Seismic behaviour of a through-beam connection between concrete-filled steel tubular columns and reinforced concrete beams

• A new type of connection between CFST column and reinforced concrete (RC) beams is presented.
• Cyclic loading tests and subsequent axial compressive tests are reported on six specimens.
• The favourable seismic performance of the connection is demonstrated in the tests.
• A finite element model is developed and validated by a comparison with the experimental results.

This paper aims to investigate the seismic and post-seismic behaviour of a new and innovative type of through-beam connection between a concrete-filled steel tubular (CFST) column and a reinforced concrete (RC) beam. In this new connection system, the steel tube is completely or partially cut with the cut or openings being at the corresponding beam location, with the longitudinal steel reinforcing bars for the beam remaining continuous through the connection region. A strengthening ring beam is used to enlarge the connection zone in order to compensate for the possible decrease of the axial load carrying capacity as a result of the discontinuity of the steel tube that encases the column. Cyclic loading tests and subsequent axial compressive tests are reported on six beam–column specimens. Based on the experimental results, the hysteretic response, the skeletal and post-cyclic static load–deflection curves, the strain, ductility, strength and the stiffness degradation and energy dissipation are discussed. The favourable seismic performance of the connection is demonstrated in the tests. A finite element model is then developed and validated by a comparison with the experimental results. The relative effects of the reinforcement ratio of the frame beam and the ring beam, and the axial compressive force in the column on the seismic behaviour of the connection are elucidated through parametric studies.