### International Building Code 1908.1

General. The text ofACI 318 shall be modified as indicated

in Sections 1908.1.1 through 1908.1.16.

ACI 318, Section 10.5. Modify ACI 318, Section

10.5, by adding new Section 10.5.5 to read as follows:

10.5.5 # In structures assigned to Seismic Design Category

B, beams in ordinary moment frames forming part

of the seismic-force-resisting system shall have at least

two main flexural reinforcing bars continuously top and

bottom throughout the beam and continuous through or

developed within exterior columns or boundary elements.

ACI 318, Section 11.11. ModifyACI 318, Section

11.11, by changing its title to read as shown below and by

adding new Section 11.11.3 to read as follows:

11.11# Special provisions for columns.

11.11.3 # In structures assigned to Seismic Design Category

B, columns of ordinary moment frames having a

clear height-to-maximum-plan-dimension ratio of five

or less shall be designed for shear in accordance with

21.12.3.

ACI 318, Section 21.1. Modify existing definitions

and add the following definitions to ACI 318, Section

21.1.

DESIGN DISPLACEMENT. Total lateral displacement

expected for the design-basis earthquake, as specified by

Section 12.8.6 of ASCE 7.

DETAILEDPLAINCONCRETESTRUCTURALWALL.

A wall complying with the requirements of Chapter 22,

including 22.6.7.

ORDINARY PRECAST STRUCTURALWALL. A precast

wall complying with the requirements of Chapters 1 through

18.

ORDINARY REINFORCED CONCRETE STRUCTURAL

WALL. A cast-in-place wall complying with the

requirements of Chapters 1 through 18.

ORDINARY STRUCTURAL PLAIN CONCRETE

WALL.Awall complying with the requirements of Chapter

22, excluding 22.6.7.

WALL PIER. A wall segment with a horizontal

length-to-thickness ratio of at least 2.5, but not exceeding 6,

whose clear height is at least two times its horizontal length.

ACI 318, Section 21.2.1. Modify ACI 318 Sections

21.2.1.2, 21.2.1.3 and 21.2.1.4, to read as follows:

21.2.1.2 # For structures assigned to Seismic Design

Category Aor B, provisions of Chapters 1 through 18 and

22 shall apply except as modified by the provisions of

this chapter. Where the seismic design loads are computed

using provisions for intermediate or special concrete

systems, the requirements of Chapter 21 for

intermediate or special systems, as applicable, shall be

satisfied.

21.2.1.3 # For structures assigned to Seismic Design

Category C, intermediate or special moment frames,

intermediate precast structural walls or ordinary or special

reinforced concrete structural walls shall be used to

resist seismic forces induced by earthquake motions.

Where the design seismic loads are computed using provisions

for special concrete systems, the requirements of

Chapter 21 for special systems, as applicable, shall be

satisfied.

21.2.1.4 # For structures assigned to Seismic Design

Category D, E or F, special moment frames, special reinforced

concrete structural walls, diaphragms and trusses

and foundations complying with 21.2 through 21.10 or

intermediate precast structural walls complying with

21.13 shall be used to resist forces induced by earthquake

motions. Members not proportioned to resist earthquake

forces shall comply with 21.11.

ACI 318, Section 21.2.5. Modify ACI 318, Section

21.2.5, by renumbering as Section 21.2.5.1 and adding

new Section 21.2.5.2 to read as follows:

21.2.5 # Reinforcement in members resisting earthquake-

induced forces.

21.2.5.1 # Except as permitted in 21.2.5.2, reinforcement

resisting earthquake-induced flexural and axial forces in

frame members and in structural wall boundary elements

shall comply with ASTM A 706. ASTM 615,

Grades 40 and 60 reinforcement, shall be permitted in

these members if (a) the actual yield strength based on

mill tests does not exceed the specified yield, fy, strength

by more than 18,000 psi (124 MPa) [retests shall not

exceed this value by more than an additional 3,000 psi

(21 MPa)], and (b) the ratio of the actual tensile strength

to the actual yield strength is not less than 1.25.

