F5Special plate shear walls (SPSW)

AISC 341-22, Seismic Provisions for Structural Steel Buildings

Last Updated 29 Oct 2026

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F5.1 Scope

Special plate shear walls (SPSW) of structural steel shall be designed in conformance with this section. This section is applicable to frames with steel web plates connected to beams and columns.

F5.2 Basis of Design

SPSW designed in accordance with these provisions are expected to provide significant inelastic deformation capacity primarily through web plate yielding and as plastic-hinge formation in the ends of horizontal boundary elements (HBE). Vertical boundary elements (VBE) are not expected to yield in shear; VBE are not expected to yield in flexure except at the column base.

F5.3 Analysis

The webs of SPSW shall not be considered as resisting gravity forces.

(a) An analysis in conformance with the applicable building code shall be performed. The required strength of web plates shall be 100% of the required shear strength of the frame from this analysis. The required strength of the frame consisting of the VBE and HBE alone shall be not less than 25% of the frame shear force from this analysis.
(b) The required strength of HBE, VBE, and connections in SPSW shall be determined using the capacity-limited seismic load effect. The capacity-limited horizontal seismic load effect, $E_{c l}$ , shall be determined from an analysis in which all webs are assumed to resist forces corresponding to their expected strength in tension at an angle, $\alpha$ , as determined in Section F5.5b and HBE resist flexural forces at each end corresponding to moments equal to $1.1 R_{y} M_{p} / \alpha_{s}$ ,

where

$M_{p}=$ plastic moment, kip-in. (N-mm)

$\begin{aligned} R_{y} & =\text { ratio of the expected yield stress to the specified minimum yield stress, } \\ F_{y}\end{aligned}$
$\alpha_{s}=\mathrm{LRFD}-\mathrm{ASD}$ force level adjustment factor $=1.0$ for LRFD and 1.5 for ASD

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 web yielding in both directions simultaneously.

The expected web yield stress shall be taken as $R_{\mathrm{y}} F_{\mathrm{y}}$ . When perforated walls are used, the effective expected tension stress is as defined in Section F5.7a.4.

Exception: The required strength of VBE need not exceed the forces determined from nonlinear analysis as defined in Section C3.

User Note: Shear forces in accordance with Equation E1-1 are included in this analysis. Designers should be aware that in some cases forces from the analysis in the applicable building code will govern the design of HBE.

User Note: Shear forces in beams and columns are likely to be high enough that member design is governed by shear yielding.

F5.4 System Requirements

F5.4a Stiffness of Boundary Elements

The stiffness of VBE and HBE shall be such that the entire web plate is yielded at the design earthquake displacement. VBE and HBE conforming to the following requirements shall be deemed to comply with this requirement. The VBE shall have moments of inertia about an axis taken perpendicular to the plane of the web, $I_{c}$ , not less than $0.0031 t_{w} h^{4} / L$ . The HBE shall have moments of inertia about an axis taken perpendicular to the plane of the web, $I_{b}$ , not less than $0.0031 L^{4} / h$ times the difference in web plate thicknesses above and below,

where

$L=$ distance between VBE centerlines, in. (mm)
$h$ = distance between HBE centerlines, in. (mm)
$t_{w}=$ thickness of the web, in. (mm)

F5.4b HBE-to-VBE Connection Moment Ratio

The moment ratio provisions in Section E3.4a shall be met for all HBE-to-VBE connections without including the effects of SPSW web plates.

F5.4c Bracing

HBE shall be braced to satisfy the requirements for moderately ductile members in Section D1.2a.

F5.4d Openings in Webs

Openings in webs shall be bounded on all sides by intermediate boundary elements extending the full width and height of the panel, unless otherwise justified by testing and analysis or permitted by Section F5.7.

F5.5 Members

F5.5a Basic Requirements

HBE, VBE, and intermediate boundary elements shall satisfy the requirements of Section D1.1 for highly ductile members.

