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Physical Model of Skyscrapers with Core, Megacolumns,
Belts, Outriggers, and Diagonals
Stott Huffaker Bushnell
A project submitted to the faculty of
Brigham Young University
in partial fulfillment of the requirements for the degree of
Table 5-1: Stiffness by Configuration ........................................................................................... 23
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LIST OF FIGURES
Figure 1-1: Current Skyscraper Model in Use ................................................................................ 1 Figure 2-1: Empire State Building under Construction .................................................................. 4 Figure 2-2: Framed Tube with Closely Spaced Exterior Columns ................................................. 5 Figure 2-3: Building Heights per Design Method .......................................................................... 6 Figure 2-4: Simplified Core and Megacolumns.............................................................................. 6 Figure 2-5: Core-supported Outrigger Structure............................................................................. 7 Figure 2-6: Building Heights per Design Method .......................................................................... 8 Figure 2-7: 3D Printers Used .......................................................................................................... 9 Figure 3-1: Shanghai World Financial Center .............................................................................. 11 Figure 3-2: Preliminary AutoCAD Model Design........................................................................ 12 Figure 3-3: Final AutoCAD Model .............................................................................................. 13 Figure 3-4: US Bank Center ......................................................................................................... 14 Figure 3-5: AutoCAD Model of Belt Truss .................................................................................. 14 Figure 3-6: Bank of China ............................................................................................................ 15 Figure 3-7: AutoCAD Model of Diagonal Brace ......................................................................... 15 Figure 3-8: Typical Outrigger Truss ............................................................................................. 16 Figure 3-9: AutoCAD Model of Outrigger Truss ......................................................................... 16 Figure 3-10: AutoCAD Model of Floor ........................................................................................ 17 Figure 3-11: AutoCAD Model of Connection .............................................................................. 17 Figure 4-1: Adhesives Tested ....................................................................................................... 19 Figure 4-2: Attaching Connections ............................................................................................... 20 Figure 5-1: Model at Rest with All Elements ............................................................................... 21 Figure 5-2: Deformation with Floor Elements Only..................................................................... 22 Figure 5-3: Deformation with Top Floor Members Only ............................................................. 22
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1 INTRODUCTION
Visual models are important for student learning. A model of a skyscraper already
existed to show students how a tall building will deform under lateral loads and with different
lateral load resisting systems. However, the current model, Figure 1-1, is not ideal for teaching.
Aesthetically, it does not look very good. Also, the structural elements are difficult to put into
place. Each piece has only one location where it fits, requiring the professor to remember where
each part fits.
Figure 1-1: Current Skyscraper Model in Use
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The main objectives of this project were to create an educational model where all parts of
the same element are interchangeable, each element has its own color coding for ease of
identification and instruction, and replacement parts can easily be obtained. By using AutoCAD
3D and 3D printing, all three of the objectives were achieved.
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2 BACKGROUND
Skyscraper Design
The desire to construct the tall buildings is not something new. It can be seen in ancient
Egypt, noted by the increasing height of each subsequent pyramid. This desire continues today
with the building of the Burj Khalifa and the future construction of the Kingdom Tower, which
will reach over a kilometer in height. As construction heights have increased, so too has the
method for reaching these heights. There have been four main methods of the design throughout
the centuries.
From the ancient Egyptians with the pyramids and the Romans with the aqueducts, to the
early European gothic cathedrals, masonry been employed for millennia in the design and
construction of tall structures. These designs relied heavily on the load bearing strength of the
masonry bricks or stone. As can be seen in the pyramids, in order to achieve greater heights,
large bases had to be used to support the taller structures.
The dominance of stone masonry waned in the late 1800s as steel became more and more
prominent in construction. Prior to the use of steel in construction, the tallest buildings were ten
to twelve stories (Leslie, 2010). As building height increased, so did the lateral loads caused by
winds as a result of the larger surface area. In order to resist these loads, more sophisticated
designs needed to be implemented. Whereas masonry relied on rules of thumb regarding wall
thickness and building proportion to resist later loads, steel frames could absorb and direct these
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loads. The Empire State Building, in Figure 2-1, was the tallest building at the time it was built.
The building used steel frames to achieve its towering height.
Figure 2-1: Empire State Building under Construction
In the 1960s, Fazlur R. Khan presented the idea of a framed tube design for high-rise
buildings (Ali, 2001). Prior to this, shear wall and braced structures relied on individual
elements to provide lateral stiffness. The framed tube incorporates the entire building plan for
resisting lateral loads (Paulino, 2010). Framed tube designs are accomplished by closely spaced
exterior columns and relatively stiff spandrels (Khan, 1965), Figure 2-2.