Page 106 - Riem-Vol6_nº3

451 IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 3
R.. G. DELALIBERA | J. S. GIONGO
umn, with performance of normal force and moment in the block.
Through numerical analysis, it was observed that the existing dif-
ferences in the areas of the struts with the piles, when compared
to the areas of the strut calculated using the criteria by Blévot &
Frémy [4] also occurred, corroborating with the experimental re-
sults found by Delalibera & Giongo [25]. In Table [6] are presented
the results of the areas of strut calculated by Blévot criterion (con-
sidering a slant of q ) and the areas of the strut obtained numeri-
cally (for the calculation of the areas of the strut obtained through
numerical results, it was used the values of the main compression
stress with the piles), as well as the eccentricities of the normal
force of each model.
5.2 Analysis of the two pile caps – normal force,
moment and rough walls
Nine pile caps solicited by action of normal compression force
and moment were analyzed, with variations in the embed length
of the column (ℓemb) and in the thickness of the bottom pile cap
“slab” (hs). The variation of the factors analyzed modified, also
in this case, the distribution of the main compression stress and
the crack panorama in the last forces increment (horizontal and
vertical) applied to the models. Table [8] presents results of the
numerical analyses, Figure [29] shows the distribution of the main
compression stress and Figure [30] the crack panorama of the
pile caps numerically analyzed.
The cause of the precocious rupture of the model Rℓe60hs10NM is
probably related to the punching shear of the “bottom slab” of the
pile cap and the rupture of the model Rℓe50hs20NM, due to the
small embed length of the column.
Through Table [8], it can be observed the differences among the
areas of the strut with the piles, calculated by analytic criterion de-
veloped by Blévot & Frémy [4] and using the numerical models. In
the same table, are presented the values of the eccentricities of the
normal force of each model numerically analyzed.
It is possible to observe through Figures [29] and [30] the formation
of the compressed diagonals and the panorama of cracking of one
of the blocks numerically analyzed. It is noted that the strut and tie
Figure 28 – Panorama cracking, pile caps with
smooth conformation, normal force and moment
Lℓe60hs20NM
Table 7 – Analysis of variance, ANOVA, pile caps with smooth conformation and action of compressive force eccentric
Factor Sum of squares Square average Freedom degrees F0 Significance F0,01
ℓemb
hs
ℓ x h
emb s
Erro
Total
2805913
2026374
302545
194219
5329056
1402956
1013187
75637,5
64734
666132
2
2
4
3
8
21,67
15,65
1,16
–
–
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
Figura 29 – Principal stress compression, pile cap
with rough conformation, normal force and moment
Lℓe60hs20NM