Designing a Super Tall Skyscraper Document Transcript
THE SHANGHAI TOWER CASE STUDY
Once completed in 2014, the Shanghai
Tower, a super tall skyscraper, will be the
tallest building in China and the second
tallest in the world. Undertaking the
design for such a mammoth project is no
easy feat. With all the complexities,
issues, and possibilities involved, what
important lessons can be learned? What
are the main highlights of this iconic
building? And why did Marshall Strabala,
Shanghai Tower’s Chief Architect said, in
exclusive interview with IQPC’s Darwin
Jayson Mariano, that in designing façade
for super tall skyscraper, “movements”
matter a great deal?
BY: DARWIN JAYSON MARIANO
PHOTOS COURTESY OF NICKY ALMSBY and
Like a battle of two Goliaths, emerging economies from Latin
America and Southeast Asia are toughing it out in the world
stage as both regions try to outdo each other in the arena of
Private Equity deals and investments. According to data
released by the Latin American Private Equity and Venture
Capital Association (LAVCA), private equity (PE) and venture
capital (VC) investing in Latin America hits 5-year high in 2012
with firms committing a total of $7.9 billion, representing 21%
increase over 2011.
Darwin Jayson Mariano: What is your definition of
‘high performance building facade’? Do you notice
a pattern or trend when it comes to envelope
engineering/design, particularly in China?
Marshall Strabala: “High performance building
façade” is a label that we attach to a building to say
that it’s very sustainable. Basically, this label refers
to a unitized system that is factory built to highperformance specifications, be it for high- or low-rise
Installing a factory-assembled exterior wall system is
a lot easier, safer, and advantageous than
constructing a system on the building from
individual parts. The latter is a basic stick system,
and the former is a “unitized system”. In a unitized
system, your tolerances are tighter, and more
consistent. You can actually get 8mm joints that
work better because, when you construct a glass and
aluminium wall in situ, weather dominates the
process. That is wind, rain and temperature can have
big impact on the wall. The contractor has to fight
the elements in a stick system, where a unitized
system is created in a controlled factory
environment at the right humidity and temperature.
The High performance coating we use on glass need
special handling to produce a well-sealed building.
Dust and dirt is another factor that goes away when
not building in situ.
Right now, China is on an upward curve – it’s
approaching the standards of Europe and America,
and I imagine they’ll overtake these standards in a
few years. So the next step is understanding the
patterns that are transferred when it comes to
envelope and engineering design.
The trend in Asia is moving towards high quality and
energy efficiency. Most building performance
criteria is controlled by the government, and there
is a certain minimum performance that the
envelope of all new construction must meet. In
addition, the building must be safe for the public,
and this is why we are seeing more laminated glass
walls to limit the chance of large glass shards falling
Because of higher performance requirements and
sustainability goals of clients, the façade is getting
to the point where we have to increase the number
of layers in the skin to reduce the amount of energy
that transmits through the façade. We are seeing K
values of 1.4/1.35, whereas a couple of years ago we
were seeing K values of 1.6/1.7. Today, the total
envelope of the building has much more stringent
insulation requirements than it used to, and this will
continue to rise in the future.
Please talk about your recent project, the
Shanghai Tower. Could you discuss some of the
building’s highlights and design strengths? How
would you characterize its envelope design?
The Shanghai Tower has a very ambitious design. It
will be the world’s tallest double skin building. From
the beginning, we tried to minimize the amount of
façade on the building in order to increase the value
of the Project. Basically, what we’re designing is a
thermos bottle, a bottle within a bottle that actually
increase the insulation value of the building. This is
like wearing a sweater. You can take the sweater off in the summer,
and when it gets colder, you can put it back on to achieve the desired
level of comfort. The double skin allows us to use less energy per year
than a single skin building.
The outer skin or what we call the A wall is not attached to a slab. The
A wall is attached to a 350mm dia steel girt, that is from 2 – 12m away
from any concrete slab – so there is no adjacent area to install the
wall. Yuanda and the General contractor developed a unique set of
hanging platforms to install both the Curtain wall Supporting structure,
and the exterior wall.
Most super tall buildings are only for the use of the tenants, and this
means 95% of the building is not public. The public is only allowed on
the observation deck through the purchase of a ticket. The Shanghai
Tower from the beginning was a building designed for people – both
public and private. The completed building takes advantage of the 5 sky
lobbies that not only reduce the size of the core because we can stack
the elevators, but also create vertical neighbour hoods containing
restaurants and other public uses. We call these “Amenity Floors”.
