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# Offshore Pile Foundation Design

A. PROJECT DESCRIPTION – PILE SECTION – SOIL PROPERTIES

In this example we will design an offshore pile foundation – a 25’x25’ rectangular concrete cap over driven pipe foundation piles. Table 1 below presents the soil properties and stratigraphy that has been estimated and used within the DeepFND software. Table 2 presents the helical pile section properties. The water table is at El: +10ft.

 Pile Type Driven Pipes with Concrete Fill Pile Section PP42x1 Material Steel Fy = 50ksi, Concrete 3ksi Pile Depth 36 ft

Table 2: Steel Pile Section Properties

B. DEEPFND/HELIXPILE SOFTWARE – SOIL TYPES AND BORINGS

C. DEEPFND SOFTWARE – PILE SECTION PROPERTIES

In this example we will use 42in diameter steel pipes (PP42x1) driven into the soil. The pipes will be filled with concrete grout. Figures 4 and 5 present the pile type and length, and the pile section properties respectively.

D. PILE GROUP – DIMENSIONS AND LOADS

In this case, we will design a 3ft thick concrete rectangular pile cap (25ft x 25ft), supported by 9 piles (PP42x1). The 8 piles at the perimeter of the cap will be battered piles (75deg inclined from horizontal & and locally rotated along the global z-z' axis to point outwards). An additional 2800 Kips vertical load and two lateral loads (250 kips along the local x and 140 kips along the local y directions) are applied on the pile cap centroid. Figure 6 presents the pile cap dimensions and the loads applied on the cap centroid. Figure 7 presents the loads are presented on the pile cap centroid (side view).

E. PILE GROUP – PILE LOCATIONS AND GENERATED MODEL

In this case, 9 piles (PP42x1) have been distributed to the pile cap. Figures 8 and 9 present the piles layout (pile center local x and y coordinates, local rotation angle) and the generated 3D model respectively.

F. PILE GROUP – PY SPRINGS ANALYSIS RESULTS

G. PILE GROUP – 3D FEM ANALYSIS RESULTS