EXPERIMENTAL STUDY ON SEISMIC BEHAVIOR OF CONCRETE-FILLED PRECAST CONCRETE TUBE COLUMN-TO-STEEL BEAM HYBRID FRAME CONSIDERING THE SLAB COMPOSIT EFFECT

The slab composite effect has a significant impact on the lateral resistant behavior and seismic response of frame structures. Insufficient consideration of this effect is one of the important reasons why the yield mechanism of ‘strong column and weak beam’ cannot be realized. To investigate the seismic performance of prefabricated reinforced concrete columns-steel beams (RCS) hybrid frames considering the slab composite effect, quasi-static loading test was conducted on a 1/2 scale, 2-story, 2-span concrete-filled precast concrete tubular column-steel beam hybrid frame. The crack development and damage evolution of the specimen were analyzed. The hysteretic behavior, distribution of inter-story deformations, force transmission conditions and joint deformation characteristics were explored. The test results indicate that plastic hinges appear at the beam ends prior to the columns. Except for local buckling, steel beam flanges experience fracture, and the panel zones remain elastic. The ultimate drift ratio is 3.33%, the maximum plastic rotation angle is 2.03%, and the ductility coefficient is 2.55, indicating good plastic deformation and energy dissipation capabilities. The inter-story displacement ratio is from 40% to 52%, indicating uniform inter-story deformation distribution with no weak story. It is recommended that the story drift ratio limit for this hybrid frame under frequent and rare earthquakes be set at 1/400 and 1/50, respectively. Additionally, the significant increase in the risk of bottom flange fracture of steel beams should be mitigated during the structural design.