The steel detailer has a critical role to lay in the steel construction industry. It is he or she that has the responsibility to accurately interpret the design intent, and from that, prepare a full set of detail documents enabling the fabricator to fabricate and the erector to erect the completed structure.
The design intent is reflected in the design documents prepared by the responsible engineer and/or architect. These documents should include:
- Design drawings – which should indicate all member sizes, member placement, levels, elevations and finishes.
- Details of all special / safety-critical connections, including: special Moment Connections, Base-plates, critical Beam and Column Splice Joints
- Placement details of all machinery and equipment to be fixed to, and supported by the structure. This should include, all relevant specifications, references and details of 3rd party equipment. In the event of a commercial or residential structure, this should include all fittings and finishes.
- Planning Schedule
- Calculations and beam end-reactions – This is optional. In many (if not most) occasions, the responsible engineer will expect the fabricator / detailer to design and select Flexible Connections – these are basically run-of-the-mill joints between beam-to-beam, bracing connections, Purlins and Girts etc…
It must be borne in mind here that the overall responsibility for the integrity of the structure remains with the responsible engineer or his delegated representative and not the detailer. However, the detailer should have at least a basic working knowledge of connection selection and be able to apply the principles of Select-and-Check.
This information may be provided digitally, all in one place, using Building Information Modelling (BIM) technology – enabling the detailer work collaboratively with all other trades and disciplines engaged in the project.
Armed with this information, the detailer should be equipped to prepare and provide the detail documents, which include:
Detail and Assembly Drawings –Detail Drawings represent instructions to the fabricator on how to fabricate each and every individual component of the structure including:
- Member cut length
- Plate sizes and thickness
- Drilling or punching details
- Welding Details
- Marking instructions where two or more parts are shop-welded or fitted together it becomes an Assembly. The assembly details should show the relationship between the parts, together with details of how they should be attached i.e. welding or bolting details.
Each assembly should identify the part numbers making up the assembly and in turn, given an assembly number.
General Arrangement Drawings (or Framing Plans) –General Arrangement Drawings present an overall composition of the steel structure. Depending on the size and complexity of the structure it may be spread over several drawings to include Plans, Elevations, Sections and where necessary, Enlarged Details.As a minimum requirement, the GA drawings should contain the following:
- Building Orientation – usually designated by a North arrow
- Plan reference grid along the X and Y axes of the building.
- Levels and Elevations
- All structural members, dimensioned relative to the grid lines or each other.
- Added to the members should be:
- Member type and size
- Unique Part Number or Assembly Number – where parts or assemblies are identical, the same part number should be used. Quantities should be reflected in the Bills-of-Material.
- Special erection instructions
- References to Detail Drawings – this is optional, useful nonetheless.
Bills of Material - A Bill-of-Materials is a list of the raw materials extracted from the detail drawings. This would include all component parts and assemblies giving their Part/Assembly Numbers, Quantities, Mass and materials. Bills-of-Materials are used for requisitioning of orders and/or reserving parts for future use.
Part / Item schedules – used for purchasing non-fabrication items such as nuts and bolts, welding materials, etc…
Planning – which means, in this context, planning the detailing process. On large projects, they are likely to be built according to an overall schedule – so the detailer must ensure the documents are prepared accordingly, so that the parts and assemblies can be fabricated and delivered to site timeously according to the overall schedule.
This may mean planning and detailing the project according to set Phases.
NC file generation – many workshops today employ CNC (Computer Numerically Controlled) technology, and much of this equipment is designed for specific operations such as, drilling, profile cutting, welding, etc... These automated operations require the digital input provided by NC files, which may be in DSTV or DXF format.
It looks like a lot of work and a lot of responsibility - and indeed it is, but fortunately advanced CAD (Computer Aided Design) can come to the rescue.
Using the latest in 3D modelling and detailing technology most of these activities are done automatically, behind the scenes, enabling the detailer to focus and direct his or her energies on the most important detailer’s function – ensuring the structure can be fabricated and put together safely, efficiently, within budget and on time.
For the detailer to achieve this, he or she should be armed with two principal skills which work in conjunction with one another:
- He or she should have a working knowledge of basic structural steel construction including, workshop practices, erection techniques and Best Practice.
- He or she should be proficient with 3D modelling and detailing technology.
For the first part, this website is here to help – each topic of reference is designed to equip and enable the detailer to understand the finer points of detailing in accordance with the principles of Best Practice.
The second part has been made easy with the assistance of Parabuild – one of the world’s leading 3D modelling and detailing developers. (Why Parabuild?)