Construction World December 2023

BUILDING CONTRACTORS

15 FREDMAN DRIVE W ith the existing building constructed in the 1980s, WBHO was appointed to execute the refurbishment of what is now the new home of the Primedia Group. It must be noted that there were no available construction drawings of the existing structure. The project’s new design required a large extent of demolition works to the existing structure as well as the preservation and restoration of existing facades and concrete elements internally and externally. The existing structure consisted of two levels of basement parking areas (1 100 m 2 per floor) and three levels of office space (1 800 m 2 per floor) with a concrete roof slab. The east and west elevations included two open to the element atriums that would later be converted into internal atrium spaces. The existing slab construction included the use of precast lintels resting on perimeter ring beams with a in-situ cast slab resting on the structure. The basement parking was expanded to both the north and south side of the existing parking areas adding an additional 1 535 m 2 of parking space per basement floor, along with a brand new third basement (1 240 m 2 ) parking level, constructed on the south of the building. This was achieved by drilling over 150# 800 diameter, 9-metre-deep piles along the existing structure as well as the neighbouring properties and roads in order to create a lateral support. The existing concrete roof was changed into an additional office floor and a structural steel sawtooth roof was built over the floor. Approximately 524 m 3 of existing concrete was carefully demolished and removed from the structure. Most of this material was removed mechanically and carted close by for removal from site. Ninety per cent of the concrete material removed was reclaimed and recycled off site.

AfriSam Innovation Award for Sustainable Construction

Based on there being no available drawings of the disposal of the structural and architectural design teams of the existing structure, a team of surveyors was tasked at the onset to conduct a full 3D scan of the existing structure across all levels, internally and externally. This scan was converted into a 3D digital model that could be merged with the Revit model whereby all disciplines were then coordinated. The preservation of the existing face brick facades was paramount to the success of the project and required structural strengthening by means of structural steel beams clamping the walls back to the concrete structure. Only once this was completed could the intermediate brick piers be demolished and the aluminum “picture frames” be installed. Internal face brick walls were carefully demolished and bricks cleaned to be re-utilised on portions of the facades where the face brick match was required to maintain the overall aesthetics. Available space in and around the existing building was extremely limited and resulted in the contractors developing specialised rigging frames. These rigging frames were constructed to install the atrium link bridge and atrium closure slab structural steel beams. This was necessary as the tower crane could only be erected once the bulk excavations of the new parking structures were completed. New penetrations through slabs required the installation of 12 mm thick, sandblasted steel plates. These plates were epoxied to the underside of the slab and anchored to the exiting beams. All beams had to be scanned in order to determine the location

34 22 nd Best Projects Awards 2023