Reaching the Sky

More Really Tall Buildings

In the second instalment of our skyscraper series, Construction in Focus takes a look at some of the world’s tallest buildings. Each with their own unique attributes, construction elements, and histories, these buildings have all made their mark upon the skyline…

I have often been the victim of a dream where I am within the upper floors of a tall building swaying back and forth to the point where I am being flung from side to side of the unit, praying to the creator of glass that the windows I am landing on don’t break and send me flying into the air. The building often sways so violently that before I wake with a start, I am nearly hitting the ground as if inside a giant water wiggle that’s slashing back and forth. The funny part of the dream is that the other occupants of the building don’t ever seem to notice that the building is wagging like a puppy’s tail; somehow, they are used to it.

Obviously, any really tall building is made to sway a bit; at most, a few metres on the very top floor, but they are made to move so that they can be pushed by the wind all day long and not fracture. The engineering, design and planning involved with these concrete marvels is nothing short of amazing. Most skyscrapers are also made to withstand pretty much anything else, save for a few exceptions.

Protection and Peril

On 28th July, 1945, lost in the fog, a B25 Mitchell bomber slammed into the Empire State Building. One of the engines flew right through the building, out the other side to land two blocks away, on top of another building. On 9th April, 1975, five years after the completion of the World Trade Center towers, a horrific fire broke out on the 11th floor of the north tower that raged for three hours, making its way down to the 9th floor and up to the 16th floor. Temperatures exceeded 700 degrees Celsius, but fireproofing prevented the building from suffering structural damage. And on 21st May, 1980, a massive fire at the MGM Grand Hotel in Las Vegas claimed 84 lives and injured 679 people.

In the basement of the 28 story stock exchange building in Bombay, India, a powerful car bomb detonated with disastrous consequences. Terrorist attacks, fires, earthquakes, tornados, hurricanes, and floods are among the things that can destroy a building along with the people who occupy it. The main structures of some buildings are so well designed that they might just survive a nuclear blast, while some may crumble and disappear.

There are a series of systems that should be in place for the safe occupation of a tall building: fire alarms, sprinkler systems, fire extinguishers, fire hoses, fire escapes, sealing, fireproofing, self closing doors, concrete construction, concrete reinforced stairwells, battery operated emergency lights, reflective strips to outline steps in stairwells, refined elevator designs for faster descent, and even huge weights designed to offset earthquake shock or sway from strong wind.

Many skyscrapers will receive both praise and condemnation upon their completion. Some say that they are too expensive and difficult to maintain; some believe them unsafe. With this world’s population steadily growing, however, it seems increasingly practical to build up rather than continue to sprawl out when we possess the technology to do the former with a great deal of safety.

Petronas Towers

The Petronas Towers stretch a modest 88 storeys, but with the height of the spires these towers were the world’s tallest from 1998 to 2004. They were designed by Argentine architect César Pelli and Filipino-Malaysian engineer Deejay Cerico under the consultancy of J.C. Guinto and Filipino designer Dominic Saibo. The towers are located in Kuala Lumpur, Malaysia.

At first, the buildings required the crew to dig twin 32 metre deep holes in the ground for the foundations, which took 13,200 cubic metres of concrete each. Next came a retaining wall that would form the basement of each building; at 21 metres high and 1000 metres in diameter, this created five basement floors. This basement area took two years to complete with over 40 tradespeople working around the clock. The construction of the towers began on 1st March, 1993 and the tenants started to move in on 1st August, 1999.

The buildings are largely composed of reinforced concrete with a steel and glass façade made to resemble some motifs of Islamic art. Super high-strength reinforced concrete was utilised due to the prohibitive cost of importing steel, resulting in a building with superior sway reduction, but one that is extremely heavy on its foundations. A defining feature of these towers is the sky bridge that spans from one building to the other. The sky bridge is a two storey, 750 tonne bridge that connects the 41st and 42nd floors of each tower.

Another interesting feature of these buildings are their efficient double-decker lift system. The top level of the lift will take its riders to even floors, whilst the lower will stop on odd floors. Patrons that need to go to an odd floor can find their elevator on the main floor and those who need to go to an even floor need to take an escalator to the second floor and enter the lift there. This system has been proven to drastically reduce wait times.

On 5th November, 2005 a fire broke out in the cinema complex, with no injuries, and on 1st September, 2009, a French urban climber by the name of Alain “Spiderman” Robert scaled to the top of Tower Two using only his hands and feet. He made it to the top in just under two hours, having been previously arrested on two separate occasions for attempting to climb these towers.