This double skin system allows a building to have an enclosed atrium
space at each “Amenity Floors” for extra public space beyond the
lobby. This “in-between space” allows public access to the edge. Levels
22,37,52,68 and 101 are designed like this. The 83 floor contains a pool
and gym, and 118 and above are for the observation population.
The double skin is created in eight zones, where each zone has a central
cylinder of useable space surrounded by a rounded triangle. These
crescents in the atria are from 12m to 7m deep. Therefore, when you
The Shanghai Tower has a very ambitious
design. It will be the world’s tallest double
- Marshall Strabala, Chief Architect, Shanghai Tower
get to the edge of your office, you don’t feel like
you’re more than 14 stories above the atria, but in
reality you are 50 -60 floors above the ground. It’s a
very comforting feeling that if the glass broke, you
wouldn’t be hanging out in the middle of space 70
Architecture is the art of making buildings both
beautiful and safe. In the Shanghai Tower, there are
redundant safety features. The exterior wall on the
outside of the building or the “A Wall” is two pieces
of Low-E and low iron glass laminated with a product
call SGP by DuPont. This is the strongest lamination
system we have in the industry, and it creates a very
safe environment if a glass panel should break. This
lamination keeps the broken pieces of glass from
falling and causing injuries. The BME system is
designed to both clean and replace the windows. All
the system’s materials are chosen for the highest
level of performance and sustainability. .
The inner wall or the “B wall” was originally thought
to be a very simple and easy design; however it
became the most technically complex wall I have
ever worked on. Conversely, we thought the outer
skin would be very complicated, but it turned out to
be very easy instead. John Perry was the façade
consultant on the project, and his background in
structural engineering helped us with the interface
of the “Curtain Wall Supporting Structure” – CWSS
The inner skin is a very rare system because of the 1
hour fire separation required between the office
space and the atria. The core of wall is a formed steel
tube clad in aluminium and glazed with a DBF high
temperature glass. This glass wall achieves both the
fire rating and visual requirements.
The lessons we learned was to always go in with
open eyes and be prepared for the worst, and just
jump for joy when something works out very well.
One of the biggest challenges is where the two wall
come together and create a structural link to the
primary building. There are three points where the
CWSS is linked to the base structure actually
touching the façade of the building.
The inner wall could actually be bolted to the slab,
and you could actually work from the slab and have
workmen and materials being delivered from the
slab area, like in any other building on the planet.
However, for the outside skin, there’s no slab, or
sometimes the slab is 10 meters away, so it’s a lot
harder to install the equipment or the exterior wall
panels. You need a platform adjacent to it as you’re
installing it, so one had to be developed and installed
by Yuanda, the contractor who’s doing the outer
skin. Yuanda, the fabricator, installed on a special set
of moveable platforms. As the façade is going up,
our role becomes that of quality control and we
assist in any odd conditions that could come up. We
work with all three contractors: Yuanda, Jangho,
and Lingyun to refine the design and make sure the
detailing is quite tidy and looks good from all angles.
In proposing a façade engineering design, do you
see a conflict between aesthetics and ROI?
Always! All commercial buildings, anywhere in the
world, are built for a return on investment. Even
museums are built to a budget. Buildings need
identity, just like people. Some attract people to the
city and others bring people to different parts of the
city. A large corporate office building or hotel
expects a certain level of return, and every operator
has a different set of criteria. These design criteria
set the cost, acoustics, and performance levels for
the project. If done at the beginning the project
becomes better. If changed often during design and
construction, it will lead to a less than satisfactory
result. Every hotel operator requires acoustic
separation from room to room, and the façade must
meet this criteria. This is done so guests in one room
don’t hear the people in the next room through the
façade. Putting acoustic separation between hotel
rooms is rather easy through drywall and insulation
but sometimes, the weak point is in the façade or the
interface between wall and façade.
So, this struggle between return on investment,
performance and aesthetics is always out there, and
what you try to do is to achieve the criteria with as
minimum amount of material as possible. This
minimum amount of material always has a safety
factor. The wall should be robust enough so it does
not deflect when the average wind blows or creak
and break when the building moves.
In all exterior walls, movement is required. In super
tall buildings, the movements are more extreme and
require another level of solutions. Too much
movement and the wall leaks, not enough and the
wall breaks under pressure. In terms of ROI, the
exterior wall of any building is about 20% of the cost,
yet the wall is 90% of the look of the building. This
piece of equipment is an investment and should be
treated as such. You need to maintain it, clean it ( at
least twice a year) and repair it, and even replace it,
because it really contributes to the image of the
building and the image of the building is the first
thing people react to. Buildings gain reputation. If
something does not work well, people talk and the
building becomes a bad place to live or work. This
Curbside feeling of quality is very important to
leasing. Also, if you let the dirt build up on the
façade, it will take longer to clean and hurt the
image of the project. So is it easy to clean? Is it easy
to replace? Does it look good between cleanings?
