Bentel Associates International.
Tony Ritchie Engineers and Ritchie Midgley Consulting Engineers
With an 18-storey curved, glazed façade, the mixed-use development, Legacy Corner, is tipped to become the new landmark of Sandton’s business hub, north of Johannesburg.
Joint venture partners Tony Ritchie Engineers and Ritchie Midgley Consulting Engineers, structural and civil consultants for the development, relied on Revit Structure software to help them meet complex engineering challenges and an aggressive project schedule. The software was used in conjunction with a suite of specialised analytical programs from Prokon.
Located on the last undeveloped site in the Nelson Mandela Square precinct, the development, for Legacy Hotels and Resorts International, comprises the 175-room
Da Vinci Hotel, an apartment block, three levels of retail space and four levels of parking.
Tony Ritchie Engineers and Ritchie Midgley Consulting Engineers collaborated on the project with Bentel Associates International (BAI) with whom they had previously worked on the 38-storey Michelangelo Towers in the same precinct.
In addition to significant changes to the scope of work, the complex structure held notable engineering challenges, while engineering and construction teams had to work to a punishing project schedule so as to meet the development’s pre-2010 Soccer World Cup opening date.
The engineering team was on the back foot from day one of the project. “Not only was BAI still involved in aspects of design development by the time we had completed our analyses and issued construction drawings for foundations and basement columns, but then the client added four floors to the structure,” says Ritchie Midgley director, Don Midgley.
Challenges in terms of lateral stability were compounded by the fact that some of the columns and shear resisting elements were not continuous throughout the structure. Several columns changed shape at some point up the building, while others had to be supported on substantial transfer beams. The structural analysis was further complicated by the column-free downstairs reception foyer.
“We had substantially developed the Revit model of the building so, despite being inundated with scope changes and revisions to floor and column layouts, we were in a position to accommodate late changes more accurately and quickly than would otherwise have been possible,” says Midgley. “This enabled us to meet the architectural requirements and demands for construction detail by the contractor.
“The facility to re-work our calculations and accurately update drawings in a fraction of the time it would have taken without the intelligence of Building Information Modelling (BIM) was a great benefit, and we are more than happy with the performance of Revit Structure.”
The software was used in conjunction with specialist analytical software from Prokon. The detail design and reinforcement detailing of coffered floor slabs throughout the super-structure were predominantly undertaken using Prokon’s ‘continuous beam’ concrete design module. Prokon’s pre-stressed concrete design module was used extensively in the design of the parking levels.
Importation of accurate structural dimensions from the Revit model into the Prokon analysis package ensured that the data used for design and reinforcement detailing was to the correct scale and size, saving time and eliminating the potential for error.
Construction of Legacy Corner, which began in 2007, is scheduled for completion towards the end of 2009.