F5.5b Webs

V_{n}=0.42 F_{y} t_{w} L_{c f} \sin 2 \alpha

(F5-1)

$\phi_{v}=0.90$ (LRFD) $\quad \Omega_{v}=1.67$ (ASD)

where

$L_{c f}=$ clear distance between column flanges, in. (mm)

$t_{w}=$ thickness of the web, in. (mm)

$\alpha$ = angle of web yielding in degrees, as measured relative to the vertical. The angle of inclination, $\alpha$ , may be taken as $45^{\circ}$ .

F5.5c HBE

HBE shall be designed to preclude flexural yielding at regions other than near the beam-to-column connection. This requirement shall be met by one of the following:

(a) HBE with available strength to resist twice the simple-span beam moment based on gravity loading and web-plate yielding
(b) HBE with available strength to resist the simple-span beam moment based on gravity loading and web-plate yielding and with reduced flanges meeting the requirements of ANSI/AISC 358, Section 5.7, Step 1, with $c=0.25 b_{f}$ ,

where

$b_{f}=$ width of HBE beam flange, in. (mm)

$c=$ depth of cut at center of reduced beam section, in. (mm)

F5.5d Protected Zones

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

(a) The webs of SPSW
(b) Elements that connect webs to HBE and VBE
(c) The plastic hinging zones at each end of the HBE, over a region ranging from the face of the column to one beam depth beyond the face of the column, or as otherwise specified in Section E3.5c

F5.6 Connections

F5.6a Demand Critical Welds

The following welds are demand critical welds and shall satisfy the requirements of Sections 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.

F5.6b HBE-to-VBE Connections

HBE-to-VBE connections shall satisfy the requirements of Section E1.6b.

F5.6b.1 Required Strength

The required shear strength of an HBE-to-VBE connection 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 shear calculated from Equation E1-1 together with the shear resulting from the expected yield strength in tension of the webs yielding at an angle $\alpha$ .

F5.6b.2 Panel Zones

The VBE panel zone next to the top and base HBE of the SPSW shall comply with the requirements in Section E3.6e.

F5.6c Connections of Webs to Boundary Elements

The required strength of web connections to the surrounding HBE and VBE shall equal the expected yield strength, in tension, of the web calculated at an angle $\alpha$ .

F5.6d Column Splices

Column splices shall comply with the requirements of Section D2.5. Where 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, $M_{p}$ , of the connected members, divided by $\alpha_{s}$ . The required shear strength, $V_{r}$ , shall be determined by Equation F4-2.

F5.7 Perforated Webs

F5.7a Regular Layout of Circular Perforations

A perforated plate conforming to this section is permitted to be used as the web of an SPSW. Perforated webs shall have a regular pattern of holes of uniform diameter spaced evenly over the entire web plate in an array pattern so that holes align diagonally at a uniform angle to the vertical. A minimum of four horizontal and four vertical lines of holes shall be used. Edges of openings shall have a surface roughness of 500 µ-in. (13 microns) or less.

F5.7a.1 Strength

The panel design shear strength, $\phi_{v} V_{n}$ (LRFD), and the allowable shear strength, $V_{n} / \Omega_{v}$ (ASD), in accordance with the limit state of shear yielding, shall be determined as follows for perforated webs with holes that align diagonally at $45^{\circ}$ from the horizontal:

V_{n}=0.42 F_{y} t_{w} L_{c f}\left(1-\frac{0.7 D}{S_{\text {diag }}}\right)

$\phi_{v}=0.90$ (LRFD) $\quad \Omega_{v}=1.67$ (ASD)

where

$D \quad$ = diameter of the holes, in. (mm)

$\begin{aligned} S_{\text {diag }} & =\text { shortest center-to-center distance between the holes measured on the } \\ & 45^{\circ} \text { diagonal, in. (mm) }\end{aligned}$

F5.7a.2 Spacing

The spacing, $S_{\text {diag }}$ , shall be at least $1.67 D$ .