For computing shear strength, the value of fyt for transverse

reinforcement, including spiral reinforcement,

shall not exceed 60,000 psi (414 MPa).

21.2.5.2 # Prestressing steel shall be permitted in flexural

members of frames, provided the average prestress,

fpc, calculated for an area equal to the member’s shortest

cross-sectional dimension multiplied by the perpendicular

dimension shall be the lesser of 700 psi (4.83MPa) or

f _

c /6 at locations of nonlinear action where prestressing

steel is used in members of frames.

ACI 318, Section 21.2. Modify ACI 318, Section

21.2, by adding new Section 21.2.9 to read as follows:

21.2.9 # Anchorages for unbonded post-tensioning tendons

resisting earthquake induced forces in structures

assigned to Seismic Design Category C, D, E or F shall

withstand, without failure, 50 cycles of loading ranging

between 40 and 85 percent of the specified tensile

strength of the prestressing steel.

ACI 318, Section 21.3. Modify ACI 318, Section

21.3, by adding new Section 21.3.2.5 to read as follows:

21.3.2.5 # Unless the special moment frame is qualified

for use through structural testing as required by 21.6.3,

for flexural members prestressing steel shall not provide

more than one-quarter of the strength for either positive

or negative moment at the critical section in a plastic

hinge location and shall be anchored at or beyond the

exterior face of a joint.

ACI 318, Section 21.7. Modify ACI 318, Section

21.7, by adding new Section 21.7.10 to read as follows:

21.7.10 # Wall piers and wall segments.

21.7.10.1 #Wall piers not designed as a part of a special

moment frame shall have transverse reinforcement

designed to satisfy the requirements in 21.7.10.2.

Exceptions:

1. Wall piers that satisfy 21.11.

2. Wall piers along a wall line within a story

where other shear wall segments provide lateral

support to the wall piers and such segments

have a total stiffness of at least six times

the sum of the stiffness of all the wall piers.

21.7.10.2 # Transverse reinforcement with seismic hooks

at both ends shall be designed to resist the shear forces

determined from 21.4.5.1. Spacing of transverse reinforcement

shall not exceed 6 inches (152 mm). Transverse

reinforcement shall be extended beyond the pier

clear height for at least 12 inches (305 mm).

21.7.10.3 # Wall segments with a horizontal

length-to-thickness ratio less than 2.5 shall be designed

as columns.

ACI 318, Section 21.8. Modify Section 21.8.1 to

read as follows:

21.8.1 # Special structural walls constructed using precast

concrete shall satisfy all the requirements of 21.7 for

cast-in-place special structural walls in addition to Sections

21.13.2 through 21.13.4.

ACI 318, Section 21.10.1.1. Modify ACI 318,

Section 21.10.1.1, to read as follows:

21.10.1.1 # Foundations resisting earthquake-induced

forces or transferring earthquake-induced forces

between a structure and the ground shall comply with the

requirements of Section 21.10 and other applicable provisions

of ACI 318 unless modified by Chapter 18 of the

International Building Code.

ACI 318, Section 21.11. Modify ACI 318, Section

21.11.2.2 to read as follows:

21.11.2.2 # Members with factored gravity axial forces

exceeding (Agf c/10) shall satisfy 21.4.3, 21.4.4.1(c),

21.4.4.3 and 21.4.5. The maximum longitudinal spacing

of ties shall be so for the full column height. Spacing, so,

shall not exceed the smaller of six diameters of the smallest

longitudinal bar enclosed and 6 inches (152 mm). Lap

splices of longitudinal reinforcement in such members

need not satisfy 21.4.3.2 in structures where the seismic-

force-resisting system does not include special

moment frames.

ACI 318, Section 21.12.5. ModifyACI 318, Section

21.12.5, by adding newSection 21.12.5.6 to read as follows:

21.12.5.6 # Columns supporting reactions from discontinuous

stiff members, such as walls, shall be designed

for the special load combinations in Section 1605.4 of

the International Building Code and shall be provided

with transverse reinforcement at the spacing, so, as

defined in 21.12.5.2 over their full height beneath the

level at which the discontinuity occurs. This transverse

reinforcement shall be extended above and below the

column as required in 21.4.4.5.

