Civil Engineering Reference
In-Depth Information
FIGURE 13.28
Pile load test data. This plot shows the actual data recorded from the pile load test shown
in Figs. 13.26 and 13.27. The vertical deformation is the average displacement recorded by the dial gauges.
The axial load is determined from a load cell.
Once the grade beams have been excavated, the next step is to trim the top of the pre-
stressed piles such that they are relatively flush, such has shown in Figs. 13.31 and 13.32.
The strands at the top of the pile are not cut off because they will be tied to the steel rein-
forcement in the grade beam in order to make a solid connection at the top of the pile.
3.
Installation of steel in grade beams:
After the pile caps and grade beams have been
excavated, the next step is to install the steel reinforcement. Figure 13.33 shows a close-up
view of the top of a prestressed concrete pile with the steel reinforcement from the grade
beam positioned on top of the pile. Note in Fig. 13.33 that the strands from the prestressed
pile are attached to the reinforcement steel in the grade beams. This will provide for a solid
connection between the pile and the grade beam. Fig. 13.34 presents an overview of the
grade beam with the steel reinforcement in place and the grade beam ready for the place-
ment of concrete.
4.
Floor slab:
Prior to placement of the floor slab, the visqueen moisture barrier and
a gravel capillary break should be installed. Then the steel reinforcement for the floor slab
is laid out, such as shown in Fig. 13.15. Although not shown, the final step is to place the
concrete for the floor slab.
5.
Columns:
When the building is designed, the steel columns that support the super-
structure can be positioned directly over the center of the pile caps.
Similar to the pier and grade beam foundation, a main advantage of the prestressed pile
foundation is that there are no open joints or planes of weakness that can be exploited by
