Structural Steel Connections
Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
Showing changes from Rev 4
to Rev 5
in Structural Steel Connections.
---
title: Structural Steel Connections
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- "Non-conformance and repair log (rejections, dispositions, re-inspections)"
- "Certificates of compliance from fabricator and erector (RCSC 2020, AWS D1.1)"
−default: [Bolt installation and inspection records (by connection, with PIV results), Welding inspection records (visual and NDE reports cross-referenced to WPS), Non-conformance and repair log (rejections, dispositions, re-inspections), Certificates of compliance from fabricator and erector (RCSC 2020, AWS D1.1)]
+default:
+ - "Bolt installation and inspection records (by connection, with PIV results)"
+ - "Welding inspection records (visual and NDE reports cross-referenced to WPS)"
+ - "Non-conformance and repair log (rejections, dispositions, re-inspections)"
+ - "Certificates of compliance from fabricator and erector (RCSC 2020, AWS D1.1)"
```
…63 unchanged lines
### The Seismic Design Category (SDC) determines whether the seismic provisions of AISC 341-22 and AWS D1.8:2016 apply to the connections of the seismic force-resisting system. {note}
+### The Seismic Design Category of the structure shall be specified, determining which AISC 341-22 and AWS D1.8 seismic connection provisions govern the seismic force-resisting system.
+
```datasheet
label: Seismic Design Category
…16 unchanged lines
### The corrosion environment of the connection determines the fastener finish and the faying-surface and coating provisions. {note}
+### Interior, dry, conditioned connections use plain (black) bolts and require no special corrosion measures.
+
+### Connections exposed to weather, high humidity, or aggressive industrial atmospheres shall use galvanized fasteners compatible with galvanized members, and the faying-surface and slip-class provisions shall account for the coating.
+
+### The connection corrosion environment shall be coordinated with the member coating system established in [[sync/structural-steel-framing]].
+
```datasheet
label: Connection Service Environment
…6 unchanged lines
```
−### Interior, dry, conditioned connections use plain (black) bolts and require no special corrosion measures.
−
−### Connections exposed to weather, high humidity, or aggressive industrial atmospheres shall use galvanized fasteners compatible with galvanized members, and the faying-surface and slip-class provisions shall account for the coating.
−
−### The connection corrosion environment shall be coordinated with the member coating system established in [[sync/structural-steel-framing]].
−
# Bolted Connections {toc}
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### ASTM F3125 is the consolidated specification that replaced the legacy A325, A325M, A490, A490M, F1852, and F2280 standards; it covers heat-treated structural bolts in two strength grades and two styles (hex-head and the twist-off tension-control style). {note}
+### The high-strength bolt grade under ASTM F3125 shall be specified for each connection based on the required strength and installation method.
+
```datasheet
label: High-Strength Bolt Specification
…15 unchanged lines
```
+### The primary bolt diameter shall be specified for each connection based on the connection design and required capacity.
+
```datasheet
label: Primary Bolt Diameter
…29 unchanged lines
### RCSC 2020 and AISC 360-22 Section J3 recognize three joint conditions: snug-tight, pretensioned, and slip-critical. {note}
−```datasheet
−label: Bolted Joint Pretension Condition
−type: select
−options:
− - "Snug-tight — bearing connections not subject to fatigue, tension, or seismic demand"
− - "Pretensioned — full pretension required, faying surface not slip-critical"
− - "Slip-critical — full pretension plus verified faying-surface slip resistance"
−default: "Snug-tight — bearing connections not subject to fatigue, tension, or seismic demand"
−```
−
### A snug-tight joint brings the plies into firm contact by the full effort of an ironworker on a spud wrench or a few impacts of an impact wrench. {note}
…8 unchanged lines
### The SER shall designate pretensioned and slip-critical connections on the contract drawings, and the fabricator shall not downgrade a designated joint to snug-tight.
+```datasheet
+label: Bolted Joint Pretension Condition
+type: select
+options:
+ - "Snug-tight — bearing connections not subject to fatigue, tension, or seismic demand"
+ - "Pretensioned — full pretension required, faying surface not slip-critical"
+ - "Slip-critical — full pretension plus verified faying-surface slip resistance"
+default: "Snug-tight — bearing connections not subject to fatigue, tension, or seismic demand"
+```
+
## Pretensioning Methods {toc}
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### The slip resistance of a slip-critical joint is the product of the bolt pretension and the mean slip coefficient (mu) of the faying surface; the surface class therefore enters directly into the connection design. {note}
+### Class A surfaces (mu = 0.30) comprise unpainted clean mill-scale steel or steel blast-cleaned and coated with a coating qualified as Class A. {note}
+
+### Class B surfaces (mu = 0.50) comprise unpainted blast-cleaned bare steel or steel coated with a Class-B-qualified coating; the higher coefficient can reduce the number of bolts but requires blast cleaning of the faying area. {note}
+
+### A faying surface in the slip-critical zone shall not be coated with an ordinary shop primer unless that primer has been tested and qualified for a slip class under RCSC 2020 Appendix A.
