F2Special concentrically braced frames (SCBF)

AISC 341-22, Seismic Provisions for Structural Steel Buildings

Last Updated 29 Oct 2026

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F2.1 Scope

Special concentrically braced frames (SCBF) of structural steel shall be designed in conformance with this section.

F2.2 Basis of Design

This section is applicable to braced frames that consist of concentrically connected members. Eccentricities less than the beam depth are permitted if the resulting member and connection forces are addressed in the design and do not change the expected source of inelastic deformation capacity.

SCBF designed in accordance with these provisions are expected to provide significant inelastic deformation capacity primarily through brace buckling and yielding of the brace in tension.

F2.3 Analysis

The required strength of columns, beams, struts, and connections in SCBF shall be determined using the capacity-limited seismic load effect. The capacity-limited horizontal seismic load effect, $E_{c l}$ , shall be taken as the larger force determined from the following analyses:

(a) An analysis in which all braces are assumed to resist forces corresponding to their expected strength in compression or in tension
(b) An analysis in which all braces in tension are assumed to resist forces corresponding to their expected strength and all braces in compression are assumed to resist their expected post-buckling strength
(c) For multi-tiered braced frames, analyses representing progressive yielding and buckling of the braces from weakest tier to strongest

For the purpose of designating a brace as acting in tension or in compression when establishing the expected brace strength, the horizontal component of the design earthquake loads shall be applied in one direction per analysis. Analyses shall be performed for each direction of frame loading. For systems that include columns that form part of two intersecting frames in orthogonal or multi-axial directions, the analysis shall consider the potential for brace yielding in both directions simultaneously.

The expected brace strength in tension is $R_{y} F_{y} A_{g}$ , where $A_{g}$ is the gross area, in. ${ }^{2}$ $\left(\mathrm{mm}^{2}\right)$ .

The expected brace strength in compression is permitted to be taken as the lesser of $R_{y} F_{y} A_{g}$ and $\left(1 / 0.877\right) F_{n e} A_{g}$ , where $F_{n e}$ is the nominal stress calculated from Specification Chapter E using expected yield stress, $R_{y} F_{y}$ , in lieu of $F_{y}$ . The brace length used for the determination of $F_{n e}$ shall not exceed the distance from brace end to brace end.

The expected post-buckling brace strength shall be taken as a maximum of 0.3 times the expected brace strength in compression.

User Note: Braces with a slenderness ratio of 200 (the maximum permitted by Section F2.5b) buckle elastically for permissible materials; the value of $0.3 F_{n}$ for such braces is 2.1 ksi (14 MPa). This value may be used in Section F2.3(b) for braces of any slenderness and a liberal estimate of the required strength of framing members will be obtained.

Exceptions:

(a) It is permitted to neglect flexural forces resulting from seismic drift in this determination.
(b) The required strength of columns need not exceed the least of the following:
(1) The forces corresponding to the resistance of the foundation to overturning uplift
(2) Forces as determined from nonlinear analysis as defined in Section C3
(c) The required strength of bracing connections shall be as specified in Section F2.6c.
(d) To compute the required strength of beams in V- and inverted V-braced frames, the expected brace strength in tension need not exceed the magnitude of the expected brace strength in compression.

User Note: When computing $F_{n e}$ for analyses in this section, including Exception (d), the brace length is defined as the distance from brace end to brace end. This length depends upon the final brace-to-gusset connection configuration and iteration may be required.

F2.4 System Requirements

F2.4a Lateral Force Distribution

Along any line of braces, braces shall be deployed in alternate directions such that, for either direction of force parallel to the braces, at least 30% but no more than 70% of the total horizontal force along that line is resisted by braces in tension. For the purposes of this provision, a line of braces is defined as a single line or parallel lines with a plan offset of 10% or less of the building dimension perpendicular to the line of braces.

Exception: Lines of bracing may be exempted from the lateral-force distribution requirement for buildings meeting the following requirements.

