UBBL Part 5 - Structural Requirements

posted Jun 16, 2018, 8:00 PM by jeffery jim
The followings are comments for structural requirements as per Part 5 of the UBBL versus in-place British Standards.

Part 5 By-law 53: Building materials
Paragraph (1) Any material used –
(a) In the erection of a building;
(b) In the structural alteration or extension of a building;
(c) In the execution of works of the installation of fittings, being works or fittings to which any provision of these By-laws applies or 
(d) For the backfilling of any excavation on a site in connection with any building or works or fittings to which any provision of these By-laws applies shall be
(aa) of a suitable nature and quality in relation to the purpose and condition in which they are used;
(bb) adequately mixed or prepared; and
(cc) applied, used or fixed so as to adequately perform the functions for which they are designed.
Paragraph (2) The use of any material or any method of mixing or preparing materials or of applying, using or fixing materials, which conforms with a Standard specification or Code of Practice prescribing the quality of material or standards of workmanship shall be deemed to be sufficiently compliance with the requirements of paragraph (1) of by-law 3 if the use of the material or method is appropriate for the purpose and conditions in which it used.

Part 5 By-law 54: General Requirements of Loading
Paragraph (2),
(a) dead loads shall be calculated in accordance with BSCP 3 Chap. V. Part 1 or as provided hereinafter in this Part: (BS6399 Part 1)
(b) imposed loads shall be calculated in accordance with BSCP 3 Chap. V. Part 1 or as provided hereinafter in this Part: (BS6399 Part 1)
Provided that, if any actual imposed load will exceed or is likely to exceed the load so calculated, that actual load shall be substituted for the load so calculated; and
(c) wind loads shall be calculated in accordance with BSCP 3 Chap V. Part 2: (BS6399 Part 2 or MS1553)
Provided that-
(aa) in no case shall the factor S3 be taken as less than 1; and
(bb) if a building falls outside the range of those which that code gives forces and pressure coefficients, values shall be used which are appropriate in relation to that building, having regard to its construction, size proportions, shape, profile and surface characteristics.
Paragraph (3), 
Advice on appropriate wind velocities applicable to a particular locality to which the building is to be located shall, whenever possible be obtained from the local meteorological office. (BS6399 Part 2 or MS1553)
Part 5 By-law 55: Dead and Imposed Loads
Paragraph (2)
The dead and imposed loads provided hereinafter shall be in addition to and not in substitution of provision relating to –
(a) loads on road bridges; (b) loads on rail bridges; (c) loads due to winds; (d) loads due to seismic forces; (e) loads due to explosions; (f) loads on structures subject to internal pressure from their contents such as bunkers, silos and water tanks; (g) loads incidental to construction; (h) loads due to lifts and escalators; (i) loads due to machinery vibration (except those due to some gantry cranes); (j) loads due to thermal effects; and (k) test loads.

Part 5 By-law 56: Dead loads calculated from weights of material used
Paragraph (1): Dead loads shall be calculated from unit weight given in BS 648 or from the actual known weights of the material used. Paragraph (2): Typical values for commonly used materials are laid out in the Fourth Schedule to these By-laws.

Part 5 By-law 57: Weight of partitions
… To provide for partitions where their positions are not shown on the plans, the beams and the floor slabs where these are capable of effective lateral distribution of the load, shall be designed to carry, in addition to other loads, a uniformly distributed load per square meter of not less than one third of the weight per meter run of the finished partitions, but not less than 1kN/m² if the floor is used for office purposes. (BS6399 Part 1 Clause 5.1.4)

Part 5 By-law 58: Contents of tanks and other receptacles
No comment

Part 5 By-law 59: Imposed floor loads
Paragraph (1) The loads appropriate to the different uses to which the parts of a building or structure may be put as specified in the Fourth Schedule to these By-laws

Part 5 By-law 60: Mechanical Stacking
Where there is the possibility of the use of mechanical stacking machines, such as fork lift trucks, special provision shall be made in the design of the floors.

Part 5 By-law 61: Imposed loads on ceiling, skylights and similar structures
Paragraph (1) The support of ceilings (other than false ceilings), ribs of skylights, frames and covering (other than glazing) of access hatches and similar structures shall be designed for the following loads: (a) 0.25kN/m² distributed uniformly all over the whole are of area supported; and (b) 0.9kN concentrated over a length of 125mm or, in the case of coverings, over a square of 125mm side so placed as to produce maximum stresses in the affected members. (BS6399 Part 1 Clause 5.2)

Part 5 By-law 62: Reduction in total imposed Floor loads
Paragraph (1) No comment. Table 1 of By-laws is similar to Table 2 of BS6399 Part 1
Paragraph (2) …For factories and workshops design for imposed load of 5kN/m² or more, the reduction shown in the Table 1 may be taken provided that the loading assumed is not less than it would have been if all floors had been designed for 5kN/m² without reduction.
Paragraph (3) Where a single span of a beam or girder supports not less than 46m² of floor at one general level, the imposed load may in the design of the beam or girder be reduced by 5% for each  46m² supported, subject to a maximum reduction of 25%. This reduction, or that given in Table 1, whichever is greater, may be taken into account in the design of columns of other types of member supporting such as beam.
Paragraph (4) No reduction shall be made for any plant or machinery which is specifically allowed for or for buildings for storage purposes, warehouses, garages and those office areas which are used for storage and filling purposes.
Para 2 to Para 4, refer to 