+
```datasheet
label: Faying Surface Slip Class — Slip-Critical Connections
…5 unchanged lines
```
+### Where corrosion protection of the faying area is required during a long shipping interval, only a coating with a documented Class A or Class B qualification shall be used, applied at the qualified dry film thickness, and the type and thickness shall be recorded.
+
```datasheet
label: Faying Surface Coating in Slip-Critical Zone
…5 unchanged lines
```
−### Class A surfaces (mu = 0.30) comprise unpainted clean mill-scale steel or steel blast-cleaned and coated with a coating qualified as Class A. {note}
−
−### Class B surfaces (mu = 0.50) comprise unpainted blast-cleaned bare steel or steel coated with a Class-B-qualified coating; the higher coefficient can reduce the number of bolts but requires blast cleaning of the faying area. {note}
−
−### A faying surface in the slip-critical zone shall not be coated with an ordinary shop primer unless that primer has been tested and qualified for a slip class under RCSC 2020 Appendix A.
−
−### Where corrosion protection of the faying area is required during a long shipping interval, only a coating with a documented Class A or Class B qualification shall be used, applied at the qualified dry film thickness, and the type and thickness shall be recorded.
−
### Oil, wax, dirt, and overspray on the faying surface destroy slip resistance and shall be prevented, and the faying area shall be masked during shop priming where the primer is not qualified.
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### Standard round holes are the default; oversized and slotted holes provide erection adjustment or accommodate thermal movement but reduce the bearing reliability of the joint, so their use carries restrictions under AISC 360-22 Section J3.2. {note}
+### Oversized holes are permitted only in slip-critical connections.
+
```datasheet
label: Bolt Hole Type
…7 unchanged lines
```
−### Oversized holes are permitted only in slip-critical connections.
−
### Slotted holes are restricted in orientation relative to the load and may require plate washers or hardened washers to bridge the slot.
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### Low-hydrogen consumables (H8 or lower diffusible-hydrogen designation) shall be used for all structural welding to control hydrogen cracking.
−### Where demand-critical welds are required by AISC 341-22, the filler metal shall additionally meet the CVN toughness requirements of AWS D1.8:2016 — a minimum of 20 ft-lb at minus 20 degrees F (and the supplemental toughness at the higher test temperature where required).
+### Where demand-critical welds are required by AISC 341-22, the filler metal shall additionally meet the CVN toughness requirements of AWS D1.8:2016 — a minimum of 20 ft-lb at minus 20°F (and the supplemental toughness at the higher test temperature where required).
### Self-shielded FCAW (FCAW-S) shall not be used for demand-critical welds.
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### Preheat shall be verified before arc initiation and interpass temperature between passes using a calibrated contact pyrometer or temperature-indicating crayons, and the verification shall be documented.
−### The minimum base-metal temperature for welding shall not be below the AWS D1.1:2025 limit (generally 0 degrees F), the surface shall be dry, and the joint shall be shielded from wind that would disturb the arc shielding gas.
+### The minimum base-metal temperature for welding shall not be below the AWS D1.1:2025 limit (generally 0°F), the surface shall be dry, and the joint shall be shielded from wind that would disturb the arc shielding gas.
## Weld Inspection and NDE {toc}
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### Connection design responsibility is established by AISC 303-22. {note}
+### The contract documents shall make clear, for each connection, whether the SER has fully detailed the connection on the drawings or has delegated its design to the fabricator's engineer.
+
```datasheet
label: Connection Design Responsibility
…7 unchanged lines
```
−### The contract documents shall make clear, for each connection, whether the SER has fully detailed the connection on the drawings or has delegated its design to the fabricator's engineer.
−
### Where design is delegated, the contract drawings shall show the required forces, moments, and any rotation or ductility demands for each connection type.
…51 unchanged lines
## The surface preparation, shop primer, galvanizing, and field touch-up of the steel are governed by [[sync/structural-steel-framing]]; this section addresses only where coatings and the connection work intersect. {note}
+## The faying surfaces of slip-critical joints shall be prepared to the slip class specified above and shall be masked off during shop priming unless the primer is qualified for the slip class.
+
```datasheet
label: Faying Surface Masking During Shop Priming
…5 unchanged lines
```
−## The faying surfaces of slip-critical joints shall be prepared to the slip class specified above and shall be masked off during shop priming unless the primer is qualified for the slip class.
−
## The masking shall be coordinated with the shop coating operation so that the qualified-coating boundary matches the connection geometry on the shop drawings.
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## The warranty does not cover damage caused by other trades, loading beyond the design basis, modifications by others after completion of the steel work, or corrosion of fasteners or welds that results from failure to maintain the coating system. {note}