Altrad RMD Kwikform, known for its falsework and formwork system, has revealed that its tubular shoring system Tubeshor – traditionally used horizontally to support the sides of excavations – is now being used as a vertical shoring system in above ground applications.
Large props are used on construction projects where an adjustable, load-bearing member is required, offering an economical method for supporting deep excavations.
But according to RMD Kwikform, when employed as vertical shoring members, the range of applications may be extended considerably.
According to RMD, potential applications range from the construction and repair of road and rail bridges to the construction of offshore platforms and even ship-building.
Historically, vertical shoring systems have relied on multiple load-bearing strut members that have to be handled and assembled individually, together with a substantial number of ledgers and diagonal braces to restrain the struts and prevent them buckling.
This usually involves bespoke fabrication of steel beams and columns to suit the specific application.
But Altrad RMD says that adapting its Tubeshor props for vertical use offers a range of benefits.
For a start, the cost of buying steel, cutting it to length and assembling a support structure is far greater than hiring props, bolting them together and erecting them on site.
The high strength capability of tubular shoring systems also means fewer struts are needed and assembly time can be reduced.
Tubeshor is available in five tube diameters ranging from 320mm to 1,370mm and with maximum load capacities from 1,400kN to 15,000kN.
With only a few individual components, assembly is easier and faster than most current methods. The system’s hydraulic ram units provide fine length adjustment and hydraulic preload. Once installed, the hydraulic element can be locked off mechanically with a threaded collar to ensure stiffness and prevent movement.
In most cases the system can be configured to carry the load from the point of application to the foundation without lateral buckling restraints. This means that the props can be assembled horizontally on the ground and then, with one end attached to the foundation via a swivel unit, craned into an upright position – a process that reduces work at height and improves safety.
Ian Fryer, global product innovation director at Altrad RMD Kwikform, has been with the company for over 30 years and has been instrumental in the development of its temporary works equipment, including Tubeshor.
He says: “In the early 2000s I was involved with efforts to gain type approval for our Megashor product [a mechanical propping system] to be used in California.
“During that trip, one of the local RMDK sales people took us to see how shoring was typically done in California by the ‘pipe-and-beam’ method, which, I believe is quite unique to California.
“We went to a project where substantial steel tube piles ran top to bottom between a header beam and the foundation, without any intermediate ledgers or braces. I was immediately struck by the structural simplicity and elegance of the system”.
Nevertheless, this method required each tube to be meticulously cut to length, trimmed and welded by skilled steel fabricators on site. It was also inherently inflexible and vulnerable to overloading.
These shortcomings meant that, though structurally appealing to Fryer’s engineering instincts, the pipe-and-beam method offered few practical advantages over existing methods. Eventually, however, Fryer found a way of combining the structural simplicity he had seen in California with the practical benefits of an efficient modular system.
“About 10 years later, when tasked up with designing the five families of RMDK Tubeshor systems, I was determined that they would, from the outset, be designed and detailed for easy configuration in both ground shoring and falsework applications,” explains Fryer.
“That’s why we call these systems ‘hybrid hydraulic shoring systems’ because they are configurable to be used in multiple applications.
“Large diameter, thin walled steel tubes are as efficient as possible when used as slender struts, which means that ledger levels can be very widely spaced or even eliminated.
“This makes possible the same simple form that struck me on that trip to California, but the versatile range of end fittings evolved for use in ground shoring applications massively reduce the time of assembly, eliminates the requirement for on-site welding, reduces waste and ensuring concentric prop loading and controlled load removal.”
RMD Kwikform has already deployed its Tubeshor system in this new configuration on a few major projects, including the Hinkley Point C nuclear power station project in Somerset.
Here, the Tubeshor system was used to support the project’s largest pre-cast concrete component, weighing a massive 862 tonnes, which was lifted and installed inside the reactor building.
The props’ 2,500kN internal hydraulic cylinders provided precise level adjustment, preloading and load control, with speedy adjustment and no need to procure separate jacks.
The Tubeshor props were fitted with spherical bearing units with 5o of rotation in any direction at both ends, allowing them to take up angular tolerances at the ends of props, reducing the need for grouting and ensuring concentric prop loading.
RMD also used its mechanical Megashor push-pull prop stabilisers as an ‘off the shelf’ method of adjusting prop alignment and providing lateral support of the props.
Other recent applications have included the supply of several Tubeshore props for falsework support on construction of the new Hong Kong airport T2 project, and two 16m-high free-standing shoring towers for the construction of an extension to the Shindagha Bridge, part of a new $1.37bn road network in Dubai.
The Dubai contract was in fact the first time Tubeshor was used in this new vertical configuration and, despite the system’s ability to support vertical loads without lateral bracing, a RMD Kwikform designed a bespoke ledger and bracing system to ensure resistance to the high lateral loads involved.
“I have heard it said that there is little that is new in construction, but the Tubeshor families of products might just be an exception to that rule,” says Fryer. “Having recently completed the design of the 10,000kN range of end fittings for our Tubeshor 1060 system, we are shortly set to develop a whole new rage of Tubeshor accessories aimed specifically at vertical falsework applications.”
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