FRP Decks One Deck vs. Two Decks
On top of the joined floating units will be a FRP deck similar to the ones increasingly used, for its many benefits, on bridge decks. The deck will cm ( in) thick when over floating units (ca. % of an HC's total surface area) and cm ( in) elsewhere. It is projected to have a density of kg/m3 ( lbs/ft3) and have an average weight load of kg/m2 ( lbs/ft2).
Examples of FRP Bridge Decks in Use
There is a somewhat open debate as to whether to build the HC with two habitable decks or just one. Currently the choice of a single deck has been made because the advantages (mainly space-wise) of a second, sub-surface deck are not really needed. If the population at an HC were to go significantly beyond its set limit of , then this sub-deck, which would be up to 9.1 m (30 ft) high, (and could potentially be subdivided in up to three sub-decks as the pointed local need is), would be advantageous. Other reasons for currently using a second sub-deck would be:
-For the housing of metro lines/stations and most manufacturing and utility facilities ("grey spaces"). They would then not be seen on the main habitable deck and would free up more space to be used for "green space." But current layout calculations based on a single deck plan show that there currently is sufficient space for both these planned/needed "grey spaces" and "green spaces." Metro lines and stations can also safely be submerged and thus double as floating units.
-To provide homes and certain buildings, (e.g., churches, schools, stores etc.,) with basements which could also, as an extreme safety measure, double as a water-tight float-structure for the construction above it. The presence of evenly spaced floating units directly under the main deck, as it will be in a one deck configuration, do not permit the building of a basement under each house. Space-wise, a basement would be a interesting addition to a house, but is not really a must, and can easily be replaced by an above surface storey. A water-tight float-structure can be incorporated in the design of an above surface crawl space, just under the first main floor. This space underneath, e.g., a house, would not have to be high in order to displace enough water to keep this house afloat. As an example, to support a large house having an area of m2 ( ft2) weighing up to kg ( lbs), this crawl space would have to be at a minimum only cm ( in) high.
-For reasons of comfort, as being up to 8.3 m (28 ft) from the level of the ocean (the floating unit's clearance of m ( ft) + the up to 6 m (20 ft) of a sub-deck), could provide a feeling of not being at sea at all; but since one will actually not be able to see the ocean except if standing on the edges of an HC, nor feel its movement due to the sheer total weight of an HC, (just like when on board a large cruise ship), then whether one is 8.3 m (28 ft), or 31 m (100 ft), or only m ( ft) above the ocean's surface level, would not be noticeable nor make a difference.
So based on all of this, and for the added benefits of the saving of otherwise unnecessarily required raw materials/resources and construction time, a single deck configuration satisfactorily meets the need of a normal HC. As stated earlier, only an increase of the population beyond currently projected limits would necessitate a second deck to continue to provide adequate living space for everyone. But based upon detailed population model and projections this would not be necessary for many years in the future (i.e., a projected years to be exact). Even then, a single-deck HC can gradually, easily be "scaled up" to a two-deck (sub and main deck) configuration with whole houses being hoisted up to the new main decks, and with some rearrangement|conversion of the current first floors of larger buildings to then become the basement floor. June 20, 2011
One Deck vs. Two Decks