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IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 1
J. E. CAMPUZANO | R. DE CASTRO
|
S. ÁVILA
|
G. DOZ
Are used types of elements that can better simulate the behavior
of each structural component molded in this case the elements
SHELL63, BEAM4, and SOLID65 SOLID45 (see Figure 1). The
SHELL63 element has six degrees of freedom at each of its four
nodes, translation in X, Y and Z and rotation about the same, is
shown to simulate the behavior of membranes and accepts ship-
ments in its own plane and orthogonal to it.
In the other hand, BEAM4 already has six degrees of freedom
in each of its two nodes (I, J), translation in X, Y and Z and,
rotation around themselves. It is an uniaxial element capable
of modeling tension, compression, torsion and bending. The el-
ement SOLID65 has eight nodes, each with three degrees of
freedom, which are translations according to the axes X, Y and
Z. It is able to simulate the behavior of materials such as con-
crete, ie, which can crack when subjected to tensile stresses
and suffers crushing in compression. The armors can be in-
cluded and resist only to axial forces. It is possible to consider
the non-linearity of the materials. This element was used in the
discretization of the concrete slab and the four pillars for the
most sophisticated models.
Finally, the element SOLID45 was used to simulate the behavior
of the metal profiles. Likewise the SOLID65, the SOLID45 also has
eight nodes, each node having three degrees of freedom relating
to translations concerning X, Y and Z. The SOLID45 also allows
considering the plasticity and the orthotropic material.
As mentioned initially, modal analyzes are performed using the
computer package for several structure configurations. The analy-
sis results for all proposed structures are discussed and evaluated
for determining the structure to be projected. Only for the chosen
structure, are also made static and dynamic analyzes.
As already mentioned, another aspect of great importance in the
analysis of induced vibrations in a structure is related to the num-
ber of people in action. This is due to the fact that when a group of
people moves synchronously or approximately synchronized, the
impact factor produced is high, which generates large values for
the induced loads in the structure. The experiments conducted in
1985 by Allen (Gomes, [12]) indicate that the impact factors can be
greater than 5, when the number of people increases.
A rigorous mathematical description of the force exerted by several
pedestrian is quite complex. Indeed, when more than one person
performs movements in a structure occurs the superposition of the
effects of each one on the structure, so that, at certain moments,
the vibration amplitudes will be added or subtracted, depending
on the frequency or phase. Hence the importance of further study,
based on experimental results, the characterization of the load in-
duced by people on the move.
2. Software tool
In this paper are analyzed numerically different slabs with views to
design of the dynamic tests deck, mentioned above. The discreti-
zation of the different structures analyzed is performed using the
software (ANSYS 2007, [7]).
Are used the type of elements that better simulate the behavior
of each molded structural component, in this case, the elements
SHELL63, BEAM4, and SOLID65 SOLID45 (see Figure 1). The
SHELL63 element has six degrees of freedom at each of its four
nodes, translation in X, Y and Z and rotation around themselves,
is indicated to simulate the behavior of membranes and accepts
shipments in its own plane and orthogonal to itself.
Figure 1 – Types of elements used in the model (ANSYS 2007, [7])