FEMA P55 Coastal Construction Manual, Fourth Edition - Mad Cad

10 DESIGNING THE FOUNDATION Volume II
For timber piles, if the connection is too close to grade, the bolt hole
is more likely to be flooded and subject to decay or termite infestation,
which can weaken the pile at a vulnerable location. All bolt holes should
be treated with preservative after drilling and prior to bolt placement.
Knee Bracing
Knee braces involve installing short diagonal braces between the upper portions of the pilings and the
floor system of the elevated structure (see Figure 10-12). The braces increase the stiffness of an elevated pile
foundation and can contribute to resisting lateral forces. Although knee braces do not stiffen a foundation as
much as diagonal bracing, they offer some advantages over diagonal braces. For example, knee braces present
less obstruction to waves and debris, are shorter and less prone to compression buckling than diagonal braces,
and may be designed for both tension and compression loads.
The entire load path into and through the knee brace must be designed. The connections at each end of each
knee brace must have sufficient capacity to handle both tension and compression and to resist axial loads in
the brace. The brace itself must have sufficient cross-sectional area to resist compression and tensile loads.
Figure 10‑12.
Knee bracing
NOTE
Bolt holes in timber piles
should be field-treated
(see Chapter 11).
10-30 COASTAL CONSTRUCTION MANUAL