Reinforced concrete scaled columns under cyclic actions

In the area of reduced-scale model testing, increasing the size of model st ructures as a means of improving the model performance is often inhibited b y the capacity limitation of the available seismic testing facilities. This was the case in a recent experimental programme conducted at NTUA in which several 1:5.5-scale model frames were tested on an earthquake simulator. I n order to improve the model reliability, the following measures were taken : strictly obeying the geometric scaling in almost all aspects; using defor med bars as model reinforcement; and using stone-aggregate microconcrete fo r constructing the models, etc. To evaluate the effectiveness of these meas ures, a parallel column test programme was conducted in which duplicates of typical columns in the test model frames were prepared, along with those o f large sizes following similitude laws. The column specimens were tested u nder reversals of lateral load. Besides the scale effects, general rules re garding the influences of transverse confinement and axial force on che duc tility and strength of columns were also confirmed on the small-scale model columns. (C) 1998 Elsevier Science Ltd. Ail rights reserved.