ACI 318, Section 21.13. Modify ACI 318, Section

21.13, by renumbering Section 21.13.3 to become

21.13.4 and adding new Sections 21.13.3, 21.13.5 and

21.13.6 to read as follows:

21.13.3 # Except for Type 2 mechanical splices, connection

elements that are designed to yield shall be capable

of maintaining 80 percent of their design strength at the

deformation induced by the design displacement.

21.13.4 # Elements of the connection that are not

designed to yield shall develop at least 1.5 Sy.

21.13.5 # Wall piers not designed as part of a moment

frame shall have transverse reinforcement designed to

resist the shear forces determined from 21.12.3. Spacing

of transverse reinforcement shall not exceed 8 inches

(203 mm). Transverse reinforcement shall be extended

beyond the pier clear height for at least 12 inches (305

mm).

Exceptions:

1. Wall piers that satisfy 21.11.

2. Wall piers along a wall line within a story

where other shear wall segments provide lateral

support to the wall piers and such segments

have a total stiffness of at least six times

the sum of the stiffnesses of all the wall piers.

21.13.6 # Wall segments wi th a horizontal

length-to-thickness ratio less than 2.5 shall be designed

as columns.

ACI 318, Section 22.6. ModifyACI 318, Section

22.6, by adding new Section 22.6.7 to read:

22.6.7 # Detailed plain concrete structural walls.

22.6.7.1 # Detailed plain concrete structural walls are

walls conforming to the requirements of ordinary structural

plain concrete walls and 22.6.7.2.

22.6.7.2 – Reinforcement shall be provided as follows:

(a) Vertical reinforcement of at least 0.20 square

inch (129 mm2) in cross-sectional area shall be

provided continuously from support to support at

each corner, at each side of each opening and at

the ends of walls. The continuous vertical bar

required beside an opening is permitted to substitute

for one of the two No. 5 bars required by

22.6.6.5.

(b) Horizontal reinforcement at least 0.20 square

inch (129 mm2) in cross-sectional area shall be

provided:

1. Continuously at structurally connected roof

and floor levels and at the top of walls;

2. At the bottom of load-bearing walls or in the

top of foundations where doweled to the

wall; and

3. At a maximum spacing of 120 inches (3048

mm).

Reinforcement at the top and bottom of openings,

where used in determining the maximum spacing specified

in Item 3 above, shall be continuous in the wall.

ACI 318, Section 22.10. Delete ACI 318, Section

22.10, and replace with the following:

22.10 # Plain concrete in structures assigned to Seismic

Design Category C, D, E or F.

22.10.1 # Structures assigned to Seismic Design Category

C, D, E or F shall not have elements of structural

plain concrete, except as follows:

(a) Structural plain concrete basement, foundation

or other walls below the base are permitted in

detached one- and two-family dwellings three

stories or less in height constructed with

stud-bearing walls. In dwellings assigned to

Seismic Design CategoryDor E, the height of the

wall shall not exceed 8 feet (2438 mm), the thickness

shall not be less than 71/2 inches (190 mm),

and the wall shall retain no more than 4 feet

(1219 mm) of unbalanced fill. Walls shall have

reinforcement in accordance with 22.6.6.5.

(b) Isolated footings of plain concrete supporting

pedestals or columns are permitted, provided the

projection of the footing beyond the face of the

supported member does not exceed the footing

thickness.

Exception: In detached one- and two-family

dwellings three stories or less in height, the projection

of the footing beyond the face of the supported

member is permitted to exceed the

footing thickness.

(c) Plain concrete footings supporting walls are

permitted, provided the footings have at least two

continuous longitudinal reinforcing bars. Bars

shall not be smaller than No. 4 and shall have a

total area of not less than 0.002 times the gross

cross-sectional area of the footing. For footings

that exceed 8 inches (203 mm) in thickness, a

minimum of one bar shall be provided at the top

and bottom of the footing. Continuity of reinforcement

shall be provided at corners and intersections.

