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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 3
Contribution to assessing the stiffness reduction of structural elements in the global stability analysis of
precast concrete multi-storey buildings
The model created in ANSYS
®
[9] was motivated by the evalua-
tion of global stability in the structural arrangements studied. The
structural arrangements show different shapes, cross-sections of
the elements, and loads. In addition, the semi-rigid behavior of
the beam-to-column connection was considered. The model ac-
counted for PNL while using finite element BEAM188, enabling the
relationship M x N x 1/r to be calculated. To evaluate the stabilities
of the arrangements, the
γ
z
coefficients were calculated from the
displacements obtained in the process. These values varied from
1.05 to 1.20, indicating that the degree of PNL in the models ana-
lyzed was not significant.
In models with non-linearity, there were variations in the configura-
tions of the axial forces on the columns because of the non-linear pro-
cesses. In the model analyzed there are GNL, PNL, and non-linearity
in the beam-to-column connection that has asymmetric behavior.
Changes in the axial forces on the columns would necessitate an
iterative analysis in the construction of the M x N x 1/r diagram.
Table 3 – Characteristic wind loading for modulation with 7.5m
Wind Load - Direction Y
Modulation 7.5m
6 FLOORS
5 FLOORS
4 FLOORS
h(m)
S
2
V (m/s)
k
2
q (kN/m )
H/L1 C
a
F (kN)
a
H/L1 C
a
F (kN)
a
H/L1 C
a
F (kN)
a
4
0.76 34.20
0.717
0.80
1.24 28.11
0.67
1.21 27.43 0.53 1.18 26.75
8
0.80 36.00
0.794
0.80
1.24 31.46
0.67
1.21 30.70 0.53 1.18 29.94
12
0.85 38.25
0.897
0.80
1.24 34.97
0.67
1.21 34.12 0.53 1.18 33.28
16
0.89 40.05
0.983
0.80
1.24 37.41
0.67
1.21 36.50 0.53 1.18 17.40
20
0.91 40.95
1.028
0.80
1.24 39.09
0.67
1.21 18.66
24
0.93 41.85
1.074
0.80
1.24 19.97
h.: Floor height; H: Structure height ; V : Characteristic wind speed; S : Factor used in V ; q: Wind pressure; L1: Structure length;
k
2
k
C : Pressure coefficient; F : Wind Load.
a
a
2
Table 4 – Axial force in columns (P50x50) for structure with modulation 7.5m and live load 3 kN/m
CC (Central Column); LC (Lateral Column);
st
N : Axial force for 1 load combination in ULS, where the wind load was taken as main;
d.1
nd
N : Axial force for 2 load combination in ULS, where the wind load was taken as single load;
d.2
rd
N : Axial force for 3 load combination in ULS, where the live load was taken as main.
d.3
N (kN)
d.1
N (kN)
d.2
N (kN)
d.3
FLOOR
CC
LC
CC
LC
CC
LC
6
534.94
318.65
330.19
216.28
605.81
354.00
5
1069.88
742.31
660.38
537.56
1211.62
813.09
4
1604.82
1165.96
990.57
858.84
1817.44
1272.19
3
2139.75
1589.62
1320.75
1180.12
2423.25
1731.28
2
2674.69
2013.28
1650.94
1501.41
3029.06
2190.38
1
3209.63
2436.93
1981.13
1822.69
3634.87
2649.47
Table 5 – Dimensionless axial force
in columns (P50x50) for structure
2
with modulation 7.5m and live load 3 kN/m
n
d.1
n
d.2
n
d.3
FLOOR
CC
LC
CC
LC
CC
LC
6
0.09
0.05
0.05
0.03
0.10
0.06
5
0.17
0.12
0.11
0.09
0.19
0.13
4
0.26
0.19
0.16
0.14
0.29
0.20
3
0.34
0.25
0.21
0.19
0.39
0.28
2
0.43
0.32
0.26
0.24
0.48
0.35
1
0.51
0.39
0.32
0.29
0.58
0.42
cd c
i
d
f
A
N
i
d
.
,
,
=
n
:Dimensionless axial force