Construction of the A$32 million, 30-storey 123-apartment Radisson Suites building in Brisbane, Queensland was quite literally given a major lift by one of the country's leading formwork and falsework companies, RMD KWIKFORM Australia.

Use of the company's Autoclimb hydraulically operated, bracket-type self-climbing formwork overcame two major challenges. It did away with the need for expensive cranage to lift the formwork used to construct the in-situ concrete external walls while achieving a rate of climb that ensured the project was completed on schedule

n plan, the angular egg-shape building is a complex 400 square metre multi-sided structure, where no two external walls are parallel to each other or at right angles with one other. The lower floors consist of the Radisson Hotel's foyer and reception, restaurant and shop, while the next four floors are devoted to car parking. The one and two bedroom apartments start on the fifth floor – which also houses the hotel's gymnasium, spa, sauna, heated pool and outdoor sundecks – and continue for the remaining 24 stories.

Among the major considerations leading to the selection of Autoclimb was that it offered the specialist formwork contractor, Di Pompo Construction Pty Ltd, a high degree of flexibility, allowing the use of a full range of traditional, modular or purpose-made conventional formwork. The automatic lifting of the formwork was responsible for dispensing with the need for cranes, while the bracket system allowed Autoclimb's components to be arranged into a greater number of configurations than is possible with complete core climbing systems.

The system's built-in adjustment facility ensured trouble-free and accurately aligned erection of the shuttering. By staying horizontal at every stage in the lifting process, ascent was smooth and free from jolting or tilting. Each individual climbing bracket has a safe working load capacity of 100kN, which enabled large areas of formwork to be supported on each bracket.

However, there were a number of other factors that were important to the Radisson Suites construction team. Autoclimb's trolley-mounted formwork panels can be retracted by 750mm; this enabled rapid and easy cleaning of the formwork and positioning and fixing of the steel reinforcement. Another benefit was the time and labour saving ease with which form faces could be aligned, thanks to the wall plates' integral vertical and horizontal adjustments.

On the Radisson Suites project, the formwork panels differed greatly in widths to up to 8.8 metres. A typical 6.9 metre “flat” section consisted of seven RMD KWIKFORM Super Slim Soldiers with bracing at either end and centrally. However, due to the plan shape of the Radisson Suites, formwork panels also had to accommodate internal and external junctions of varying angles.

For a climbing formwork system that can accommodate such diverse plan shapes and has such a high safe working design load, Autoclimb components are relatively few. Essentially – in addition to the formwork panels – an Autoclimb solution comprises five major elements:

•  A wall plate and suspension shoe that support the Climbing Bracket, Climbing Head Assembly, Climbing Mast, Retracting Trolley and the formwork panels.
• The Climbing Bracket, on which the Retracting Trolley runs.
• A Retracting Trolley that enables the formwork panels to be retracted.
• The Climbing Head Assembly with cylinder, which raises the Autoclimb equipment.
• A Climbing Mast, up which the Climbing Head Assembly is hydraulically lifted.

Stage One of the erection sequence was the first pour of the main tower block starting at Level Five, 34 metres above ground level. RMD KWIKFORM Super Slim Soldier formwork sections, 2,750mm high, were utilised to construct the gang form shutter. The inner and outer sections were restrained using RMD KWIKFORM Rapid Tie bars with spacers to form the cavity for the reinforcement and concrete. Bracing, both internally and externally was provided by push-pull props that were secured through the holes in the webs of the Super Slim Soldiers. External working platforms were fitted at the top of the external formwork using RMD KWIKFORM access equipment components.

Once this section of the external wall had cured, the internal formwork was removed and the in-situ concrete floor was laid. Stage Two was extending the gang form shutters to above Level Six by adding a further 1,620 mm of Super Slim Soldier formwork and repositioning the inner sections of formwork. At this point, the first Autoclimb steel anchor cones and ties were located, prior to pouring, and imbedded in the external concrete wall immediately above the Level Six floor level. Once this section had cured, the formwork was again removed.

The Autoclimb wall plates were then fixed securely to anchor cones cast into the wall as part of Stage Three. Suspension shoes were, in turn, fixed to the wall plates. The pre-assembled Autoclimb platforms, complete with boarded decks and handrails, were then crane lifted and attached to the suspension shoes and the bracket's lower edge was restrained against the previously cured section of the external wall.

Super Slim Soldier support frames were positioned on the Autoclimb Retractable Trolley located on the top member of the cantilevered Climbing Brackets. At this point, raking shores were fixed to the outer end of the Retractable Trolley to support the extended formwork panels.

The internal formwork was supported in the same way as in Stage One, and the next lift of concrete was poured. Again, steel anchor cones and ties were located and imbedded in the external concrete wall, this time immediately above the Level Seven floor level.

The Climbing Bracket assembly for this first Autoclimb lift at Radisson Suites was supported at its base off the roof of the fifth storey. From the sixth floor onwards, Autoclimb Climbing Masts and Climbing Head Assemblies with hydraulic cylinders were installed through the suspension shoes and end carriages, against the external face of the wall.

This Fifth Stage also saw the attaching of gang form hangers at the top of the formwork, which allowed both the internal and external formwork to be raised as a single operation on the subsequent floors. From this point on, Autoclimb's hydraulics units were used to “climb” the formwork up the face of Radisson Suites as each section of external wall was poured and cured.

At each lift, once the concrete had cured, the external formwork was retracted or “rolled back” from the face of the concrete, the support restraining the inner formwork having first been removed. This allowed the gang form hangers to roll away with the inner formwork, enabling both the inner and outer formwork to be hydraulically lifted as a single operation.

When the formwork was at the correct level for the next pour, it was rolled back into position and the internal formwork – suspended from the gang form hangers – was manually rolled into position. The inner and outer sections of formwork were then restrained using RMD KWIKFORM Rapid Tie bars with spacers to form the cavity for the concrete pour.

As the work proceeded up the face of the apartment block, wall brackets and suspension shoes were fixed to anchor cones and the redundant suspension shoes and anchors at lower levels were removed for reuse and the face of the concrete was made good.

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