Shaking table tests of steel cantilever beam-column with H-shaped section were performed under horizontal two-directional and one-directional excitation. All specimens collapsed with the excessive accumulation of displacement u. Even though the specimen was subjected to the uniaxial ground motion, the failure mode was the lateral instability... That divergent and convergent behavior of the response was well predicted by the critical axial force for convergence of the beam-column subjected to two-directional excitation derived from the theory proposed by the author.