Exceptions:

1. In detached one- and two-family dwellings

three stories or less in height and

constructed with stud-bearing walls,

plain concrete footings without longitudinal

reinforcement supporting walls are

permitted.

2. For foundation systems consisting of a

plain concrete footing and a plain concrete

stemwall, a minimum of one bar

shall be provided at the top of the

stemwall and at the bottom of the footing.

3. Where a slab on ground is cast

monolithically with the footing, one No. 5

bar is permitted to be located at either the

top of the slab or bottom of the footing.

ACI 318, Section D.3.3. Modify ACI 318, Sections

D.3.3.2 through D.3.3.5, to read as follows:

D.3.3.2 # In structures assigned to Seismic Design Category

C, D, E or F, post-installed anchors for use under

D.2.3 shall have passed the Simulated Seismic Tests of

ACI 355.2.

D.3.3.3 # In structures assigned to Seismic Design Category

C, D, E or F, the design strength of anchors shall be

taken as 0.75?Nn and 0.75?Vn, where ? is given in D.4.4

or D.4.5, and Nn and Vn are determined in accordance

with D.4.1.

D.3.3.4 # In structures assigned to Seismic Design Category

C, D, E or F, anchors shall be designed to be governed

by tensile or shear strength of a ductile steel element,

unless D.3.3.5 is satisfied.

D.3.3.5 # Instead of D.3.3.4, the attachment that the

anchor is connecting to the structure shall be designed so

that the attachment will undergo ductile yielding at a load

level corresponding to anchor forces no greater than the

design strength of anchors specified in D.3.3.3, or the

minimum design strength of the anchors shall be at least

2.5 times the factored forces transmitted by the attachment.

### International Building Code 1908.1.1

ACI 318, Section 10.5. Modify ACI 318, Section

10.5, by adding new Section 10.5.5 to read as follows:

10.5.5 # In structures assigned to Seismic Design Category

B, beams in ordinary moment frames forming part

of the seismic-force-resisting system shall have at least

two main flexural reinforcing bars continuously top and

bottom throughout the beam and continuous through or

developed within exterior columns or boundary elements.

### International Building Code 1908.1.10

ACI 318, Section 21.10.1.1. Modify ACI 318,

Section 21.10.1.1, to read as follows:

21.10.1.1 # Foundations resisting earthquake-induced

forces or transferring earthquake-induced forces

between a structure and the ground shall comply with the

requirements of Section 21.10 and other applicable provisions

of ACI 318 unless modified by Chapter 18 of the

International Building Code.

### International Building Code 1908.1.11

ACI 318, Section 21.11. Modify ACI 318, Section

21.11.2.2 to read as follows:

21.11.2.2 # Members with factored gravity axial forces

exceeding (Agf c/10) shall satisfy 21.4.3, 21.4.4.1(c),

21.4.4.3 and 21.4.5. The maximum longitudinal spacing

of ties shall be so for the full column height. Spacing, so,

shall not exceed the smaller of six diameters of the smallest

longitudinal bar enclosed and 6 inches (152 mm). Lap

splices of longitudinal reinforcement in such members

need not satisfy 21.4.3.2 in structures where the seismic-

force-resisting system does not include special

moment frames.

### International Building Code 1908.1.12

ACI 318, Section 21.12.5. ModifyACI 318, Section

21.12.5, by adding newSection 21.12.5.6 to read as follows:

21.12.5.6 # Columns supporting reactions from discontinuous

stiff members, such as walls, shall be designed

for the special load combinations in Section 1605.4 of

the International Building Code and shall be provided

with transverse reinforcement at the spacing, so, as

defined in 21.12.5.2 over their full height beneath the

level at which the discontinuity occurs. This transverse

reinforcement shall be extended above and below the

column as required in 21.4.4.5.

### International Building Code 1908.1.13

ACI 318, Section 21.13. Modify ACI 318, Section

21.13, by renumbering Section 21.13.3 to become

21.13.4 and adding new Sections 21.13.3, 21.13.5 and

21.13.6 to read as follows:

21.13.3 # Except for Type 2 mechanical splices, connection

elements that are designed to yield shall be capable

of maintaining 80 percent of their design strength at the

deformation induced by the design displacement.