(a) The required strength of each brace in compression along the exempted line is the overstrength seismic load.
(b) Removal of noncompliant lines of bracing, singly or in combination, would not result in more than a 33% reduction in story strength, nor does the resulting system have an extreme torsional irregularity in accordance with ASCE/SEI 7.

User Note: Compliance with Exception (b) may be performed similar to the ASCE/SEI 7 redundancy determination in accordance with Table 12.3-3, with all braces on the noncompliant line(s) removed. In some cases, the removal of one noncompliant line may be more severe for torsion than the removal of two.

Where opposing diagonal braces along a frame line do not occur in the same bay, the required strengths of the diaphragm, collectors, and elements of the horizontal framing system shall be determined such that the forces resulting from the post-buckling behavior using the analysis requirements of Section F2.3 can be transferred between the braced bays. The required strength of the collector need not exceed the required strength determined by the load combinations of the applicable building code, including the overstrength seismic load, applied to a building model in which all compression braces have been removed. The required strengths of the collectors shall not be based on a load less than that stipulated by the applicable building code.

F2.4b V- and Inverted V-Braced Frames

Beams that are intersected by braces away from beam-to-column connections shall satisfy the following requirements:

(a) Beams shall be continuous between columns.
(b) Beams shall be braced to satisfy the requirements for moderately ductile mem- bers in Section D1.2a.

As a minimum, one set of lateral braces is required at the point of intersection of the V- or inverted V-braced frames, unless the beam has sufficient out-of-plane strength and stiffness to ensure stability between adjacent brace points.

User Note: One method of demonstrating sufficient out-of-plane strength and stiffness of the beam is to apply the bracing force defined in Equation A-6-7 of Appendix 6 of the Specification to each flange so as to form a torsional couple; this loading should be in conjunction with the flexural forces determined from the analysis required by Section F2.3. The stiffness of the beam (and its restraints) with respect to this torsional loading should be sufficient to satisfy Equation A-6-8 of the Specification.

F2.4c K-Braced Frames

K-braced frames shall not be used for SCBF.

F2.4d Tension-Only Frames

Tension-only frames shall not be used in SCBF.

User Note: Tension-only braced frames are those in which the brace compression resistance is neglected in the design and the braces are designed for tension forces only.

F2.4e Multi-Tiered Braced Frames

A special concentrically braced frame is permitted to be configured as a multi-tiered special concentrically braced frame (MT-SCBF) when the following requirements are satisfied.

(a) Braces shall be used in opposing pairs at every tier level.
(b) Struts shall satisfy the following requirements:
(1) Horizontal struts shall be provided at every tier level.
(2) Struts that are intersected by braces away from strut-to-column connections shall also meet the requirements of Section F2.4b. When brace buckling occurs out-of-plane, torsional moments arising from brace buckling shall be considered when verifying lateral bracing or minimum out-of-plane strength and stiffness requirements. The torsional moments shall correspond to $1.1 R_{y} M_{p} / \alpha_{s}$ of the brace about the critical buckling axis, but need not exceed forces corresponding to the flexural resistance of the brace connection, where $M_{p}$ is the plastic moment, kip-in. (N-mm) and $\alpha_{s}=\mathrm{LRFD}-\mathrm{ASD}$ force level adjustment factor $=1.0$ for LRFD and 1.5 for ASD.
(c) Columns shall satisfy the following requirements:
(1) Columns shall be torsionally braced at every strut-to-column connection location.

User Note: The requirements for torsional bracing are typically satisfied by connecting the strut to the column to restrain torsional movement of the column. The strut must have adequate flexural strength and stiffness and an appropriate connection to the column to perform this function.