These are the question we always ask.
Here’s a key thing: if you can design your façade so
the dirt and the rain don’t actually show up between
cleanings, you’re ahead of the game. The gaps
between the façade pieces actually channel the rain
and the particles in the air, so it doesn’t look like it’s
dirty between cleanings. That’s what we strive to do.
We try to plan where the water goes so we’re not
getting stains and dirt doesn’t build up where we
don’t want them; we always specify weeps in our
building to get internal moisture out of the building.
We actually look for a high return on investment not
5 or 6 years, but 50 years, and I think that looking
longer-term is the right way to do it.
Do you think building owners are receptive to these
Yes, all building owners want a good ROI and these
criteria help improve the profit. Sometimes with very
complex and unusual shapes the fabricators can help
you achieve the right aesthetics with the lowest cost.
The owner sets the price, the architect sets the look,
the façade team sets the performance and the
fabricators pull them all together. And sometimes,
the fabricator comes up and says, if we change this
and adjust that, we can reduce the cost of façade and
make it look like 90% of what the architect had in
mind. You should always be a little flexible and listen.
Allowing the fabricator input early on is always good
for the ROI.
Once completed, the Shanghai Tower will be the
tallest building in China. What important lessons
one must learn in designing façade for super tall
The lessons learnt are Movement, Movement and
First of all, the overall movement of the building.
This can be as much as two meters at the top! The
distance the building moves must be accounted for
in the façade. From a comfort standpoint, you need
to control the acceleration, not the distance. It’s
important to fine-tune the structural system to allow
enough movement so earthquakes and wind forces
are balanced and correctly mitigated. This overall
movement is very high at the top and very low at the
bottom. Panels at the top can be significantly
damaged, while the panels at the bottom of the
building might not have much impact at all. In super
tall buildings, the details might change as you go
But there is fourth movement that you need to be
aware of, especially in this idea of a double-skin
building: the movement induced by high
temperatures, or fire. We don’t want fire to cause
breakage and movements in the structure that
might cause something else to break. In the rare
event of a fire, you need to make sure that smoke
does not migrate from one part of the building to
another. We also need to think of what a fire does to
the façade, which can result in pieces falling off.
Thirdly, after the fire is out, did the temperature
impact the system that might make it unsafe for the
fireman who is putting out the fire? We have to
make sure that there are no “second-order
repercussions” from a fire. This gets very
complicated and we often employ RJA as a fire
consultant to review the work.
At the end of the day, it really comes to down to
Movement, Movement, Movement, Movement, and
even more Movement.
The second movement pertains to all the nonreversible changes in the size of members (i.e.,
column shortening). Under loading things change.
In super tall buildings, this can be very significant.
Then there is settlement of the entire structure that
might affect the façade. There is movement vis-àvis deflection. Deflection is the reversible beam
movement under load. So we have to account for
that when designing the façade system. If we had 12
meter long beams, the exterior wall panels need to
accommodate this centre beam deflect so as not
to lockup under the overall building movements.
Panels in the middle of the span need enough
adjustments to make the appearance level on the
outside of the building.
Then we get to the third, a non-reversible
movement in tall buildings, called concrete creep. As
you start stacking these floors on top of each other
and going up to, say, 120 floors, the columns start to
get a little shorter on the ground level. So you have
to plan for that column shortening either in the
façade or in the concrete itself. Generally, we start
adding taller “stack” joints in the façade at the
bottom than at the top.
Marshall Strabala AIA AFAAR LEED ap. is the co -Founder and Design Partner of 2DEFINE Architecture.
He is an American architect, living in Shanghai, who has lead the design team of three of the ten tallest
“constructed” buildings in the world. For the last three years, Strabala has been the principal of his own
architectural firm, with over 30 years of combined experience. He was an Associate Partner at SOM in
Chicago, and the only Director of Design M. Arthur Gensler Jr. & Associates, Inc. Currently, Strabala and
2DEFINE Architecture are the chief architect for the Shanghai tower scheduled for completion in 2014.
Hear more from Marshall Strabala and other distinguished speakers at the 3rd Annual Facades Design and
Engineering China 2013, happening on 18-21 June at Shanghai, China.
About the Author:
Darwin Jayson Mariano is the Online Content Manager and Regional Editor - Asia for International Quality & Productivity Center
(IQPC), a leading producer of events and conferences for business leaders around the world. Connect via LinkedIn or email
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