Falsework & formwork: The bespoke experts
By Helen Wright05 March 2012
Manufacturers of falsework and formwork need to be flexible, with design teams that can respond quickly to new demands from contractors, and changing situations on the ground. Core products need to be flexible so they can be used in different combinations to build different structures, and the safety of workers is a huge consideration that needs to be incorporated into formwork designs.
A good illustration of this custom approach comes from Pilosio, which designed a support structure using its MP multidirectional scaffolding to build struts for a difficult project constructing a waste-to-energy plant in Turin, Italy.
Contractor Coopsette needed to temporarily stabilise a 40 m free wall as part of the project, and Pilosio's technical department designed a custom support structure using the MP system - a flexible, modular tube and joint scaffolding product which offers four fastenings for stringers as well as four more slotted holes, allowing struts to be fastened at almost any angle.
The MP falsework was used with the company's T28 tower system, making it possible to support all floors while maintaining simple dimensional characteristics.
Pilosio CEO Dario Roustayan said that while the company had seen the market for pre-fabricated falsework saturate in recent years, demand for the multi-directional product had grown - the company recorded a +30% increase in sales of its MP falsework in Italy last year.
"This type of falsework opened lots of opportunities for us, especially in South America and Canada. Large businesses still purchase traditional products, which then they use typically on yards abroad, but the demand for multidirectional scaffolding is stronger, since it is particularly flexible in special applications from restoration to industrial maintenance, in shipyards and so on," he said.
The MP system comes in two sizes - the smaller measures
830 mm centre to centre and has a maximum capacity of
150 kg/m2, while the 1.15 m product has a maximum capacity of 300 kg/m2.
Pilosio said uses for the MP system could include as facade scaffolding for maintenance and construction, as a loading tower, service stair, a high capacity structure for work at a height or as a suspended structure when it is impossible to start from the bottom.
Harsco, too, has been involved in a number of high-profile projects - its self-climbing formwork (SCF) was used on the world's longest cable-stayed bridge, the 3.1 km long Russky Island Bridge in Vladivostock, Russia, for instance - and the key has been to find custom solutions to particular problems.
Harsco provided a formwork foreman and a number of technicians to support the construction of the bridge and ensure the planned work processes were followed on site.
The SCF was used to help ensure quick and safe access during the construction of a 320 m tall pylon for the new bridge. It was adapted to the tapering and inclined geometry of the pylon itself, forming an enclosed temporary working environment which protected against extreme weather conditions during construction of the pylon and its 70 m tall approach piers.
To accommodate the tight construction schedule the system was specifically designed to allow adjustments to the formwork, and the 72 climbing cycles of 4.5 m, to be performed quickly.
Rigid separation between the steel fixing levels and the shuttering and climbing operations meant that once the steel fixing was completed, the formwork could be retracted and cleaned before the climbing shoes were fitted and the climbing rails raised and tied for the next pouring cycle. This allowed the SCF platforms to be raised immediately after completion of the steel fixing and the formwork to be moved into its new position ready for the next pour.
But as well as making their products as flexible as possible, manufacturers have also concentrated on safety.
Indeed, several new safety-related products will be introduced to the market this year. Efco, for instance, has developed a building perimeter protection system called Power Shield for high-rise building construction.
Designed to provide wind and weather protection for construction workers while at the same time people below from falling debris, the barrier covers up to five storeys.
By covering multiple floors, the sheer size of the Power Shield means panels do not have to be raised as often during the construction cycle. The system is also self-climbing, eliminating the need for a crane to move perimeter panels from floor-to-floor.
The Power Shield is made of steel and can be used with both plywood sheeting and a combination of synthetic mesh, corrugated light gauge steel and clear polycarbonate panels to allow for air and light to enter.
Peri has also focussed on safety in its latest developments and will showcase its new Prokit EP110 safety System at this year's Intermat show in Paris. Prokit is a new temporary edge protection system that has been designed with a small number of components to facilitate rapid assembly.
Measuring 1.1 m high, the Prokit EP 110 is designed to prevent workers and objects from falling off edges, stairs and other areas up to inclination angles of 10%. The set-up involves just a 2.6 m long side mesh barrier, which weighs less than 20 kg, a post and assembly feet for slabs or walls.
Peri said any edge length could be secured by overlapping variations of the mesh barrier, while a 1.30 m long side mesh barrier is also available for length compensations.
The new Prokit system was used on a project to construct an arched tunnel on Route Nationale 88 in France. Peri's Variokit formwork, which has generously-sized working levels of up to 2.5 m width, was used on the project.
The construction site team attached the side mesh barriers to all open edges. The slab feet were screwed onto the wooden planking and accommodated the posts, making attaching the mesh barriers simple and allowing the construction team to achieve the project's planned three-day cycle.