(2) Columns shall have sufficient strength to resist forces arising from brace buckling. These forces shall correspond to $1.1 R_{y} M_{p} / \alpha_{s}$ of the brace about the critical buckling axis but need not exceed forces corresponding to the flexural resistance of the brace connections.
(3) For all load combinations, columns subjected to axial compression shall be designed to resist bending moments due to second-order and geometric imperfection effects. As a minimum, geometric imperfection effects are permitted to be represented by an out-of-plane horizontal notional load applied at every tier level and equal to 0.006 times the vertical load resulting in compression in the column and contributed by the compression or tension brace intersecting the column at the tier level. In all cases, the multiplier $B_{1}$ , as defined in Specification Appendix 8, need not exceed 2.0.
(d) Each tier in a multi-tiered braced frame shall be subject to the drift limitations of the applicable building code, but the drift shall not exceed 2% of the tier height.

F2.5 Members

F2.5a Basic Requirements

Columns, beams, and braces shall satisfy the requirements of Section D1.1 for highly ductile members. Struts in MT-SCBF shall satisfy the requirements of Section D1.1 for moderately ductile members.

F2.5b Diagonal Braces

Braces shall comply with the following requirements.

(a) Slenderness: Braces shall have a slenderness ratio of $L_{c} / r \leq 200$ .
(b) Built-up braces: The spacing of connectors shall be such that the slenderness ratio, $a / r_{i}$ , of individual elements between the connectors does not exceed 0.4 times the governing slenderness ratio of the built-up member,

where

$a=$ distance between connectors, in. (mm)

$r_{i}=$ minimum radius of gyration of individual component, in. (mm)

The sum of the available shear strengths of the connectors shall equal or exceed the available tensile strength of each element. The spacing of connectors shall be uniform. Not less than two connectors shall be used in a built-up member. Connectors shall not be located within the middle one-fourth of the clear brace length.

Exception: Where the buckling of braces about their critical bucking axis does not cause shear in the connectors, the design of connectors need not comply with this provision.

(c) The brace effective net area shall not be less than the brace gross area. Where reinforcement on braces is used, the following requirements shall apply:
(1) The specified minimum yield strength of the reinforcement shall be at least equal to the specified minimum yield strength of the brace.
(2) The connections of the reinforcement to the brace shall have sufficient strength to develop the expected reinforcement strength on each side of a reduced section.

F2.5c Protected Zones

The protected zones of SCBF shall satisfy Section D1.3 and shall include the following:

(a) For braces, the center one-quarter of the brace length and a zone adjacent to each connection equal to the brace depth in the plane of buckling
(b) Elements that connect braces to beams and columns
(c) For beams of V- and inverted V-braced frames designed using Exception (d) of Section F2.3, a zone adjacent to each gusset plate edge equal to the beam depth

F2.6 Connections

F2.6a Demand Critical Welds

The following welds are demand critical welds and shall satisfy the requirements of Section A3.4b and I2.3:

(a) Groove welds at column splices
(b) Welds at column-to-base plate connections

Exception: Welds need not be considered demand critical when both of the fol- lowing conditions are satisfied.

(1) Column hinging at, or near, the base plate is precluded by conditions of restraint.
(2) There is no net tension under load combinations including the overstrength seismic load.

F2.6b Beam-to-Column Connections

Where a brace or gusset plate connects to both members at a beam-to-column connection, the connection shall satisfy one of the following requirements:

(a) The connection assembly shall be a simple connection meeting the requirements of Specification Section B3.4a, where the required rotation is taken to be 0.025 rad.
(b) The connection assembly shall be designed to resist a moment equal to the lesser of the following:
(1) A moment corresponding to the expected beam flexural strength, $R_{y} M_{p}$ , multiplied by 1.1 and divided by $\alpha_{s}$ , where

$R_{y}=$ ratio of the expected yield stress to the specified minimum yield stress of the beam, $F_{y}$

(2) A moment corresponding to the sum of the expected column flexural strengths, $\Sigma\left(R_{y} F_{y} Z\right)$ , multiplied by 1.1 and divided by $\alpha_{s}$ , where
$R_{y}=$ ratio of the expected yield stress to specified minimum yield stress of the column, $F_{y}$
$Z=$ plastic section modulus of the column, in. ${ }^{3}\left(\mathrm{~mm}^{3}\right)$

This moment shall be considered in combination with the required strength of the brace connection and beam connection, including the diaphragm collector forces determined using the overstrength seismic load.

