ASP/Combisafe beams and the EN1999 Standard.

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AshReactive

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After quite an interesting few days, i was wondering if anybody else has seen the new capacities for ASP/Combisafe beams generated from the EN1999 standard and not the old BS8118.

If so, how have you reacted to the information, that the manufactures capacities have pretty much 'halved'.
 
Certainly have, fortunately we use mainly Layher although i suspect their advise will be changing in the none to distant future. My best guess on the way forward is to use the US/Australian method of testing to failure in all practicable load conditions and then divide the least favorable result by a factor of safety (3 or 4 usually does the trick)
 
The interesting thing will be to see how temporary roofs are affected. They will surely have to reduce the spans. Which is far from ideal.
 
looks like we will be using triangular beams for temporary roofs of any decent span in the future more expence to be passed on to the customer.
 
AshReactive said:
After quite an interesting few days, i was wondering if anybody else has seen the new capacities for ASP/Combisafe beams generated from the EN1999 standard and not the old BS8118.

If so, how have you reacted to the information, that the manufactures capacities have pretty much 'halved'.
Click to expand...

Where is that information publicly available? I can't find it on the Combisafe web site. Having used the published data for design for the last few years and not noticed lots of beamed jobs falling down, I am surprised that the capacity has halved - they must have been marginally safe.
 
I now have the tables.
As an example, the capacity of a 6m span 732mm beam has dropped from 8.1 kN/m down to 3.4 kN/m.
At 10m, the drop is from 2.9 kN/m down to 1.3kN/m. They are really not worth much more than a ladder beam.

These capacities being only around 40% of what we were using last month suggests that there are lots of jobs around the uk which are under designed by a factor of 2.5 - are they falling down all over the place? I hadn't read about a spate of scaffold roof and bridge jobs collapsing so you have to ask whether the Eurocodes are delivering what they promised which was more economical design.

25 years ago I had a major row about the introduction of Eurocodes with some influential people in the business. I lost that argument but the more I see of Eurocodes, the more I think that I should have kept fighting against them to stop this sort of thing happening now.

Are all the other manufacturers of ali beams, unit beams and ladder beams producing revised safe load tables?
 
Yeah, It's fairly far from ideal, It casts an enormous grey area over everything that is already up, For example I've had a long standing temporary roof up at a 12m span, An absolute doddle for the old specification, Fails miserably to the new one.

The hardest part so far has been explaining to people, who have extensive knowledge in the industry, that what they have previously erected with beams that are exactly the same, no longer works.

Also does anyone have any insight into how the PI insurance would (or wouldn't) cover this.
 
has this affected 780mm beams ? and 750mm X beams


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So how would that work with a job that's been designed before and erected before these new specifications ,
And is now deemed to be no good ,
Would it need to be struck Or bolstered up :worried:
 
"The hardest part so far has been explaining to people, who have extensive knowledge in the industry, that what they have previously erected with beams that are exactly the same, no longer works."

We've been doing that since before I started in 1974 so nothing new there.

"are they falling down all over the place?

They don't have to be failing is the issue, how do you know if they have been loaded to their design capacity?



Don't get me wrong I am a big fan of big span roofs etc but I have seen beam failure, I have seen beams fall apart whilst partially loaded due to poor manufacturing processes.


Steve is on the right track, beams need to be tested not just designed in calculation.
Unless someone is going to tell me different, Haki test their 750 beams may make their product a bit more costly but they work.
 
Good point about knowing what load is actually in the beams. Having done a job a while back when 780 beams were relatively new, we used them to carry some generators while they were rolled into a building. The weight was defined and the beams were very close to safe limits. Taking the current quoted strength and the safety factor, those beams should have failed but they didn't. I think that halving the rated capacity and quoting a safety factor of 1.65 does put a lot of old designs in the failure zone.

Haki beams may be tested but I wonder if anyone has done the same calculation for them as has been done for Combisafe - if I was in the position of down rating my company's beams, be sure I would have samples of all of the competition to be able to do a like for like comparison. The last time I did a comparison like that on timber beams, the numbers came out similarly but when we tested them, an awful lot failed below the calculated safe strengths.

As far as testing is concerned, I would go for testing using production beams as a much better way of assessing strength but unfortunately the way the Euro code is worded this can only be used as supplementary to calculations - previously it was an alternative method that could be used on its own merits.

Combisafe's designer chappie is at pains to point out a final comment: Please remember that the beams are not weaker in reality, they are just calculated differently. It sounds like he doesn't believe what he has worked out.

Tim
 
Morning Tim
I have as yet to see the code, or indeed to receive anything from any manufacturers from whom I have purchased beams. If their beam capacity is to be or indeed has been reduced they must have a responsibility to inform their customers.

Ken Barber at HAKI will be able to advise on the test v's Calc capacity of the 750 beam.

Proving product via calc should only ever be the first stage of manufacture, this should always be followed by testing be it beams, tube, fittings or system.

The statement that the beams are not actually weaker is a little open ended and misleading; in so far as, no they are probably no weaker than they were yesterday. The question is, when calculated do they still have the same stated safe design capacity as they had yesterday?

Tricky subject and no manufacturer will want to down rate their product.
They find themselves in a similar position to scaffold companies who have representatives sitting on both Euro and Brit code makers who down rate their own business and then complain about it after they have done it. The time to resolve the issue is before it is in the code.

If they do not get the calc v test revisited this could drive the industry back to steel beams and who the F**k wants that??
 
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We had exactly the same issue a few years ago except it was 2 different interpretations of the Eurocode that made the figures different; 2 different engineers, both chartered and working for different consultancies, came up with vastly different figures for the same type of beam. One of the sets of figures, which happened to be the ones coming out stronger, also had the beams tested to back up the figures and the calculated results were within 5% of the test results, proving that the figures were correct. The other consultant refused to back down, making their beams among the weakest in the industry on paper but in practice we had loaded them to the "old" higher figures for many lifting frames and loading platform jobs and never had an issue.
 
Personally I prefer unit beams as they are easier to work on ,
It's just a shame they are so heavy :D
 
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