A new type of nail for wooden structures with increased resilience

  • 1 Relo-Nail Ltd., Oborishte Str. 1/A/17, 1504 Sofia, Bulgaria
  • 2 Georgian Technical University (GTU), Faculty of Transportation and Mechanical Engineering, 0171 Tbilisi – Georgia


In the following work, we present the results from a research of a type of nail with a new form of section, in comparison to the round section that currently used nails have. This new form is similar to an equilateral triangle, the sides of which’ are curves [Reuleaux Triangle]. The body section of this new type of nail has three curves and three edges; his surface SR is with 5.56% larger than the surface SC of a round nail with the same section area. From the experimental research that has been made so far, it was established: (i) because of the larger compaction of the wooden material in the ends of the edges, and of the larger surface, you get a bigger friction force, resulting in a pulling-out force Fto,R that is on average twice as bigger as the pulling-out force Fto,C; (ii) because that the new form of nail has edges, this leads to bigger resistance during the rotating of the joined wooden elements one against another – the moment Mr is on average 60% bigger than the one with elements, joined with a normal nail. These advantages, as well as the use of the existing technology and machines for the production of nails without having to effect any major changes, create the conditions for the application of the new type of nail in construction, furniture production and in the everyday life, for an output of products with larger resistance to external forces. This effect will be especially useful for increasing the residential buildings’ resilience during earthquakes, hurricanes and other natural disasters.



  4. M.Haroldsen, Needles made from non-round stock, EU Application 93112434.1, 09.02.1994
  5. V.Kolev, A.Ivanov, Nail, Patent BG 65071 B1, 31.01.2007.
  7. ml
  8. N.Anward, F.Najam, Structural Cross-Sections Analysis and Design, Butterworth-Heinemann, 2016, ISBN 9780128044438
  9. J.Ochshorn, Structural elements for Architects and Builders. Design of Columns, Beams and Tension Elements in Wood, Steel and Reinforced Concrete, Butterworth-Heinemann, 2009, ISBN 9781856177719
  10. P. Bodurov, P. Sirakov, T. Penchev, D. Mihaylov, NAIL, HAGUE, European Union(EM), (DM/213 785), 12.04.2021.

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