Falsework and Formwork: Many and varied

The world of falsework and formwork is a very varied one, as the techniques and equipment can be used in many interesting and different ways on a multitude of different products.

Paschal, for example, has been involved in the creation of a waterproof concrete structure for drinking water.

Elevated tanks to hold 1,200m³ of drinking water are being made for Stadtwerke Zweibrücken in Germany.

A waterproof concrete structure in one cast was made by using formwork and shoring systems from Paschal – 580m² LOGO.3, 180m² TTK, 280m² Paschal Deck and 314m² GASS.

The new structure – to be built according to plans by CP Beratende Ingenieure & Co, Spiesen-Elversberg, and the architecture firm Molter Linnemann Architekten from Kaiserslautern, on behalf of Stadtwerke Zweibrücken – aims to ensure the drinking water supply of the southern zone of Zweibrücken

According to the architect’s plans, the shape evolved from the environment itself. The gable peaks of adjacent buildings, which are visible from the foot of the slope, are reflected in the diamond-shaped facade field that will be the only visible part of the building after the underground reservoir is covered with earth. Only the contours of the overall structure will be perceptible.

For the formwork of the concrete structures, the contractor, Wolf & Sofsky SF Tief- und Ingenieurbau, which specialises in the turnkey construction of plants and technical facilities for supply and waste management, relies solely on formwork and shoring components by Paschal.

During the bidding phase, the calculation department of Wolf & Sofsky was supported by the Paschal partner HSB Handels- und Servicegesellschaft für Baumaschinen, and the formwork design was supported by Paschal. It said this service was essential for the contractors in order to compile the quotation as well as to ensure compliance with the DVGW (German Association for Gas & Water) regulations.

Paschal said that because of the specified architecture, the structural engineering and the DVGW regulations for drinking water storage, the combination of its TTK, LOGO.3, Paschal Deck and the shoring system GASS were combined to build the entire concrete structure with system formwork components.

To ensure compliance with the strict DVGW hygiene requirements, the contractor had to submit comprehensive material samples, and to demonstrate organisational and personnel qualifications.

Because of the DVGW regulations, an absolutely closed-faced exposed concrete surface was specified for the concrete structures for the insides of the container, which, without further coating, comply with the hygiene requirements. Therefore, all wall formwork for the inside tank walls – combined from LOGO.3 and TTK – were coated on site with Zemdrain by Max Frank.

Complicated business

By its very nature, falsework and formwork is a complicated business, and Austrian-based Doka said that co-ordinating various parts of a project in confined spaces was one of the greatest challenges it faced.

The Aquis Plaza shopping centre, which opened last month, has been built in the heart of an Aachen, Germany, pedestrian zone.

It said there was virtually no room for storage and only one road to access the 100m x 200m area. On peak days, it has been accommodating up to 20 trucks carrying building materials, concrete and formwork. All this led to careful application of logistics by building contractor Ed Züblin, the general contractor for the turnkey shopping centre.

As a result of this, said Doka, it was important to find a formwork partner “with a product portfolio that allowed for realisation of extraordinary jobs”.

At the same time, the ability to procure large volumes of formwork just in time and with the shortest-possible lead time was crucial, it added. The lack of space required that part of it had to be pre-assembled.

The shopping centre features retail space of 29,200m2 distributed over three levels.

A car park with 600 parking spaces is available on the two upper floors, accessed by an intricate, spindle-shaped parking ramp, and connected to public roadways through a tunnel. The third and fourth upper levels contain apartments.

Doka said project was characterised by organic shapes such as the overhangs of a false ceiling to the large-scale glass roof.

“This is to say that there is virtually no right angle in sight,” it said. “Rather, with its curved shapes, the entire body of the structure is nestled against the buildings along the streets of Aachen’s historic centre.”

Describing the project as the region’s largest construction site, Doka said that cast-in-place building construction was combined with the use of (semi) pre-cast members.

The first step was to lay the foundations. Then came completion of the base plate that extends across 15,000m² and is up to 100cm thick. The next task was building what it described as an access dam descending into the interior of the structure, which had to be freely accessible to vehicles throughout the entire period of construction.