21.13.4 # Elements of the connection that are not

designed to yield shall develop at least 1.5 Sy.

21.13.5 # Wall piers not designed as part of a moment

frame shall have transverse reinforcement designed to

resist the shear forces determined from 21.12.3. Spacing

of transverse reinforcement shall not exceed 8 inches

(203 mm). Transverse reinforcement shall be extended

beyond the pier clear height for at least 12 inches (305

mm).

Exceptions:

1. Wall piers that satisfy 21.11.

2. Wall piers along a wall line within a story

where other shear wall segments provide lateral

support to the wall piers and such segments

have a total stiffness of at least six times

the sum of the stiffnesses of all the wall piers.

21.13.6 # Wall segments wi th a horizontal

length-to-thickness ratio less than 2.5 shall be designed

as columns.

### International Building Code 1908.1.14

ACI 318, Section 22.6. ModifyACI 318, Section

22.6, by adding new Section 22.6.7 to read:

22.6.7 # Detailed plain concrete structural walls.

22.6.7.1 # Detailed plain concrete structural walls are

walls conforming to the requirements of ordinary structural

plain concrete walls and 22.6.7.2.

22.6.7.2 – Reinforcement shall be provided as follows:

(a) Vertical reinforcement of at least 0.20 square

inch (129 mm2) in cross-sectional area shall be

provided continuously from support to support at

each corner, at each side of each opening and at

the ends of walls. The continuous vertical bar

required beside an opening is permitted to substitute

for one of the two No. 5 bars required by

22.6.6.5.

(b) Horizontal reinforcement at least 0.20 square

inch (129 mm2) in cross-sectional area shall be

provided:

1. Continuously at structurally connected roof

and floor levels and at the top of walls;

2. At the bottom of load-bearing walls or in the

top of foundations where doweled to the

wall; and

3. At a maximum spacing of 120 inches (3048

mm).

Reinforcement at the top and bottom of openings,

where used in determining the maximum spacing specified

in Item 3 above, shall be continuous in the wall.

### International Building Code 1908.1.15

ACI 318, Section 22.10. Delete ACI 318, Section

22.10, and replace with the following:

22.10 # Plain concrete in structures assigned to Seismic

Design Category C, D, E or F.

22.10.1 # Structures assigned to Seismic Design Category

C, D, E or F shall not have elements of structural

plain concrete, except as follows:

(a) Structural plain concrete basement, foundation

or other walls below the base are permitted in

detached one- and two-family dwellings three

stories or less in height constructed with

stud-bearing walls. In dwellings assigned to

378 2006 INTERNATIONAL BUILDING CODE

CONCRETE

?

?

Seismic Design CategoryDor E, the height of the

wall shall not exceed 8 feet (2438 mm), the thickness

shall not be less than 71/2 inches (190 mm),

and the wall shall retain no more than 4 feet

(1219 mm) of unbalanced fill. Walls shall have

reinforcement in accordance with 22.6.6.5.

(b) Isolated footings of plain concrete supporting

pedestals or columns are permitted, provided the

projection of the footing beyond the face of the

supported member does not exceed the footing

thickness.

Exception: In detached one- and two-family

dwellings three stories or less in height, the projection

of the footing beyond the face of the supported

member is permitted to exceed the

footing thickness.

(c) Plain concrete footings supporting walls are

permitted, provided the footings have at least two

continuous longitudinal reinforcing bars. Bars

shall not be smaller than No. 4 and shall have a

total area of not less than 0.002 times the gross

cross-sectional area of the footing. For footings

that exceed 8 inches (203 mm) in thickness, a

minimum of one bar shall be provided at the top

and bottom of the footing. Continuity of reinforcement

shall be provided at corners and intersections.

Exceptions:

1. In detached one- and two-family dwellings

three stories or less in height and

constructed with stud-bearing walls,

plain concrete footings without longitudinal

reinforcement supporting walls are

permitted.

