Hysteretic performance of a new blind bolted connection to concrete filled columns under cyclic loading: An experimental investigation

The structural performance and reliability of a new blind-bolting technique is investigated in this study. The new blind-bolt is termed Extended Hollobolt (EHB) and is a modification of the standard Hollobolt. The EHB enhances the tensile resistance and stiffness of the fastener by anchoring it in the concrete infill of a tubular column. This paper reports on an investigation into the cyclic behaviour of end-plate connections to concrete filled tubular (CFT) columns using the EHB. A series of six full-scale connections were tested under quasi-static cyclic loading. The key parameters investigated were amplitude of cyclic loading procedure, bolt grade, tube wall thickness, and concrete grade. The strength, stiffness, rotation capacity and energy dissipation capacity of the connections were evaluated at different load cycles. The EHB provided stable hysteretic behaviour with appropriate level of strength and stiffness, where strength is comparable to that of standard bolt-and-nut fasteners and where rigid behaviour can be achieved. The influence of tube wall thickness and concrete grade on the performance of the connection in terms of strength, stiffness, ductility and failure mode is investigated. It is shown that the required performance can be achieved by controlling the tube wall thickness and concrete strength. The results indicate that the connection can offer energy dissipation capacity and ductility appropriate for its potential use in seismic design.

► Reports on hysteretic behaviour of a new blind bolted endplate connection to concrete filled tubes. ► The new connection offers good energy dissipation capacity and ductility for seismic application. ► The new connection provides stable hysteretic behaviour with appropriate strength and stiffness. ► Required performance can be achieved by controlling tube wall thickness and concrete strength.