The Magnificent One Za’abeel is a prestigious mixed-used development located between the old and new business districts in bustling Dubai. Its scale is as complex as it is enormous, with two beautifully designed towers standing at 304 metres and 241 metres, sitting over the top of an operational six lane carriageway. The development also features seven basements 28 metres below ground level.

Above ground, the One Za’abeel towers sit on podiums A and B, connected by a 125 metre tall (in the air) and 225 metre horizontal steel and glass structure – the world’s longest cantilever.

BG&E’s Role and Expertise

BG&E was appointed as the contractor’s third-party engineer, tasked with verifying the structural calculations and drawings of the link bridge, which were provided by the steelworks contractor. BG&E’s team also designed the necessary temporary works for the construction and erection of the link bridge, ensuring that all project phases met the strict architectural and serviceability criteria.

Safe Installation & Monitoring

A critical aspect of BG&E’s role involved monitoring the stresses and deformations in the towers during the entire construction programme, including the erection of the link. This was essential to ensure the safe installation of the bridge, which needed to meet stringent serviceability requirements.

The cores and columns of the towers were pre-set out of plumb to accommodate expected movements during the link’s construction. The link bridge was fabricated on a temporary steel structure over Podium A and Podium B, with both podiums partially strengthened to support the bridge’s incremental launch.

Innovative Cantilever & Launch Solutions

BG&E devised an innovative cantilever solution that allowed the 225 metre long link bridge to be launched incrementally across a live highway, eliminating the need for intermediate supports. This approach reduced highway closure time, eliminated the need for additional foundation structures, and minimised disruption to traffic.

The link bridge was lifted in two segments – one weighing 7,500 tonnes and the other 2,500 tonnes. This staged lifting ensured that deformations in the cantilevered end did not impede the structure’s welding to the towers. BG&E also ensured that the construction program avoided the need for a second lift to be placed on the critical path by allowing tower construction to continue in parallel.

Simultaneous Tower Construction

Initially, the construction of the towers was expected to halt until the link bridge was fully welded to both towers. However, through detailed sensitivity analysis, BG&E demonstrated that tower construction could continue up to certain levels during the lifting and fixing of the link bridge. This allowed the project to remove tower construction from the critical path, reducing overall construction time and cost.

Lifting and Strengthening Solutions

During the lifting process, highly high loads were transferred to the towers. BG&E worked closely with the steelworks and lifting contractors to provide multiple design options for the lifting gantries and developed solutions for strengthening the towers. This included using the existing permanent steelwork to reinforce the towers, which reduced the need for additional embedded steel elements to be constructed on-site.

Basement Structure Coordination

The close proximity of the two plots required significant retaining structures, such as soil anchors and walling beams, during the shoring stage. BG&E coordinated these basement works to avoid conflicts with the permanent basement structure. By optimising the construction staging and reducing the extent of retaining structures, BG&E minimised the time additional contractors were required on-site, further improving efficiency.