Saturday, 2 August, 2014

South Africa’s flagship shopping centre, Sandton City, scored a world-first when it underwent a major revamp of its entire upper deck without impacting commercial trade on any levels nor causing major disruptions to traffic.

The challenge

Mark Axelrod of consulting engineers, Aurecon, says Sandton City, like so many other successful shopping centres worldwide, possess a particular challenge to owners and developers wishing to build on the success of the property. Its stature as the premium shopping and tourism node for the region makes it near impossible to close for renovations. In addition, uncertainty of design parameters used to cast slabs 40 years ago (as well as general fatigue)would almost certainly make it risky to make substantial additions to the structure.

“The only way to overcome the challenge was to avoid placing any additional load on existing slabs by constructing new slabs over the top of them suspended by the building’s own structural columns.This allows us to determine exact weight bearing capacities and remove any uncertainty that may exist about future structural integrity.It also negates the need to strip out shop fittings, ceiling and services and as a result overcomes the challenge not to disrupt the commercial undertakings of tenants within the building.”

Contracts director, Richard Amm of Grinaker-LTA explains,“Another major challenge was the crowded sidewalks and roads below the construction site, which meant that crane access would be impossible. All structural elements would therefore need to be lifted with the use of mobile cranes from road level and material handlers and forklifts while concrete would need to be pumped from up to 500 metres away. The modular nature of the formwork structures and versatility of Form-Scaff’s design provided the ideal solution and ensured that even despite these massive challenges work would be able to progress quickly without disruption.”

Project requirements

Form-Scaff technical director, Chris Erasmus, reveals that the Sandton City Level 8 Parkade project was bigger than anyone ever thought possible. It required precision levelling of the entire top level of the shopping centre which encompasses an area of approximately 40 000 m². All areas of differing heights needed to be remodelled,while existing air-conditioning refrigeration units, electrical units and other utilities were to be kept operational and incorporated into the works.

“With lack of crane access and other challenges facing us, we realised that the tasks that lay ahead were daunting and that they would require all our technical resources to get the job done professionally and on time. Meanwhile, with deadlines mounting and pressure growing, these were the first of many engineering challenges that needed to be overcome by our combined teams from Form-Scaff, Aurecon, Aveng Grinaker LTA/WBHO (joint venture) and independent consulting engineer, Richard Beneke.”

He explains that Form-Scaff’s unique Super-Beam system is an easy-to-transport product that is commonly hired by contractors for bridge construction purposes. As a result the required components were more manageable on site. In addition, the off-the-shelf solution ensured stock was readily available and that no additional time would be lost waiting for custom-built supports to be manufactured.The modular nature of the beams (designed to span large portals across roads and freeways) also allowed spans between columns to be easily bridged using standard 3 m, 4,5 m or 9 m lengths or combinations used in tandem to span longer distances if required.Super-Beam’s massive weight-bearing capacity would easily be able to carry the entire weight of the support system, decking and new floors.

Scope of work

Once work began, the existing columns needed to be exactly located and core samples taken to establish the composition and strength of materials. Thereafter the top screed had to be removed from the existing floors, column toppings taken off and the original columns needed to be exposed so that new reinforced stubs could be cast onto the original column. The stubs were then used to mount Form-Scaff’s Super-Beam system to carry the main weight of the new slab using specially manufactured clamping systems.

Designed and manufactured by Form-Scaff’s Specials Factory in Elandsfontein, the clamping system allowed the beams to be fastened directly to the stubs and enabled the company’s Kwik-Stage support to be placed on top of the Super-Beams. Form-Scaff’s Kwik-Deck system provided the flat slab formwork to receive the reinforcing steel and ready-mix concrete. Due to the Form-Scaff’s large stock holding of temporary works, more than 2 500 tons of support work and formwork could be supplied and erected on site as required. Form-Scaff’s Martin Boschoff – a highly experienced formwork coordinator was also placed on site and acted as a link between all role-players in the construction team.

Variances between old records and the actual position of columns proved tricky as differences were often substantial. This brought about a special requirement for Form-Scaff to ensure that the Super-Beam solution catered for any such variances – this was handled through adjustable beams and multi-pronged connection plates to attach beams where variances occurred. These were attached to the specially designed column stubs that would anchor and spread the weight of the new slab evenly through the column.

Post tensioning struts were attached and concrete was poured to a depth of between 300-350 mm. After curing and post tensioning,thousands of carefully torqued high tensile bolts were removed and discarded (as each bolt would have been deflected through the compression of the concrete).

Once completed, services such electricity and air-conditioning units could be secured to the new structure. Thereafter the mammoth task of stripping away the temporary works could be easily accomplished with forklifts and removed from the site.

The solution

Form-Scaff’s engineering expertise supported by its huge stockholding of appropriate modern product solutions ensured that the project was completed safely and within specification. Due to the off-the-shelf Super-Beam solution, there was only limited requirement for custom made propping and support materials. Through the ingenious use of available formwork and support structures tied to the building’s existing columns, the solution meant that the entire project could be carried-out effectively and with accrued savings of millions of rands.

“The ground-breaking engineering solutions used on this site mean that the doors have effectively been opened for shopping centres (and other high traffic buildings) to be extensively rebuilt and upgraded while remaining fully functional throughout the entire construction process,” concludes Erasmus.

Friday, 1 August, 2014

Contractors working on a slew of giant new shopping malls across Africa are opting to make use of an advanced new decking system that radically improves construction time while allowing easy and safe access to tradesmen working beneath deck supports.

The Kwik-Deck system, developed by Form-Scaff, is an evolution of the decades-old coffer system used to produce concrete slabs with a waffled soffit finish. The new system however takes less time to erect and can be stripped in just three to four days after pouring of concrete and, as a result, significantly reducing investment in additional falsework and also labour. 

Having been designed from the outset to facilitate the use of either coffers or flat slabs, Kwik-Deck uses props to facilitate quick erection of the falsework. While this is not unique in the industry, the addition of quick-release beam supports is, and it allows the decking falsework to be removed after just three or four days (depending on curing requirements) while the props remain in position until the concrete slab has achieved sufficient design strength. 

This is in contrast with other prop-based systems that require at least 21 days before coffers and falsework can be removed. Traditional stage-type systems, by comparison, also allow the removal of falsework within three to four days in most cases, but are comparatively labour intensive, take much longer to erect and limit thoroughfare underneath the deck. Breakdown and re-erection of staging is also time-consuming.

Need for speed

“Contractors working on modern construction projects strive to achieve the fastest possible pour cycles and, in doing so, still have access to wet and dry trades underneath deck pouring areas where possible.

Until recently, prop-based systems provided a reasonable solution for easy erection and access underneath, but due to the 21-day period before stripping could take place they needed an enormous amount of falsework to be employed on each site.

“This was costly and time consuming. In addition, the reduced stability of props compared with traditional staging was a concern and the benefits were, in the opinion of some, not sufficient to outweigh the drawbacks.”

“That is why we developed a system that effectively draws on the best of both types.

“Our system is also designed to be seamlessly interchangeable with either system and for stability sake many of our contractors now choose to combine props with braced staging systems.

“For example, they can use our staging for perimeters or on a corner of the deck for initial stability and edge protection, then use props for the rest of the floor.

This interchangeability of our system is unique and is a major advantage for clients to simplify their falsework requirements on site. It will even work seamlessly with contractors’ own staging systems,” says Klaas Pouwels, Form-Scaff business development director.

Showcase developments

Operations director, Darryl Voysey says these benefits have quickly been recognised and is the reason why contractors currently building the five biggest malls of their type in Africa are using Kwik-Deck to complete their projects.

WBHO and Group 5 (in a joint venture) have opted for the system on the giant Mall of Africa in Midrand, which is soon to be the largest mall in South Africa to be constructed in a single phase. WBHO is also using Kwik-Deck to construct the Westhills Mall in Ghana, while Murray and Roberts is using the system on a further three regional malls, namely Baywest Shopping Centre in Port Elizabeth, Dainfern Square in Fourways and Matlosana Mall in Klerksdorp.

“These are flagship developments and the contractors are using our Kwik-Deck coffer systems because of the speed of erecting, stripping, and re-erection, as well as the ability to grant access to tradesmen to complete work underneath the supports.”

“Contractors also have access to a range of props for different roof heights, or to suit weight and strength requirements and can supplement requirements with their own staging equipment if needed. An additional benefit is that Form-Scaff has the unique ability to maintain sufficient stock-holdings to support the sheer scale of all these projects without delay. Our engineers, technical staff and crews are also readily available to assist with requirements on each of these sites, if and when there is a requirement,” adds Voysey.

Looking at some of the technical issues and advantages of the new system, Chris Erasmus Form-Scaff technical director, says the new Kwik-Deck system can be supported on any of the company’s support-work systems. A Kwik-Deck drop-head is attached to the upper end of each prop which allows the coffers and Kwik-Deck Beams to be easily stripped for re-use. One of notable technical differences on the system is the change from the standard 900 X 900 mm grid to 925 X 900mm. This additional 25 mm is to accommodate the Kwik-Deck Beams required to hold the coffers in place and translates into beams in one direction being 25 mm wider and using slightly more concrete.

“We initially viewed this as a potential stumbling block, but our customers (contractors) on all of the projects where the new system is being used easily managed to convince their clients that the advantages of speed, space, transport and lower labour requirements of the new system far outweigh the need to resize drawings etc. In future architects and engineers wanting to use the system will simply take the new grid size into account and design accordingly. In addition, a slightly wider rib adds extra strength to the floor and may even increase the loading capacity of floors in certain circumstances,” concludes Chris.

Monday, 28 July, 2014

Anniversary celebrations were recently held in four major centres of South Africa to celebrate the historic occasion of Form-Scaff’s 50 years of service to the South African market.

Since then just about every major construction project that has shaped the country has used Form Scaff equipment at some point in the development. Having grown to become leaders in the supply of shoring, scaffolding and formwork systems in the country, Form-Scaff invited its prestigious clients to share the occasion and looked back at some of the highlights and projects accomplished over the years.

More than 1200 guests were present at the parties throughout the country with a guest list that represented the biggest gathering of construction firm executives in the country in recent history.

Glitz and glamour

High kicks and entertainment there was aplenty with good food along with the good company of colleagues, retired ex-staff, including one of the founder members Mike Sullivan, as well as peers and all who played a part in the ongoing success of the company. Guests were taken on an entertaining audio visual journey through the founding of the company from a humble garage in Johannesburg, to become a powerhouse in the local economy and one of the largest companies of its sort in the world.

“We will continue to play a leading role in support of the construction industry in South Africa and across the world”.

With never a dull moment, the company’s journey has been an exciting one that has taken its staff and equipment to the top of the country’s tallest buildings, to the crest of its massive dam walls, to the high-speed Gautrain and the pitches of its World Cup soccer stadiums. It has stood up to every challenge and provided truly South African solutions that have shown the world what this country is capable of.

Form-Scaff formed the basis on which the Waco International Group was built and successfully established wholly owned operations in countries as diverse as Chile, Australia, Mauritius, New Zealand and the United Kingdom.

Through this it has provided products and services for some of the most prestigious projects of their kind on the planet, including the serious business of renovating the Houses of Parliament in England, Congress Hill in the United States and some of the world’s most high-tech bridges in Hong Kong.

Future Unwritten

Looking towards the future, the company is stronger than ever before and will continue to play a leading role in support of the construction industry in South Africa and across the world. No matter where the company is operating globally, it will always maintain its South African attitude and will never walk away from a challenge, no matter how big or complex it may be. Form-Scaff will find a solution.

Head Office
181 Barbara Road
Tel 011 842 4000
Technical Advice Centre
Toll free help line 0800 205 029

Branch Locator