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IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 1
Concrete compressive characteristic strength analysis of pile caps with three piles
2.2 Numerical analysis
The software ATENA 3D [2], which has its main architecture based
on the finite element theory and tridimensional non-linear analysis
of reinforced concrete structures, was used to develop the numeri-
cal analysis. The ultimate load is calculated by an integer in time
of force increments, applying the Arc-Length or Newton-Rhapson
methods. To determine the structural behavior of the deformed
structure either the Lagrange or the Euler formulation is used.
the column’s cross-section projection, as shown in Figure 1. The
pile caps analyzed were originated from [1] research. All original
geometric, materials characteristics and reinforcement configu-
ration were maintained, varying only the concrete compressive
strength. In total, three pile caps with three piles with different
concrete compressive strength (f
ck
) were modeled, as shown in
Table 1.
2.1 Geometric model and reinforcement disposal
The pile caps have a prismatic shape with 60 cm height. The columns
are rectangular with 35 cm height and 25 cm x 25 cm cross-section.
The piles are cylinders with 32 cm diameter and 60 cm height.
The pile cap’s reinforcement has principal ties (bars with hooks dis-
posed above the piles and parallel to the sides of the pile cap) and
complementary reinforcement passing through the cross-section pro-
jection of the column, as shown in the Figures 1 and 2. The column
reinforcement have eight bars with 12,50 mm diameter and stirrups
with 6,30 mm diameter, spaced with 10,0 cm, as shown in Figure 3.
Figure 1 – Pile caps reinforcement details
Table 1 – Numerical models analyzed
Model 1
Pile cap with
f = 30 MPa
ck
Model 2
Pile cap with
f = 35 MPa
ck
Model 3
Pile cap with
f = 40 MPa
ck