Recommended Reading: Philip Jodidio and Janet Adams Strong, I.M Pei: Complete Works, Rizzoli 2008
Bank of China Tower is a 70 story 1205ft skyscraper located in Hong Kong. Completed in 1990, it was the first building over 1000ft in height to be constructed outside the United States. The tower was designed by the noted architect I.M. Pei and engineered by Les Robertson. While Pei wasn’t very interested in designing skyscrapers, he accepted the commission partially due to a personal connection: his father had once been a manager for the bank. He looked for a way to express a reason behind the great height of a tower and that led to a structural expressionism approach.
The small site and space requirements of the building program dictated a tall tower. The budget however was fixed at a mere $130 million. A highly efficient design would be needed. In contrast the nearby rival Hong Kong & Shanghai Banking Corporation (HSBC) headquarters, designed by Norman Foster, had a similar amount of office space but a budget nearly five times greater. It had turned out to be one of the most expensive office towers ever built. Pei's design needed to avoid cost overruns and excessive material useage.
The tower geometry is a 54m square base in plan divided into four triangular quadrants that rise to varying heights giving the tower a unique shape. The inspiration is said to be from bamboo shoots. It’s a simple concept, but the building's form radically transforms with viewing angles making it appear much more complicated. The structural cross bracing pattern is expressed on the façade, but the actual structural elements are hidden behind the glass. The Bank of China occupied the larger lower floors and leased out the small upper floors while maintaining an impressive board room on the very top floor. That space is nicknamed The Barn due to its vaulted glass ceiling.
Robertson devised a highly efficient structural space frame using steel corner mega columns encased in concrete to deal with eccentric column loading distributed from the central column. Rather than create geometrically complicated (and expensive) welded joints at all the structural intersections, the steel beams are simply joined via concrete nodes. The building is designed to withstand sustained 140mph typhoon winds and earthquakes found in the region.
The tower design has been accused of bad feng-shui due to the cross bracing pattern and sharp edges. At the request of bank officials, Pei changed the original concept to remove the horizontal expressions on the façade, thus changing the “X” pattern to one of diamonds. The trusses themselves remained hidden beneath the glass façade.
The design for the LEGO model came together rather quickly. I drew some inspiration from David Drake’s pioneering model, but realized that to build at a much smaller scale a unique internal structural system was required. The resulting model is a hybrid of System and Technic LEGO elements. As a bonus, I built a second model with the façade removed to illustrate the underlying structure. I highlighted each of the main components in different colors. To visualize things better I recommend examining the high resolution photos on Brickshelf.
This is an underside plan view of the basic structural system. All the major systems are represented here.
White - major vertical exterior columns. These resist overturning bending. However all the cross bracing is cosmetic and non-structural.
Grey - 3x3 Technic central core. The core supports and partially envelops the 1x1 brick-built central column. The Technic axle corners of the core terminate at different levels depending on the module and also provide connection points for the yellow outriggers. Only the brick core runs the entire height of the tower.
Red - Shear walls connecting the four external columns to the central core column. As they carry up through the building they gradually become trans-blue exterior walls before terminating at different heights. Bars and clips attached with bits of flex tubes to headlight bricks constitute the cross beams on these segments.
Yellow - Outrigger supports for the facade. They provide attachment and support the trans-blue facade behind each of the complete X's and help tie the shear walls together at select points.
I took three major design liberties with my model.
1. I used white for the exterior structural elements. The actual building is clad in highly reflective aluminum. On sunny days the building can appear near whitish in photographs and I felt this looked more beautiful than if I had chosen light grey. The fact that the clip elements used on the cross bracing are available in white, but not light grey, probably sealed the deal.
2. I chamfered the corners of the building to make them appear thinner and also to better flow the form into the central column. The actual building has square corners, but hey, what building doesn’t look good with chamfered corners?!
3. The structural cross bracing of my model is external structure on top of the facade. In the real tower, the bracing is only expressed with diagonal paneling on the exterior glazing. However nearly every LEGO representation of this building is forced into this compromise. I tried to keep these elements as thin as possible.
Great work Spencer! Another gorgeous creation, and as is almost always the case, ground-breaking building techniques. This is a rare view into the inside of one of your structures to see how it is all put together, and well worth the look!
From the thumbnail, I assumed that this was a build with an interesting shape achieved by using a big scale and a lot of bricks. The photos showing the internal structure suddenly reveal how complex and quite beautiful, a piece of engineering this is. It was also interesting to be let into your thoughts when designing the MOC. Excellent building indeed.
Impressive! Thanks for showing the insides of this, too. Always interesting to see how people come up with design solutions. Well done, Chief!
I like it
September 2, 2014
Very impressive! The overall finished result looks fantastic -- it's hard to tell that it is made of LEGO bricks in all of the pictures except the close-ups. The structural model is very revealing, and is a nice addition.