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✍️ By: Team BC1.NL
Why do gallery floors need to be reinforced?
A few years ago, a gallery slab broke off a block of flats in Leeuwarden, The Netherlands. Since then, the safety of these cantilevered structures has received closer attention. At the Zwedenburg gallery flat in The Hague, for instance, investigation revealed that the reinforcement in the cantilevered gallery floors sits too low, leaving the floors insufficiently strong and failing to meet safety standards. Gallery floors and balconies have to be strengthened when they no longer meet the safety standards, for instance because the reinforcement sits too low or because of concrete cancer. Additional anchoring restores them to the required strength.
Who developed the system?
The VVUV system, Dutch for "Vogel's anchoring system for cantilevered concrete floors", was developed by Vogel BV and S&P Clever Reinforcement Company, together with engineering consultancy ABT BV. Using carbon rods, the system significantly improves the safety of cantilevered structures. Vogel has held a patent on it since August 2016.
Where does the strength come from?
From the interplay between the mortar and the carbon rod. A rod of about 14 millimetres was chosen, which is a considerable overcapacity: such a rod can take a tensile force of roughly 35 tonnes. The system took two years to develop, more than a year of which went into that combination.
Full-scale tests revealed a warning capacity
ABT recommended full-scale testing from the outset, and it was precisely those tests that led various parties and regulatory bodies to accept the system. The tests showed not only that balconies and galleries became safer once reinforced, but also that they give a warning sign when overloaded. This helps prevent accidents like the one in Leeuwarden in 2011. For each project, ABT calculates how many anchors are needed per slab.
Minimal disruption for residents
Another advantage of this innovative system is that it causes minimal disruption for residents, who can keep using the gallery while the work is carried out.
