Fusion of experimental and numerical data for development of Extended Hollo-bolt component based model

Research on blind bolted connections to Concrete-Filled Steel Tubes (CFST) has primarily focused on the behaviour of two isolated components: blind bolts in tension and tube face in bending. This paper reports on the experimental behaviour of full scale connections using Extended Hollo-Bolt (EHB) blind bolts subjected to static monotonic tensile load, when all components contribute to failure. Numerical studies and component method models were developed based on the experimental behaviour of the studied connections. The experimental programme consisted of 28 single sided tensile pull-out tests using single and double rows of Extended Hollo-Bolts (EHBs). Three failure modes of interest were produced within the range of tested parameters: column face failure, bolt failure, and combined column face-bolt failure. The gauge and pitch distances that determine the individual and group behaviour of the EHBs were also identified. Non-linear FE models were developed and validated based on the results of the full-scale tests. The FE model is shown to accurately replicate the experimentally determined, initial stiffness, ultimate resistance, and observed failure modes. Based on the findings from the experimental and numerical programmes, a component model was developed and assembled to predict the load–displacement curves of the EHB component. The component model builds upon previous studies and factors are calibrated specifically for the findings of the combined failure reported herein. It is concluded that the proposed numerical and analytical models capture the EHB combined failure behaviour and can be used for design purposes.