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191
IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 2
R. M. F. CANHA |
G. M. CAMPOS |
M. K. EL DEBS
The pressure resultant
topr
H
on the upper third of the rear trans-
verse wall is approximately equal to the pressure
r
H
distributed
on the upper half of that wall.
Experimental results confirmed that the upper part of the front and
rear transverse walls of rough sockets were subjected to combined
bending and tension, with the predominance of tension. This be-
havior under bending-tension was observed from obtained rein-
forcement strains and cracks configuration of the transverse walls.
Hence, the proposed analysis model presented in Figure 9, based
on the experimental investigation, consists of representing the top
of transverse walls as a simply supported beam with the distrib-
uted pressure given by two parts: a pressure H
topf-b
and H
topr-b
which
causes bending of the beam, and a pressure H
topf-t
and H
topr-t
that is
transmitted to the beam supports at an angle of θ=45º, represent-
ing the average crack inclination of the tested specimens, causing
tension of the beam. The total upper pressure on the front wall
topf
H
and on the rear wall
topr
H
is the sum of the portions
referring to bending and tension.
Based on the obtained strain gauge results, the percentages adopted
for the case of bending- tension was 15% for pressures
b topf
H
and
b topr
H
, and 85% for pressures
t
topf
H
and
t
topr
H
. Besides these percentages, only the tension force, for which
t
topf
topf
H H
=
and
t
topr
topr
H H
=
, can be considered.
Concerning the average inclination of the compression struts of the
Table 1 – Theoretical and experimental internal forces in reinforcement A
s,tmh
with varying angles of
β
for the front transverse wall of rough interface sockets
f
Specimen
Design
model
Angle
b
f
R (kN)
s,tmhe
R (kN)
s,tmhi
Theoretical Experimental
Theoretical
Experimental
IR-1
Bending-
tension
45º
205.5
87.0
41.8
15.7
60º
118.6
24.1
Tension
45º
145.5
145.5
60º
84.0
84.0
IR-2
Bending-
tension
45º
206.8
51.4
42.1
9.9
60º
119.4
24.3
Tension
45º
146.4
146.4
60º
84.5
84.5
IR-3
Bending-
tension
45º
172.4
42.0
33.6
20.5
60º
99.5
19.4
Tension
45º
121.1
121.1
60º
69.9
69.9
IR-4
Bending-
tension
45º
208.2
54.9
25.2
4.2
60º
120.2
14.5
Tension
45º
137.3
137.3
60º
79.3
79.3
walls, Canha et al. [10] indicates a value of 45º for
f
β
and
r
β
.
However, it is noticed that, in some cases, with these inclination an-
gles, the theoretical results did not represent well the experimental
results. Because of this, an analysis with the variation of the average
inclinations of the compression struts in the front and rear transverse
walls was developed. The obtained results were then complement-
ed with experimental results of Nunes [11]. For the angle
f
β
, the
values of 45º and 60º were compared, and for
r
β
, the values of 45º
and 35º.
An analysis and comparative study of the experimental and theo-
retical results was carried out for specimens IR-1 and IR-2 tested
by Canha [4], for IR-3 by Jaguaribe Jr. [9] and for IR-4 by Nunes
[11]. Table 1 presents the results of the force in the reinforcement
tmh ,s
A
with variation in
f
β
of the front transverse wall.
Analyzing the results, for all cases when
o
f
60
=b
was con-
sidered, the obtained theoretical and experimental forces showed
close agreement. For instance, for specimen IR-2, considering the
bending-tension and an angle of 60º, the difference between the
theoretical and experimental force was found to be approximately
132%, compared to approximately 300% when a strut inclination of
45º was taken into account.
However, considering the bending-tension, and
o
f
60
=b
for speci-
men IR-3, the theoretical internal force was found to be below the ob-
served experimental result. It is noteworthy however that this specimen