2. For foundation systems consisting of a

plain concrete footing and a plain concrete

stemwall, a minimum of one bar

shall be provided at the top of the

stemwall and at the bottom of the footing.

3. Where a slab on ground is cast

monolithically with the footing, one No. 5

bar is permitted to be located at either the

top of the slab or bottom of the footing.

### International Building Code 1908.1.16

ACI 318, Section D.3.3. Modify ACI 318, Sections

D.3.3.2 through D.3.3.5, to read as follows:

D.3.3.2 # In structures assigned to Seismic Design Category

C, D, E or F, post-installed anchors for use under

D.2.3 shall have passed the Simulated Seismic Tests of

ACI 355.2.

D.3.3.3 # In structures assigned to Seismic Design Category

C, D, E or F, the design strength of anchors shall be

taken as 0.75?Nn and 0.75?Vn, where ? is given in D.4.4

or D.4.5, and Nn and Vn are determined in accordance

with D.4.1.

D.3.3.4 # In structures assigned to Seismic Design Category

C, D, E or F, anchors shall be designed to be governed

by tensile or shear strength of a ductile steel element,

unless D.3.3.5 is satisfied.

D.3.3.5 # Instead of D.3.3.4, the attachment that the

anchor is connecting to the structure shall be designed so

that the attachment will undergo ductile yielding at a load

level corresponding to anchor forces no greater than the

design strength of anchors specified in D.3.3.3, or the

minimum design strength of the anchors shall be at least

2.5 times the factored forces transmitted by the attachment.

### International Building Code 1908.1.2

ACI 318, Section 11.11. ModifyACI 318, Section

11.11, by changing its title to read as shown below and by

adding new Section 11.11.3 to read as follows:

11.11# Special provisions for columns.

11.11.3 # In structures assigned to Seismic Design Category

B, columns of ordinary moment frames having a

clear height-to-maximum-plan-dimension ratio of five

or less shall be designed for shear in accordance with

21.12.3.

### International Building Code 1908.1.3

ACI 318, Section 21.1. Modify existing definitions

and add the following definitions to ACI 318, Section

21.1.

DESIGN DISPLACEMENT. Total lateral displacement

expected for the design-basis earthquake, as specified by

Section 12.8.6 of ASCE 7.

376 2006 INTERNATIONAL BUILDING CODE

CONCRETE

?

?

?

?

?

DETAILEDPLAINCONCRETESTRUCTURALWALL.

A wall complying with the requirements of Chapter 22,

including 22.6.7.

ORDINARY PRECAST STRUCTURALWALL. A precast

wall complying with the requirements of Chapters 1 through

18.

ORDINARY REINFORCED CONCRETE STRUCTURAL

WALL. A cast-in-place wall complying with the

requirements of Chapters 1 through 18.

ORDINARY STRUCTURAL PLAIN CONCRETE

WALL.Awall complying with the requirements of Chapter

22, excluding 22.6.7.

WALL PIER. A wall segment with a horizontal

length-to-thickness ratio of at least 2.5, but not exceeding 6,

whose clear height is at least two times its horizontal length.

### International Building Code 1908.1.4

ACI 318, Section 21.2.1. Modify ACI 318 Sections

21.2.1.2, 21.2.1.3 and 21.2.1.4, to read as follows:

21.2.1.2 # For structures assigned to Seismic Design

Category Aor B, provisions of Chapters 1 through 18 and

22 shall apply except as modified by the provisions of

this chapter. Where the seismic design loads are computed

using provisions for intermediate or special concrete

systems, the requirements of Chapter 21 for

intermediate or special systems, as applicable, shall be

satisfied.

21.2.1.3 # For structures assigned to Seismic Design

Category C, intermediate or special moment frames,

intermediate precast structural walls or ordinary or special

reinforced concrete structural walls shall be used to

resist seismic forces induced by earthquake motions.

Where the design seismic loads are computed using provisions

for special concrete systems, the requirements of

Chapter 21 for special systems, as applicable, shall be

satisfied.

