Video: 'Crowning moment' for Expo 2020 Al Wasl dome

Dubai: The final piece of the Al Wasl dome was successfully lifted into place today after months of planning and a complex construction operation.

Al Wasl dome encircles the Al Wasl Plaza that sits at the heart of the Expo 2020 Dubai site.

It will be the focal point for the celebrations over the six months from 20 October 2020 to 10 April 2021, and is set to become Dubai’s newest iconic landmark. More than one million man hours have been completed on the structure to date.

The crowning of the dome is a key milestone for Expo 2020 Dubai, with all permanent Expo-led construction on track to be completed by the end of the year, say officials.

Fitting the steel crown: one chance to get it right

The dome’s huge steel crown was positioned in an inspiring feat of precision engineering. Enclosing a space of 724,000 cubic metres and standing 67.5 metres tall (higher than the Leaning Tower of Pisa), the 130-metre-wide domed steel trellis is made up of 1,162 individual curved steel sections.

According to Chief Development and Delivery Officer Expo 2020 Dubai, Ahmed Al Khatib, “The trellis canopy has stretched fabric for shading.

The grand trellis serves as both an inspirational and performative architectural feature to enhance the use of Al Wasl.

It includes integrated lighting and projection systems for events, and will form a stunning 360-degree projection surface, with projections visible both from within and outside the dome, providing a unique visitor experience.

It will be fitted with state-of-the-art projectors by audio-visual experts Christie, Expo 2020’s Official Displays and Projection Partner”

Al Khatib calls this the “most exhilarating day of my entire career. We had one chance to get this right.”

New architectural marvel

Shaikh Ahmed Bin Saeed Al Maktoum, Chairman of the Expo Dubai 2020 Higher Committee, President, Dubai Civil Aviation Authority, Chairman, Dubai Airports, Chairman and Chief Executive, Emirates Airline and Group, said: “The crowning of the Al Wasl dome is a significant landmark not just for Expo 2020 Dubai but for the whole of Dubai and the UAE.

"This new architectural marvel joins a long list of inspiring designs that our country has created through collaboration, sheer hard work and the unending, ambitious vision of our leadership and people.”

Weighing 550 tonnes of moulded steel, Al Wasl dome’s 22.5-metre crown had to be precisely positioned on top of the vertical trellis, with a margin of error of only three millimetres.

It was completed using a technique called strand-jacking. Including the structures and equipment required to lift the dome during this process, the total weight was 830 tonnes — equivalent to 600 saloon cars.

How it was done

Eighteen hydraulic jacks, aided by steel lifting ropes connected to 18 freestanding temporary columns, were used to slowly raise the curved steel crown.

It was positioned directly on top of the trellis already in place 45 metres above the ground, and attached using 53 temporary connection brackets.

Working through the night, 800 engineers and construction technicians carefully monitored every millimetre of the process, using GPS indicators throughout to ensure perfect alignment.

To retain the geometry of the trellis structure as it was lifted, a series of tension cables was installed, connecting the perimeter of the trellis crown to a central temporary compression ring. Multiple test lifts were conducted to measure the movement of the structure as it was lifted off the ground.

The tensioned cables were adjusted until the trellis perimeter connection points were in the positions required for the full lift to commence.

Lifting such a large and heavy structure involved a huge number of variables. Something as simple as a shift in direction of the wind or change in air temperature could have had a big impact on our calculations, so constant monitoring and reassessment was essential throughout the process.

- Ahmed Al Khatib, Chief Development and Delivery Officer Expo 2020 Dubai

Calling this one of the most challenging engineering operations in the world, Al Khatib said: “Lifting such a large and heavy structure involved a huge number of variables. Something as simple as a shift in direction of the wind or change in air temperature could have had a big impact on our calculations, so constant monitoring and reassessment was essential throughout the process.”

Al Wasl dome’s crowning was the culmination of 14 months of preparation, beginning when the final pieces of the dome’s steel trellising left Italy on 26 June 2018.

The individual elements first arrived in Dubai in July 2018 and the crown was carefully assembled at ground level before being raised into place.

Now positioned, the final piece of Al Wasl dome will be welded to the rest of the trellis, a process that will take 25 days to complete.

The urban room

The Al Wasl Plaza has been designed to form a grand ‘urban room’, a meeting place that creates a shaded microclimate that simultaneously encompasses vibrant performances and natural landscaping. The name Al Wasl means ‘connection’ in Arabic.