City Foundation

* See also Construction of Rapture
* See also Concrete IS Your Friend
* See also Tunnels
* See also Rapture_City_Layout
* See also Rapture_Cityscape
* See also Utility_Stuff
* See also UnderWater_Construction
* See also Airlocks
* See also TechnicalDrawings (Diagrams)
* See also Trams
extract foundation detail description from Concrete IS Your Friend
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The City Foundations :
* The Building Foundations of the city of Rapture were built/embedded into the irregular seabed ( Rapture is located on the side of an ancient undersea volcano ) to support the city's buildings and other structures. In some places they go deep into looser rock and sediment to reach bedrock.
* The Foundations are built out of water-setting concrete, and have a significant volume/mass to properly support/anchor the heavy buildings. Rapture's taller buildings would need larger Foundations to secure them properly.
* MANY Shiploads of the special cement were needed for the huge volumes of concrete used ( Concrete is a combination of cement, sand and aggregate(rock filler), and water ). US Mainland cement plants would be the most cost-effective source. Appropriate Aggregates could be produced locally.
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The Rapture Underworld :
You frequently see on my revised maps, the Foundation level contains various utilities, is the location of maintenance airlocks, and having large cells full of bulk concrete filler to anchor the building to the ocean seabed ( usually with pilings going deeper ). That foundation concrete contains ALOT of aggregate/rock to form a large solid mass. It wedges into holes excavated into the bedrock, so to solidly anchor the primary building structures. 
Inspection/Access Tunnels within the Foundation mass give access to multiple divided sections, all separated/sealed with simpler (cheaper) manual pressure doors ( like those on Submarines ). The buildings always seep ( and the unheated walls precipitate humidity continually ), and so there is a system of Sump Pumps and channels to drain that seepage - including from the floors above (behind false walls, as the concrete seeps slowly there too). 
There are various/numerous Utility conduits and machinery used to distribute the required Heat/Air/Water/Waste/Ppower/Communications/Pneumo.
This is a whole part of Rapture you hardly got to see in the Solo Games ...
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Heeeeere's Johnny... :
Looks like one of the Tunnels in the Concrete Foundations underneath Rapture's buildings ( YOU ARE IN A MAZE OF TWISTY LITTLE PASSAGES, ALL ALIKE A reference from an early text computer game... ) ... These interior Tunnels allow the foundations to use significantly less concrete than if they were made solid, and facilitate relieving of stresses in the mass concrete as it set. They also allow internal inspections of structural integrity. The remaining Foundation mass is still more than sufficient to support and anchor the building built atop it.
MMORPG Missions can use these fairly generic Tunnels as reusable Destinations/Paths ( Who will remember where they were led in the maze ?? ), and it is easy enough to programmatically create them 'On-the-Fly', and to be extended as needed.
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== Diagram Building and Foundation : ==
Note : This building ( less its Foundation ) is not even 20 stories high.  Go back and see how many were shown to be 40 or even 60 floors ( if the rows of windows denote floors ) in the exaggerated Outside views of the Cityscape.
* Central Core of building running to height of building :
** Elevator shafts (2 passenger, 1 freight)
** Utility 'building mains' tube with access ladder ( Power, Heat, Air, Water, Communications, Waste )
** Stairwell linking all floors
** Notice how much space the utility core takes up from each floor of the building.
** Separately water/pressure sealed
* Thick Walls of reinforced concrete (Ryanium ? and Steel Rebar)
** To not just hold up the multi hundred foot structure but also to hold out the sea pressure.
* Floors :
** Interchangeable floor layouts for different purposes/needs (commercial, residential)
** Compression struts (structural) to counter external sea pressure (280+ psi) on walls every couple of floors.
* Basement with elevator and environmental control machinery (and sumps/pumps)
* Windows of 'super glass' insets with Ryanium framing set into walls.
* The Foundation is a mass of water setting concrete ( cut deep into the seafloor and bedrock to stabilize the tall building ).   Many smaller buildings may NOT need a large Foundation - particularly the tall part shown here above the seafloor ( or like many game views which was done as a graphical simplification ). 
** The Foundation would need sufficient excavated depth BELOW the seafloor to anchor the large building properly. 
** This diagram has a rather over-sized Foundation (costs more), and it would be simpler to construct most buildings on solid seabed closer to a 600 foot (or less) Depth. Excavation of volumes of rock to 'level off' areas would not be too hard.
** Filled with 'Plumstones' - large solid rocks used to save on concrete to build that mass ( being something like half the volume )
** Filled with chambers/tunnels to save on concrete, and to provide secondary storage.
** Inspection tunnels at various levels to check for leaks/structure failure (during Construction)
** Airlock at seafloor level for maintenance access (with internal stairwells)
* Water tanks on top roof level - for fire suppression systems and local water supply pressure.
* Optional Bathysphere/Submarine dock ( simple type - those Metro stations take up very large spaces )
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A Journey Through 'The Rapture Catacombs' :
* There are numerous Tunnels/chambers in the foundations employed to reduce the amount of concrete required ( and to assist in the cements proper setting ). The early construction Tram tunnels running everywhere also are largely intact.
* These passages were usually sealed after construction was completed, but many were later opened for storage or 'other' uses.
* Many of the construction plans were lost and the networks of Foundation tunnels are largely unexplored.
* Players can access the Tunnels, as the openings are usually in the basement level of most buildings and structures.
* Expeditions into these tunnel complexes should include surveying them for City Achievement credit.
* Alot of abandoned and forgotten equipment and other 'odd' items have been found in these tunnels.
* By MMORPG times, more than a few of these sealed 'Catacombs' are filled with icy water from slow leaks. Others are kept dry by the drainage systems originally built into them ( or just were well water-sealed to begin with )
* Warnings about stagnant air and poisonous gases accumulating should be observed and proper precautions taken.
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The Sub-Level of the City : 
This is generally the areas below the 'Street' level :
* Includes the Foundation 'Catacombs' ( access passages )
* "Below the Tracks" is a term referring to less desirable levels generally below the Street level ( and the Trolley Tracks ). Some residences were built in that lower part of various buildings.
* Basement machinery within buildings, as well as Sumps ( draining rest of building )
* Also location of building Airlocks to give access to the seabed.
* Secondary Tram system at 'basement' level for garbage handling and freight/maintenance service.
* Sewer system
* Utility systems
* Maintenance power systems ( redundant to power mains ) usually located down there. Power cables from the construction era run adjacent to the Trams ( a passage which can be used if a building is otherwise cutoff ).
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In the BS2 Ryan Amusements, the museum exhibit shows divers working on girders to allegedly build Rapture's Foundation.
* Steel does NOT like Salt Water (Corrosion). The BaS Aluminum Stupidity, likewise.
* Divers cannot exist at that depth in that kind of suit
* Tedious manual work is made far more difficult and costly when done deep underwater ( substitute Remote controlled automation ).
* Sorry, Riveting was just too primitive.
* There seemed to be Talk of 'The Sinker' ( that submersible platform used in City Construction) being used as 'the foundation' ( as if Rapture was one lump and 'The Sinker' was huge enough for the City to sit upon ) was another 'plain wrong' mention.
It is all a very heroic image, but should be corrected for the Rapture Reborn MMORPG.
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Many passages would exist below the Streets of Rapture to access utilities and sump drainages. The access-ways go thru masses of anchoring concrete and are partitioned by Submarine-type doors. The Big Daddies would do alot of clomping up and down such stairways.
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Rapture had some views like this to avoid rendering anything more detailed.
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Infrastructure Is Under There :
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