The seismic response of three-story one-third-scale steel frames with columns allowed to uplift is evaluated and compared with that of fixed-base frames by three-dimensional shaking table tests. The test frames were retested using four different frame conditions: uplift-base and fixed-base frames; plan symmetric and asymmetric frames. The results are: 1) While the column uplift displacements of the uplift frames is increased by the vertical component of the input motion, the horizontal response values such as the roof drifts and base shears are not affected by that; 2) The difference of the roof floor rotations between the symmetric and asymmetric uplift frames are not increased in spite of the increase of the input motion intensity; 3) The base shears of the uplift frames are effectively reduced from those of the fixed-base frames; and, 4) The deformation of the uplift frames excluding the rocking component is nearly equal to or smaller than the elastic response value of the fixed-base frames.
