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190
IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 2
Design model and recommendations of column-foundation connection through socket with rough interfaces
where:
f
β
: average struts inclination on the compression side.
csf
R
: Compression force resultant in the socket determined from
equation 5.
On the compression side of the column, the pressures distribution
is similar to that of the front wall. Hence, the pressures at the top of
the column and of the front wall are the same:
(11)
topf
topf
p '
p
=
The pressure resultant
topf
H
is thus equal to the resultant of the
trapezoidal pressure block acting at the top of the front transverse
wall. This means that
topf
H
is a portion of
f
H
and is determined
according to equation 12:
(12)
f
topf
H6,0
H
×
@
On the tension side (rear transverse wall), the transfer by compres-
sion struts of most of the tension force
s
R
, from the column to the
rear wall, results in the tension force
ssf
R
in the socket and in the
pressure
r
H
on the rear wall. It can be noticed that the pressure
r
H
is concentrated mostly at the top of the wall due to the smaller inclina-
tion of the compression struts in this region relative to the horizontal
axis, and the base of the rear transverse wall does not transmit forces.
The pressure
r
H
is determined by equation 13 as:
(13)
r
ssf
r
tan
R H
b
=
where:
r
β
: average compression struts inclination on the tension side.
ssf
R
: Force resultant in the vertical reinforcements
tsv ,s
mv ,s
A A.2
+
calculated by equation 4.
In case of the tensile side of the column, the compression struts
are known to initiate at the bottom of the column. Because of this,
the triangular pressure distribution occurs all over the tensioned
column base with length
l
emb
, such that the pressure at the column
top is half of that acting on the rear wall:
(14)
2
p
'
p
topr
topr
=
Figure 9 – Design model proposed for the front and rear walls of socket with r
ough interfaces (Canha et al. [10]))
V =
ab
H /2
topf-t
V =
bt
H /
2
topf-t
V =
at
H /
2
H =
ab
0
q
topf
Plan of front transverse wall
Plan of rear transverse wall
topf
p
topf
H
topr
p
topr
H
topf-b
V =
bb
H /2
~
~~
+
topr-b
V =
bb
H /2
topr-b
V =
ab
H /2
H =
ab
0
topr-b
H
int
b
int
b
w
+h
int
b
p =
topr
topr-t
V =
bt
H /2
topr-t
V =
at
H /2
H =
at
0
q
q
topr-t
H
2.sen
q
topr-t
H
2.sen
q
H =
at
0
topf-t
H
2.sen
topf-t
H
2.sen
q
topf-b
H
int
b
+
int
b
w
+
p =
h
int
b
q
q
topf-b