Steel joints have always
been considered as
important parts of any structural steel
building because they provide
the strong
links between the principal structural
members. The properties and
behaviour of
joints in both steel and composite
structures
have been widely studied
for some
time. The focus has
recently
been on
improving the design of structural
frames by taking advantage of realistic connection
moment-rotation response. This has necessitated
the development of an effective and
practicable methodology
to describe steel connection
behaviour, despite its inherent
complexity. Although, the evaluation of steel connections' performance at ambient
temperature has been a continuous research
topic, the investigation of steel
connections at elevated
temperatures has only recently been tackled by
researchers.
However, the determination of
the behaviour, available strength and stiffness of
moment connections
in fire conditions
has been a dominant theme
in these research
works. Moreover, over a number of years
the Component Method has been
developed to describe the moment-rotation characteristics of end-plate connections,
and
the method
is now
included in Eurocode 3. To date, most of
the research
conducted on steel connections using
the component method
has focused on
relatively stiff and strong connections
-
flush
end-plates and extended end-plates.
The modelling of more
flexible ("pinned")
connections using
the Component
Method has not received much attention, since
the benefits arising
from
consideration of
their behaviour in overall
frame
response are usually modest.
However, in fire
conditions connections are subject
to complex
force combinations
of moment and
tying forces, as well as vertical shear
forces, and
the real behaviour,
even of nominally pinned connections, can have a significant effect on
the overall
response of
the
frame. To date
very
little information on
the behaviour and
the
resistance of simple shear connections
in fire
conditions
has been generated. Fin
plate shear connections, which are economic
to fabricate and easy
to use
in erection,
are among
these shear connections which are assumed
to act as pins
in normal
service conditions In this research, the behaviour and robustness of simple
fin plate beam-to-column
connections has been investigated, under the conditions of catenary
tension from
highly deflected beams which occurs
in fire. In addition, detailed investigations have
been made on applying the component method approach to this connection at both
ambient and elevated temperatures.
ABAQUS software has been selected
to create a very detailed 3D finite element
model. This is a complex model accounting
for material nonlinearity,
large
deformation
and contact behaviour. The connection model has been analysed through
the elastic and plastic ranges up
to failure. Bolt shear and bending,
plate and web
bearing have been observed as
failure modes. A comparison between available
experimental data at ambient and elevated
temperatures and FEA
results shows that
the model has a high level of accuracy. However, by implementing
the FE model
the
opportunity was
then available
to explore the connection tying
resistance and the
application of
the Component Method to the fin
plate connection. An intensive
investigation has been conducted
to develop
a representation of
this connection type
via a simplified component model, enabling prediction of the connection response at
both ambient and elevated
temperatures. The three main components of a
fin-plate
connection
have been identified
as plate bearing, bolt
shearing and web-to-plate
friction. These components have been described in detail at ambient and elevated
temperatures via
intensive
parametric FE analyses,
leading to a simplified component
model of a
fin plate connection. This model has been evaluated against FE models of
complete
fin
plate
joints. Eventually,
a
fin plate connection spring model
is proposed
and successfully evaluated
for
tying,
rotation, and shear actions. The Component
Model presented
in
this
research offers an opportunity
to explore complicated
behaviour of
fin plate shear
joints,
and can be incorporated into frame analysis
in fire
conditions.