H4Composite ordinary shear walls (C-OSW)

AISC 341-22, Seismic Provisions for Structural Steel Buildings

Last Updated 29 Oct 2026

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H4.1 Scope

Composite ordinary shear walls (C-OSW) shall be designed in conformance with this section. This section is applicable to reinforced concrete shear walls with composite boundary elements and coupled reinforced concrete shear walls, with or without composite boundary elements, with structural steel or composite coupling beams that connect two or more adjacent walls.

H4.2 Basis of Design

C-OSW designed in accordance with these provisions are expected to provide limited inelastic deformation capacity through yielding in the reinforced concrete walls and the steel or composite elements.

Reinforced concrete walls shall satisfy the requirements of ACI 318, excluding Chapter 18, except as modified in this section.

H4.3 Analysis

Analysis shall satisfy the requirements of Chapter C as modified in this section.

(a) For wall piers, uncracked effective stiffness values for elastic analysis shall be assigned in accordance with ACI 318, Chapter 6. Composite coupling beam effective stiffness shall be taken as the following:
(1) For flexure

(E I)_{e f f}=0.07\left(\frac{g}{h}\right)(E I)_{t r a n s}

(H4-1)

(2) For axial strength and deformation

(E A)_{e f f}=1.0(E A)_{t r a n s}

(H4-2)

(3) For shear $(GA)_{eff}=1.0GA_{w}$ (H4-3)

where

$A_w$ = area of steel beam web, in. $^2$ (mm $^2$ ) $(EA)_{trans}$ = axial rigidity of the transformed section, kip (N) $(EI)_{trans}$ = flexural rigidity of the cracked transformed section, kip-in. $^2$ (N-mm $^2$ ) $G$ = shear modulus of steel, ksi (MPa) $g$ = clear span of coupling beam, in. (mm) $h$ = overall depth of composite section, in. (mm)

(b) When concrete-encased shapes function as boundary members, the analysis shall be based upon a transformed concrete section using elastic material properties.

H4.4 System Requirements

There are no requirements specific to this system.

H4.5 Members

H4.5a Boundary Members

Boundary members shall satisfy the following requirements:

(a) The required axial strength of the boundary member shall be determined assuming that the shear forces are carried by the reinforced concrete wall and the entire gravity and overturning forces are carried by the boundary members in conjunction with the shear wall.
(b) When the concrete-encased structural steel boundary member qualifies as a composite column as defined in Specification Chapter I, it shall be designed as a composite column to satisfy the requirements of Chapter I of the Specification.
(c) Headed studs or welded reinforcement anchors shall be provided to transfer required shear strengths between the structural steel boundary members and reinforced concrete walls. Headed studs, if used, shall satisfy the requirements of Specification Chapter I. Welded reinforcement anchors, if used, shall satisfy the requirements of Structural Welding Code—Reinforcing Steel (AWS D1.4/ D1.4M).

H4.5b Coupling Beams

H4.5b.1 Structural Steel Coupling Beams

Structural steel coupling beams that are used between adjacent reinforced concrete walls shall satisfy the requirements of the Specification and this section. Wide-flange steel coupling beams shall satisfy the following requirements.

(a) Structural steel coupling beams shall be designed in accordance with Chapters F and G of the Specification.
(b) The design connection shear strength, $\phi_{v} V_{n \text {, connection }}$ , shall be computed from Equation H4-4 or H4-4M, with $\phi_{v}=0.90$ .

V_{n, \text { connection }}=1.54 \sqrt{f_{c}^{\prime}}\left(\frac{b_{w}}{b_{f}}\right)^{0.66} \beta_{1} b_{f} L_{e}\left(\frac{0.58-0.22 \beta_{1}}{0.88+\frac{g}{2 L_{e}}}\right)

(H4-4)

V_{n, \text { connection }}=4.04 \sqrt{f_{c}^{\prime}}\left(\frac{b_{w}}{b_{f}}\right)^{0.66} \beta_{1} b_{f} L_{e}\left(\frac{0.58-0.22 \beta_{1}}{0.88+\frac{g}{2 L_{e}}}\right)

(H4-4M)

The embedment length provided shall not be less than $d$ , irrespective of the calculated value of $L_{e}$ ,

where

$L_{e}=$ embedment length of coupling beam measured from the face of the wall, in. (mm)

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

$b_{w}=$ thickness of wall pier, in. (mm)

$d=$ depth of beam, in. (mm)
$f_{c}^{\prime}=$ specified compressive strength of concrete, ksi (MPa)
$\beta_{1}=$ factor relating depth of equivalent rectangular compressive stress block to neutral axis depth, as defined in ACI 318
(c) $M_{u}$ shall be multiplied by $1+\left[(2 L_{e}) /(3 g)\right]$ , where
$L_{e}=$ minimum embedment length of coupling beam measured from the face of the wall that provides sufficient connection shear strength based on Equation H4-4 or H4-4M, in. (mm)
(d) Wall longitudinal reinforcement with nominal axial strength equal to the required shear strength of the coupling beam multiplied by

