Experimental study on seismic behavior of assembly CFST column-to-cap beam connections

For the advantages of easy construction and accelerated construction, the assembly CFST column-to-cap beam connections are popularly used in the bridge construction. The assembling process of precast members is introduced. 7 large scale specimens with the column diameter larger than 508mm are designed for the cyclic loading tests, and the seismic responses of 6 shear ring connections and 1 steel cage connection are analyzed. Based on the comparison of damage behavior, equivalent stiffness, ductility capacity, hysteretic capacity, conclusions are obtained as follows: the drift at the initial tearing of the steel tube will increase with the equivalent stiffness of the composite column. The cracking level of the cap beam will decrease with the CFST column embedded length. When the embedded length values are similar, the ultimate loading capacity of ER connection is larger than that of the RC connection. Furthermore, the ductility of the ER connections will decrease with the D/t value, which means tube diameter divides by tube thickness.