Glossary
Steel detailing terms, explained
Plain-language definitions for the Tekla, BIM, shop drawing and fabrication terms that come up on every project — written for fabricators, erectors and anyone new to structural steel detailing.
AISCAWSBIMBOMMTO
CJP weldPJP weldDSTV fileNC file
IFC modelGA drawingMarking plan
Erection drawingShop drawingRFI
PEB / PEMBPurlinGirtBase plate
Gusset plateChemset / TruboltSlip-critical bolt
Clash detectionPiece markRevision cloud
AFC drawingWrench clearanceFRP grating
- AISC
- American Institute of Steel Construction — publishes the design, fabrication and erection standards most US structural steel projects are detailed against.
- AWS
- American Welding Society — publishes the welding codes (including AWS D1.1) that define weld symbols, joint types and inspection requirements used on shop drawings.
- BIM (Building Information Modeling)
- A 3D, data-rich model of a structure — built in software like Tekla Structures — that drives drawings, schedules and fabrication data automatically, instead of maintaining separate 2D sheets by hand.
- BOM (Bill of Materials)
- A full list of every component in a structure — profile, grade, length, thickness, quantity and piece mark — generated directly from the 3D model.
- MTO (Material Take-Off)
- The procurement-focused summary of raw material needed to fabricate a project, used to place mill and stock orders and plan cutting.
- CJP weld (Complete Joint Penetration)
- A weld that extends fully through the joint thickness, giving 100% strength transfer across the connection. Used on high-stress structural joints.
- PJP weld (Partial Joint Penetration)
- A weld that only partially penetrates the joint depth. Used where the connection doesn't require full-section strength.
- DSTV file
- A standardized data file format that carries geometry, hole patterns and cut data straight from a 3D model to CNC fabrication machines, eliminating manual re-entry at the machine.
- NC file (Numerical Control)
- Machine-readable fabrication data exported from a 3D model to drive CNC saws, drills, punches and plasma/laser cutting equipment.
- IFC model
- Industry Foundation Classes — an open, vendor-neutral 3D file format used to exchange building and structural models between different BIM software packages.
- GA drawing (General Arrangement)
- A plan and elevation view showing the overall layout of a structure, used for coordination and design approval rather than shop fabrication.
- Marking plan
- A layout drawing that maps every structural member's unique piece mark onto a grid, with North orientation, elevations and anchor locations, so field crews know exactly where each piece goes.
- Erection drawing
- A drawing showing how structural members assemble on site — framework layout, member positions, field bolts and field welds — used to guide the erection crew.
- Shop drawing
- A fabrication-level drawing showing exact cuts, holes, welds and dimensions for a single piece or assembly, used by the fabrication shop to build it.
- RFI (Request for Information)
- A formal question raised by the field or shop when a drawing is unclear or a site condition doesn't match the design, tracked and answered by the engineer or detailer.
- PEB / PEMB (Pre-Engineered Building)
- A structure built from tapered, built-up members and cold-formed secondary framing (purlins, girts), optimized for standardized, rapid fabrication and erection.
- Purlin
- A horizontal secondary structural member that spans between rafters or trusses to support roof cladding.
- Girt
- A horizontal secondary structural member that spans between columns to support wall cladding.
- Base plate
- A steel plate welded to the bottom of a column that transfers structural loads into the foundation through anchor bolts.
- Gusset plate
- A plate used to connect intersecting structural members — such as bracing to a beam or column — transferring load between them.
- Chemset / Trubolt
- Common post-installed anchor systems — chemical anchor and mechanical expansion anchor respectively — used to fix steel base plates into cured concrete after the pour.
- Slip-critical bolt
- A high-strength bolted connection tightened to a specified tension so the connected plies transfer load through friction rather than bolt shear, preventing any slip under service load.
- Clash detection
- The process of digitally checking a 3D model for physical conflicts between structural steel, MEP, architectural and concrete elements before fabrication begins.
- Piece mark
- A unique identifier assigned to each fabricated member or assembly, used to track it from the shop drawing through fabrication, shipping and field erection.
- Revision cloud
- A cloud-shaped marking drawn around a part of a drawing that has changed since the previous issue, flagging it for reviewers and the shop floor.
- AFC drawing (Approval For Construction)
- The current, formally approved drawing revision that the field and shop are authorized to build from.
- Wrench clearance
- The physical space required around a bolt to fit a wrench or impact tool for tightening, which must be checked during connection detailing.
- FRP grating (Fiberglass Reinforced Plastic)
- A lightweight, corrosion-resistant decking material used for platforms, walkways and boardwalks in place of steel grating.
“Have a term you think we're missing, or want to contribute a definition from your own project experience? Get in touch — this glossary grows with the community.”
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