1. The purpose of this engineering article is to explain minimum requirements for the design of steel framed buildings.
2. Technical Specification Steel Framed Buildings
The question is where we use steel frame buildings in plants? This technical specification is used for compressor house buildings (including overhead crane gantries), outdoor crane gantries, and other steel framed buildings design. In plants we observed steel frame buildings are not used for oxygen compressor barriers.
3. RELATED DOCUMENTS
There is following some articles which can be helpful to understand design requirements of steel framed buildings.
Supply and Fabrication of Structural Steelwork
Supply and Fabrication of Steel-Framed Buildings
British Standards Institute (BSI)
BS 2853 The design and testing of steel overhead runway beams
BS 5950: Part 1 Structural use of steelwork in building: Code of practice for design in simple and continuous construction: hot rolled sections
BS 5950: Part 2 Structural use of steelwork in building: Materials, fabrication and erection: hot-rolled sections
BS 6399: Part 1 Loadings for buildings: Code of practice for dead and imposed loads
BS 6399: Part 2 Loadings for buildings: Code of practice for wind loads
4. Steel Framed Buildings Design Procedure
4.1 The initial planning study for the area shall include a plan of the compressor house and any gantry showing the following:
- Plan outline of building.
- Layout of mezzanine floors, compressors and associated equipment, laydown areas, and hook height of cranes.
- Location of pipe racks and wall penetrations, including any removable roof areas.
- Location and size of doors.
4.2 Positions of columns and framing shall then be agreed with the Lead Piping Designer, but shall be as follows whenever possible:
- Compressor house columns at 5,500 to 6,500 mm centres.
- Open gantry columns at approximately 8,000 mm centres.
4.3 The overall height of the building shall then be established in consultation with the Lead Piping Designer.
4.4 The location of electrical supplies to cranes shall be ascertained from the Electrical Section.
4.5 The final arrangement of the building shall be agreed upon amongst all of the disciplines.
5. Steel Framed Buildings Design Loads
5.1 General
5.1.1 Dead and imposed loads shall be in accordance with BS 6399: Part I.
5.1.2 Wind loads shall be in accordance with BS 6399: Part II. Open-topped buildings shall be in accordance with clause K.3.5, with the coefficient used in design being the sum of the coefficients for the external wall and “internal” wall (in this case the internal and external walls being the same).
5.1.3 Crane loads shall be in accordance with BS 5950 and BS 6399, Part I.
5.2 Piping Loads
The Lead Stress Engineer shall supply the estimated piping loads. The piping arrangement shall minimise the number of openings in the walls of the building.
5.3 Equipment Loads
Machinery Applications and Process Package Section (MAPPS)/Electrical Sections shall provide both the maintenance loads so that oversizing of the crane is eliminated, and all other relevant load data for foundation design as detailed in design procedures.
5.4 Platforms and Stairs Loading
Live loading shall be 5 kN/m2.
5.5 Wind Loads on Open Gantries
When evaluating wind loads on open gantries, a factor of 1.5 shall be applied to the areas on which the wind acts.
5.6 Loading Combinations
Load combinations and factors shall be as stated in Table 2 of BS 5950. Earthquake loads shall be factored as wind loads. Earthquake and wind should not be considered to act at the same time.
5.7 Additional Loading
When the layout of any mezzanine floor is not finalised at the start of design, an additional load of 6 tonnes shall be added to the main stanchion loads when evaluating the maximum foundation loading.
6. Steel Framed Buildings Structural Design
6.1 Compressor House
Design of structural steelwork, crane gantry, girders, cladding, partitions, sheeting rails, framing columns, and their connections shall be in accordance with BS 5950. Design of overhead runway beams shall be in accordance with BS 2853.
7. DETAILED DESIGN OF COMPRESSOR HOUSES
7.1 Cladding
7.1.1 For plants, cladding will generally be of plastic-coated, preformed metal sheeting.
7.1.2 For third party sales, unpainted galvanised steel sheeting may be used.
7.1.3 A specification shall be provided by the MAPPS Section detailing all acoustic requirements.
7.2 Lighting
7.2.1 Natural lighting shall be provided by translucent sheeting matching the profile of the cladding. The minimum area shall be 15% of the floor area.
7.3 Ventilation
7.3.1 MAPPS Section shall provide a specification detailing all ventilation requirements.
7.4 Pipe Penetration Hoods
7.4.1 When banks of pipes penetrate the wall, protective hoods shall be provided to prevent ingress of rain. For small openings, up to 600 mm in width, pressed steel preformed flashing pieces can be used. Larger openings should be provided with fully framed hoods clad with the same sheetings as the rest of the building.
7.4.2 For acoustic requirements, special details are required.
7.5 Anchorages
7.5.1 Standard anchor bolts shall be used. Their details, together with the safe allowable tension, are shown on QS1340C.
7.5.2 Shear anchors under stanchions may be required when the horizontal shear is excessive or when seismic forces are considered. Anchor bolts may be assumed to act in shear.
7.6 Crane Maintenance Access
7.6.1 An access ladder from the mezzanine or from the floor, as applicable, shall be provided to the crane platform. The location shall be agreed with the Lead Piping Designer. Reference shall also be made to V06 for crane access.
8. DRAWINGS
8.1 Compressor Houses
8.1.1 General arrangement drawings shall be produced containing the following information:
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- Fully dimensioned elevations with locations of sheeting rails, doors, windows, pipe penetrations, rain water pipes, translucent sheeting, ventilation, and dwarf walls.
- Fully dimensioned cross sections.
- Foundation plan with positions and sizes of all holding down bolts.
- Details of frame at knee and apex for portal frame design. Other connections should show joint forces to allow design by the supplier.
- Details of mezzanine floor connections.
- Details of drillings in the crane gantry for downshop leads brackets.
- Shoe, or other details, at the bottom or rainwater pipes. The extent of supply shall be clearly stated when rainwater pipes connect to offsets or gullies supplied by Civil Contractors.
- Details of bases of all stanchions and posts.
- Details of pipe penetration hoods and flashings to brickwork.
- When flashings, or other items, supplied by the steelwork supplier are fixed to brickwork or concrete by the Civil Contractor, a note to this effect shall be included on the drawing.
- All important details which are unique to the building.
8.2 Outdoor Crane Gantries
8.2.1 General arrangement drawings shall be produced containing the following information:
- Fully dimensioned elevations with sizes of members, setting and details of bases, ties, brackets, etc.
- Joint forces at minor connections to allow design by the supplier. Major connections shall be designed by Company and detailed on the drawings.
- Foundation plan with positions and sizes of holding down bolts.
- Details of mezzanine floor connections.
- Details of drillings necessary for downshop leads brackets.
8.3 General
8.3.1 All drawings shall include a note stating “supplier to supply and erect all items shown on the drawing unless specified otherwise.” All items not supplied by the Supplier shall be clearly identified and called up as supplied “by others.” When possible, the Supplier should be named, e.g. ‘by Civil Contractor’.
8.3.2 The drawings shall include cross references to specifications Supply and Fabrication of Structural Steelwork where appropriate.