Experimental investigation on seismic performance of an enhanced embedded base for CFST columns

To reduce the embedded depth and improve the seismic performance of the embedded column base for concrete-filled steel tubes, an enhanced embedded column base is proposed. The column base is strengthened by a pair of strengthening steel beams and anchor bolts. Four embedded column bases were tested under axial compression load and cyclic lateral load, and the test parameters included the type of column base, height of strengthening beam, and axial load ratio. The hysteresis curves, skeleton curves, stiffness degradations, energy dissipation capacities, and strain developments were analyzed based on the test results. The test results indicated that the enhanced embedded column base exhibited high strength and a high energy dissipation capacity compared with the traditional embedded column base. An embedded depth ratio of 0.7 enabled the enhanced embedded column base to achieve the ultimate strength of the CFST column. Finally, a calculation method for the ultimate strength of the enhanced embedded column base was proposed. This method considers the resistance resulting from the interaction between the steel tube and concrete, the interaction between the strengthening steel beam and concrete, and the deformation of anchor bolts.