Seismic Design of Steel Structures: North ... - ICHA.clicha.cl/wp-content/uploads/2014/03/icha_presentacion_robert... · Seismic Design of Steel Structures: North American Practice

1

Robert TremblayÉcole Polytechnique de Montréal

Colegio de IngenierosSantiago, ChileMarch 18, 2014

Seismic Design of Steel Structures: North American Practice &

Challenges for Industrial Buildings

R. Tremblay, Polytechnique Montreal, Canada 2

2


RASCE/SEI 7-10

3-1/468

3-1/24-1/2

87


3



4

• Ductile seismic design

• Braced frame systems

– Concentrically braced frames

– Eccentrically braced frames 341-10

– Buckling restrained braced frames

• Moment frames and plate wall systems

• Heavy industrial buildings: challenges

Plan


Ductile Seismic Design

h

h

W

T = 0.38 s5% damping

Elastic

0.0 10.0 20.0 30.0 40.0

Time (s)

-0.5

0.0

0.5

ag (g)

-1.0

0.0

1.0

/ h (%)

Horizontal 90 deg.

0.0126 h-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

V / W

1.28 W

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

/ h (%)

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

V /

W


5

Take advantage of thehigh ductility of steel

F

F

Fracture,instability,etc.

Ductileresponse

y

u


0.0 10.0 20.0 30.0 40.0

Time (s)

-0.5

0.0

0.5

ag (g)

-1.0

0.0

1.0

/ h (%)

Horizontal 90 deg.

0.0126 h-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

V / W

1.28 W

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

/ h (%)

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

V /

W

-1.0

0.0

1.0

/ h (%)

-0.017 h

-1.0

-0.5

0.0

0.5

1.0

V / W

0.33 W

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

/ h (%)

-1.0

-0.5

0.0

0.5

1.0

V /

W

h

h

h

W


Vy = 0.25 W

Elastic


6

-0.06 -0.04 -0.02 0.00 0.02 0.04 0.06

Plastic Rotation (rad.)

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

M /

Mp

r

M. Englehardt Ecole Polytechnique of Montreal, 1996

Ecole Polytechnique of Montreal, 1996


-8 -4 0 4 8

/ y

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

P / Py

HSS 102x76x6.4 - KL/r = 112

Tensionyielding (typ.)

Inelastic bucklingwith plastic hinge (typ.)

P

PPlasticHinge

+

-

+


7

h

h

W


Vy = 0.25 W

0.0 10.0 20.0 30.0 40.0

Time (s)

-0.5

0.0

0.5

ag (g)

-1.0

0.0

1.0

/ h (%)

Horizontal 90 deg.

0.018 h-0.4

-0.2

0.0

0.2

0.4

V / W

-0.36 W -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

/ h (%)

-0.4

-0.2

0.0

0.2

0.4

V /

W

-1.0

0.0

1.0

/ h (%)

-0.017 h

-0.4

-0.2

0.0

0.2

0.4

V / W

0.33 W

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

/ h (%)

-0.4

-0.2

0.0

0.2

0.4

V /

W

h

Vy = 0.25 W


Effects of Magnitude and Distance

0.0 0.5 1.0 1.5 2.0 2.5 3.0Period, T (s)

0.0

0.5

1.0

1.5

2.0

2.5

Sa

(g) M 7.0-7.5

10-20 km

0.0 0.5 1.0 1.5 2.0 2.5 3.0Period, T (s)

0.0

0.5

1.0

1.5

Sa

(g)

M 7.0-7.530-50 km

0.0 0.5 1.0 1.5 2.0 2.5 3.0Period, T (s)

0.0

0.4

0.8

1.2

1.6

2.0

Sa

(g) M 6.5-7.0

10-20 km

0.0 0.5 1.0 1.5 2.0 2.5 3.0Period, T (s)

0.0

0.5

1.0

Sa (

g)

M 6.5-7.030-50 km

0.0 0.5 1.0 1.5 2.0 2.5 3.0Period, T (s)

0.0

0.5

1.0

Sa

(g)

M 6.5-7.070-100 km

0.0 0.5 1.0 1.5 2.0 2.5 3.0Period, T (s)

0.0

0.5

1.0

Sa

(g) M 6.0-6.5

30-50 km

Earthquakes in California Site Class B – 5% damping


8

0.0 0.5 1.0 1.5 2.0 2.5 3.0Period, T (s)

