Structural performance of blind bolted end plate joints to concrete-filled thin-walled steel tubular columns

Abstract

This paper presents the results of an experimental study on the structural behavior of blind bolted end plate connections between steel beams and concrete-filled thin-walled steel tubular (CFTST) columns under monotonic loading. The square tube in each CFTST column connection was fabricated by seam welding four pieces of lipped angle with nominal wall thickness 1.5mm or 3mm together. In order to enhance the stiffness of the connection, extensions are provided to the blind bolts to link the connection back into the concrete with the tube. The objective of this study is to develop a novel bolted moment connection which is easy to use in the thin-walled structures. The structural performance of the blind bolted connection is evaluated in terms of the failure modes, moment–rotation relationship, connection rigidity and strain response of critical components. Some anchorage strengthening methods were proposed to enhance the strength and stiffness of the connection. The experimental results indicate that the proposed CFTST column connections behave in a semi-rigid and partial strength manner according to the EC3 specification, whilst its rotation capacity satisfies the ductility design requirements for earthquake-resistance in most aseismic region. Adopting reasonable connection measurement, the proposed blind bolted connection to the CFTST columns was a reliable and effective solution for low-layer and multilayer frame structures.