Projects Category

Winner: Rebcon Engineering
Project : Cladding of Timeball Tower

This year’s winner of the Stainless Steel Award for best project goes to Rebcon for its awe-inspiring
Timeball Tower. The purpose of constructing the Timeball Tower had both a historical and architectural impact
on the new Durban Point Development Project. From a historical perspective, in the early 1900s Durban Port
had a Timeball Tower that played an important role in advising ships entering port what the time was.
The design team on this project wanted to incorporate this historical importance into the structure.

From an architectural perspective the structure symbolises the origin of the public focal point of the Point
Waterfront Development, namely the information kiosk, amphitheatre and ablution block. It also provides a link
between the various icons within the development. The architectural design was undertaken by
Rodney Choromanski of CNN Architects and the structural design was undertaken by Leezane Greyling of
Arup Consulting Engineers & Linda Ness of Linda Ness Associates.

The architect’s concept was modelled using wire as a sculpting medium, and the challenge to recreate this
filigree effect could only be realised with the use of structural steel. The final constructed product is a visual
scaled model of the architects’ original wire frame model.

The structural design offered challenges due to the slenderness of the structure. Analysis of effects of wind
loading was undertaken by Arup (UK), and strakes were introduced to accommodate the effects of wind loading
to the upper sections of the structure. The lower section of the structure comprises a compression framework
fabricated ex grade 350WA central core tube with grade 350WA fabricated plate compression rings and grade
350WA rectangular hollow section diagonal bracing, all post tensioned by use of 36 diameter grade 316
stainless steel Macalloy tendons, post tensioned by means of hydraulic jacking prior to erection. The top
section of the structure comprises of a continuous fabricated tapering box section ex grade 350WA plate.
Weld procedures, monitoring, inspections and testing were undertaken by Innovative Inspection Services.
All carbon steel was coated with a Denso coating designed for the aggressive environment in Durban.
Application of this coating was undertaken by Pipe Coatings. The holding bolts are ex 36 diameter grade
316 stainless steel, all connection bolts are ex either grade 316 stainless steel or grade 8.8 hot dipped
galvanised.

The cladding to the lower and upper portions of the structure is ex grade 316 stainless steel plate perforated
to suit the architect’s requirements. The Timeball operation mechanism is manufactured on a pulley drive system
driven by a servo motor that is linked to a computer at the base that operates the sequenced movement of
the ball. The ball was manufactured ex GRP and painted with a chromed finish.

The “copper bangles” were manufactured ex GRP by AGS Glassfibre. The design of the electrical & lighting to
the structure was undertaken by Imvuselelo Consulting and all electrical supply and LED lighting requirements
was supplied and installed by Cato Ridge Electrical.

The contract period was originally set for six months, commencement being July 2006 and completion
December 2006, however, due to delays in shipping the Macalloy tendons from the UK the project completion
date was delayed to April 2007. The project was finished within the client’s budget allocation.