F2.6c Brace Connections

The required strength in tension, compression, and flexure of brace connections (including beam-to-column connections if part of the SCBF system) shall be determined as required in the following. These required strengths are permitted to be considered independently without interaction.

F2.6c.1 Required Tensile Strength

The required tensile strength shall be the lesser of the following:

(a) The expected yield strength in tension of the brace, determined as $R_{y} F_{y} A_{g}$ , divided by $\alpha_{s}$ ,

where

$A_{g}=$ gross area of brace, in. ${ }^{2}\left(\mathrm{~mm}^{2}\right)$
$F_{y}=$ specified minimum yield stress of the brace, ksi (MPa)
$R_{y}=$ ratio of the expected yield stress to the specified minimum yield stress of the brace, $F_{y}$

Exception: Braces need not comply with the requirements of Specification Section J4.1 for this loading.

User Note: This exception applies to braces where the section is reduced or where the net section is effectively reduced due to shear lag. A typical case is a slotted hollow structural section (HSS) brace at the gusset plate connection. Section F2.5b requires braces with holes or slots to be reinforced such that the effective net area exceeds the gross area.

The brace strength used to check connection limit states, such as brace block shear, may be determined using expected material properties as permitted by Section A3.2.

(b) The maximum load effect, indicated by analysis, that can be transferred to the brace by the system

When oversized holes are used, the required strength for the limit state of bolt slip need not exceed the seismic load effect determined using the overstrength seismic loads.

User Note: For other limit states, the loadings of (a) and (b) apply.

F2.6c.2 Required Compressive Strength

Brace connections shall be designed for a required compressive strength, based on buckling limit states, that is equal to the expected brace strength in compression divided by $\alpha_{s}$ , where the expected brace strength in compression is as defined in Section F2.3.

F2.6c.3 Accommodation of Brace Buckling

Brace connections shall be designed to withstand the flexural forces or rotations imposed by brace buckling. Connections satisfying either of the following provisions are deemed to satisfy this requirement:

(a) Required flexural strength: Brace connections designed to withstand the flexural forces imposed by brace buckling shall have a required flexural strength equal to the expected brace flexural strength multiplied by 1.1 and divided by $\alpha_{s}$ . The expected brace flexural strength shall be determined as $R_{y} M_{p}$ of the brace about the critical buckling axis.
(b) Rotation capacity: Brace connections designed to withstand the rotations imposed by brace buckling shall have sufficient rotation capacity to accommodate the required rotation at the design earthquake displacement. Inelastic rotation of the connection is permitted.

User Note: Accommodation of inelastic rotation is typically accomplished by means of a single gusset plate with the brace terminating before the line of restraint. The detailing requirements for such a connection are described in the Commentary.

F2.6c.4 Gusset Plates

For out-of-plane brace buckling, welds that attach a gusset plate directly to a beam flange or column flange shall have available shear strength equal to $0.6 R_{y} F_{y} t_{p} / \alpha_{s}$ times the joint length,

where

$F_{y}=$ specified minimum yield stress of the gusset plate, ksi (MPa)

$R_{y}=$ ratio of the expected yield stress to the specified minimum yield stress of the gusset plate, $F_{y}$

$t_{p}=$ thickness of the gusset plate, in. (mm)

Exception: Alternatively, these welds may be designed to have available strength to resist gusset-plate edge forces corresponding to the brace force specified in Section F2.6c.2 combined with the gusset plate weak-axis flexural strength determined in the presence of those forces.

