Steel Connections Design and Fabrication Drawings

ECHRO

Project

Structural Engineering 

STEEL CONNECTIONS DESIGN AND FABRICATION DRAWINGS

 

Where steelworks are used, connections need to be designed and they can be by Fabricator or Structural Engineer. However, after the design of the connection the fabrication process will continue with the steel detailing process.


Steel detailing process

 

Steel detailing is part of the integral Structural Design and the result is called Fabrication Drawings. These drawings are used to produce the steelwork. 


Drawing requirements

 

The Fabrication Drawings needs to contain sufficient information on the fabrication drawings to allow the fabricator to produce the required works without any queries. The fabrication drawings are nowadays supplied by NC (Numerical Command files) and DXF files to assist the automatic cutting machinery (egg. Plasma cut).

 

General Assembly Drawing

It is common practice that a General Assembly drawing is produced first for comment and approval. 3D CAD Modelling is now the standard for steel detailing. This means the GA drawing is derived from the 3D CAD model.

The General Assembly drawing has to contain sufficient detail to allow the structural engineers, architects, and the steel erectors an excellent understanding of the steel model without any assumptions being made.


The GA drawing should show:

  • Dimensioned Grid
  • Plan view, fully dimensioning all columns, beams to Grid position
  • Elevations & sections showing top of steel (TOS) heights and general dimensions for erection
  • Typical connections in detail views
  • All section sizes, bolts types, sizes and number.
  • Material type of all sections (hot & cold rolled) and plates

 

Once the GA drawing has been approved by the structural engineer and architect the detailed fabrication drawings can be produced. There is no point for the detailed drawings to be produced prior approval and fabrication should never commence prior approval of the GA.

 

The construction issue will additionally state the assembly number of each beam to assist with the erection. Additional views can be added to the GA in order to assist the steel erection team. This type of GA drawings is also referred to as a Steel Erection Drawing.

 

When the Structural Engineer is appointed to produce fabrication drawings as well as primary design, the design and detailing goes straight to the endpoint, avoiding delays from coordination. The SE will deliver IFC models to Architects or assembly drawings for coordination at different detailing stages and the process moves forward faster. After the final check with architects, steelworks can be produced.


The detailed fabrication drawings mainly consist of Assembly Drawings & Single Part Drawings.

 

Assembly Drawing

Assembly Drawings show the welded item made up of different single parts. A typical beam assembly often consists of a beam and a few plates which are welded to the beam. Assembly drawings will not necessarily show all the plate dimensions but must contain all necessary information that will allow to all single parts (plates and beams) to be welded together with the right weld type and size and at the right location.

 

Assembly drawings should be dimensioned and labelled in a way to allow the welder to assemble and weld all parts together. This means an assembly drawing should show:

  • Plate and beam positions dimensioned to each other.
  • All parts should be dimensioned on visible views. No hidden lines should be dimensioned if possible. Additional views should be added to avoid this.
  • Hole size and position;
  • Weld type and size (weld size often only needs adding if it differs from the standard weld stated in the notes)
  • All part numbers need to be labelled for each part
  • The finish is stated on each drawing (such as galvanised or primed)

 

Single Part Drawing

Single Part Drawings only show one fully dimensioned part. This can be a plate or a beam.

 

Single Part Drawings should be dimensioned and labelled in a clear way to allow cutting and punching of holes without any queries or assumptions. The single part drawings should state:

  • Size (width, height, depth) of all cuts dimensioned
  • The position of all holes dimensioned
  • Section size stated on drawing –not dimensioned
  • The overall quantity of each part

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