Prolyte Campus blog: Eurocodes
Slowly but steadily the Eurocodes are implemented in our industry as well. Raising huge discussions amongst structural engineers, they finally seem to have found common ground, now placing responsibility with the truss manufacturers to comply with these regulations.
The issue: All truss modules now simply need to comply with one or more of the Eurocodes, this being Eurocode 1 (EN 1991: (Eurocode 1) Actions on structures), 3 (EN 1993: (Eurocode 3) Design of steel structures) or 9 (EN 1999: (Eurocode 9) Design of aluminium structures). How will this help our industry?
The answer: All manufacturers can now be compared by the same standards. No more hiding behind standards or claiming that ‘ours is better’. A clear-cut base of comparison is provided in the Eurocodes, backed up by the CPR (Construction Products Regulation 305/2011/EU CPR).
Manufacturers can now compete on equal grounds, one would say. When using the same alloy, the same dimensions, identical chords, braces and connection system etc., it should result in equal loading capacities.
The verdict: Not yet! When more or less accidentally comparing trusses to be fitting in a standardized Capacity Category (Cap Cat) it turned out that a particular type of compact fork-lug truss can still show great differences in loading capacity. Unfortunately, despite the Euro codes there’s still uncertainty about the factor that should be used in the calculation. This differs from a factor 1.5 to 1.35.
So yes there is more clarity because we speak the same language, but the basis for the calculation is still not the same everywhere.
The EN1990 allows for several "working life” periods, this might explain the difference in factor used. For temporary structures this is 10 years and runs up to 100 years for fixed installations.
A good manufacturer should mention the used calculation factor in the product manual. A good user should check which factor is used, to be sure to make a fair comparison. We still have a long way to go…
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