Introduction
The Canton Tower is the 2nd
tallest observatory in the world standing at a height of 600 m. It is situated
alongside the Yijuan Road in the Haizhu District of Guangzhou, China. Several
famous landmarks surround the tower such as a few pagodas and a park, several
high-rise apartments, buildings and skyscrapers. The tower appears as a luminous icon on Guangzhou’s skyline. An interesting feature about its lighting is that every node in the LED lighting design is individually controllable to allow for animations and color changes across the height of the tower.
Parametric Modeling
The main body of the tower is 460 m combined with another 140 m antenna. The tower’s twisted shape or hyperboloid structure is a state-of-the-art design. The form, volume and structure of the tower is generated primarily by two ellipses, one at ground level and the other at the top of the main body. Other series of ellipses are defined at various key elevations to place the mesh elements. The
center and the orientation of these ellipses change with elevation which are defined parametrically with respect to
elevation. Also, the major and minor radius of the ellipses change with elevation, the ratio of which is assumed to be a constant.
 |
| Fig 1: Ellipse at Ground level (+0.0 m) and at top of main body (+460.4 m) |
Here, OT is also the origin of the coordinate system. As we move up from the ground level, the ellipse shrinks to the minimum at the waist level (+280 m elevation) thereafter which it opens up at reduced rate as we go further upwards. Hence there are 2 rates of change of radius of major-axis and minor-axis – one from ground level to waist level, the other from waist level to top of the main body. Densification of materials causes limited transparency at the waist level.
The center of the ellipses are determined by the following parameters with elevation (in mm) and angles (in degrees) as functions.
 |
| Table 1: Parametric equations for determining center and orientation of ellipse at different elevations |
Here, ‘x-length’ is the horizontal component and ‘y-length’ is the vertical component of the parametric point with respect to the origin of the reference plane at ground level. ‘Ellipse Angle’ define the angle of major axis of the ellipse with respect to the vertical axis of the same reference plane. The following dimensions are used as a reference for the creation of ellipses.
Ground level
|
Major-axis length
|
=
|
78620
|
mm
|
Minor-axis length
|
=
|
59180
|
mm
| |
Waist level
|
Major-axis length
|
=
|
27500
|
mm
|
Minor-axis length
|
=
|
20700
|
mm
| |
Top level
|
Major-axis length
|
=
|
48310
|
mm
|
Minor-axis length
|
=
|
36360
|
mm
|
Based on the above information, it was found that the parametric equations governing the center of the ellipses at key elevations are –
Length of major axis = 78620 – 182.571*y 0<y<280 m
27500 + 115.355*(y-280) 280<y<460.4 m
where ‘y’ is elevation in meters.
Ratio of radius of major-axis to minor-axis = 1.328
Rate of change of angle with respect to elevation (m) = 0.0847° per m
The key elevations are considered as follows.
Elevation
|
Level Name
|
Ellipse Angle
(in degrees) |
|
460.4 m
|
Open-air Top deck
|
0.0
|
|
424.0 m
|
Revolving Restaurant
|
3.1
|
|
408.4 m
|
VIP Restaurant
|
4.4
|
|
356.4 m
|
Future Development
|
8.8
|
|
174.4 m
|
Sky-garden refuge
|
24.2
|
|
169.2 m
|
Observation Deck
|
24.7
|
|
153.6 m
|
Snack-Bar
|
26.2
|
|
91.2 m
|
4D-Cinema
|
31.3
|
|
8.0 m
|
Entrance at Deck
|
38.2
|
|
0.0 m
|
Ground
|
39.0
|
Table 2:
Key elevations and ellipse orientation angles
 |
Fig. 2: Top View of
outer mesh of the structure model
|
OUTER MESH
24 cylindrical shafts run along the structural column core in a twisted manner. Braces and rings adorn the perimeter of the main body throughout its height.
 |
Table 3: Parameters for
defining radius of shaft, inclined braces and rings in outer mesh
|
The following images show the change in the size of the outer mesh elements.
 |
| Fig 3: Parametric outer mesh elements 1 |
 |
| Fig 4: Parametric outer mesh elements 2 |
CURTAIN PANEL
The curtain panel has a triangular form with rectangular and circular cross-section elements for which the dimensions are parametrically defined.
 |
Table 4: Parametric equations
for Curtain Panel elements
|
The following images show the change in the size of the outer mesh elements.
 |
| Fig 5: Parametric Curtain Panel 1 |
 |
| Fig 6: Parametric Curtain Panel 2 |
MASS MODELING
The mass of the central structure and the outer mesh is loaded into the project from 2 different files since Revit could not create floors when these were loaded from a single file due to the enormity of the structure. The central mass of structure has been divided into 37 floors throughout its height. The mass of outer mesh is placed in position such that it surrounds the central mass. The structure does not contain a roof since it has an open air deck. Curtain panels decorate the meshed curtain system created at the sides of the central mass.
 |
| Fig 7: Exterior rendering |
 |
| Fig 8: Interior rendering |
Thanks and Gig'em!
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