Polish Roof Collapse Kills at Least 12
Polish Roof Collapse Kills at Least 12
(OP)
This is very tagfic event. Read at Yahoo:
ht tp://news. yahoo.com/ news?tmpl= story& cid=514&am p;e=4& u=/ap/2006 0128/ap_on _re_eu/pol and_roof_c ollapse_16
This is the second roof collapse in Europe in less than one month.
ht
This is the second roof collapse in Europe in less than one month.
Regards,
Lutfi






RE: Polish Roof Collapse Kills at Least 12
RE: Polish Roof Collapse Kills at Least 12
RE: Polish Roof Collapse Kills at Least 12
They also said that it had been very cold lately and the reporter pondered whether there was metal fatigue from the cold (never heard of that in a building with cold winters...). The building was about 7 years old.
I wonder if there was simply a too heavy snow, and the original design (with tension members for the roof) didn't have any redundancy along with a weak link somewhere in the load path.
RE: Polish Roof Collapse Kills at Least 12
Hg
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RE: Polish Roof Collapse Kills at Least 12
1] The weight of snow collapsed the roof. There was a quote from the owners/managers? stating they regularly cleared the roof from snow.
2] The intense cold caused the connections to fail because of environmental stress/strains.
One in Germany and now one in Poland. Both caused in part by the extreme cold weather. No global warming here then.
RE: Polish Roof Collapse Kills at Least 12
Global warming, incidentally, is associated with extreme weather conditions, ie. cold/heat/hurricanes etc. and not with a general increase in temperature as such.
corus
RE: Polish Roof Collapse Kills at Least 12
the problem in europe in the last few years is the dramatical change in the weather conditions.
The snowfalls are 2 times greater than usual. Or at least from what is regarded as usual in the codes)
Also the temperatures falling down to -35 for weeks ( every year!!!!).
This may be the reason why so many roofs colapsed lately.
So.
Europe needs new codes reagrding the snow and wind loads.
This is for sure.
Y
(to get it right assume you are wrong)
RE: Polish Roof Collapse Kills at Least 12
1. There were attempts to remove snow build-up from the roof (according to the building owners) but they keep referring to rescuers removing snow from the collapsed roof to get the debris moved...which suggests that there was still considerable snow there.
2. One report stated that the structure was wood beams with concrete slabs.
3. Someone else stated that the heated building may have started melting the snow in contact with the roof. In which case, ponding may have played a part.
I recall a roof collapse in San Antonio, Texas, some years ago after San Antonio received 13 inches of snow (yes, I know it doesn't snow in south Texas but that year it did). The roof collapsed due to melting snow and the water couldn't get to the roof drains at the back of the roof area due to ponding.
RE: Polish Roof Collapse Kills at Least 12
RE: Polish Roof Collapse Kills at Least 12
RE: Polish Roof Collapse Kills at Least 12
Your figures are correct. 70 (0.69kN/m2) to 80 (0.78kN/m2) kg/sq.m is about 14 to 16 psf.
The UK loading code gives a minimum snow load of 0.6kN/m2. The snow load on the ground around Aberdeen-Inverness (North Scotland)is 1.0kN/m2. This will increase as the altitude increases.
From what I can gather from the eurocodes, which dont cover Poland and only go as far as Germany, the snow load at sea level is 1.2 kN/m2 (about 25psf). Again this will increase with altitude.
So based on that I would say those figures you quote are very low.
RE: Polish Roof Collapse Kills at Least 12
1)this is the third I know,happened some 2 years ago, one happened in Moscow and killed at least 50(The Moscow water park,heavy dome). It was a reinforced concrete roof(ribbed membrane kind), resting on slender columns, Long span. Failure started by the movement of heavy snow-it was a buckling problem mainly(as seen by us), and the effect of chloride from the swimming pool(as reported by Russian engineers) on the durability of concrete.
2)All failures so far, have involved long spans and heavy snow loading.
Analysis after failure,most of the time, concentrate on heavy loading and ignores such issues as durability and stability.
best regards pals
RE: Polish Roof Collapse Kills at Least 12
RE: Polish Roof Collapse Kills at Least 12
www.SlideRuleEra.net
RE: Polish Roof Collapse Kills at Least 12
RE: Polish Roof Collapse Kills at Least 12
RE: Polish Roof Collapse Kills at Least 12
RE: Polish Roof Collapse Kills at Least 12
RE: Polish Roof Collapse Kills at Least 12
I struggle with this as well. I think the confusion arises because multiplying by g converts to Newtons, not kN, as one would expect. 1kg weighs 9.81N. To get from kg/m^2 to kN/m^2 multiply by .00981. To get from kg/m^2 to psf, multiply by .2048161.
RE: Polish Roof Collapse Kills at Least 12
I did a little more digging in the Eurocode to see what it would have suggested for a snow load. I have never used it so, if I have got it wrong, please dont shoot me.
Katowice is in the south of Poland at an altitude of 284m. BS EN 1991-1-3:2003 Figure C.13 gives the snow map of Poland and from what I can gather the town is on the border of Zone 2 and Zone 3. The snow load on the ground sk=0.9 kN/m2 for Zone 2, and sk=(0.006*284)-0.6 but not less than 1.2kN/m2 for Zone 3.
There is also a requirement for an exceptional snow load, sad=2.0*sk=2.4kN/m2.
The corresponding snow load on roof (I have had to guess as I dont know roof pitch, GA etc) s=mu*Ce*Ct*sk or sad
giving s=0.8*1.0*1.0*2.4= 1.92kN/m2 (40psf) or 0.96kN/m2 (20psf).
Sounds like these ae still substantially lower than you apply in the US.
200psf = 9.6kN/m2 is very high. That is well in excess of the floor loading we use for say a plant or boiler room (at 7.5kN/m2), including weight of machinery.
RE: Polish Roof Collapse Kills at Least 12
As to the US units being complicated...all through school & college, we are taught the SI system- then find in the real world, people are using kgf/cm^2 and other oddball units. And even the SI system has its oddities- why is the fundamental unit a KILOgram, and not a gram?
RE: Polish Roof Collapse Kills at Least 12
I guess when they were picking the seven base units for the SI system someone had an off day, because length is in metres as opposed to KILOmetres.
RE: Polish Roof Collapse Kills at Least 12
Out west, with a drier climate in the mountains, the snow load drops except in the higher altitudes of the mountains such as JStephens pointed out.
In my area (midwest - Nebraska/Iowa) the roof snow usually comes out at about 17 to 21 psf.
RE: Polish Roof Collapse Kills at Least 12
RE: Polish Roof Collapse Kills at Least 12
Hg
Eng-Tips policies: FAQ731-376
RE: Polish Roof Collapse Kills at Least 12
For instance we rarely use centimetres, and I have never come across decimetres.
RE: Polish Roof Collapse Kills at Least 12
Hg
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RE: Polish Roof Collapse Kills at Least 12
Units used by the general public in the UK can be anything. I was taught centimetres at school, my family use feet and inches, miles etc. In day to day things (non-engineering) I will use a hotch-potch of units, metres, miles, gallons, pints, stone. I only use feet and inches when giving my height though.
At work however, its only millimetres for lengths and metres for levels.
Its all a bit of mess really, and I think as long as everyone is clear what unit is being used it doesn't make much difference.