A Design Method for One-Side Bolted Connection Joints of Prefabricated Concrete-Encased CFST Composite Column and the Analysis of Seismic Performance of CECFST Frames

Concrete-encased concrete-filled steel tubular (CECFST) composite columns possess better durability and fire performance, and have been widly used in engineering practice. However, welding joints are generally used to connect the steel beam to CECFST column, leading significant difficulty in joint construction accompanied by a large amount of welding work. Moreover, welding joints are more likely to appear fracture under earthquake loads. The load transfer mechanism within the encased concrete was analyzed and its influence on the bearing capacity and stiffness of one-side bolts in tension and beam flanges in compression were discussed. The calculation model for the bearing capacity and stiffness of joints was established. OpenSEES software was employed to model the CECFST frame, in which the moment-rotation and shear force-shear curves were obtained based on the component method and superstition method, respectively. The accurary of the model was verified through test results, and the dynamic response of the CECFST frame with one-side bolted connections under different seismic intensities was studied. The seismic performance for such frame structures was investigated to determine whether it meets the requirements of current relevant specifications.