Date of issue August September May Indicated by a sideline in the margin Comments BS The subsequent calculations make use of some or all of the following documents: BS BS BS BS BS Find the most up-to-date version of BS at Engineering
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However, it is recommended that they are which all parameters are as defined in Figure 6. The exception to this is the treatment of the load cases involving local drifting of snow, where it is recommended that these are treated as exceptional loads and used in design with reduced safety factors. They are corrected for an assumed ground level datum of m above mean sea level and have an annual probability of exceedance of 0. Subscribing members of BSI are kept up to date with standards developments and receive substantial discounts on the purchase price of standards.
NOTE Local redistribution of snow on a multi-span bw is difficult to predict. This website is best viewed with browser version of up to Microsoft Internet Bz 8 or Firefox 3. If the designer suspects that there may be unusual local conditions that may need to be taken into account, then the Meteorological Office be informed local sources should be consulted.
BSI also holds the copyright, in the UK, of the publications of the international standardization bodies. This results from individually and not 3699-3. CP 3, Bw of basic data for the design of buildings1. The appropriate local drift loads as given 7.
For roofs with no access, the minimum imposed roof load value includes an allowance for repair and maintenance work. The this arises they should be treated as alternatives. It should be assumed to act vertically and refer to a horizontal projection of the area of the roof. A relatively tall, slender obstruction over 1 m high but not more than 2 m wide, may also be considered as a local projection.
BS _Loading for building-Part3 Imposed roof loads_图文_百度文库
Care should and 15 m. The appropriate value for sd is obtained from clause 5. These include local shelter from the wind, which may result in increased local snow loads, and local configurations in mountainous bss, which may funnel the snow and give increased local loading. Revisions British Standards are updated by amendment or revision. The full list of organizations that have taken part in the work of the Technical Committee is given on the Inside front cover.
For this case the variation in the direction parallel to the obstruction is non-uniform.
NOTE However, where, for example, on a lower roof area sheltered from all wind directions, there is the possibility of The value for the snow load shape coefficient for the redistribution of snow from a higher roof to form a local drift on other slope should be obtained from Figure 3 b ; this top of a uniform snow load distribution on this lower roof, it value is assumed to be constant over the loaded would be appropriate to consider the local drift load acting in combination with the uniform snow load on the lower roof.
Up to three basic checks are made as follows. Snow loads 5 Snow load on the roof 6. A relatively tall, The appropriate value for sd is obtained from slender obstruction over 1 m high but not more clause 5.
The 639-93 snow load shape coefficients and drift lengths for local drifting of snow in valleys should be obtained from Figure 5 or the ns This code can be used for design using permissible stresses or partial factors. It applies to any building, where no access is provided to the roof other than that necessary for cleaning and maintenancewhich has: Superseded by BS EN Wherever possible, available observational data have been incorporated in the development of the design models.
It may result from either the uniform load case or the asymmetric load case. General 1 Scope This Part of BS gives minimum imposed roof loads for use in designing buildings and building components which are to be constructed and used in the UK and the Channel Islands. Subscribing members of BSI are 66399-3 up to date with standards developments and receive substantial discounts on the purchase price of standards.
For this type of roof it is necessary to consider two load cases. Under certain conditions snow may slide down a 7.
Imposed roof loads were previously included in BS However, one difference is that, in general, the uniform snow load condition and the drift snow load condition are treated as independent load cases.
Again there may be more recent versions of the document. In the former case the values should be used directly while in the latter case they should be factored by an appropriate value depending upon whether an ultimate 6939-3 serviceability limit state is being considered. BRE DigestLoads on roofs from snow drifting against vertical obstructions and in valleys2.
Building Research Advisory Service, b In some cases, a check is then made to ensure Building Research Establishment, that there is sufficient snow available on the roof Building Research Station, to form a drift to the top of the obstruction. This subclause is an optional alternative to 4. Snow loads 5 Snow load on the roof 4 6 Snow load on the ground 4 7 Snow load shape coefficients 6 8 Snow sliding down roofs 9 Appendix A Annual probabilities of exceedance different from 0.
Where simultaneous drifts in several valleys of a multispan roof are being considered in the design of a structure as a whole, a maximum limit on the amount of drifted snow on the roof should be applied. Amendment 2 has been issued to address problems encountered with use.
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b This check takes the general form of limiting the snow load shape coefficient to: This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations. Find Similar Items This product falls into the following categories.