When designing a tall building, two structural challenges increase dramatically with height.
A. Distribution of load to the ground. A skyscraper needs to taper down as it goes up in order to remain stable.
B. Continuous Flexibility. It should be flexible enough to withstand high magnitude of lateral forces i.e. building sway.
Building concepts once merely considered theoretical such as One Mile High Skyscraper are now being materialized and our new conceptual limits stretch beyond farthest atmospheric strata, entering space. It is so because the line where two edges meet, that between earth atmosphere and space, is a man-made construct. So, how do we approach an ultimate tall building which is anchored in planet earth?
Solution in Nature
A very similar scenario of structural forces acting upon an object are found at deep sea level. Lateral movement of the currents cause tremendous amount of sway pressure (air is fluid like water). One of the life forms which have developed a seemingly invincible resistance to such forces is Calliarthon Thalli, a coralline macroalga. This macroalga faces similar extremity of conditions under water which we expect to face beyond our first few miles of vertical construction. Structure of the macroalga follows two important principles:
1. It has calcified fronds which provide a constant buoyancy. This internally embedded, permanent upward force keeps the fronds aiming up vertical.
2. The only parts of this macroalga which exhibit a tolerance for lateral forces (horizontal currents) are the joints between its segments. These joints called genicula provide all the tensile strength it needs to compensate for its tough and rigid segments.
Row1Column1: A Closeup of Coralline Macro-algae
Row1Column2: Viscoelastic Joints of Coralline Macro-Algae
Row1Column3: Size, Strength and Allometry of Joints of Coralline Macro-algae
Row1Column4: Bending of Coralline Macro-algae
Row2Column1: Tube Structures
Row2Column2: Comparison of Tallest Buildings of the World
Row2Column3: Bigelow Expandable Activity Module (BEAM)
Row2Column4: A Conceptual Image of the NASA Transhab
Row3Column1: Inflatable Modular Space Habitat
Row3Column2: Concept of a Spacescraper Hung from an asteroid
Row3Column3: Space Elevator
Row3Column4: Analysis of (Conceptual) 20-Mile Long Spacescraper
Row4Column1: Inflatable Kevlar Tube Concept
Row4Column2: Helium Balloon Tower Concept
Row4Column3: An Example of Biotensegrity
Row4Column4: Filamentosa- An Ultra-Lightweight Skyscraper
Following conclusions are drawn from the sources of research which are presented in the form of a montage above. After comparing construction technology of the macroalga with a high-rise building, it becomes evident that our design prerequisite for a tall building that it should taper down as it goes up becomes redundant in the new system of design. A structural system inspired from Calliarthron Thalli directs toward two new design principles:
- Building should be designed for an upward force instead of the downward gravity. Helium structures and space-grade inflatable architecture helps in the design and selection of materials.
- Structural system of the building should exhibit a discrete mode of flexibility. That is, its compression and tension-based structural components should be separate from each other, unlike in our system of construction where these two elements intertwine and reinforce each other. Lateral movements should be tolerated only at the intermediary layer between two habitat segments. Details of this structure are provided below: