Housebuilders looking for commitment - The Rake’s Progress

When a company’s business is selling luxury cars, image is all-important. Mercedes is on course to take its image to a higher level thanks to the complex that parent company Daimler Chrysler is building at the Brooklands racetrack, near Weybridge in Surrey.

The complex, known as the Brooklands Heritage and Technology Centre, will have its own skid pan and test track so that Mercedes’ customers can try before they buy. It is the futuristic building, however, that will create the biggest wow factor when it opens in summer 2006.

It was designed by architect Aukett – before its merger with Fitzroy Robinson – and structural engineer Gifford. The building is subdivided into three parts, with an east wing and a west wing flowing from a central area. The central area contains the “brand gallery” that will showcase the latest products from the German carmaker as well as historic racing machines.

The curvaceous two-storey brand gallery also demonstrates the engineering excellence of concrete contractor O’Keefe Construction. In certain areas, there are concrete walls that are circular on plan and rise 6 m, but also lean inwards. In other areas, there are 30 raking concrete columns that lean both inwards and sideways at the same time. Many of these raking columns also link up to overhead ring beams, which just to complicate matters a little more are circular on plan but have an outer surface that tapers inwards.

These elements combine to create a geometry that is as striking to look at as it is challenging to build – especially those raking columns.

James Bourke, O’Keefe’s contracts manager, observes wryly: “We have done lots of bigger jobs and lots of higher jobs, but the complexity of this project beats them all.”

The first consideration was whether the columns could be formed in precast concrete thereby eliminating some of the problems of casting them on site. Bourke says this option was soon dismissed because of the high loads that the columns had to take, coupled with the complexity of tying them into the concrete slabs that they had to support.

This left O’Keefe’s project manager Tom Diffley and his team of carpenters no option but to devise a shuttering system to enable the columns to be cast in situ. Their task was to ensure that the system could be easily erected and taken down, and that it allowed the installation of the prefabricated reinforcement cage within the shutters. They also had to make sure the shuttering was adequately propped to support the eccentric weight of the column while it was being cast, and that it permitted enough movement to enable the entire assembly to be adjusted to ensure it was inclined at the correct angles.

The solution chosen was to use two L-shaped shutters supplied by Peri that would fit together and enclose the 500 × 300 mm rectangular columns, together with a system of push-pull props that would act as supports and allow the columns to be correctly aligned.

The first operation was to fit the shutter that would form the underside of the column and secure it in position with the adjustable props. Even this was no easy task because the props had to lie in the same plane as the columns were leaning. O’Keefe’s setting-out engineers had to calculate exactly where the anchorage bolts needed to be installed in the floor slabs to secure the base of the props. Even the walers – the horizontal beams that provide stiffness to the shutters – had to be augmented by purpose-built additions. These were attached to the shutters at an angle calculated to provide the maximum support for the top of the raking props.

Fixing the reinforcement cage within the bottom section of the shutter was resolved by using a block and chain that inclined the cage at an angle that allowed it to be lowered into position by tower crane.

This operation was followed by an easy bit: fixing the upper half of the L-shaped shutter in place. Next came the delicate task of finally checking that the column was aligned correctly. An EDM, or electronic distance meter, was used to check the co-ordinates of the four corners at the top of the shuttering and the props slackened or tightened to bring the column into position.

These jobs were not made any easier by the 6 m floor-to-ceiling height of the columns, which meant that the operatives had to use man-riders and cherry pickers to gain access. In addition to their complexity, the tasks required a significant to crane time compared with a typical vertical column.

Compared with the columns, Diffley describes the rest of the building’s concrete frame as “pretty standard”, even though the floor slabs were formed from post-tensioned concrete to create a relatively column-free interior space.

Client Daimler Chrysler
Architect Aukett
Structural engineer Gifford
Main contractor Warings
Concrete frame contractor O’Keefe Construction