Abstract：In order to investigate the dynamic behavior and failure mechanism of semi-rigid CFST
composite frames under seismic loading, two-layer one-span specimens of semi-rigid CFST frames
with composite beams were tested under pseudo-dynamic actions. The flush or extended end plates
were employed to form the beam-column connections and the composite floor slab is made of rebar
truss embedded in concrete slab. The test parameters are cross-section type of column and end
plate type. The whole loading progress and failure modes of two specimens under El Centro
earthquake waves were studied. Dynamic responses, including displacement, acceleration, hysteretic
curves, degradation curves of stiffness and ductility as well as energy dissipation capacity, were
also analyzed. The influence of semi-rigid connection and floor slab composite effect on the
performance of overall frame were evaluated. The test results show that the semi-rigid CFST frames
with composite beams have good seismic behavior and energy dissipation capacity. Under the same
width and steel ratio of column cross-section, the maximum displacement response and accumulated
energy dissipation of circular CFST frame were higher than those of square CFST frame, while the
rule was opposite for horizontal bearing capacity and initial rigidity. The research results may
provide the scientific basis for design theory and application of fabricated composite structures.
