Construction materials

How high can we build? Materials and construction methods for the skyscrapers of the future

How high can we build? Materials and construction methods for the skyscrapers of the future

Many city planners predict that in 2050, more than 6 billion people will live in cities, and in places where outward building is not an option, the only way to keep up with increasing density is to build. Building taller always comes with many challenges and not-so-subtle competition for architecture firms to get their name tied to taller buildings. Almost as quickly as one building is named one of the tallest in the world, another makes its way to the drawing board, taking the title a few years later. While the sky is the limit, what impact does this have on the constructability of projects, and what feats of construction methods and materials have enabled us to build in the clouds?

First, it is important to understand how to technically define high-rise buildings. The Council on Tall Buildings and Urban Habitat (CTBUH) defines two subgroups of buildings that reach significant heights. A “supertall” building is defined as being 300 meters (984 ft) or taller, and a “megatall” structure is at least 600 meters (1,968 ft) tall. At the current rate, at least one supertall skyscraper is completed each year, with 132 supertall skyscrapers having completed construction as of June 2020. The Burj Khalifa is still the tallest skyscraper in the world, standing 2,722 feet, or just over half a mile. Recently, after 8 years of construction, the Merdeka 118 in Malaysia completed its construction and was only 500 feet shorter than the Burj Khalifa. It is predicted that the world’s first mile-high building could be completed within the next 30 years, also driving a new trend of buildings over 3,200 feet tall.

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Shenzhen-Hong Kong International Center. Image courtesy of Adrian Smith + Gordon Gill

High-rise buildings present all kinds of mechanical and structural problems. How long will people be waiting for an elevator when going from the lobby to the 200th floor? How will the mega-buildings withstand the natural forces that we can predict and those that we cannot? Many of these problems are solved by hacking the modern materials and systems we already know and creating those that support an innovative construction industry.

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One of the main issues when constructing tall structures is the ability to keep building materials close to the site, as the building footprint and surrounding area are typically small, especially in urban areas. This creates problems for the construction of structural members, as precast panels are often brought to site as they are completed due to their inability to be stored. However, many contractors now use a construction of sloping walls process, allowing them to cast and assemble the panels on site and use a crane to put them in place.

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Brooklyn Tower, JDS Development Group, SHoP Architects. Image © Selvon Ramsawak

Skyscrapers are also turning to steel alternatives, but as a building increases in height, its weight becomes a significant issue. Aluminum offers a lightweight alternative with its easy extrusion process that allows it to conform to a variety of shapes for almost any facade design. It also responds well to stress from internal structural elements and external forces such as rapid temperature changes and seismic disturbances caused by earthquakes. Another emerging material is carbon fiber, which is also lightweight, but has long strands that are intertwined to form a fabric-like structure. As a result, it is significantly stronger than steel, allowing it to be implemented in buildings that receive high impact loads. Carbon fibers are already making their way into precast concrete elements. By placing the mesh in the concrete mix instead of the traditional steel mesh, the overall weight of the structural unit is reduced, allowing it to be lifted into place safely and securely knowing that it maintains integrity. important structure.

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W350 project. Image © Sumitomo Forestry Co and Nikken Sekki

Even more forward-looking ideas are what the future of concrete might look like. Concrete has remained virtually unchanged for hundreds of years. Although it is extremely durable, many people are pushing for new alternatives as it continues to be a major source of CO2 emissions. Some researchers are looking into bio-concretes, which have the ability to heal their own cracks by adding calcareous bacteria which can extend the life of concrete up to two hundred years. Even wood, which seems unlikely to be used as a major structural element in a tall structure, finds new life in cross-laminated timber structures that give it strength comparable to steel. To demonstrate the capabilities of wood, Sumitomo Forestry, a Japan-based design firm, recently revealed plans to build a 350-meter-tall wooden structure in Tokyo. Taller buildings are on the horizon, and materials and construction methods are rapidly catching up to be able to make those mile-tall dreams a reality.

This article is part of the ArchDaily topics: The future of Construction materials. Each month we explore a topic in depth through articles, interviews, news and projects. Learn more about our ArchDaily topics. As always, at ArchDaily, we welcome contributions from our readers; if you wish to submit an article or a project, Contact us.

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