In addition to the Prokit safety barrier, Peri will also be introducing its new shoring tower, Peri Up MDS at the Intermat show. The shoring tower is equipped with working platforms hanging from the handrails and is said to provide a high level of security during the erection and the dismantling phases.
The company said the working platform hanging from the handrails means the working position is automatically 1 m below the handrail.
"The platforms always follow the top of the tower, their evolution is spontaneous, automatic and constant. The obligation to manipulate the platform from above completely changes the philosophy inside the tower," Peri said.
Meanwhile, the refurbishment of the over 100 year old National Library in Strasbourg, France, required sensitive construction techniques and particularly painstaking planning of logistics and deliveries.
Paschal's structural design division had to develop two completely new climbing systems that fitted between the narrow walls and also fulfilled the safety requirements. The available space was so limited that typical working-platforms could not be applied to the formwork, so the manufacturer developed 1.05 m wide brackets with integrated ladders for the project.
The library's exterior front, roof and numerous inner structures of the building had to remain intact while the complex was gutted by contractors Demathieu & Bard and Urban BTP during the € 61 million (US$ 80 million) project, funded by the French government.
The most difficult part of the job involved gutting and supporting the middle structure, which was crowned by a cupola which could not be accessed from above or by using a crane.
Paschal built a 24 m high sub-structure from four towers that would absorb the load of the building's 600 tonne cupola. A pivot arm of a hoist crane was then installed on the four corners of the sub-structure and a diamond-shaped cocnrete binding beam was built on which the cupola could rest.
L-shaped concrete columns were then built to face the binding beam and ultimately carry the total load, allowing the supporting falsework to be removed.
Paschal built up the towers using horizontally-positioned elements of its Logo Alu formwork system (up to 2.7 m long), which has a low weight and can be adjusted to the required length by 10 mm intervals. Paschal Deck was used as a supporting system, and Logo 3 formwork was used for the L-shaped columns.
Logo 3 has a 70 kN/m² capacity and its profiled flat-steel frame is said to be particularly suited to narrow conditions. Fast cycle times saw two formwork sets applied to the diagonally-opposed columns every two days.
Assembling, relocating and disassembling shoring towers can be key to the efficiency of projects, with many falsework and formwork manufacturers claiming the shoring tower method can save much more time than using conventional climbing systems.
Meva said its light-weight shoring tower system helped a bridge construction project on the A6 road in Germany run on schedule. Meva reported that its Space shoring towers - which were used to pour the piers for the bridge into its Mammut formwork - completed the job twice as fast as a conventional climbing system would have done.
The shoring tower is designed to transfer the loads of the props that brace the formwork place on it. Assembled from light-weight frame units that are 3 m high, it can be crane-transported as a complete tower or in several units, depending on the height of the shoring tower and formwork.
RMD Kwikform also designed an integrated formwork and shoring solution to support Qatar Diar Vinci Grand Projects Joint venture (QDVC) in the construction of a 6.5 km tunnel in Qatar.
Developed especially for the project, the manufacturer supplied six complete sets of formwork and shoring that could be used to cast the 1.2 m thick slabs and walls. Measuring 14 m long, each tunnel set used lightweight aluminium Alshor Plus shoring that was made up into specialist travellers. This in turn supported Superslim Soldier steel primary and GTX secondary beams to form the tunnel roof slab.
With Megashor heavy-duty shoring used as back propping, Superslim Soldiers and GTX beams completed the overall design for the construction of the tunnel walls, creating a complete travelling tunnel set.
Meanwhile, a project to build the Mississippi River Bridge, which will create a new link between Illinois and Missouri, US, provided another example of bespoke formwork development.
Joint venture partners Massman Construction, Traylor Brothers, and Alberici Constructors chose to use Doka formwork to help build the two pylons for the cable stayed bridge, which are set in the Mississippi river bed with 6 m deep footings.
The Doka team worked with the contractors to develop custom support brackets for single sided walls to ensure there were no conflicts with the form design, while custom steel brackets and splice plates were used to connect gang forms together.
A custom aluminium pouring platform was also used, while a bespoke protection screen was installed on the outside of Doka's SKE climbing system to keep workers safe and comfortable during the harsh winter weather.
Doka's SKE climbing systems also allowed the contractors to climb all four legs efficiently without using a tower crane - a factor which it said saved time and money.
There can be no doubt that these manufacturers' willingness and ability to develop products that are individually tailored to the contractor's needs has helped to win them the work. And with many more major infrastructure projects planned around the world, falsework and formwork producers can expect to face even more complex challenges over the next 12 months.