The new £15m healthcare centre is situated within the Braid Valley Hospital site in Ballymena.
The health centre includes a wide range of primary care facilities from GP surgeries to dentists and other allied health professionals such as physiotherapists.
The project also has close involvement from the local politicians. As a result, there are a significant number of stakeholders. Waterman Moylan engaged with the stakeholders early as a collective design team under the control of the project manager and this enabled the design of the building to be developed efficiently and effectively.
The centre is a part two-storey and part three-storey building with associated new site access, internal access road, car park and soft landscaping. The architectural concept of the building is such that the u-shaped two-storey wing is wrapped around three sides of a central courtyard. The three-storey block is situated on the fourth side of the courtyard and has a central enclosed full height atrium space.
The southern elevation and part of the eastern and western elevations of the three-storey building cantilevers at first floor level. The extents of the cantilevers vary in relation to the position of ground floor walls. The roof is a series of monopitches in a saw-tooth arrangement of steel frame construction.
The roof of the two-storey wing is a flat roof constructed with a reinforced concrete slab on composite metal decking with insulation and an externally applied waterproof membrane.
The upper floors are reinforced concrete slabs supported on composite metal decking, supported on composite steel beams. External cladding of the building is generally facing brick with punched window fenestration and glazed curtain walling above second floor levels to the east and west elevations.
In conjunction with the architect, we provided BIM compatible 3D models of the structure using Revit. These BIM representations of the design, as it developed, were used to review the requirements with the stakeholders and we found that this allowed progress to be maintained in line with the revised programme. We were able to highlight any impacts on the structural design at stakeholder design reviews to avoid any reworking of proposals. One example of this was the desire to have a cantilevered section of the building with minor surgery treatment areas close by. We were able to demonstrate that the design needed to take account of vibration limit criteria associated with the treatment area and this had an impact on the scale of the structure required in this area. This was explained during stakeholder design review meetings, and we believe that this approach has been of great benefit in managing stakeholder input on this project.
The original foundation design solution involved a sleeved mini-pile system that was specifically specified to minimise noise and vibration during the construction phase of the project. With the development being in very close proximity to a live hospital site, minimizing noise and vibration was key to maintaining patient comfort. However, following contract award due to the accelerated programme the successful contractor was not able to secure the availability of such a specialist piling rig. Waterman worked collaboratively with the contractor to assess several proposed alternative piling construction methods and assessed these against the original specification of minimising noise and vibration. A number of proposals were discounted but, in the end, a cased CFA pile method was approved. The cased CFA piling scheme has since been successfully installed with no impact of patient comfort.
The superstructure includes a two-storey cantilever overhang above the main entrance. As the architectural design included several large window openings around the building envelope, typical methods of constructing cantilevers using trussed frames was not feasible. Waterman developed a structural solution which involved the construction of Vierendeel Trusses on the primary frame lines to achieve the required clear openings. This complex structural design involved careful analysis and consideration towards detailing and added value to the project by ensuring that the architect’s desired vision was not only maintained but enhanced as original schemes considered variations of diagonal “bracing” which compromised the full height/width glazed walling.
Whilst the project is a health centre, the clients’ requirements stated that the structure must be designed in accordance with current best practice for hospitals. A key consideration for hospital buildings and the NHS is floor vibration, particularly where delicate or sensitive operations are to be undertaken. As such, the entire building has been designed to provide a structure which is not susceptible to vibration. As cantilevers are typically susceptible to the effects of floor vibrations, the Vierendeel Trusses within the cantilever overhang have been designed to ensure that they are stiff enough to mitigate against floor vibration and provide a high natural frequency value which is within the current NHS Hospital guidance.
Client: Northern Ireland Health Trust
Architect: Keppie Design/Hoskins Architects