The distance between the first holes and web connections to the HBE and VBE shall be at least $D$ but shall not exceed $D+0.7 S_{\text {diag }}$ .

F5.7a.3 Stiffness

The stiffness of the regularly perforated plate shall be calculated using an effective web-plate thickness, $t_{\text {eff }}$ , given by the following:

t_{e f f}=\frac{1-\frac{\pi}{4}\left(\frac{D}{S_{\text {diag }}}\right)}{1-\frac{\pi}{4}\left(\frac{D}{S_{\text {diag }}}\right)\left(1-\frac{N_{r} D \sin \alpha}{H_{c}}\right)} t

(F5-3)

where

$H_{c}=$ clear column (and web-plate) height between beam flanges, in. (mm)

$N_{r}=$ number of horizontal rows of perforations
$t \quad$ = thickness of web plate, in. (mm)
$\begin{aligned} \alpha & =\text { angle of the shortest center-to-centerlines in the opening array to vertical, } \\ & \text { degrees }\end{aligned}$

User Note: Perforating webs in accordance with Section F5.7a imposes the development of web yielding in a direction parallel to that of the hole alignment. Therefore, $\alpha$ is equal to $45^{\circ}$ for the case addressed by Section F5.7a.

F5.7a.4 Effective Expected Tension Stress

The effective expected tension for analysis is $R_{y} F_{y}\left(1-0.7 D / S_{\text {diag }}\right)$ .

F5.7b Reinforced Corner Cut-Out

Quarter-circular cut-outs are permitted at the corners of the webs provided that the webs are connected to arching plates that align with the edge of the cut-outs and serve to reinforce the web along the cut-outs. The plates shall be designed to allow development of the full strength of the solid web and maintain its resistance when subjected to deformations corresponding to the design earthquake displacement.

F5.7b.1 Design for Tension

The required axial strength of the arching plate in tension, $P_{r}$ , resulting from web-plate tension in the absence of other forces, shall be taken as the following:

P_{r}=\frac{R_{y} F_{y t_{w}} r^{2} / \alpha_{s}}{4 e}

where

$\begin{aligned} F_{y} & =\text { specified minimum yield stress of the web plate, in. }^{2}(\mathrm{~mm} 2) \\ R_{y} & =\text { ratio of the expected yield stress to the specified minimum yield stress, } \\ e & =r\left(1-\sqrt{2} / 2\right), \text { in. (mm) } \\ r & =\text { radius of the cut-out, in. (mm) }\end{aligned}$

HBE and VBE shall be designed to resist the axial tension forces acting at the end of the arching reinforcement.

F5.7b.2 Design for Combined Axial and Flexural Forces

The required strength of the arching plate under the combined effects of axial compression force, $P_{r}$ , and moment, $M_{r}$ , in the plane of the web resulting from connection deformation in the absence of other forces shall be taken as the following:

P_{r}=\frac{15 E I_{y}}{\alpha_{s}\left(16 e^{2}\right)}\left(\frac{\Delta_{D E}}{H}\right)

(F5-6)

M_{r}=P_{r} e

(F5-7)

where

$E \quad=$ modulus of elasticity of steel
= 29,000 ksi (200 000 MPa)

$H \quad$ = height of story, in. (mm)

$\begin{aligned} I_{y} & =\text { moment of inertia of the plate about the } y \text {-axis, in. }^{4}\left(\mathrm{~mm}^{4}\right)\end{aligned}$
$\begin{aligned} \Delta_{D E} & =\text { frame drift corresponding to the design earthquake displacement, in. } \\ & \text { (mm) }\end{aligned}$

HBE and VBE shall be designed to resist the combined axial and flexural required strengths acting at the end of the arching plate.

End of chapter · NextChapter G Composite moment frame systems

F5Special plate shear walls (SPSW)

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.

F5.1 Scope

Special plate shear walls (SPSW) of structural steel shall be designed in conformance with this section. This section is applicable to frames with steel web plates connected to beams and columns.