Doka said it served as the lifeline for the entire cramped site’s logistics. It added that its project engineers planned and calculated a structure equal to the task – 9m high and a span across 7m. The heavy-duty supporting system DokaShore bridge formwork was used. It is composed of high-capacity columns and system beams from the modular system SL-1. Its type-tested columns absorb individual loads up to 430kN.

It said that above this base support, jobs could be achieved safely and on time, while the construction site traffic could move freely underneath.

The building interior features some large and curved open storeys. They were bridged by components from the SL-1modular system. Load-bearing towers up to 9m high were set-up on the profiles of their SL-1 beams. They served to shore up the 40cm thick floors of the next levels.

Some Staxo towers were back-stayed so they could safely absorb higher horizontal loads as well. Doka said that with its rugged steel frames, Staxo 100 was designed for great shoring-heights and high loads. It aims to be adaptable to different layouts, with basic frames of 0.90, 1.20, and 1.80m in height. The distance between them can be set anywhere from 0.60m to 3.00m.

Doka’s solid web beams are used in the superstructure. Depending on the load, either H20 beams with blue ends were selected or the new composite formwork beams I tec 20 with grey end-reinforcement. Both beams weigh nearly the same. However, because of their design, the composite formwork beams claim to be able to handle around 80% higher loads.

Doka said this saved on equipment and hours of work.

Flexibility

A new central university campus with three faculties being built in Delémont, Switzerland, is using products from Meva, which said its system’s flexibility allowed slabs and beams to be poured in one go, saving labour and time

The campus complex is 200m long and comprises four offset blocks with four levels each, plus an underground car park and a nine-storey tower on the south side.

The slabs, 30cm thick and partly with irregular recesses, include longitudinal beams on every level. They are 40, 70 or 100cm thick.

Meva said the requirements for concrete works and formwork engineers were challenging – slabs and beams to be completed in single pours, on schedule and on budget.

It claimed the joint pours of slabs and beams proved the main stumbling block for other approaches, and contractor Parietti & Gindrat chose the slab system of MevaDec to handle the complex job time.

The MevaDec props, beams and panels are set up by only two workers. When reaching the position where a concrete beam is to be poured, MEP shoring towers are moved into place with wooden beams and panels to form the underside of the beams.

AluStar or StarTec wall panels are mounted horizontally to form the beam edges while wooden beams close the gap between the slab and concrete beam formwork. Then MevaDec panels are again set up for the slab area until the next beam position is reached.

It said that different slab areas were all formed without time-consuming filler areas by using different panel sizes and combining them in varying directions and in offset position within the primary beams.

Once the slab had reached its minimum strength, the props’ drop heads were lowered to pull out the MevaDec beams and panels, and move them to the next pour. A few props remain for reshoring.

Meva has begun an educational campaign to promote the new ACI (American Concrete Institute) Guide to Formed Concrete Surfaces.

It has launched a broad campaign to reach a professional audience on the benefits of the new ACI guide, which was published in December 2014.

It said the ACI was one of the most influential concrete institutions and was active in 120 countries across the globe.

Six years of hard work and Meva know-how are said to have gone into the new guide, which defines the features of formed concrete surfaces. Meva said this put everyone – the contractor, the developer, the architect, the engineer – in a better position to agree on the desired concrete finish.

Rolf Spahr, head of Meva Formwork Systems sales operations in Germany since 1988, said, “A few years ago, I was asked to get involved in the ACI to bring in my formwork knowledge and experience.

“After looking at the various guides and documents, I realised that there was no clarity on surface texture. My goal was to define clearly the various features of a formed surface, and the result is the new ACI 347 3 R­13 – Guide to Formed Concrete Surfaces.”

He said that it was a case now of educating contractors and architects about the new guide.

“lt will take time to gain experience with this, but I believe it will put everyone in a better position and will push people to sit together as a team. Talking together is always the best way,” he added.

Capping beam

Spanish-based Alsina is currently collaborating on the construction of a submerged mooring at the Civil Guard area in the Port of Barcelona, Spain.

