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Design of Concrete Moment gFrames

Anindya Dutta, Ph.D., S.E.

Topics to be Covered

• Preferred Lateral Mechanisms

•Code Provisions for Member Design

•Shear Design of Beams

•Column Confinement Design

•Joint Design

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Structural Behavior of Frames

Undesirable Desirable

Story Mechanism

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Code Provisions

Chapter 21 deals with members resisting earthquake loads

Performance Objectives of ACI 318

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Code Provisions

Beam Design

Code Provisions

Beam Design

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Code ProvisionsBeam Design-Reinforcement

Code ProvisionsBeam Design

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Code ProvisionsBeam Design-Splice Requirements

Code Provisions

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Code Provisions

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Code ProvisionsBeam Design-Lateral Reinforcement

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Code Provisions

Code Provisions

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Code Provisions

Column Design

Code Provisions

Note:

Column Design

c1 is the dimension in the direction of framing and c2 is the perpendicular dimension

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Code Provisions

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ral S

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Col

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Flex

Code Provisions

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men

tsxu

ral S

treng

th R

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Col

umn

Flex

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Code Provisions

Column Longitudinal Reinforcement Design

Code ProvisionsColumn Longitudinal Reinforcement Design

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Code Provisionsem

ents

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Col

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Co

Code Provisions

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Code Provisionsem

ents

onfin

emen

t Req

uire

Col

umn

Co

Code Provisions

emen

tson

finem

ent R

equi

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n C

o

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Code Provisions

emen

tson

finem

ent R

equi

reC

olum

n C

o

Code ProvisionsColumn Confinement Requirements

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Code ProvisionsColumn Spiral Hoop Requirements

Code ProvisionsColumn Supporting Discontinuous Stiff Members

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Code Provisions

Undesirable Desirable

Code ProvisionsHysteretic Behavior of Well Confined Concrete Columns

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Moment Frame Example

Moment Frame Example

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Moment Frame ExampleReinforcement Layout

Shear Design of Beams

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Shear Design of Beams-Example

Shear Design of Beams-Example

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Shear Design of Beams-Example

Shear Design of Beams-Example

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Shear Design of Beams-ExampleBeam Reinforcement Layout

Total 6-#8

Total 6-#8

Shear Design of Beams-Example

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Shear Design of Beams-Example

Special Moment Resisting Frame Joints - Design intent -

Vcol For seismic design, beam yielding defines demands

Beam

wMpr

Mpr

Vp

Mpr

Vp

lc

defines demands

Beam Section

lnbVp

VpVp

MprVcol

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Joint demands C2 = Ts2

Ts1 = 1.25Asfy

Vcol

Vb1 Vb2

(b) internal stress resultants acting on joint

Ts2 =1.25Asfy

C1 = Ts2

Vcol

Vcol

(a) moments, shears, axial loads acting on joint

(c) joint shear

Ts1 C2

Vu =Vj = Ts1 + C1 - Vcol

Joint shear strength

γ = 20 γ = 20γ = 20

hbfVV jcnu'φγφ ==

d) RoofInterior B.1

e) Roof Exterior B.2

f) RoofCorner B.3

ACI 352

φ = 0.85

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Joint Details - Interior

hcol ≥ 20db

ACI 352

Joint Details - Corner≥ ldh

ACI 352

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Code-conforming joints

Joint failures

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Joint Design-ACI Requirements

Joint Design-ACI Requirements

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Joint Design-ACI Requirements

Joint Design-ACI Requirements

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Joint Design-ACI Requirements

Joint Design-ACI Requirements

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Joint Design-ACI Requirements

Column Transverse Reinf. Design

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Column Transverse Reinf. Design

Column Transverse Reinf. Design

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Column Transverse Reinf. Design

Column Transverse Reinf. Design

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Column Transverse Reinf. Design

Column Transverse Reinf. Design