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Newsletter No 23 - July 2011

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Report Overview

This Newsletter starts with a report about the use of water filled containers when used as ballast for temporary structures such as those erected for music festivals. In Scotland in the winters of 2009/2010 and 2010/2011 there were many collapses of, mainly agricultural, buildings during periods of high snow loads and reports on these have been consolidated to provide an overall picture of the events which took place. The CROSS panel have provided comments and the information, in co-operation with the Scottish Government, has been forwarded to the British Standards Institution for consideration. A further report is about dangerous and almost simultaneous snow slides from 100 domestic roofs, and there is a salutary lesson in a news report about a column constructed with no foundation. Finally the British Parking Association is requesting information about the condition of multi-storey car parks. CROSS needs reports all the time so that lessons can be learned and if you can contribute please do so.

Overview of Reports in this Newsletter

183 Snow loading in Scotland - No.1

A reporter’s practice specialises in the investigation and remediation of civil and structural engineering failures. Over the past month or so (January 2010), he has had new instructions on five roof collapses.

184 Snow loading in Scotland - No.2

A reporter’s practice specialises in the investigation and remediation of civil and structural engineering failures. Over the past month or so (January 2010), he has had new instructions on five roof collapses.

185 Snow loading in Scotland - No.3

A reporter’s practice specialises in the investigation and remediation of civil and structural engineering failures. Over the past month or so (January 2010), he has had new instructions on five roof collapses.

191 Snow loading in Scotland - No.4

The reporter said that a modern storage building constructed from cold formed sections had collapsed under the weight of snow on its roof.

193 Snow loading in Scotland - No.5

A reporter provided a list of 40 whisky warehouse buildings that had collapsed in the recent heavy snow conditions in northern Scotland (January/February 2010).

195 Snow loading in Scotland - No.6

A reporter says that nine agricultural buildings have collapsed in the past few days in a region of north east Scotland where there is currently (January 2010) 1.2m of snow.

199 Snow loading in Scotland - No.7

The reporter has examined 25 cases of agricultural buildings which collapsed in the winter of 2010 in the north east of Scotland. The depth of snow was 1.2m and because there was no wind the snow lay evenly. Most of the buildings were steel framed portals with spans around 20 – 30m.

221 Missing column foundation leads to fines (news)

Part of the first and second floors of a new build commercial development were supported on a blockwork column. However, the column had been constructed directly on top of the ground floor beam and block floor construction, rather than continuing down to the foundation. With the gradual increase in load from the construction of the upper floors, the column eventually punched through the ground floor construction causing partial collapse of the building.

236 Farm buildings collapse after heavy snow (news)

Dozens of farm buildings collapsed under the weight of snow in January 2011, prompting safety warnings for both farmers and livestock. Worst affected was North East Scotland, where more than 60cm of snow fell, closely followed by North East England. One roof collapsed following 43cm of snow.

246 Dangerous snow slides from 100 houses

A reporter is a structural engineer and was been involved in the investigation of gutters collapsing under snow load in Scotland the winter of 2011. A noticeable feature was the influence of the roof construction on snow build up. All the houses that were investigated had cold roofs i.e. the insulation at ceiling level prevented any heat reaching the roof surface. The effect of this, says the reporter, was that the snow built up rapidly on the roofs (35 degree slope) and stuck to the roof tiles.

248 Snow loads on agricultural buildings in Scotland

The reporter here says that the snow loading situation with regards to agricultural buildings (in Scotland) and perhaps all buildings may require review. In some areas of Scotland, in the first week of January 2010, there were unprecedented accumulations of snow on the roofs of buildings in lower and up lying areas. The snow fell for over a month in windless conditions which meant the BS6399 x 0.8 factor to allow for wind blowing snow off roofs to reduce load did not occur in practice.

255 Use of water filled containers to anchor temporary structures

The reporter is a local authority Environmental Health Officer who is responsible for licensing the safety aspects at a local festival. As part of the structure of the main stage, water filled plastic containers are used as anchors/ballast. He says that he has concerns over the suitability of these as he believes they could become crushed quickly and not provide the weight that is intended.

264 Snow loading in Scotland - summary of reports

There were heavy snowfalls over the entire United Kingdom in the winters of 2009/2010 and 2010/2011 and CROSS received a number of reports, mostly from Scotland where a significant number of buildings suffered roof collapses. The reports have been summarised to give an overview from the reporters but individual reports can be found on the web site data base. A common thread is that the snow in Scotland fell vertically, in low temperatures, and in still air conditions which resulted in significant depths. These were reported as being from 600 mm up to 1,200 mm with ice underlying snow in some cases.