\frac{\frac{g}{2 L_{e}}+0.33 \beta_{1}}{0.88-0.33 \beta_{1}} \geq 1.0

(H4-5)

shall be placed over the embedment length of the beam. This wall longitudinal reinforcement shall extend a distance of at least one tension development length above and below the flanges of the structural steel coupling beam. It is permitted to use longitudinal reinforcement placed for other purposes, such as for vertical boundary members, as part of the required longitudinal reinforcement.

H4.5b.2 Composite Coupling Beams

Encased composite sections serving as coupling beams shall satisfy the following requirements:

(a) Structural steel coupling beams shall have an embedment length into the reinforced concrete wall that is sufficient to develop the required shear strength, where the design shear strength of the connection is determined from Section H4.5b.1(b). The embedment length provided shall not be less than d, irrespective of the calculated value of $L_{e}$ .
(b) The design shear strength of the composite beam, $\phi_{v} V_{n c}$ , shall be computed from Equation H4-6 or H4-6M, with $\phi_{v}=0.90$ .

V_{n c}=V_{p}+\left(0.0632 \sqrt{f_{c}^{\prime}} b_{w c} d_{c}+\frac{A_{s r} F_{y s r} d_{c}}{s}\right)

(H4-6)

V_{n c}=V_{p}+\left(0.166 \sqrt{f_{c}^{\prime}} b_{w c} d_{c}+\frac{A_{s r} F_{y s r} d_{c}}{s}\right)

(H4-6M)

where

$A_{s r}=$ area of transverse reinforcement, in. ${ }^{2}\left(\mathrm{~mm}^{2}\right)$

$\begin{aligned} F_{y s r} & =\text { specified minimum yield stress of transverse reinforcement, ksi } \\ & \text { (MPa) }\end{aligned}$

$V_{p}=0.6 F_{y} A_{w}$ , kips (N)

$F_{y} \quad$ = specified minimum yield stress of encased steel beam, in ${ }^{2}\left(\mathrm{~mm}^{2}\right)$

$b_{w c}=$ width of concrete encasement, in. (mm)

$d_{c}$ = effective depth of concrete encasement, in. (mm)

$s \quad$ = spacing of transverse reinforcement, in. (mm)
(c) Longitudinal and transverse coupling beam reinforcement shall be distributed around the beam perimeter with total area in each direction of at least $0.0002 b_{w c}$ and spacing not exceeding 12 in. (300 mm). Longitudinal reinforcement shall not extend into the wall and shall not be included in the computation of flexural strength.
(d) The requirements of Sections H4.5b.1(c) and H4.5b.1(d) shall be satisfied.

H4.5c Protected Zones

There are no designated protected zones.

H4.6 Connections

There are no additional requirements beyond Section H4.5.

H4.6a Demand Critical Welds

There are no requirements specific to this system.

H4Composite ordinary shear walls (C-OSW)

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.

H4.1 Scope

H4.2 Basis of Design

Reinforced concrete walls shall satisfy the requirements of ACI 318, excluding Chapter 18, except as modified in this section.

H4.3 Analysis

Analysis shall satisfy the requirements of Chapter C as modified in this section.

(a) For wall piers, uncracked effective stiffness values for elastic analysis shall be assigned in accordance with ACI 318, Chapter 6. Composite coupling beam effective stiffness shall be taken as the following:
(1) For flexure

(E I)_{e f f}=0.07\left(\frac{g}{h}\right)(E I)_{t r a n s}

(H4-1)

(2) For axial strength and deformation

(E A)_{e f f}=1.0(E A)_{t r a n s}

(H4-2)

(3) For shear $(GA)_{eff}=1.0GA_{w}$ (H4-3)

where

(b) When concrete-encased shapes function as boundary members, the analysis shall be based upon a transformed concrete section using elastic material properties.

H4.4 System Requirements

There are no requirements specific to this system.

H4.5 Members

H4.5a Boundary Members

Boundary members shall satisfy the following requirements:

(a) The required axial strength of the boundary member shall be determined assuming that the shear forces are carried by the reinforced concrete wall and the entire gravity and overturning forces are carried by the boundary members in conjunction with the shear wall.
(b) When the concrete-encased structural steel boundary member qualifies as a composite column as defined in Specification Chapter I, it shall be designed as a composite column to satisfy the requirements of Chapter I of the Specification.
(c) Headed studs or welded reinforcement anchors shall be provided to transfer required shear strengths between the structural steel boundary members and reinforced concrete walls. Headed studs, if used, shall satisfy the requirements of Specification Chapter I. Welded reinforcement anchors, if used, shall satisfy the requirements of Structural Welding Code—Reinforcing Steel (AWS D1.4/ D1.4M).

