This World War II era pier is still in great shape today because the designers of that era were pretty sharp. They knew the importance of keeping the timber wet by constructing the deck very close to the tide level. Another neat feature may not be so obvious. The pier was constructed with about five feet of fill dirt piled on the deck. This, of course, raised the working surface well above the water level but, more importantly, added the required mass to the pier for its lateral stability.
Piers are subjected to lateral forces from docking ships and wind loads. These lateral forces must be carried to the sea bottom through the piling. Typically, batter (sloped) piles are paired with vertical piles to resist the lateral loads. The pair of piles act together (in the shape of an A), one taking the load in compression and the other pile taking the load in tension. Piers built with concrete decks can effectively lock the compression and tension together, in the concrete deck, thereby transfering the vertical component of the force from one pile to the other. The wood framed pier, pictured above, was not afforded this connection. The wood pile cap just rests, by gravity, on top of the pile. So when a lateral force strikes, what keeps the pile cap from lifting? How is the vertical component of the batter pile resisted? The five feet of dirt acts as the downward force and thereby resists the lateral load.
