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580
IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 5
Shear force and torsion in reinforced concrete beam elements: theoretical analysis based
on Brazilian Standard Code ABNT NBR 6118:2007
model used in relation to complementary mechanisms of the truss.
As previously demonstrated, calculation model I considers a por-
tion of constant reduction (V
c0
) given by equation (4). The reduc-
tion portion (V
c1
) is variable in calculation model II, depending on
the intensity of the design value of shear force (V
c0
), according to
equation (6). Another factor which influences this calculation is that
in portion (V
c0
), the value of f
ctd
is obtained according to the class
of the concrete, that is, it depends directly on the value of the cha-
racteristic resistance to compression of the concrete, f
ck
. Finally,
the value of (V
Rd2
) in calculation model II depends on the angle θ of
Ta�le � � �ercentage of transverse reinforcement area from calculation model I and II
Força
Cortante
Ângulos
(graus)
A /A (%)
sw (M I
sw (M I)
C25
C30
C35
C40
C45
C50
20, 40, 60 e
80% de V
Rd2
Ɵ
= 45º
122
121
120
119
119
119
Ɵ
= 42º
110
109
108
108
107
107
Ɵ
= 39º
99
98
98
97
97
97
Ɵ
= 36º
89
89
88
88
87
87
Ɵ
= 33º
81
80
79
79
79
79
Ɵ
= 30º
73
72
71
71
71
71
Figure � � �ercentage reduction of transverse reinforcement area obtained form
design models I and II in accordance with
θ
angle