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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 1
A variable limit for the instability parameter of wall-frame or core-frame bracing structures
next sections present a series of examples assaying the feasi-
bility of equation (93).
5. Examples
5.1 Description of the tests
The plan of figure 5 shows the basic configuration of the transver-
sal bracing system of a rectangular on plane building (examples 1,
3, 5 and 7); it is constituted by walls 1 and 5 on the lateral faces
and the rigid frames 2, 3 and 4 spanning over a single bay (7,5 m
between column axes). In the same way, figure 6 shows the basic
configuration of the transversal bracing system of a building with
an oblong octagonal shape on plane (examples 2, 4, 6 and 8); it is
also composed by two walls and three frames which, in this case,
span over three equal bays (5m between column axes). Each of
these systems was employed in buildings having 5, 10, 20 and 30
floors with a 3 m height, constituting examples 1 to 8, whose gen-
eral information is mentioned in table 2.
Tests were performed for each of the eight buildings, varying the
rectangular cross sections of walls and frame members, in such
a way to result the sequence of
I
C1
/
I
C
ratios mentioned in table 3.
In some cases, this required changes in the basic configurations
of figures 5 and 6, but keeping the double symmetry of the brac-
ing system on plane. For
I
C1
/
I
C
= 1, the walls were suppressed; for
decreasing values of
I
C1
/
I
C
, the frames were gradually suppressed,
becoming excluded for
I
C1
/
I
C
= 0. In the examples with 30 floors,
some additional frames were included in some cases and some
additional walls in others. The cross sections dimensions adopted
in the tests are listed in table 4.
Figure 5 – Transversal bracing system: examples 1, 3, 5 and 7
Figure 6 – Transversal bracing system: examples 2, 4, 6 and 8