Metal-based products – Steel grades
Differences in steel grade designations depending on the type of fastener.
European standards (e.g. EN ISO 898-1) allow steel classification for hex bolts and threaded rods in the following notation:
X.Y
where:
X – number related to steel ultimate strength fuk
Y – number related to steel yield strength fyk
e.g. for steel grade 5.8
fuk = 5 100 MPa = 500 MPa
fyk = 0.8 fuk = 0.8 500 MPa = 400 MPa
This classification is harmonized and applies to all the manufacturers and their products. Therefore, any product with this marking, regardless of other variables, should meet the requirements of the standard.
For some of the fasteners above classification is not valid. Presentation of steel properties of mechanical anchors, concrete screws or steel elements of frame fixing is different. Such products are not harmonized. Approval process is based on appropriate EAD documents, e.g.:
- EAD 330232-01-0601 Mechanical fasteners for use in concrete
- EAD 330011-00-0601 Adjustable concrete screws
- EAD 330284-00-0604 Plastic anchors for redundant non-structural systems in concrete and masonry
Performance data (including steel capacity) are presented in ETA for selected products as a direct values for each size and type of fastener. Parameters are showed in tables in Annex C of ETA – Performance. Values called “Steel failure for tension load NRk,s” and “Steel failure for shear load VRk,s” are given as a direct values in [kN], not via steel grade or steel parameters.
Due to unique character of the production process individual performance data and geometry (e.g. variable cross section of element) they are not subject to classification as the products mentioned at the beginning (bolts and threaded rods).
Moreover, looking on issue from anchor theory point of view, steel failure almost never is decisive failure mode. Substrate failure modes or pull-out failure is decisive mostly. In other word, steel capacity is not crucial for final result in most cases. Then, preselection of products based on steel parameters does not guarantee optimized choice.
Sample data for R-XPTIII-HD throughbolt below:
ETA 23/0887 of 29.12.2023
Annex C1 and C2