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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 4
Parametric study on the behaviour of bolted composite connections
(CRACKING), with discrete cracking (DISCRETE CRACKING)
and brittle behaviour.
n
Reinforcement, bolts and shear connectors
The bolts, the slab reinforcement and the shear connectors were
represented by REINFORCE, a tool of the software DIANA spe-
cific to simulate the behaviour of steel bars. The finite element
crossed by the REINFORCE is stiffened, causing the same ef-
fect that steel bars cause in reinforced concrete structures.
To describe these elements was used the von Mises with
ideal plasticity model, because they are steel elements, as
already explained.
5.2 Finite element
Two types of finite elements were used to construct the mesh: ele-
ments of plane stress and interface elements.
The plane state elements were used to represent the concrete and
steel, while the interface elements are used at the joint between the
endplate and the column and between the beam flange and the slab.
The finite element used for concrete and steel was the quadrilat-
eral isoparametric element Q8MEM. This element has four nodes,
two degrees of freedom per node, which represent the translations
in x and y and linear interpolation function (Figure 15).
In the beam-column and beam-slab connections were used the
L8IF interface element, which has 2 + 2 nodes with two degrees
of freedom, relating to translations in x and y. This element is rep-
resented by two parallel lines in a plane configuration, as shown
in Figure 15.
The structure of these elements describes the behaviour of the
interface in terms of the relationship between the normal and shear
forces at the site. According to [12], these elements are commonly
used in the construction of meshes for numerical representation of
masonry structures, connections and to describe the adherence
along the reinforcement.
5.3 Mesh
The bidimensional model was selected to describe the connection
because of this kind of modeling supplies the required information
for analysis and provides less time in the processing of numerical
models. Another thing used to decrease the time spent on model-
ing was the representation only the half of physical model.
The final finite element mesh presented 903 nodes and 775 ele-
ments. Figure 16 shows the finite element mesh with an indication
of the structural elements that compose the numerical model.
Figure 15 – Finit Elements [7]
Figure 16 – Finite elements mesh
Figure 17 – Boundary conditions
of the numerical model