A new scheme was approved in central London that required the demolition of the existing building for the construction of a hotel with a rooftop bar, a restaurant at ground level and event space at basement levels 2 and 3. Due to the limited space available on-site, welfare facilities and storage were situated on a cantilevered scaffolding gantry that was tied into the existing building. RDG became involved during the second phase of demolition to modify the support of the gantry to allow the remaining section of the building to be demolished.
The original concept for the removal of the gantry ties was to provide concrete kentledge. This would have been unsustainable, expensive and difficult to execute. Following a site survey, RDG developed a solution that utilised the existing concrete structures. A bespoke steel bracket was designed that connected the front line of standards for the gantry into the ceiling slab of the basement. Each bracket consisted of a top section and bottom section and were installed in six locations, varying slightly due to site conditions.
The top bracket consisted of a PFC section with stiffener plates positioned on either side of the scaffold legs. Each bracket connected to three scaffold legs and was anchored into the top of the RC wall. The stiffener plates and scaffold tubes were drilled to accommodate a threaded rod, which was then capped on either side. Two steel strips were attached to the flange using tork bolts. These strips ran down the RC walls and connected to the bottom bracket. The bottom bracket was connected into the basement retaining slab either by bolting longer steel strips into the RC wall or by anchoring scaffold legs into the slab or retaining wall.
Site space within the gantry was extremely congested as the initial configuration used cross bracing within the width. Modifications were made to change the bracing to ‘A’ configuration which provided additional access and storage space.