21.2.1.4 # For structures assigned to Seismic Design

Category D, E or F, special moment frames, special reinforced

concrete structural walls, diaphragms and trusses

and foundations complying with 21.2 through 21.10 or

intermediate precast structural walls complying with

21.13 shall be used to resist forces induced by earthquake

motions. Members not proportioned to resist earthquake

forces shall comply with 21.11.

### International Building Code 1908.1.5

ACI 318, Section 21.2.5. Modify ACI 318, Section

21.2.5, by renumbering as Section 21.2.5.1 and adding

new Section 21.2.5.2 to read as follows:

21.2.5 # Reinforcement in members resisting earthquake-

induced forces.

21.2.5.1 # Except as permitted in 21.2.5.2, reinforcement

resisting earthquake-induced flexural and axial forces in

frame members and in structural wall boundary elements

shall comply with ASTM A 706. ASTM 615,

Grades 40 and 60 reinforcement, shall be permitted in

these members if (a) the actual yield strength based on

mill tests does not exceed the specified yield, fy, strength

by more than 18,000 psi (124 MPa) [retests shall not

exceed this value by more than an additional 3,000 psi

(21 MPa)], and (b) the ratio of the actual tensile strength

to the actual yield strength is not less than 1.25.

For computing shear strength, the value of fyt for transverse

reinforcement, including spiral reinforcement,

shall not exceed 60,000 psi (414 MPa).

21.2.5.2 # Prestressing steel shall be permitted in flexural

members of frames, provided the average prestress,

fpc, calculated for an area equal to the member’s shortest

cross-sectional dimension multiplied by the perpendicular

dimension shall be the lesser of 700 psi (4.83MPa) or

f _

c /6 at locations of nonlinear action where prestressing

steel is used in members of frames.

### International Building Code 1908.1.6

ACI 318, Section 21.2. Modify ACI 318, Section

21.2, by adding new Section 21.2.9 to read as follows:

21.2.9 # Anchorages for unbonded post-tensioning tendons

resisting earthquake induced forces in structures

assigned to Seismic Design Category C, D, E or F shall

withstand, without failure, 50 cycles of loading ranging

between 40 and 85 percent of the specified tensile

strength of the prestressing steel.

### International Building Code 1908.1.7

ACI 318, Section 21.3. Modify ACI 318, Section

21.3, by adding new Section 21.3.2.5 to read as follows:

21.3.2.5 # Unless the special moment frame is qualified

for use through structural testing as required by 21.6.3,

for flexural members prestressing steel shall not provide

more than one-quarter of the strength for either positive

or negative moment at the critical section in a plastic

hinge location and shall be anchored at or beyond the

exterior face of a joint.

### International Building Code 1908.1.8

ACI 318, Section 21.7. Modify ACI 318, Section

21.7, by adding new Section 21.7.10 to read as follows:

21.7.10 # Wall piers and wall segments.

21.7.10.1 #Wall piers not designed as a part of a special

moment frame shall have transverse reinforcement

designed to satisfy the requirements in 21.7.10.2.

Exceptions:

1. Wall piers that satisfy 21.11.

2. Wall piers along a wall line within a story

where other shear wall segments provide lateral

support to the wall piers and such segments

have a total stiffness of at least six times

the sum of the stiffness of all the wall piers.

21.7.10.2 # Transverse reinforcement with seismic hooks

at both ends shall be designed to resist the shear forces

determined from 21.4.5.1. Spacing of transverse reinforcement

shall not exceed 6 inches (152 mm). Transverse

reinforcement shall be extended beyond the pier

clear height for at least 12 inches (305 mm).

21.7.10.3 # Wall segments with a horizontal

length-to-thickness ratio less than 2.5 shall be designed

as columns.

### International Building Code 1908.1.9

ACI 318, Section 21.8. Modify Section 21.8.1 to

read as follows:

21.8.1 # Special structural walls constructed using precast

concrete shall satisfy all the requirements of 21.7 for

cast-in-place special structural walls in addition to Sections

21.13.2 through 21.13.4.