake. By increasing the reinforcement ratio, the ultimate bearing capacity of the column is increased, though not proportionally. However, increased reinforcement ratio causes increased stiffness of the column. Therefore, for equal dynamic excitation, these columns induce greater seismic (inertial) forces than columns with lower longitudinal reinforcement ratio. In the performed experimental tests with reinforcement cross-section ratio of 1:3, the bearing capacity ration of columns was up to 1:2.

reinforcement ratio ; concrete cantilever column ; shake-table ; earthquake

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