Page 93 - Riem-Vol6_nº3

438 IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 3
Numerical analysis of two pile caps with sockets embedded, subject the eccentric compression load
also fixed, varying the length of the embed of the column (ℓemb) and
the thickness of the pile cap bottom slab (hs ). The dimensioning of
the main reinforcement of the pile cap (tie) and the verifications of
the crushing of the concrete of the compressed diagonal with the
inferior nodal zone (pile/pile cap) and with the superior nodal zone
(column/pile cap) were performed according to the recommenda-
tions of the model proposed by Blévot & Frémy [4]. It was used as
limits to verify the stress with the superior and inferior nodal zones
the values observed by the French researchers, in other words,
1,40∙fck near the column and f ck near the pile.
We opted for using straight anchoring, because it was verified
through the recommendations of the NBR 6118:2007[1] that the
hook was not necessary (anchoring criteria in extreme supports).
By admitting this hypothesis the researcher did not consider (proj-
ect decision) the recommendation of NBR 6118:2007[1] which de-
mands the use of hooks in pile caps. We remember the results
obtained by Delalibera [5], Miguel [6] e Adebar et al. [7], for rigid
pile caps, where the stress on the tip of the rod was negligible, cor-
roborating this decision.
For the dimensioning of the pile caps, we used a pattern pile cap, in
other words, all pile caps had the same dimensions in plant of the
pattern pile cap, varying only the embed length of the column (ℓemb)
and the thickness of the pile cap bottom slab (hs ). It is understood,
The purpose of this work is to analyze the structural behavior of
two piles caps with embed precast, with smooth and rough inter-
faces of the walls of the column and the precast, subject to the
action of normal eccentric compression force and, verify by vari-
ance analysis, which variable presents the biggest relevance in
their behavior.
The method used was the one related to works with emphasis in
numeric analysis. Definite the models which were studied, it was
developed a statistical analysis, using values obtained by numeric
simulations. The pile caps were numerically analyzed by a com-
puter program based on the methods of the finite elements – MEF.
The physical and geometrical nonlinearities were considered. The
cracking of the concrete and the reinforcement of the pile caps
were also taken into account. For the numerical analysis of the pile
caps via method of the finite elements, it was used the program
ANSYS® [23] (ANalyser SYStem).
2. Geometric properties of the
numerically analyzed models
The models were dimensioned with the criteria of Blévot & Frémy
[4]. The rates of reinforcement were fixed, because they were not
analysis objects. The distance between the axles of the piles was
Figure 3 – Geometric properties of standard pile cap
1
5 5 5 5 5
Dimension A Shear key B