The challenge was to design a pair of 27 metre high towers, which could provide temporary support at the mid-span of the 56 metre wide parabolic structure. As the acknowledged innovator in the field, RMD Kwikform made full use of its experience to carry out the structural analysis and risk assessment, while utilising both standard and specially engineered components to meet the multiple demands.
The solution to the project brief was developed in partnership with the client over a period of months with RMD Kwikform engineers attending meetings with the clients in Germany, France and Morocco. Once the final configuration had been confirmed, bespoke equipment was manufactured and the equipment erection phase of the project began onsite in June of 2012. This phase of the project was supported by two of the RMD Kwikform’s site specialists, who trained and supported the erection teams onsite at Jorf Lasfar.
Perhaps of greatest significance to the client, SOGEA was the fact that the RMD Kwikform solution avoided the onerous task of erecting conventional scaffolding down the entire centreline to the hangar, saving both time and money. Instead the two linked towers, with an overall footprint of 13.3 x 5.14 metres are mounted onto rails that enable them to be moved from the line of one structural rib to the next. When the project is complete, the shoring can be dismantled for reuse on other sites.
Whilst the majority of the towers are assembled using RMD Kwikform’s standard Megashor heavy-duty shoring system, the top and bottom sections were bespoke engineered and fabricated specifically for the task. These sections provide both stability, mobility and a highly accurate mounting point where the ends of the 1.6 tonne precast members could be positioned before the engineers made the permanent connections between them.
This meant creating a first stage that not only had to be mobile, but that could carry a total of 86 tonnes of concrete counterweights, or kentledge, to provide stability. The towers were designed to resist wind speeds of up to 70km per hour, in what is an exposed coastal location, so tethering cables were also included in the design.
On top of the Megashor Towers, RMD Kwikform’s engineers developed man accessible platforms on hydraulic jacks, which support the cradle into which the precast beams are lowered. This is strutted by Superslim Soldier raking shores which assisted in positioning and holding the beam ends temporarily in position while the permanent connections are made.
RMD Kwikform’s Major Project Manager, Andrew Gardner, commented:
The towers were designed to be erected on steel rails to allow them to be moved along the centreline of the hangar. They feature a platform on the top with a frame and hydraulic jacks that are tightened up as the beams are lowered into their final position.
Our Megashor solution is not only very neat, but with the bespoke elements, it has cut out the need for the client to erect a forest of conventional scaffold tube and fittings along the length of the hangar which is several hundred metres long. SOGEA made the decision to invest in a proper support system and streamline their method of construction. This is clean, efficient and time-saving for the customer, who is planning to use it again for a number of these hangars that are planned to be built around the country.
In addition to Megashor, RMD Kwikform supplied Rapidshor stair towers to provide safe access up to the working platform which is fully decked and surrounded by handrails.