Analysis

Building a Vertical City with BIM

 

As the world’s population skyrockets, living space is becoming a serious concern. What happens when we can’t expand our cities horizontally anymore?

One possible solution is the concept of building up instead of out. This first manifested in the form of skyscrapers, but building information modeling (BIM) is now being used for projects that dwarf these towers – projects like the Shanghai Tower.

The Shanghai Tower is a 632 m (2,703 ft) skyscraper that functions as a city within a city. The darker horizontal bands mark the tower’s “neighborhood” sections.The Challenge of Building a Supertall Skyscraper

At 632 m (2,073 ft), Shanghai Tower cuts quite the figure – it’s China’s tallest building and the world’s second tallest* as of this writing.

The area chosen for its construction, which was farmland just 20 years ago, is not ideal for supertall skyscrapers. Its soil is clay-based and the whole area is prone to earthquakes and strong winds.

The typical approach to supertalls is to use a concrete and steel core with a suspended curtain wall – exterior walls are rarely load-bearing anymore. A 1,000-metric-ton tuned mass damper near the top of the tower helps it deal with earthquakes.

Shanghai Tower puts a spin on the traditional curtain wall.

With each floor slightly rotated from the one below, the whole structure curves at a 120° angle from top to bottom. The resulting graceful spiral actually reduces wind resistance.

An Urban Center from the Ground Up

Supertall skyscrapers make up the skylines of most of the world’s largest cities. What makes the Shanghai Tower different? Its mission – to create a sustainable vertical city.

“Shanghai Tower represents a new way of defining and creating cities,” said Art Gensler, founder of Gensler, the design architecture firm on the project.

When you think of a city neighborhood, you probably picture a row of houses on a street next to another neighborhood. The tower takes this concept and turns it on its side by creating nine 15-story “neighborhood” sections and stacking them atop one another.

However, the tower’s total usable space is just 154 acres – not nearly enough to house an entire city. It will be populated primarily by businesses and even a hotel, so it may be more accurate to call Shanghai Tower a vertical urban center – a city within a city.

Using BIM for a Complex Structure

As functional and appealing as it is, the spiral presented its own issues in the design stages.

Its shape necessitated the design of over 7,000 unique geometries. Designing and generating an accurate model with that many pieces would have been incredibly difficult using any one CAD program.

Instead, the design team used a range of BIM software to get the job done, including AutoCAD Architecture, Autodesk Revit Architecture, Autodesk 3ds Max, Autodesk Ecotect Analysis, CSI SAP2000 and Rhino.

Precise tolerances were analyzed with laser measurements.

Designing a Sustainable Building

Another unique aspect to the Shanghai Tower is its emphasis on sustainable technology. In fact, its design team claims a grand total of 43 types of green tech were incorporated into the vertical urban center.

The most noticeable green design feature is the tower’s surface. The all-glass exterior wall encases an interior glass wall. The combination creates an insulation layer around the structure — like that travel mug does for your morning coffee.

An observer might not notice the shape of the parapet, which collects rainwater for use in heating and cooling systems. Wind turbines placed near the parapet to power upper floors might also go unnoticed, although the Lujiazui Financial and Trade Zone Management Committee says they generate a combined annual total of nearly 1.2 million kWh of electric power.

The interior of the building is designed with plenty of green space, which will reportedly take up roughly one third of the building’s footprint. This includes public park areas and vertical gardens.

Overall, Gensler suggested that Shanghai Tower’s sustainable tech will reduce the building’s carbon footprint by 34,000 metric tons per year. This has earned the tower a LEED Platinum certification.

Construction on the tower has been completed and it’s now preparing for operation. If you’re curious about the project, check out Shanghai Tower’s website.

*The tallest building is the Burj Khalifa in Dubai, which stands at approximately 828 m (2716 ft).

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Source: www.caddigest.com/building-a-vertical-city-with-bim