User Note: The expected shear strength of the gusset plate may be developed using double-sided fillet welds with leg size equal to 0.74tp for ASTM A572/ A572M Grade 50 (345) plate and 0.62tp for ASTM A36/A36M plate and E70 electrodes. Smaller welds may be justified using the Exception.

F2.6d Column Splices

Column splices shall comply with the requirements of Section D2.5. Where groove welds are used to make the splice, they shall be complete-joint-penetration groove welds.

Column splices shall be designed to develop at least 50% of the lesser plastic moment of the connected members, $M_{p}$ , divided by $\alpha_{s}$ .

The required shear strength shall be $\left(\Sigma M_{p} / \alpha_{s}\right) / H_{c}$ ,

where

$H_{c}$ = clear height of the column between beam connections, including a structural slab, if present, in. (mm)
$\Sigma M_{p}=$ sum of the plastic moments, $F_{y} Z$ , of the top and bottom ends of the column, kip-in. (N-mm)
$F_{y} \quad$ = specified minimum yield stress of column, ksi (MPa)

F2Special concentrically braced frames (SCBF)

AISC 341-22, Seismic Provisions for Structural Steel Buildings

Last Updated 29 Oct 2026

Hover any section to copy its link or text, ask Copilot about it, or bookmark it.

F2.1 Scope

Special concentrically braced frames (SCBF) of structural steel shall be designed in conformance with this section.

F2.2 Basis of Design

SCBF designed in accordance with these provisions are expected to provide significant inelastic deformation capacity primarily through brace buckling and yielding of the brace in tension.

F2.3 Analysis

(a) An analysis in which all braces are assumed to resist forces corresponding to their expected strength in compression or in tension
(b) An analysis in which all braces in tension are assumed to resist forces corresponding to their expected strength and all braces in compression are assumed to resist their expected post-buckling strength
(c) For multi-tiered braced frames, analyses representing progressive yielding and buckling of the braces from weakest tier to strongest

The expected brace strength in tension is $R_{y} F_{y} A_{g}$ , where $A_{g}$ is the gross area, in. ${ }^{2}$ $\left(\mathrm{mm}^{2}\right)$ .

The expected post-buckling brace strength shall be taken as a maximum of 0.3 times the expected brace strength in compression.

Exceptions:

(a) It is permitted to neglect flexural forces resulting from seismic drift in this determination.
(b) The required strength of columns need not exceed the least of the following:
(1) The forces corresponding to the resistance of the foundation to overturning uplift
(2) Forces as determined from nonlinear analysis as defined in Section C3
(c) The required strength of bracing connections shall be as specified in Section F2.6c.
(d) To compute the required strength of beams in V- and inverted V-braced frames, the expected brace strength in tension need not exceed the magnitude of the expected brace strength in compression.

F2.4 System Requirements

F2.4a Lateral Force Distribution

Exception: Lines of bracing may be exempted from the lateral-force distribution requirement for buildings meeting the following requirements.

(a) The required strength of each brace in compression along the exempted line is the overstrength seismic load.
(b) Removal of noncompliant lines of bracing, singly or in combination, would not result in more than a 33% reduction in story strength, nor does the resulting system have an extreme torsional irregularity in accordance with ASCE/SEI 7.

F2.4b V- and Inverted V-Braced Frames

Beams that are intersected by braces away from beam-to-column connections shall satisfy the following requirements:

(a) Beams shall be continuous between columns.
(b) Beams shall be braced to satisfy the requirements for moderately ductile mem- bers in Section D1.2a.

F2.4c K-Braced Frames

K-braced frames shall not be used for SCBF.

F2.4d Tension-Only Frames

Tension-only frames shall not be used in SCBF.

User Note: Tension-only braced frames are those in which the brace compression resistance is neglected in the design and the braces are designed for tension forces only.

F2.4e Multi-Tiered Braced Frames

A special concentrically braced frame is permitted to be configured as a multi-tiered special concentrically braced frame (MT-SCBF) when the following requirements are satisfied.

