What is the purpose of the structure/ project?
To create an exciting and popular tourist stop over point on the Panorama Route at Graskop, Mpumalanga. The gorge has established itself as an adventure destination through the Big Swing, which is a well-known operation, so there had been some “human footprint” in the gorge for a while. The client wanted to expand on the adventure concept and added the lift and interactive walking trail in the rain forest below. The purpose of the structure is to accommodate the glass viewing panoramic lift taking visitors 51m down the face of the Graskop Gorge into the forest below, where wooden walkways and suspension bridges meander along a 600 metre trail through the indigenous forest with interactive exhibits.
What was the brief to the architect?
To design a lift shaft structure to accommodate the panoramic glass viewing lift for the Graskop Gorge Lift Company, as well as the buildings around the panoramic lift at the Graskop Gorge Adventure Centre. The site was chosen adjacent to a structure for informal curio traders and a protruding rock outcrop which had been a viewing point with a small pub. This was the ideal position for the lift shaft. The brief was to incorporate the traders into the adventure tourism complex and upgrade the existing structure. The centre should accommodate the ticketing office, shops of various sizes, a restaurant and general viewing areas for the public. Support services for the centre also had to be included. The servicing of the lift required easy access to the lift motor room. A viewing platform was subsequently added around the lift motor room as an extension to the public deck.
Was the project envisaged in steel from the start? If not – why was it built in steel in the end?
Yes. Structural Steel was the choice of material for the Lift Shaft Structure from the beginning. Reasons include compatibility with the lift installation, and the open truss-like nature of the shaft structure to simulate the waterfall on the opposite side of the gorge.
Give a brief description of the structural framing. What type of sections were used (e.g. hollow, cellular, I beams etc) and why?
The distance from the base to the top of the shaft is 60m, with the total vertical lift travel distance of 51m. The shaft structure was designed as a vertical structure with two top fixing points apart from the fixing at the concrete base. UC 305x305x97 H-profiles were used for the 6 main shaft columns, because adequate l/r ratios were required for 10m segment lengths. Each segment was fully braced using 63,5×3 and 88.9×2,5 Circular hollow sections cross bracing between 203x133x25 UB lateral stiffness beams. 305x165x46 UB profiles were used for the access platform beams at the top of the shaft with 80x80x6 Angles for bracing. UC 152x152x23 profiles were used as knee brace elements to support and fix the top viewing platform to the main shaft structure.
Give a brief description of the cladding process (complexity, difficulty, innovation etc)
Cladding formed a minimal part of the Shaft Structure itself, only the top machine room side walls and roof received IBR cladding after the access platform to the machine room was completed.
Were there any challenges in the fabrication of the project from the engineer’s design – if yes, please tell? Tell more about fabrication and erection process if it was complex, difficult, innovative etc.
A national shortage of 305x305x97 H profiles, required the design to be altered to use 254x254x73 in the top part of the shaft. For the erection of the shaft a 70 tonne crane was planned, but it would require the crane to be too close to the edge of the cliff, and the crane cables were too short to reach the 51m deep bottom.. Instead a 9 tonne Spierings Mobile Tower Crane had to be hired that could lift 2.5 t per lift at a 27m reach, with adequate cable length to reach down to the bottom.
What is special/ unusual/ innovative/ aesthetic about the steelwork/cladding in this project?
The exquisite setting of the lift shaft structure opposite the Panorama Waterfall forms a truly aesthetic pleasing view from a distance, with the natural waterfall at one side of the gorge and the grey coloured, open truss-like lift shaft structure simulating the waterfall on the opposite side of the gorge, forming a beautiful parallel with each other.
How did the project team work together (e.g contractor involved early, challenges/ ease of communication etc.)
Two weekly formal project meetings were conducted with a formal “Request for Information” procedure that were frequently communicated and updated per email between the various team members.
|Tons of structural steel used||110 t|
|Structural profiles used||Hot rolled H-profiles, hot rolled I-profiles, Angle profiles, circular hollow sections|
|Cladding profile/ type used||IBR|
|Cladding area/ coverage and tonnage||1100m2 2.8 tons|
|Project Team Role||Company|
|Nominator||Fourie Consulting Engineers|
|Graskop Gorge Lift Company
In partnership with the NEF
(National Empowerment Fund)
|Architect||Förtsch and Associates Architects|
|Structural Engineer||LEW Consulting Engineers (Pty) Ltd|
|Engineer||LEW Consulting Engineers (Pty) Ltd|
|Quantity Surveyor||Siyakha Quantity Surveyors (Pty) Ltd|
|Project Manager||Purlin Consulting|
|Main Contractor||ENZA Construction (Pty) Ltd|
|Steelwork Contractor||Quality Steel Construction (Pty) Ltd|
|Steel Erector||Quality Steel Construction (Pty) Ltd|
|Cladding Manufacturer||Safintra (part of the Safal Group)|
|Cladding Supplier||Safintra Roofing Nelspruit (part of the Safal Group)|
|Cladding Contractor||Roofing Solutions CC|
|Babcock Nthuthuko Powerlines (Pty) Ltd|
|Photographer, Photo competition||Förtsch and Associates Architects|
|Photographer, Other submitted images||Förtsch and Associates Architects
ENZA Construction (Pty) Ltd