Works within this project involved extensive demolitions, refurbishment, remedial works, strengthening works and new construction. All of these works were conducted with the client in occupation within the previously completed phase and within surrounding buildings on the complex.
The works to the two-storey office building, that comprised a hybrid of structural steelwork frame and pre-cast concrete floors and roof and load-bearing internal and elevation brickwork, included addition of roof-mounted plant and additional roof-mounted supporting steelwork, demolition and in-filling of pillar-box skylights, construction of a new two-storey elevation cavity wall and a single-storey elevation cavity wall upon existing foundations to envelop the building at demolition demarcations, establishing a raised structural floor in the defunct low-level ground floor plant room area, formation of openings through load-bearing walls to suit new office layouts, reconfiguration of the main entrance stairs to enable extension of the first floor over part of the stair-well to incorporate additional accommodation.
Prior to commencement of construction works, and in order to minimise risks to cost and programme, intrusive investigation of the decanted building was conducted by THe Consultants concurrently with inspection of trial pits and borehole extracts formed by the soil investigation specialist. The findings of the gathered information concluded that the superstructure possessed adequate spare capacity to bear the proposed additional plant loads but the proposed roof plant-support structure would require careful configuration and the existing foundations would need to be strengthened. Advice was given to adopt a sequence of working for the strengthening exercise to ensure that the stability of the building was preserved at all times.
Other items of defect were found during the intrusive investigations including minimal and precarious support of a localised area of the pre-cast concrete floor planks, and every instance such as this was brought to the attention of the design-and-build contractor to ensure proper dissemination of information so that any additional designs could be produced and co-ordinated expeditiously.
The focal point of the project was the new three-storey Reception Building to be located against (the junction of the single-storey building of Phase II and the existing two-storey office building of this phase) and serving the existing two-storey building. The structural form of this new building utilised structural steelwork for the main frame with in-situ concrete foundations and lift-pit and ground slab, and upper floors of lightweight concrete composite with profiled metal decking. Foundations of the single-storey building were relatively shallow by comparison therefore it was necessary to underpin these foundations so that they would be compatible against the juxtaposed line of foundations proposed for the Reception Building.
During the excavation works a substantial unknown air-raid shelter was unearthed, monolithic with the deep foundations of the two-storey building, at the position of the proposed Reception Building. The proposed foundations and proposed superstructure of the Reception Building had to be redesigned and re-detailed to bridge beyond the plan position of the air-raid shelter.
Management systems implemented by the Project Manager included regular Design Team Meetings and Progress Meetings, and the exchange of Request for Information Sheets, and these enabled full liaison with the design team and the design and build contractor, and the several sub-contractors and specialist contractors thereby allowing the momentum of the project to continue to completion.