(a) Braces shall be used in opposing pairs at every tier level.
(b) Struts shall satisfy the following requirements:
(1) Horizontal struts shall be provided at every tier level.
(2) Struts that are intersected by braces away from strut-to-column connections shall also meet the requirements of Section F2.4b. When brace buckling occurs out-of-plane, torsional moments arising from brace buckling shall be considered when verifying lateral bracing or minimum out-of-plane strength and stiffness requirements. The torsional moments shall correspond to $1.1 R_{y} M_{p} / \alpha_{s}$ of the brace about the critical buckling axis, but need not exceed forces corresponding to the flexural resistance of the brace connection, where $M_{p}$ is the plastic moment, kip-in. (N-mm) and $\alpha_{s}=\mathrm{LRFD}-\mathrm{ASD}$ force level adjustment factor $=1.0$ for LRFD and 1.5 for ASD.
(c) Columns shall satisfy the following requirements:
(1) Columns shall be torsionally braced at every strut-to-column connection location.

(2) Columns shall have sufficient strength to resist forces arising from brace buckling. These forces shall correspond to $1.1 R_{y} M_{p} / \alpha_{s}$ of the brace about the critical buckling axis but need not exceed forces corresponding to the flexural resistance of the brace connections.
(3) For all load combinations, columns subjected to axial compression shall be designed to resist bending moments due to second-order and geometric imperfection effects. As a minimum, geometric imperfection effects are permitted to be represented by an out-of-plane horizontal notional load applied at every tier level and equal to 0.006 times the vertical load resulting in compression in the column and contributed by the compression or tension brace intersecting the column at the tier level. In all cases, the multiplier $B_{1}$ , as defined in Specification Appendix 8, need not exceed 2.0.
(d) Each tier in a multi-tiered braced frame shall be subject to the drift limitations of the applicable building code, but the drift shall not exceed 2% of the tier height.

F2.5 Members

F2.5a Basic Requirements

Columns, beams, and braces shall satisfy the requirements of Section D1.1 for highly ductile members. Struts in MT-SCBF shall satisfy the requirements of Section D1.1 for moderately ductile members.

F2.5b Diagonal Braces

Braces shall comply with the following requirements.

(a) Slenderness: Braces shall have a slenderness ratio of $L_{c} / r \leq 200$ .
(b) Built-up braces: The spacing of connectors shall be such that the slenderness ratio, $a / r_{i}$ , of individual elements between the connectors does not exceed 0.4 times the governing slenderness ratio of the built-up member,

where

$a=$ distance between connectors, in. (mm)

$r_{i}=$ minimum radius of gyration of individual component, in. (mm)

Exception: Where the buckling of braces about their critical bucking axis does not cause shear in the connectors, the design of connectors need not comply with this provision.

(c) The brace effective net area shall not be less than the brace gross area. Where reinforcement on braces is used, the following requirements shall apply:
(1) The specified minimum yield strength of the reinforcement shall be at least equal to the specified minimum yield strength of the brace.
(2) The connections of the reinforcement to the brace shall have sufficient strength to develop the expected reinforcement strength on each side of a reduced section.

F2.5c Protected Zones

The protected zones of SCBF shall satisfy Section D1.3 and shall include the following:

(a) For braces, the center one-quarter of the brace length and a zone adjacent to each connection equal to the brace depth in the plane of buckling
(b) Elements that connect braces to beams and columns
(c) For beams of V- and inverted V-braced frames designed using Exception (d) of Section F2.3, a zone adjacent to each gusset plate edge equal to the beam depth

F2.6 Connections

F2.6a Demand Critical Welds

The following welds are demand critical welds and shall satisfy the requirements of Section A3.4b and I2.3:

(a) Groove welds at column splices
(b) Welds at column-to-base plate connections

Exception: Welds need not be considered demand critical when both of the fol- lowing conditions are satisfied.

(1) Column hinging at, or near, the base plate is precluded by conditions of restraint.
(2) There is no net tension under load combinations including the overstrength seismic load.

