Rank: Super forum user 
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Rank: Super forum user 
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Good link Bob. Is this another case of the assessments not including a "what if" scenario about how much snow will the canopy hold before collapsing?
I know it is a freak event but "what ifs" do turn into reality on occasions.
An interesting comment from someone in the store at the time saying fire exits were blocked and referring to evacuation of disabled in wheelchairs. A current topic on this forum.
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Rank: Super forum user
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Contrary to the paper report the store is 8 years old and I am wondering what the engineering designer is feeling at this moment. The store probably sharres similarity with many other superstores.
Bob
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Rank: Super forum user
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I suppose right place wrong time (or something like that) might fit the bill.
How often would this, or any other similar store suffer that weight of snow for such a long period of time?
Should structural engineers now instigate trigger points for inspection of such structures during bad weather?
Does anyone have any idea what the weight of snow was? I wonder what the calculation/formula is ?
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Rank: Super forum user 
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Chris,
Even when I did my structural design course at HNC level we were taught that for "roof" beams the highest loading on a roof would be snow load.
I was taught to design for the maximum anticipated snow load.
There is obviously more to this than meets the eye as this would be a stitistical value?
However, when I designed a canopy at the rear of my house I designed to take 18" of snow load, I however was NOT designing to a cost!!!
IMHO this should never happen, that is IF the design was done correctly and was "installed" correctly.
Millenium bridges come to mind........
The loading would be estimated as a uniformly distributed load at the average snow density IIRC.
When I did mine I used the desnity of water as I could not decide on what it would be for snow!
Frozen snow I guess would be nearer to the 1000kg/m^3 of water?
Too late and not enough time to verify my figures etc. sorry!
You may have to look at possible prevailing winds with regard to drifting etc.
Not sure, that's why I don't design buildings now!!!
Too many unknowns for me!
HTH
Paul
Debate?...
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Rank: Super forum user
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The snow loading was I guess around 12-15" from the rest of the area but interestingly my pitch roof was less than 9". Yes the arguments now start between contractor and designer
Bob
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Rank: Super forum user 
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Rank: Super forum user
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Paul, thanks for that insight, I don't design buildings either, just as well.
I suppose you never know how much snow to design for so there must be added safety factors.
Probably stable door stuff now but is it possible to include some heating into the roof/canopy? A design similar to electrical underfloor heating?????? Maybe a sandwich between layers of glazing?
Auto switch on at a set temperature?
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Rank: Forum user
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Chris,
Are you trying to spoil the birds?
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Rank: Super forum user
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Of course we should not forget that Tesco and the like have very specific design parameters for their stores. Most of the remaining stores are likely to have the same or very similar design.!!!!!!
I am also tempted to mention that 30 weeks from start on site to practical completion is not unusual. Tight programmes can often lead to poor quality control on critical areas such as bolt tightening on steelwork. I have been there many times.
Bob
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Rank: Super forum user
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As you say Bob. These were some of the findings from the similar collapses I referenced above.
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Rank: Super forum user
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Bob,
Thanks for this link and I do hope that SHP keep us up to date on the enquiries into this incident.
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Rank: Super forum user
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Just to update you all on this story. During the Christmas shutdown period, the Tesco Toton Store in Nottingham had new brackets welded onto the canopy struts.
Could forum members let us know if this has happened elsewhere?
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Rank: Super forum user
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Sounds like a recalculation of the loadings to me. Soon see if this is widesprerad
Bob
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Rank: Super forum user
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The horse may have left the stable but at least they are getting it back in and closing the door.
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Rank: Super forum user
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Maybe, the standard design was changed? - this often happens in construction and has more to do with costs.
Many other factors could come into play, fatigue; ground bearing factors; modifications etc......
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Rank: Super forum user
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Freelance
You are very generous to the designers etc but my experience suggests that it was a matter of building to a price not designing to a duty/load
Bob
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Rank: Super forum user
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Happened last February in the States. Owner of ice rink surprised by the amount of snow despite usual local forecast being for below freezing from December through to end of February. http://www.wtae.com/news/22563198/detail.html
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