Part 5 By-law 63: Imposed roof loads
Paragraph (2) On flat roofs and sloping roofs up to and including 10⁰, where access (in addition to that necessary for cleaning and repair) is provided to the roof, allowance shall be made for an imposed load of 1.5kN/m² measured on plan, or a load of 1.8kN concentrated on a square with 300mm side, measured in the plane of the roof, whichever produces the greater stresses in the part of the roof under consideration. (BS6399 Part 3 Clause 4.2)
Paragraph (3) On flat roofs and sloping roof up to and including 10⁰ where no access is provided to the roof except for maintenance, allowance shall be made for an imposed load of 0.25kN/m² measured in the plane of the roof, or a vertical load of 0.9kN concentrated on a square with 125mm side, measure in the plane of the roof, whichever produces the greater stresses in the part of the roof under consideration.
Paragraph (4) On surfaces where accumulation of rain is possible the loads due to such accumulation of water and the imposed loads for the roofs as given above shall be considered separately and the more critical of the two shall be adopted in the design.
Paragraph (5) On roofs with a slope greater than 10⁰, and with no access provide to the roof (other than that necessary for cleaning and repair), the following imposed loads shall be provided: (a) for a roof-slope of 30⁰ or less 0.25kN/m² measured on plane or a vertical load of 0.9kN concentrated on a square with a 300mm side, whichever produces the greater stress. (b) for a roof slope of 75⁰ or more no allowance is necessary.
For Roof slopes between 30⁰ and 70⁰, the imposed loads to be allowed for may be obtained by linear interpolation between 0.25kN/m² for a 30⁰ roof slope and nil for a 75⁰ roof slope.

Part 5 By-law 64: Curved roofs
The imposed load on a curved roof shall be calculated by dividing the roof into not less than five equal segments and then calculating the load of each, appropriate to its mean slope, in accordance with paragraph (2) and (3) of by-law 63. (BS6399 Part 3 Clause 4.4)

Part 5 By-law 65: Roof Covering
To provide for loads incidental to maintenance, all roof coverings, other than glazing, at a slope less than 45⁰ shall be capable of carrying a load of 0.9kN concentrated on any square with a 125mm side, measured in the plane of the roof. (BS6399 Part 3 Clause 4.6)

Part 5 By-law 66: Internal suspended loads on primary structural members
No comment.

Part 5 By-law 67: Amount of suspended load
Any panel point of the lower chord of such roof trusses or any point of such other primary structural members supporting roofs over garages, manufacturing or storage floors shall be capable of carrying safely a suspended concentrated load of not less than 9.0kN in addition to the imposed loads on the roof.

Part 5 By-law 68: Dynamic loading
Deleted in BS6399 and refer to Annex A and Table 1.

Part 5 By-law 69: Crane gantry girders
Not detailed on type of cranes. Refer to BS 2573 Design of Cranes

Part 5 By-law 70: Parapets and Balustrades
The design criteria changed. Refer to Clause 10 and Clause 12 of BS6399

Part 5 By-law 71: Vehicle barriers for car parks
Refer to BS 6399 Part 1 Clause 11 and Clause 12

Part 5 By-law 72: Basement walls and floors
No detailed description. Refer to BS 6399 Part 1 Clause 12

Part 5 By-law 73: Foundations
Paragraph (2) The requirements of paragraph (1) shall be deemed to be satisfied if the foundations of a building are constructed in accordance with the relevant recommendation of the DSCP 2004 Foundation. (BS8004 CP for Foundations)

Part 5 By-law 74: Foundations of Buildings not exceeding four storeys
IF the foundations form part of a building other than a factory or storage building, having not more than 4 storeys the requirements of by-law 73 shall be deemed to be satisfied if such foundations are constructed in accordance with BSCP 101 0 Foundations and Substructures for Non-Industrial buildings not more than 4 storeys. Refer to BS 8103 Structural design of low-rise buildings, Part 1.

Part 5 By-law 75: Reinforced concrete foundations
The requirements of by-law 73 shall be deemed to be satisfied as to such part of any foundations as in constructed of reinforced concrete if the work complies with BSCP 10 – The structural use of the concrete, BSCP114, BSCP115 or BSCO 116, where applicable.
BSCP-110 to BS8110. BSCP114 to BS8110. 

Part 5 By-law 76: Strip Foundation
No detailed description. Refer to BS 8004 Clause 3.2.5.

Part 5 By-law 77: Brick Footings
Overrule. BS8004 Foundation, Clause 3.2.4 Pad footing. For buildings such as low rise dwellings and lightly framed structures, pad foundations may be of unreinforced concrete provided that the angle of spread of load from the pier or baseplate to the outer edge of the ground bearing does not exceed one (vertical) in one (horizontal) and that the stresses in the concrete due to bending and shear do not exceed those in Table 11 of Civil Engineering Code of Practice No. 2 1951. Where brick or masonry foundations have been used, the same rules apply with permissible stresses as given in Civil Engineering Code of Practice No. 2. For buildings other than low rise and lightly framed structures, it is customary to use reinforced concrete foundations.

Part 5 By-law 78: Foundation below inverts of drains
No comment.

Part 5 By-law 79: Foundation under external and party walls
No comment.

Part 5 By-law 80: Structure above Foundations
Refer to Eurocodes or other basic code of practice for design.

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