CCL’s Rabih Hajjar discusses the company’s design and project delivery support for the Eden Roc residential development in Cyprus
Designed by London-based architectural practice, UHA, for Cypriot property development company, Prime Property Group, the Eden Roc development in Limassol is a striking project, designed to stand out in the Cypriot property market with its unusual terraced design.
The project is being delivered in two phases. Phase A involves construction of three adjacent residential blocks ranging from five to seven storeys and featuring numerous penthouses with large terraces and private swimming pools. Phase B is a single residential block with eight swimming pools at roof level. Phase B has only recently begun on site but Phase A, constructed to a cantilevered design with the structure stepping in as much as four metres in some locations has now completed.
CCL, the specialist in engineered solutions for structures, has been responsible for designing the post-tensioned slabs for both phases to enable extended spans, provide a solution for the cantilevered design and address the point loads from the rooftop swimming pools.
The structural solution, designed by CCL’s team in Lebanon, has enabled the original design intent, while providing time savings on the programme and reducing the amount of concrete required.
Revising the design
To create a luxurious open plan playout in the phase A apartments, the properties were designed with large 7-8 metre spans and generous ceiling heights.
The phase A buildings are terraced at roof level, reducing the area of each floor as the building rises and creating a cantilever of up to 4m in some locations. Several of the terraces feature swimming pools, creating additional loads for the cover slab.
Achieving this design using conventional reinforced concrete (RC) slabs would have resulted in the need for drop beams within the proposed open plan apartments. It would also have required an onerous slab thickness to cope with the planted loads from the cantilevered sections and the additional roof terrace swimming pools loads.
Working with load calculations provided by ASD Sotiriou, the CCL team engineered the slabs. Typically, the slabs were reduced to 250mm in most areas, increasing to 350mm for planted and point loads. CCL designed each slab individually to deliver the optimum slab thickness for each location, incorporating the transition between slab thicknesses at the interface between internal walls to ensure that it is not perceptible from inside the apartments.
Each of the swimming pools had to be considered in the context of its individual position and relationship with the structure.
Where existing columns were in place to help support the additional loads, or a planted column could be introduced, the slab thickness did not need to be adjusted. Where this was not the case, the CCL team had to calculate the increase in reinforcement and the slab thickness required at critical locations.
Additional design expertise was required to determine the level of reinforcement needed at the edges of each slab to control the deflections to within an exacting tolerance due to the apartments’ floor-to-ceiling windows.
From design to construction
The use of PT is still relatively unusual in the Cyprus market and the main contractor had never built a project with PT before. To overcome this, the CCL team took an active role in designing the PT specification to aid buildability and worked with the construction team to ensure they were familiar with the system.
CCL specified the company’s XF bonded flat slab system, which connects bare strands, fed through flat ducts. The strands are individually stressed before the ducts are sealed with a cementitious grout.
This specification enabled the contractor to remove the formwork as soon as each slab had been stressed and move on with the programme to the next level, returning to carry out the grouting when the schedule allowed.
To ensure that the contractor had the confidence and competence to install the PT system, CCL invited them to Lebanon to learn about the system. The CCL team also worked with the contractor to select and train the site operatives and supported the construction team on site throughout the installation.
The project has now moved on to phase B, which, at 7000m2, is around half the size of phase A. For this phase, the slab thickness will vary between 250mm and 350mm, in order to support planted loads and enable cantilevers of up to 4m, while minimising the need for beams. All the swimming pools for this building will be located on the roof, between the columns, requiring a slab thickness of 350mm.
The same XF bonded system from CCL will be used on this phase of the project and CCL will once again provide supervision of the installation.
Thanks to CCL’s collaboration with the design and construction team at Eden Roc, the design intent will continue to be realised during phase B, overcoming the structural challenges to deliver a stand-out development.