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
63999-3 Information on standards BSI provides a wide range of information on national, European and international standards through its Library and 639-3 Technical Help to Exporters Service. Users of British Standards should make be that they possess the latest amendments or editions.
This subclause applies where there is an abrupt change of height greater than 1 m, except that relatively slender obstructions e.
For these roofs it is necessary to consider a single load case resulting from a uniform layer of snow over the complete roof. For sites whose altitude is above m specialist advice should be sought see clause 1 and appendix C. 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. Gibb Limited, Gibb Ltd, March 19,Uncontrolled Copy, c BSI This 639-3 briefly describes the general process adopted for determining the maximum local load intensity resulting from snow in a drift at a change in roof height.
As the basic on the ground at the site location and altitude the snow load on the ground is given for an assumed site snow load by a factor known as the snow load ground level altitude of m, it is necessary to shape coefficient in accordance with the following adjust the value for locations where the ground level equation: ISOBases for design of structures — Determination of snow loads on roofs1. The exception to this is the treatment of the load cases involving local 66399-3 of snow, where it is recommended that these are treated as exceptional loads and used in design 3699-3 reduced safety factors.
However, for certain cases in the UK specific consideration may have to be given to temperature effects, e. This results from individually and not together. The values are given as lines of equal load intensity isopleths on the map in Figure 1.
If permission is granted, the terms may include royalty payments or a licensing agreement. Use of the uniformly distributed snow loads are subject to an overriding minimum requirement.
The treatment of snow drifting against obstructions in section two is similar to that given in BRE Digestissued 3699-3 Octoberbut now withdrawn.
It is incorporated by Royal Charter. For parapets, see 7.
To provide for these situations, if they are likely to occur and if other information is not available, a load case should be considered comprising the minimum imposed uniformly distributed load according to clause 4 on any portion of the roof area and zero load on the remainder of the area.
Therefore, it is curved roofs of single span. These include local shelter from the wind, which may result in increased local snow loads, and local configurations in mountainous areas, which may funnel the snow and give increased local loading.
This results from a uniform layer of snow over the complete roof. This results from transport of snow from one side of the ridge to the other side.
NOTE The effect of structures close to, but not abutting the roof under consideration will depend partly on the roof areas For roofs of more than two spans with available from which snow can be blown into the drift and the approximately symmetrical and uniform geometry, difference in levels. For type 1 curved roofs the equivalent in the direction parallel to the eaves. For asymmetric pitched roofs, each windward side. However, one difference is that, in general, the uniform snow load condition and the drift snow load condition are treated as independent load cases.
The force Fs in kN per metre width exerted by a sliding mass of snow in the direction of slide is calculated from the following equation: It presents the UK view on standards in Europe and at the international level.
This can be caused by general debris or ice and consideration may need to be given in design to what happens to the drain water if this occurs. Superseded by BS EN Snow is treated specifically in this code while the minimum imposed roof a vertical load on a given area in plan of varying load value allows for loads resulting from rain, ice and local load intensity temperature.
For type 2 This clause gives roof snow loads for multi-span curved roofs the equivalent slope is the angle pitched, multi-span convex-curved and northlight between the horizontal and a line drawn from the roofs. This check takes the general form of Meteorological Office, limiting the snow load shape coefficient to: This check takes the general form of limiting the snow load shape coefficient to: Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services.
BS _Loading for building-Part3 Imposed roof loads_图文_百度文库
6939-3 It should be assumed to act vertically and refer to a horizontal projection of the area of the roof. This Code models the actual drift shapes and load intensities by simplified linear distributions, based on assumptions on the amount of snow available to drift and limitations on the drift height.
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. A relatively tall, The appropriate value for sd is obtained from slender obstruction over 1 m high but not more clause 5.
The equations given in Figure 2 to Figure 9 for determining the snow load shape coefficients are empirical; where they are associated with local drifting of snow they include a correction to allow for an increased weight density in the drift. In response to orders for international standards, it is BSI policy to supply the BSI implementation of those that have been published as British Standards, unless otherwise requested. Compliance with a British Standard does not of itself confer immunity from legal obligations.
It applies to any building, where no access is provided to the roof other than that necessary for cleaning and maintenancewhich has: If these details are to be used for any other purpose than implementation then the prior written permission of BSI must be obtained. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 22, an inside back cover and a back cover. This force should be taken into account in the design of snowguards or snowfences if snow is likely to slide off the roof endangering people or property below.
These include local shelter from the wind, which may result in increased local snow loads, and local configurations in mountainous areas, which may funnel the snow and give increased local loading.
For this type of roof it is necessary transport of snow from one side of the curved roof to to consider two load cases. Copyright Copyright subsists in all BSI publications. However, for certain cases in the UK specific consideration may have to be given to temperature effects, e. Both types of redistribution should be considered if appropriate. Click here to find out how to access this document.
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