J1General provisions

J1.1 Design Basis

The design strength, $\phi R_{n}$, and the allowable strength, $R_{n} / \Omega$, of connections shall be determined in accordance with the provisions of this chapter and the provisions of Chapter B.

The required strength of the connections shall be determined by structural analysis for the specified design loads, consistent with the type of construction specified, or shall be a proportion of the required strength of the connected members when so specified herein.

Where the gravity axes of intersecting axially loaded members do not intersect at one point, the effects of eccentricity shall be considered.

J1.2 Simple Connections

Simple connections of beams, girders, and trusses shall be designed as flexible and are permitted to be proportioned for the reaction shears only, except as otherwise indicated in the design documents. Flexible beam connections shall accommodate end rotations of simple beams. Some inelastic but self-limiting deformation in the connection is permitted to accommodate the end rotation of a simple beam.

J1.3 Moment Connections

End connections of restrained beams, girders, and trusses shall be designed for the combined effect of forces resulting from moment and shear induced by the rigidity of the connections. Response criteria for moment connections are provided in Section B3.4b.

User Note: See Chapter C and Appendix 7 for analysis requirements to establish the required strength for the design of connections.

J1.4 Compression Members with Bearing Joints

Compression members relying on bearing for load transfer shall meet the following requirements:

• (a) For columns bearing on bearing plates or finished to bear at splices, there shall be sufficient connectors to hold all parts in place.
• (b) For compression members other than columns finished to bear, the splice material and its connectors shall be arranged to hold all parts in line and their required strength shall be the lesser of
• (1) An axial tensile force equal to 50% of the required compressive strength of the member; or
• (2) The moment and shear resulting from a transverse load equal to 2% of the required compressive strength of the member. The transverse load shall be applied at the location of the splice exclusive of other loads that act on the member. The member shall be taken as pinned for the determination of the shears and moments at the splice.

User Note: All compression joints should also be proportioned to resist any ten- sion developed by the load combinations stipulated in Section B2.

J1.5 Splices in Heavy Sections

When tensile forces due to applied tension or flexure are to be transmitted through splices in heavy shapes, as defined in Sections A3.1d and A3.1e, by complete-joint-penetration (CJP) groove welds, the following provisions apply: (a) material notch-toughness requirements as given in Sections A3.1d and A3.1e; (b) weld access hole details as given in Section J1.6; (c) filler metal requirements as given in Section J2.6; and (d) thermal cut surface preparation and inspection requirements as given in Section M2.2. The foregoing provision is not applicable to splices of elements of built-up shapes that are welded prior to assembling the shape.

User Note: CJP groove welded splices of heavy sections can exhibit detrimental effects of weld shrinkage. Members that are sized for compression that are also subjected to tensile forces may be less susceptible to damage from shrinkage if they are spliced using partial-joint-penetration (PJP) groove welds on the flanges and fillet-welded web plates, or using bolts for some or all of the splice.

J1.6 Weld Access Holes

Weld access holes shall meet the following requirements:

• (a) All weld access holes required to facilitate welding operations shall be detailed to provide room for weld backing as needed.
• (b) The access hole shall have a length from the toe of the weld preparation not less than 12 times the thickness of the material in which the hole is made, nor less than 12 in. (38 mm).
• (c) The access hole shall have a height not less than the thickness of the material with the access hole, nor less than 3/4 in. (19 mm), nor does it need to exceed 2 in. (50 mm).
• (d) For sections that are rolled or welded prior to cutting, the edge of the web shall be sloped or curved from the surface of the flange to the reentrant surface of the access hole.
• (e) In hot-rolled shapes, and built-up shapes with CJP groove welds that join the web-to-flange, weld access holes shall be free of notches and sharp reentrant corners.
• (f) No arc of the weld access hole shall have a radius less than 3/8 in. (10 mm).
• (g) In built-up shapes with fillet or partial-joint-penetration (PJP) groove welds that join the web-to-flange, weld access holes shall be free of notches and sharp reentrant corners.
• (h) The access hole is permitted to terminate perpendicular to the flange, providing the weld is terminated at least a distance equal to the weld size away from the access hole.
• (i) For heavy shapes, as defined in Sections A3.1d and A3.1e, the thermally cut surfaces of weld access holes shall be ground to bright metal.
• (j) If the curved transition portion of weld access holes is formed by predrilled or sawed holes, that portion of the access hole need not be ground.

J1.7 Placement of Welds and Bolts

Groups of welds or bolts at the ends of any member that transmit axial force into that member shall be sized so that the center of gravity of the group coincides with the center of gravity of the member, unless provision is made for the eccentricity. The foregoing provision is not applicable to end connections of single-angle, double-angle, and similar members.

J1.8 Bolts in Combination with Welds

Bolts shall not be considered as sharing the load in combination with welds, except in the design of shear connections on a common faying surface where strain compatibility between the bolts and welds is considered.

It is permitted to determine the available strength, $\phi R_{n}$ and $R_{n} / \Omega$, as applicable, of a joint combining the strengths of high-strength bolts and longitudinal fillet welds as

the sum of (1) the nominal slip resistance, Rn, for bolts as defined in Equation J3-4 according to the requirements of a slip-critical connection and (2) the nominal weld strength, Rn, as defined in Section J2.4, when the following apply:

(a) $\phi=0.75$ (LRFD); $\Omega=2.00$ (ASD) for the combined joint.

• (b) When the high-strength bolts are pretensioned according to the requirements of Table J3.1 or Table J3.1M using the turn-of-nut or combined method, the longi- tudinal fillet welds shall have an available strength of not less than 50% of the required strength of the connection.
• (c) When the high-strength bolts are pretensioned according to the requirements of Table J3.1 or Table J3.1M using any method other than the turn-of-nut method, the longitudinal fillet welds shall have an available strength of not less than 70% of the required strength of the connection.
• (d) The high-strength bolts shall have an available strength of not less than 33% of the required strength of the connection.

In joints with combined bolts and longitudinal welds, the strength of the connection need not be taken as less than either the strength of the bolts alone or the strength of the welds alone.

J1.9 Welded Alterations to Structures with Existing Rivets or Bolts

In making welded alterations to structures, existing rivets and high-strength bolts in standard or short-slotted holes transverse to the direction of load, and tightened to the requirements of slip-critical connections are permitted to be utilized for resisting loads present at the time of alteration, and the welding need only provide the additional required strength. The weld available strength shall provide the additional required strength, but not less than 25% of the required strength of the connection.

User Note: The provisions of this section are generally recommended for alteration in building designs or for field corrections. Use of the combined strength of bolts and welds on a common faying surface is not recommended for new design.

J1.10 High-Strength Bolts in Combination with Existing Rivets

In connections designed as slip-critical connections in accordance with the provisions of Section J3, high-strength bolts are permitted to be considered as sharing the load with existing rivets.