F5.2 Basis of Design

F5.3 Analysis

The webs of SPSW shall not be considered as resisting gravity forces.

(a) An analysis in conformance with the applicable building code shall be performed. The required strength of web plates shall be 100% of the required shear strength of the frame from this analysis. The required strength of the frame consisting of the VBE and HBE alone shall be not less than 25% of the frame shear force from this analysis.
(b) The required strength of HBE, VBE, and connections in SPSW shall be determined using the capacity-limited seismic load effect. The capacity-limited horizontal seismic load effect, $E_{c l}$ , shall be determined from an analysis in which all webs are assumed to resist forces corresponding to their expected strength in tension at an angle, $\alpha$ , as determined in Section F5.5b and HBE resist flexural forces at each end corresponding to moments equal to $1.1 R_{y} M_{p} / \alpha_{s}$ ,

where

$M_{p}=$ plastic moment, kip-in. (N-mm)

$\begin{aligned} R_{y} & =\text { ratio of the expected yield stress to the specified minimum yield stress, } \\ F_{y}\end{aligned}$
$\alpha_{s}=\mathrm{LRFD}-\mathrm{ASD}$ force level adjustment factor $=1.0$ for LRFD and 1.5 for ASD

The expected web yield stress shall be taken as $R_{\mathrm{y}} F_{\mathrm{y}}$ . When perforated walls are used, the effective expected tension stress is as defined in Section F5.7a.4.

Exception: The required strength of VBE need not exceed the forces determined from nonlinear analysis as defined in Section C3.

User Note: Shear forces in beams and columns are likely to be high enough that member design is governed by shear yielding.

F5.4 System Requirements

F5.4a Stiffness of Boundary Elements

where

$L=$ distance between VBE centerlines, in. (mm)
$h$ = distance between HBE centerlines, in. (mm)
$t_{w}=$ thickness of the web, in. (mm)

F5.4b HBE-to-VBE Connection Moment Ratio

The moment ratio provisions in Section E3.4a shall be met for all HBE-to-VBE connections without including the effects of SPSW web plates.

F5.4c Bracing

HBE shall be braced to satisfy the requirements for moderately ductile members in Section D1.2a.

F5.4d Openings in Webs

F5.5 Members

F5.5a Basic Requirements

HBE, VBE, and intermediate boundary elements shall satisfy the requirements of Section D1.1 for highly ductile members.

F5.5b Webs

V_{n}=0.42 F_{y} t_{w} L_{c f} \sin 2 \alpha

(F5-1)

$\phi_{v}=0.90$ (LRFD) $\quad \Omega_{v}=1.67$ (ASD)

where

$L_{c f}=$ clear distance between column flanges, in. (mm)

$t_{w}=$ thickness of the web, in. (mm)

$\alpha$ = angle of web yielding in degrees, as measured relative to the vertical. The angle of inclination, $\alpha$ , may be taken as $45^{\circ}$ .

F5.5c HBE

HBE shall be designed to preclude flexural yielding at regions other than near the beam-to-column connection. This requirement shall be met by one of the following:

(a) HBE with available strength to resist twice the simple-span beam moment based on gravity loading and web-plate yielding
(b) HBE with available strength to resist the simple-span beam moment based on gravity loading and web-plate yielding and with reduced flanges meeting the requirements of ANSI/AISC 358, Section 5.7, Step 1, with $c=0.25 b_{f}$ ,

where

$b_{f}=$ width of HBE beam flange, in. (mm)

$c=$ depth of cut at center of reduced beam section, in. (mm)

F5.5d Protected Zones

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

(a) The webs of SPSW
(b) Elements that connect webs to HBE and VBE
(c) The plastic hinging zones at each end of the HBE, over a region ranging from the face of the column to one beam depth beyond the face of the column, or as otherwise specified in Section E3.5c

F5.6 Connections

F5.6a Demand Critical Welds

The following welds are demand critical welds and shall satisfy the requirements of Sections 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.

