When Pfeifer Seil- und Hebetechnik GmbH, of Memmingen, Germany, brought the VS® system to market almost 15 years ago with its first product, the classic VS® Box, nobody would have believed that this system would be taken up so enthusiastically. But the product’s obvious positive features and the associated revolution in the joints between precast concrete walls led to a rapid spread of the VS® system. The continuous enhancement of the system, taking into account customer needs and changes in the world of Standards, was and still is regarded by Pfeifer as a mission, and the company invests significant development resources in this area. For example, some milestones in product development have been:
- the unique wire rope loop fixings in box systems
- the first series-production application of steel ferrules for anchoring the full force of the wire rope (Fig. 1)
- the first rail systems without additional formwork requirements
- the first National Technical Approval for a wire rope loop system in Germany
- the first rail system for the connection column-to-wall (Fig. 2)
- the first Approval with rated design resistances for all directions – 3D
This list does not include the continual, small improvements, such as the profile modifications to improve the bond between the precast component and the grouting filler. These are just a natural part of the ongoing improvement process. In 2011, the company launched a new generation of the VS® System3D, namely the PFEIFER VS® ISI System3D (Fig. 3). With this new product, Pfeifer took even more account of lessons learned in practice. The aim was to make the system simpler to use and eliminate potential faults, and the economics of the whole system were once again put under the microscope.
Common criticisms in the past included the quantities of mortar needed and also - a point often raised - the risks involved in direction-dependent installation of the rail profiles. It had frequently resulted in deviations in the arrangement of the loops, especially where the precast elements for a construction project had to be produced in several different plants. The completely new 'ISI' variant of the VS® rail now solves all these problems at a stroke. The possibilities for incorrect use have been minimised and the mortar used for each joint has been significantly reduced. All true to the motto "Not just simple, but 'ISI'." The design for an application of the new VS® ISI System3D is based on the verification of the individual forces (Fig. 4) from their various directions of action, their interaction (Fig. 5) and finally the tensile components. Instead of manually, verification can also take place with the aid of the free dimensioning software from Pfeifer. Depending on user requirements, the software can generate an auditable analysis for structural and fire-protection purposes, as well as exportable CAD data for the complete installation arrangement (Fig. 6). Just as important as good products is their usability on the building site. There, joints manufactured with PFEIFER VS® systems are filled with VS® PAGEL® GROUT. The material is very free-flowing when mixed so that it can reach absolutely all joint corners and angles between the wire rope loops. Experience shows that high shuttering pressure builds up over the maximum filling height of 3.54 m, therefore painstaking formwork is required. Pfeifer has solved the problem with the practical and very easy to use FDS joint pressure formwork (Fig. 7 and 8). Using this joint pressure formwork, smaller projects with joint lengths to be poured of between 20 and 40 m per day can now also be implemented quickly, securely and inexpensively. The use of the very free-flowing VS® PAGEL® GROUT also ensures that each joint is filled without defects. The FDS joint pressure formwork is available in standard lengths of 4 m and 1.2 m. There are three diameters - FDS Minus, FDS Regel and FDS Plus - which are optimally tailored to the normal joint tolerances. Construction site experience from the first few months is thoroughly positive and confirms that with Pfeifer’s new product development, 'FDS Joint Pressure Formwork', the on-site construction work is considerably simplified. Where more than 40 m/day of joint has to be filled, the alternative VS® P-PAGEL®-JOINT FILLER GROUT is available. Using this grout, the joint can be filled with the malleable material without extensive formwork measures (Fig. 9). It requires the use of appropriate machines and equipment and experienced personnel with the necessary specialist skills. Where these conditions exist, 80 to 100 m of 'finished' joint per day can be completed without problem. Once again, all the advantages of the PFEIFER VS® ISI System3D at a glance:
- symmetrical arrangement of the loops; direction-dependent installation is no longer necessary – simply 'ISI'
- optimised loop overlaps and therefore reduced grout volume, with consumption of mortar reduced by up to 30 %
- flatter profiles; no change of reinforcement required
- improved bond between the concrete and the metal profile
- adaptable joint-filling methods; the right one for every construction sequence!
- high load-carrying capacities
- great flexibility thanks to system solutions for all conceivable applications
The sum of all these benefits make the VS® ISI System3D simple and safe to use and yet extremely efficient as well; a success factor for every construction site. Further information is available from Pfeifer Seil- und Hebetechnik GmbH, Dr.-Karl-Lenz-Straße 66, DE-87700 Memmingen, Telephone +49 8331 937-290, Telefax +49 8331 937-937, E-Mail: email@example.com.