F2.6b Beam-to-Column Connections

Where a brace or gusset plate connects to both members at a beam-to-column connection, the connection shall satisfy one of the following requirements:

(a) The connection assembly shall be a simple connection meeting the requirements of Specification Section B3.4a, where the required rotation is taken to be 0.025 rad.
(b) The connection assembly shall be designed to resist a moment equal to the lesser of the following:
(1) A moment corresponding to the expected beam flexural strength, $R_{y} M_{p}$ , multiplied by 1.1 and divided by $\alpha_{s}$ , where

$R_{y}=$ ratio of the expected yield stress to the specified minimum yield stress of the beam, $F_{y}$

(2) A moment corresponding to the sum of the expected column flexural strengths, $\Sigma\left(R_{y} F_{y} Z\right)$ , multiplied by 1.1 and divided by $\alpha_{s}$ , where
$R_{y}=$ ratio of the expected yield stress to specified minimum yield stress of the column, $F_{y}$
$Z=$ plastic section modulus of the column, in. ${ }^{3}\left(\mathrm{~mm}^{3}\right)$

F2.6c Brace Connections

F2.6c.1 Required Tensile Strength

The required tensile strength shall be the lesser of the following:

(a) The expected yield strength in tension of the brace, determined as $R_{y} F_{y} A_{g}$ , divided by $\alpha_{s}$ ,

where

$A_{g}=$ gross area of brace, in. ${ }^{2}\left(\mathrm{~mm}^{2}\right)$
$F_{y}=$ specified minimum yield stress of the brace, ksi (MPa)
$R_{y}=$ ratio of the expected yield stress to the specified minimum yield stress of the brace, $F_{y}$

Exception: Braces need not comply with the requirements of Specification Section J4.1 for this loading.

The brace strength used to check connection limit states, such as brace block shear, may be determined using expected material properties as permitted by Section A3.2.

(b) The maximum load effect, indicated by analysis, that can be transferred to the brace by the system

When oversized holes are used, the required strength for the limit state of bolt slip need not exceed the seismic load effect determined using the overstrength seismic loads.

User Note: For other limit states, the loadings of (a) and (b) apply.

F2.6c.2 Required Compressive Strength

F2.6c.3 Accommodation of Brace Buckling

(a) Required flexural strength: Brace connections designed to withstand the flexural forces imposed by brace buckling shall have a required flexural strength equal to the expected brace flexural strength multiplied by 1.1 and divided by $\alpha_{s}$ . The expected brace flexural strength shall be determined as $R_{y} M_{p}$ of the brace about the critical buckling axis.
(b) Rotation capacity: Brace connections designed to withstand the rotations imposed by brace buckling shall have sufficient rotation capacity to accommodate the required rotation at the design earthquake displacement. Inelastic rotation of the connection is permitted.

F2.6c.4 Gusset Plates

where

$F_{y}=$ specified minimum yield stress of the gusset plate, ksi (MPa)

$R_{y}=$ ratio of the expected yield stress to the specified minimum yield stress of the gusset plate, $F_{y}$

$t_{p}=$ thickness of the gusset plate, in. (mm)

F2.6d Column Splices

Column splices shall comply with the requirements of Section D2.5. Where groove welds are used to make the splice, they shall be complete-joint-penetration groove welds.

Column splices shall be designed to develop at least 50% of the lesser plastic moment of the connected members, $M_{p}$ , divided by $\alpha_{s}$ .

The required shear strength shall be $\left(\Sigma M_{p} / \alpha_{s}\right) / H_{c}$ ,

where

$H_{c}$ = clear height of the column between beam connections, including a structural slab, if present, in. (mm)
$\Sigma M_{p}=$ sum of the plastic moments, $F_{y} Z$ , of the top and bottom ends of the column, kip-in. (N-mm)
$F_{y} \quad$ = specified minimum yield stress of column, ksi (MPa)