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192
IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 2
Design model and recommendations of column-foundation connection through socket with rough interfaces
had been tested by Jaguaribe Jr. [9] with a reduced embedded length
and consequently the observed deviation of the experimental results was
duemainly to this factor. On the other hand, considering only tension and
an angle of 60º for specimen IR-1, the obtained theoretical force in the
external branch was found to be approximately 3.5% below the experi-
mental result. In determining the experimental values, however, a modu-
lus of elasticity of 210 GPa for the reinforcement steel was adopted even
though it may be slightly lower, thus making up for this small difference.
A general analysis showed that the theoretical model which best
represents the experimental results is that corresponding to an av-
erage strut inclination of 60º on the compression side of the socket
foundation. Based on this, a strut angle of 60º will be adopted in
the present study.
Although the observed percentage differences are large, it is
important to highlight here that the two other models cited in
the literature for analysis of the front transverse wall were found
to result in much higher differences compared to experimental
results. Table 2 compares the experimental results with those of
the proposed model, Melo [12] and CNR 10025:1998 [13] mod-
els. The bending theory based model by Melo [12] considers the
upper part of front transverse wall as a beam on two fixed sup-
ports and subjected to bending moments, with resulting plastic
bending moments at the extremities. The tension model given
in CNR 10025:1998 [13,] however, recommends the application
of a strut and tie model to the upper part of front transverse
wall considering only the existence of tensile stresses in this re-
CNR 10025:1998 [13]
668.9
668.9
Table 2 – Comparison between the proposed model and that given
by Melo [12] and CNR 10025:1998 [13]
Specimen
Design model
R (kN)
s,tmhe
R (kN)
s,tmhi
Theoretica l
Theoretica l
Experimental
Experimental
IR-1
Bending-
tension
118.6
87.0
24.1
15.7
Tension
Proposed
b
f
= 60º
Proposed
b
f
= 60º
Proposed
b
f
= 60º
Proposed
b
f
= 60º
84.0
84.0
Melo [12]
542.7
542.7
CNR 10025:1998 [13]
686.9
686.9
IR-2
Bending-
tension
119.4
51.4
24.3
9.9
Tension
84.5
84.5
Melo [12]
546.3
546.3
CNR 10025:1998 [13]
691.4
691.4
IR-3
Bending-
tension
99.5
42.0
19.4
20.5
Tension
69.9
69.9
Melo [12]
558.1
558.1
CNR 10025:1998 [13]
717.0
717.0
IR-4
Bending-
tension
120.2
54.9
14.5
4.2
Tension
79.3
79.3
Melo [12]
497.2
497.2