For this project, Alsina is using its Capping Beam formwork system, as well as its Alisply Heavy Walls and Vertical Multiform formwork systems.

Alsina’s capping beam system is a semi-automatic formwork solution that allows performing concrete formwork sections on three sides. It is claimed to be a versatile system, as it is able to adapt to any geometry.

This system allows a seamless move to the next section by having front and rear wheeled frames, said Alsina, as well as easy removal thanks to the mechanical and/or hydraulic system used in the stripping function, a semi-automatic driving system of three immersed formwork sides.

The company said that with just a single crane, it achieves the stripping of the three sides and allows, from the previous set, placing the dywidag bars with no need to remove the formwork out of water completely, making it ready for next set.

Alsina is using its Alisply Heavy Walls system, a recoverable formwork system for concrete walls designed to be used with a crane and which allows the implementation of large surfaces with minimal joints between the panels. It is also using Vertical Multiform, a similarly recoverable modular system, described as cost-effective, for the implementation of straight sided walls with all kinds of polygonal geometries and a concrete finish.

Alsina is also collaborating on a civil works project in Italy, with the Genoa port extension project. The work is being undertaken by Loruso Costruzioni, which has used Alsina’s systems in the past.

The expansion of the Port of Genoa includes the construction of a new pier that rests on four cellular concrete blocks, each 12m high. Alsina provided its Alisply Walls formwork system for each in two 6m high spills, which were executed in a warehouse and will later be submerged in their final location with the help of specialised machinery.

The Alsina Group has launched a new website. Currently, the contents of the page can be viewed in English or Spanish, although it is planned to include French and Portuguese languages later on.

The site includes a news section in which there are more than 40 published stories about the company; a section dedicated to Alsina subsidiaries with information on each one; a section about Alsina’s formwork systems – 65 descriptions organised by category; and, a section about projects. The new website is at www.alsina.com.

On schedule

Peri has devised and supplied a formwork and scaffolding solution for the construction of the Foz Tua dam in Portugal, as well as the associated pumped-storage power station.

The Peri specialists supported the construction firm, Barragem de Foz Tua, to ensure the build was completed on schedule. This included co-ordination on site by a Peri project manager in addition to the Peri engineers’ collaboration with all project participants.

The dam, in northern Portugal, will reach a height of 108m, while the dam crest measures 275m long. Peri said that from a formwork perspective, the particular challenge was caused through the complex design of the double curvature reinforced concrete structure with the 5m-wide dam crest, and its integrated overflow mechanism.

The hydraulic circuit covers over 700m along the bank of the river and includes two independent tunnels, as well as an underground power station with two reversible units.

Peri’s engineers devised a solution using the SCS Climbing System and the Vario GT 24 Wall formwork for the double curvature dam. This combination was said to facilitate both the single-face load transfer and the high finish requirements.

Peri said that SCS enabled single-face concreting by transferring the loads from the fresh concrete pressure without formwork anchors through the bracket into the climbing anchor of the previous concreting step.

It said that thanks to the modular concept with multi-piece brackets, the SCS Climbing System could easily be adapted to the structural geometry. Large climbing units are possible as a result of the special load capacity of the brackets and high load factor of the anchoring, which it claimed ensured rapid progress on site. The working platforms, with a width of 1.9m, remain horizontal despite an inclined position on the dam, providing secure working conditions.

It said the flexible Vario GT 24 Girder formwork made units with the platforms that could be moved by crane. The planned project-specific wall formwork also ensured the best architectural concrete results thanks to the planned arrangement of joints, said Peri.

It also supplied a modified climbing and falsework solution for the complex geometry, such as the overflow area of the dam crest.

The Trio Panel formwork was used for the less complex wall structures of the dam, such as in the area of the dam galleries. The universal formwork system is designed for simple shuttering and to reduce shuttering times.

The Foz Tua pumped-storage power station is being built on the River Tua, a tributary of the Douro, as part of the Portuguese national energy plan and costing €370 million. Construction work on the dam began in 2011 and is expected to take five years.