Whilst the moment-rotation behaviour of typical connection configurations has been
extensively examined in previous studies, there is a relative lack of information on the
performance under more generalised loading conditions, particularly in relation to
semi-rigid connections to tubular columns. To this end, this research aims to provide
fundamental information that would enable an extension of the assessment and design
of semi-rigid tubular column connections to loading scenarios involving significant
axial or shear actions. In particular, the thesis focuses on the behaviour of two cost-effective
semi-rigid open beam-to-tubular column alternatives: i) blind-bolted angle
connections and ii) reverse channel connections with angles. The work involves
experimental investigations, detailed numerical simulations and analytical studies, as
well as application-oriented studies.
Firstly, two experimental investigations that are concerned with the behaviour of
beam-to-tubular column connections under predominant axial and shear loads
respectively are presented. The experimental set-up, connection configurations and
material properties are introduced followed by a detailed account of the results and
observations from the tests. The main behavioural patterns are identified and their
effect on the connection performance is discussed. Subsequently, detailed three-dimensional
finite element models are constructed by means of the nonlinear program
ABAQUS, and their results are validated against the experimental data obtained in
this research in addition to that provided from previous bending tests conducted at
Imperial College London. Complementary component-based mechanical models for
both blind-bolted and combined channel/angle connections are also suggested and
described. Various component characteristics including tension and compression load-displacement
relationships as well as load-displacement expressions in shear are proposed. The findings offer information which is of direct relevance to strength
prediction in conventional design procedures, as well to more involved
characterisation of stiffness, capacity and ductility for modelling and assessment
purposes, particularly under extreme loading conditions.
In the concluding part of the thesis, the component-based models are employed,
together with detailed finite element simulations, to illustrate the applicability of the
proposed connection models under a number of possible load combinations involving
bending and/or shear actions. As an example of application of the suggested models in
frame analysis under extreme loading, selected frame and beam simulations are
carried out under idealised pseudo-static conditions representing column removal and
floor-on-floor collapse situations. Finally, the findings of the thesis are summarized
and a number of possible future research areas are highlighted.