Shake Table Test of a Half-Scale 2-Storey Steel Building Seismically Retrofitted Using Rocking Braced Frame System

摘要

The article introduces a shake table test program that was conducted to investigate the response of a two-storey rocking braced frame for which self-centring capacity is provided solely by the gravity loads supported by the frame. The test specimen is a 0.5 scaled model of a prototype rocking frame that was studied for the retrofit of a seismically deficient steel structure. The main objectives of the test program were to study the effects of column uplift and impact on shear forces and moments in the beams connected to the columns. Higher mode effects on brace forces were also of interest. Three different energy dissipation mechanisms located at the rocking interface were examined for drift control: friction, ring spring dampers, and vertical steel bars yielding in tension and buckling in compression. By changing the seismic weight of the test specimen, tests could be conducted for structures located in two different seismic regions of Canada to study the effect of the signature of the ground motions. Increases in beam forces due to column uplift and impact, as predicted by previous numerical simulations, were confirmed by the tests. High axial loads induced by the second vibration mode were also measured in the second storey braces.