Carrying the weight of the world

Since November 2013, when Dubai won the bid to host the Expo, there have been a lot of construction projects related to the event. Apart from the building site, supporting infrastructure such as roads, bridges and the Dubai Metro Route 2020 line is also being constructed.

The centrepiece of the Expo 2020 site will be the beautifully domed Al Wasl Plaza, which has been hailed as an architectural masterpiece. Heavy-lift specialists Sarens provided 24 strand jacks and 12km of strands to raise its crowning dome into place as one single intact piece.

The lower dome structure was already in place; raising the dome as a complete unit limited the work at height and helped improve efficiency and safety at the busy worksite.

All of the equipment needed for the operation was shipped in about ten containers and assembled on site over the course of six weeks. It took two days to lift the 110m diameter, 850t dome to a height of 46m.

Eighteen strand jacks, of 200t capacity, were used for the lift, positioned at 20° intervals around the dome. Six more strand jacks were placed on the ground to restrain any horizontal movement during the lift, from wind or from other factors. The jacks were inserted into cribs so they could adapt to different angles and work with more flexibility than if they had been placed vertically. This flexibility was vital because 18 jacks pulling up a big structure in unison need to adapt to its movements, not the other way around. The lift had to be conducted with extreme precision, since the structure could deform easily should one jack pull more than another. This required constant monitoring of the dome. In addition, several restraining cables were installed horizontally within the dome, and their tension was monitored so the crew could see the shape the dome was taking in real time.

The interior of the dome will be covered in textile and will be the largest 360° projection screen in the world, using 240 projectors located all around the structure. As for the ground inside the dome, it will be home to fountains and gardens where visitors will be able to enjoy the videos displayed on the dome itself.

The crew worked in a humidity level close to 100%, and temperatures reaching 45°C. “A real bond was established between the client and the team, allowing them to perform to the best of their abilities,” said Philippe Verdeure of Sarens. “This trust allowed the job to be completed successfully: the client’s trust in Sarens’ state-of-the-art equipment and operating knowledge, trust from the Expo 2020 Committee to hand over to Sarens such a masterpiece of architecture for a few days, and trust within the control room to share the right information at the right time and with the right people.”

The construction of individual country pavilions also required complex lifting. Al Faris was awarded the contract to lift and install 42 structural steel elements of the UAE pavilion structure at the EXPO 2020 site in Dubai.

The company provided a complete solution for the lifting and installation of structural steel elements whose lengths ranged from 24m to 46m. The weights ranged from 8t to 55t. After careful consideration a 1,000t Liebherr LR 1000 crawler crane was used due to the large working radius that was required.

Challenges included a limited and congested working area for the placing of the crane, due to adjacent ongoing projects; assembly time and space was also restricted.

A working radius of 132m was needed on a site that is subject to strong winds. The structures had to be lifted at a given specific angle, which imposed further restraints on the lifting gear to be selected. Steel mats were fabricated for maintaining ground pressure to meet the site requirements. For the final stage Al Faris’s 750t Liebherr LTM 1750-9.1 all terrain mobile crane lifted the oculus structure that forms the crowning centre of the pavilion rooftop.

“All surveys, planning, technical support documentation, execution plans and schedules were prepared in-house prior to job execution. This helped organise all activities smoothly with minimum delays. Execution was safely carried out by our trained operators,” said Al Faris.