Taipei 101

The Petronas Towers were surpassed as the world’s tallest when Taipei 101 was completed in 2004. Taipei 101 is one of the world’s tallest structures and happens to contain one of the world’s largest tuned mass dampers, weighing 660 tonnes. The damper is a steel pendulum, suspended from the 92nd to the 87th floor, which sways to offset movements in the building caused by strong gusts of wind. Its sphere, the largest damper sphere in the world, consists of 41 circular steel plates, each with a height of 125 mm, welded together to form a 5.5 metre diameter sphere. Another two tuned mass dampers, each weighing six tonnes, sit at the tip of the spire, preventing damage to the structure due to strong wind loads.

This building was designed by C.Y. Lee and Partners, and constructed through a KTRT Joint Venture. The building boasts 101 floors aboveground, with five basement floors. It was architecturally designed to signify the evolution of technology and Asian tradition. Its look is actually quite traditional, albeit with a modern twist. The building’s blue-green, double paned and glazed glass curtain walls offer UV protection, blocking external heat by 50 per cent and able to withstand seven tonnes of impact.

Due to the volatility of its natural environment, it was critical to utilise design innovations above and beyond the typical structural elements. The building owes its strength and flexibility to its high-performance steel structure and 36 concrete columns. Every eight floors, trusses connect the outside steel structure to the inner columns. These features, combined with the solidity of the foundation – 380 piles driven 80 metres into the ground and extended as far as 30 metres into the bedrock – make Taipei 101 the most stable building in the world.

This building was also climbed by Alain Robert in 2004, but this time he was granted permission by the authorities.

Burj Khalifa

Surpassing Taipei 101 is the Burj Khalifa in Dubai, the world’s tallest skyscraper to date. This structure is 829.84 metres tall and contains 900 apartments on 162 floors. Construction began 21st September, 2004 and the exterior completed on 1st October, 2009. The interior was then completed and the building opened to the public in January, 2010. It was designed by Skidmore, Owings and Merrill of Chicago, with Adrian Smith as chief architect, and Bill Baker as chief structural engineer. The primary contractor was Samsung C&T of South Korea. The building was designed to be the centrepiece of a new mixed use development comprising 30,000 dwellings, nine hotels, three hectares of parkland, 19 residential towers, the Dubai mall and a manmade lake.

The building is an all residential building that boasts a y-shaped plan that is said to increase the outward view and inward natural light. The tower comprises three elements arranged around a central core. As the tower rises from its flat base, setbacks occur at each element in a spiralling pattern, decreasing the cross section of the tower as it stretches toward the sky. The primary structure is made of over 45,000 cubic metres of reinforced concrete made into 192 piles buried 50 meters deep. The entire structure boasts 330,000 cubic metres of concrete and 55,000 tonnes of steel rebar and took 22 million man-hours to construct.

The building is equipped with pressurised, air conditioned refuge floors located every 35 floors where people can stop and rest on their long journey to safety in event of an emergency. The air conditioning system draws air from the upper floors where the air is cooler and cleaner than on the ground. At peak cooling times, the tower’s cooling is equivalent to that provided by 13,000 tonnes of melting ice in one day. The condensate collection system, which uses the hot and humid outside air, combined with the cooling requirements of the building, results in a significant amount of condensation of moisture from the air. The condensed water is collected and drained into a holding tank located in the basement car park; this water is then pumped into the site irrigation system for use on the Burj Khalifa Park.

The exterior cladding of Burj Khalifa consists of 142,000 square metres of reflective glazing, and aluminium and textured stainless steel spandrel panels with vertical tubular fins. The cladding system is designed to withstand Dubai’s extreme summer temperatures, and the exterior temperature at the top of the building is thought to be 6° C cooler than at its base. Over 26,000 glass panels were used in the exterior cladding of Burj Khalifa.

Although it is equipped with a tuned mass damper, Burj Khalifa will quite literally sway back and forth about two metres on the very top floor and some say that when they are in the building they can actually hear it creaking like an old sailboat.

This time, Alain Robert used a rope and harness for his climb. He scaled the building to the top of its spire in six hours.

Home Automation

Call it ‘domotics,’ and you are likely to receive a blank stare, but refer to it as ‘smart home’ or ‘home automation,’ and you will get a nod of acknowledgement. For the past few years, consumers have heard the word ‘smart’ attached to countless products and services, from food and drink to snacks like popcorn and mobile phones, which no one seems to refer to as a ‘cellphone’ anymore. Yet what, exactly, constitutes ‘smart’?

June 2, 2020, 1:57 PM AEST