Posts
Houses and buildings located along coastal areas are often susceptible to storm surges of ocean water, especially during hurricanes and extreme weather events. The damage done by this violent weather can be exacerbated by high tides.
These buildings are typically placed atop wooden posts and pilings. This configuration allows a storm surge to pass under the building, so that the building itself is not struck by the full force of a storm surge. The forces of wind, water and wave are unrelenting for a building located along coastal plains, with a close proximity to the ocean. They are constantly under a barrage or attack by the forces of nature.
As Sea Level Rise (SLR) increases, the effects of wind water and wave are more pronounced on waterfront properties. Failure of the support systems currently used to keep these buildings above the plain of storm surge have become more common. It is expected that this situation will become more widespread and increasingly worse as SLR continues. Recently, failure of these support structures has taken place, especially on the Outer Banks of North Carolina. An article in today's USA Today (May 29, 2024) describes some of this damage.
There is a better way to keep a building located in a coastal plain elevated, other than the old, vulnerable method of using wooden posts. High-strength masonry arches, made with an appropriate concrete mix, and reinforced with basaltic FRP (Fiber Reinforced Polymer) rebar provide a very stable configuration. The high strength of concrete exceeds the strength of wood. The proper concrete mix, suitable for marine environments, can last much longer than a piece of wood. The arch configuration of this type of support structure is better able to withstand the lateral forces which are created by waves, wind and water; much stronger and more robust than vertically placed wooden posts.
This method can be rapidly assembled (done in just a few days), it is cost competitive with wooden posts, and it creates a visually striking pedestal for the building. The arches also provide easy access for parking, so the area underneath the building can be readily used. Any number of platforms can be placed on top of the arch support structure, including reinforced flat concrete slabs, bubble decks, post-tensioned slabs, and so on.
Last summer, we made a concrete ping pong table (table tennis) out of concrete. The legs for the table were made as arches. using basaltic FRP rebar, cast within the concrete forms. This served as a scale model for a structure which could be used to support a building in a coastal plain, subject to storm surges, wave, wind and water. One can imagine this configuration made around 10 times larger; it would provide the perfect platform for building a house in a coastal flood plain, with parking underneath.
The scalability of these designs is easy to grasp, if one looks at some of the larger arches made from our "Arch" block, which is assembled with 3 pieces of basaltic FRP rebar, as shown below (this shows a 30 ft. span). This configuration is very strong. The straight sections, or legs, as shown on the corners of the ping pong table can be made from regular CMUs, where the hollow cores are reinforced with grouted FRP rebar.
This method will allow houses to be built on very strong, affordable, long-lasting, elegant support systems which will allow them to survive further into the future in coastal areas prone to storm surges which are vulnerable to SLR. This will make coastal homes more resilient.