F5.6b HBE-to-VBE Connections

HBE-to-VBE connections shall satisfy the requirements of Section E1.6b.

F5.6b.1 Required Strength

F5.6b.2 Panel Zones

The VBE panel zone next to the top and base HBE of the SPSW shall comply with the requirements in Section E3.6e.

F5.6c Connections of Webs to Boundary Elements

The required strength of web connections to the surrounding HBE and VBE shall equal the expected yield strength, in tension, of the web calculated at an angle $\alpha$ .

F5.6d Column Splices

F5.7 Perforated Webs

F5.7a Regular Layout of Circular Perforations

F5.7a.1 Strength

V_{n}=0.42 F_{y} t_{w} L_{c f}\left(1-\frac{0.7 D}{S_{\text {diag }}}\right)

$\phi_{v}=0.90$ (LRFD) $\quad \Omega_{v}=1.67$ (ASD)

where

$D \quad$ = diameter of the holes, in. (mm)

$\begin{aligned} S_{\text {diag }} & =\text { shortest center-to-center distance between the holes measured on the } \\ & 45^{\circ} \text { diagonal, in. (mm) }\end{aligned}$

F5.7a.2 Spacing

The spacing, $S_{\text {diag }}$ , shall be at least $1.67 D$ .

The distance between the first holes and web connections to the HBE and VBE shall be at least $D$ but shall not exceed $D+0.7 S_{\text {diag }}$ .

F5.7a.3 Stiffness

The stiffness of the regularly perforated plate shall be calculated using an effective web-plate thickness, $t_{\text {eff }}$ , given by the following:

t_{e f f}=\frac{1-\frac{\pi}{4}\left(\frac{D}{S_{\text {diag }}}\right)}{1-\frac{\pi}{4}\left(\frac{D}{S_{\text {diag }}}\right)\left(1-\frac{N_{r} D \sin \alpha}{H_{c}}\right)} t

(F5-3)

where

$H_{c}=$ clear column (and web-plate) height between beam flanges, in. (mm)

$N_{r}=$ number of horizontal rows of perforations
$t \quad$ = thickness of web plate, in. (mm)
$\begin{aligned} \alpha & =\text { angle of the shortest center-to-centerlines in the opening array to vertical, } \\ & \text { degrees }\end{aligned}$

F5.7a.4 Effective Expected Tension Stress

The effective expected tension for analysis is $R_{y} F_{y}\left(1-0.7 D / S_{\text {diag }}\right)$ .

F5.7b Reinforced Corner Cut-Out

F5.7b.1 Design for Tension

The required axial strength of the arching plate in tension, $P_{r}$ , resulting from web-plate tension in the absence of other forces, shall be taken as the following:

P_{r}=\frac{R_{y} F_{y t_{w}} r^{2} / \alpha_{s}}{4 e}

where

HBE and VBE shall be designed to resist the axial tension forces acting at the end of the arching reinforcement.

F5.7b.2 Design for Combined Axial and Flexural Forces

P_{r}=\frac{15 E I_{y}}{\alpha_{s}\left(16 e^{2}\right)}\left(\frac{\Delta_{D E}}{H}\right)

(F5-6)

M_{r}=P_{r} e

(F5-7)

where

$E \quad=$ modulus of elasticity of steel
= 29,000 ksi (200 000 MPa)

$H \quad$ = height of story, in. (mm)

$\begin{aligned} I_{y} & =\text { moment of inertia of the plate about the } y \text {-axis, in. }^{4}\left(\mathrm{~mm}^{4}\right)\end{aligned}$
$\begin{aligned} \Delta_{D E} & =\text { frame drift corresponding to the design earthquake displacement, in. } \\ & \text { (mm) }\end{aligned}$

HBE and VBE shall be designed to resist the combined axial and flexural required strengths acting at the end of the arching plate.

End of chapter · NextChapter G Composite moment frame systems