Page 108 - Riem-Vol6_nº3

453 IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 3
R.. G. DELALIBERA | J. S. GIONGO
Table 9 – Analysis of variance, ANOVA, blocks with rough conformation and action of compressive force eccentric
Factor Sum of squares Square average Freedom degrees F0 Significance F0,01
ℓ emb
hs
ℓ x h
emb s
Erro
Total
1697377
875380
43964
1606137
4223308
848688
437915
10991
535379
527913
2
2
4
3
8
1,58
0,82
0,02
–
–
8,65
8,65
7,01
–
–
Note: ℓ x h , coupling between the embedded length and the thickness of the column “slab” background.
emb s
the factors previously chosen for this analysis were not relevant,
i.e., did not present substantial values. Such results corroborate
with the results presented by Canha & El Debs [14], where it was
found that respecting the minimal embed length of the column es-
tablished by NBR 9062:2006, it can be considered monolithic the
behavior of the link column-sockets.
5.3 Stress on the steel bars
Analyzing Figure [32], it can be noticed that reinforcement of the
models presented consistent values and in some cases, occurred
yield. It was observed that in some reinforcement of the piles, oc-
curred traction tensions. These results are coherent as a function
of the external actions applied.
The results presented in Figure [32] corroborate with the results
presented by Adebar et al. [7], Miguel [6] and Delalibera [5], i.e.,
the stress in the reinforcement is not constant, having null values
(or even negative) on the tip of the rods and maximum values in
the middle of the span. It can also be observed that, the reinforce-
ment that of the piles present stress with different values, what
indicates flexion-compression on the piles.
Figure 32 – Strength of reinforcement,
Lℓ 60hs20NM, strengths expressed in MPa
e
6. Conclusion
The numerical simulations proved to be coherent and pointed
tendency of the structural behavior of two pile caps with embed
socket, with smooth and rough conformation of the socket walls
and of the columns.
It was observed for the pile caps with smooth interface between the
socket and column walls, the following factors: embed length of the
column - ℓemb and thickness of the bottom slab hs, has got relevant
importance in the bearing capacity of the models. Because, the
models numerically analyzed with bigger embed lengths of the col-
umn and bigger thicknesses of the bottom “slab”, presented higher
bearing capacity. Furthermore, it was evident that in the situations
in which there was embed length of the column diminished and
small thickness of the bottom “slab”, the possible ruin occurred by
punching shear of the pile caps in the region of contact between
the column base and the pile cap base.
For the models simulated with rough interface between the
socket and column (shear key), the factors analyzed (ℓemb and
hs) were not relevant in the determination of the bearing capac-
ity of the pile caps. These results are interesting, because it is
possible to project pile caps with embed socket and shear key,
with strut and tie model, only getting worried with the punching
shear of the bottom “slab” of the pile cap, during the assem-
bling phase (i.e., before the application of the filling material),
since respecting the minimal embed length of the column in the
socket, suggested by NBR 9062:2006. It is necessary a higher
number of experimental tests, so that it can be verified the
possibility of the reduction of the embed length of the column
in the socket.
It was also observed that the rigidity of the pile cap influences in
the bearing capacity of it. This can be stated as a function of the
results obtained, because the models with higher heights were the
ones that presented higher resistant capacity.
It was found, and it was expected, that the models numerically
analyzed with smooth interface, presented minor bearing capacity
in relation to the models numerically analyzed with rough interface.
7. Acknowledgments
To: CNPq – Conselho Nacional de Desenvolvimento Científico e
Tecnológico and to FAPESP – Fundação de Amparo à Pesquisa
do Estado de São Paulo for the financial support to perform the
research that made it possible to write this paper.