Civil Engineering Reference
In-Depth Information
Table 4.1
Global analysis, and types of joint and joint model
Method of
Classification of joint
global analysis
Elastic
Rigid-plastic
Elastic-plastic
Nominally pinned
Nominally pinned
Nominally pinned
Rigid
Full-strength
Rigid and
full-strength
Semi-rigid
Partial-strength
Semi-rigid and partial-strength
Semi-rigid and full-strength
Rigid and partial-strength
Type of joint model
Simple
Continuous
Semi-continuous
Table 4.2
Properties of beam-to-column joints in composite frames
Type of joint
Stiffness
Strength
Nominally pinned
Capable of transmitting the
internal forces, without
developing significant moments
that might adversely affect
members of the structure
Capable of accepting the resulting
rotations under the design loads
As given for Stiffness
Rigid and full strength
Has stiffness such that its
deformation has no significant
influence on the distribution of
internal forces and moments in
the structure, nor on its overall
deformation
Capable of transmitting the forces
and moments calculated in design
Has a design resistance not
less than the resistances of
the members connected
Has rigidity such that, under
the design loads, the
rotations of the necessary
plastic hinges do not exceed
their rotation capacities
The links between appropriate methods of global analysis, these cat-
egories, and the three types of joint model are defined in EN 1993-1-8, as
shown in Table 4.1.
The most widely-used joint models in current practice are 'continuous'
for bridges, and 'simple', for buildings. The scope of this topic is limited
to the types of joint used in the examples, which are either 'nominally
pinned' or 'rigid and full strength', and to global analyses that are either
elastic or rigid-plastic.
A summary of the relevant requirements for these joints, from EN
1993-1-8, is given in Table 4.2.
The use of nominally-pinned joints simplifies analysis of the structure
because, at the assumed location of the pin, there is no bending moment.
Action effects in beams are then independent of the properties of the
columns that support them. Rigid joints transmit bending moments as