H4.5b Coupling Beams

H4.5b.1 Structural Steel Coupling Beams

(a) Structural steel coupling beams shall be designed in accordance with Chapters F and G of the Specification.
(b) The design connection shear strength, $\phi_{v} V_{n \text {, connection }}$ , shall be computed from Equation H4-4 or H4-4M, with $\phi_{v}=0.90$ .

V_{n, \text { connection }}=1.54 \sqrt{f_{c}^{\prime}}\left(\frac{b_{w}}{b_{f}}\right)^{0.66} \beta_{1} b_{f} L_{e}\left(\frac{0.58-0.22 \beta_{1}}{0.88+\frac{g}{2 L_{e}}}\right)

(H4-4)

V_{n, \text { connection }}=4.04 \sqrt{f_{c}^{\prime}}\left(\frac{b_{w}}{b_{f}}\right)^{0.66} \beta_{1} b_{f} L_{e}\left(\frac{0.58-0.22 \beta_{1}}{0.88+\frac{g}{2 L_{e}}}\right)

(H4-4M)

The embedment length provided shall not be less than $d$ , irrespective of the calculated value of $L_{e}$ ,

where

$L_{e}=$ embedment length of coupling beam measured from the face of the wall, in. (mm)

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

$b_{w}=$ thickness of wall pier, in. (mm)

$d=$ depth of beam, in. (mm)
$f_{c}^{\prime}=$ specified compressive strength of concrete, ksi (MPa)
$\beta_{1}=$ factor relating depth of equivalent rectangular compressive stress block to neutral axis depth, as defined in ACI 318
(c) $M_{u}$ shall be multiplied by $1+\left[(2 L_{e}) /(3 g)\right]$ , where
$L_{e}=$ minimum embedment length of coupling beam measured from the face of the wall that provides sufficient connection shear strength based on Equation H4-4 or H4-4M, in. (mm)
(d) Wall longitudinal reinforcement with nominal axial strength equal to the required shear strength of the coupling beam multiplied by

\frac{\frac{g}{2 L_{e}}+0.33 \beta_{1}}{0.88-0.33 \beta_{1}} \geq 1.0

(H4-5)

H4.5b.2 Composite Coupling Beams

Encased composite sections serving as coupling beams shall satisfy the following requirements:

(a) Structural steel coupling beams shall have an embedment length into the reinforced concrete wall that is sufficient to develop the required shear strength, where the design shear strength of the connection is determined from Section H4.5b.1(b). The embedment length provided shall not be less than d, irrespective of the calculated value of $L_{e}$ .
(b) The design shear strength of the composite beam, $\phi_{v} V_{n c}$ , shall be computed from Equation H4-6 or H4-6M, with $\phi_{v}=0.90$ .

V_{n c}=V_{p}+\left(0.0632 \sqrt{f_{c}^{\prime}} b_{w c} d_{c}+\frac{A_{s r} F_{y s r} d_{c}}{s}\right)

(H4-6)

V_{n c}=V_{p}+\left(0.166 \sqrt{f_{c}^{\prime}} b_{w c} d_{c}+\frac{A_{s r} F_{y s r} d_{c}}{s}\right)

(H4-6M)

where

$A_{s r}=$ area of transverse reinforcement, in. ${ }^{2}\left(\mathrm{~mm}^{2}\right)$

$\begin{aligned} F_{y s r} & =\text { specified minimum yield stress of transverse reinforcement, ksi } \\ & \text { (MPa) }\end{aligned}$

$V_{p}=0.6 F_{y} A_{w}$ , kips (N)

$F_{y} \quad$ = specified minimum yield stress of encased steel beam, in ${ }^{2}\left(\mathrm{~mm}^{2}\right)$

$b_{w c}=$ width of concrete encasement, in. (mm)

$d_{c}$ = effective depth of concrete encasement, in. (mm)

$s \quad$ = spacing of transverse reinforcement, in. (mm)
(c) Longitudinal and transverse coupling beam reinforcement shall be distributed around the beam perimeter with total area in each direction of at least $0.0002 b_{w c}$ and spacing not exceeding 12 in. (300 mm). Longitudinal reinforcement shall not extend into the wall and shall not be included in the computation of flexural strength.
(d) The requirements of Sections H4.5b.1(c) and H4.5b.1(d) shall be satisfied.

H4.5c Protected Zones

There are no designated protected zones.

H4.6 Connections

There are no additional requirements beyond Section H4.5.

H4.6a Demand Critical Welds

There are no requirements specific to this system.