0.0

0.4

0.8

1.2

1.6

2.0

Sa (

g)

Los Angeles AreaSite Class B

M6.0 - M7.5Dist. = 10-100 km

0.0 0.5 1.0 1.5 2.0 2.5 3.0Period, T (s)

0.0

0.4

0.8

1.2

1.6

Sa (

g),

Cs

Los Angeles AreaSite Class B

Sa (Elastic)

Cs (OCBF - R = 6.0)

x 1/R

Design Spectra

& Design for Inelastic Response



9


Ve

RV =

Perimetermembers

RoofDiaphragm

Braceconnections

Bracingmembers

Anchor rods

Foundations

V V

Capacity Design ProcedurePoutrelle(typ.) Poutre de toit

(typ.)

Poteau(typ.)

Feuille de tablier métall ique

typ.)

Contreventement (typ.)


10

Grav.

Grav.

C

C'T

u

uy

Grav.

E

> E

> E

Grav.

Grav.

Grav.

Column designed for gravity plus expected brace tensilestrength

Gusset plates designed incompression for the expectedbrace compressive strength

2. Design other elements :

1. Select Braces:

Design for gravity + ECheck KL/r, b/t, etc. for ductile response

Gusset plate designed in tensionfor the expected brace tensilestrength

Two-Step “Capacity Design” Procedure:


Plastic Hinge (typ.)

Shearyielding


Tensionyielding

Plastic HingeTension

yielding

Tensionyielding

Compressionyielding e


Plastic Hinge

End-plateBending

Shearyielding

Ductile Seismic Force Resisting Systems


11

AISC 360-10

ASCE 7-10

AISC 341-10


NBCC 2010

CSA S16-09


12

Building code main objective is to protect life and prevent structural collapse under ground motions

In view of high level of ground motion considered (2% in 50 years) and the difficulty in predicting ground motions and their effects on structures …

… ductile seismic design represents an effective strategy to achieve code objectives by controlling the system response and force demand.


Control ofLocal Buckling


13

Expected (probable)material strength

Liu, J. et al. (2007). AISC Eng.


Concentrically Braced Frames (SCBFs)

Energy dissipated in bracing members through tensile yielding and flexural hinging

Connections and other members expected to remain essentially elastic

Tensionyielding (typ.)

Inelastic bucklingwith plastic hinge (typ.)


14



15



16

Rehabilitation


Kobe 1995


17


Northridge 1994Photos from Peter Maranian, Brandow and Associates (P. Uriz Thesis, 2005)


18

Uriz and Mahin (2004) Univ. of California, Berkeley

Fracture in1st cycle at1 ≅ 2% hs

1

2


-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

/ LH (%)

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

P /

AgF

y

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 / hs (%)

HSS 254 x 254 x 12

b/t = 18, KL/r = 42


19



20


-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

/ LH (%)

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

P /

Py

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 / hs (%)

RHS-4KL/r = 40b0/t = 17

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

/ LH (%)

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 / hs (%)

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

/ LH (%)

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 / hs (%)

RHS-2KL/r = 40b0/t = 13

RHS-19KL/r = 60b0/t = 13

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

/ LH (%)

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

P /

Py

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 / hs (%)

CHS-1KL/r = 42b0/t = 30

-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

/ LH (%)

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 / hs (%)

-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

/ LH (%)

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

-4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 / hs (%)

CHS-2KL/r = 62b0/t = 31

W-6KL/r = 67b0/t = 5.9


21

0.0 0.5 1.0 1.5 2.0 2.5

Brace Slenderness, = (Fy / Fe)0.5

0

5

10

15

20

25

Du

cti

lity

at F

ract

ure

, f

f = 2.4 + 8.3

y

-6 -4 -2 0 2 4 6

-10 -8 -6 -4 -2 0 2 4 6 8 10

.

KL/r = 93HSS 127x76x4.8

KL/r = 142HSS 76x76x4.8

f f

yy

-6 -4 -2 0 2 4 6

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

P /

AgF

y

KL/r = 42HSS 254x254x12

f



22


W4

W6

W4 W6‐6000

‐4000

‐2000

0

2000

4000

6000

‐3 ‐2 ‐1 0 1 2 3

Interstorey Drift Angle (%)

P (kN)


23

Design – Bracing Configuration

• Along any braced line, between 30% & 70% of lateral load is resisted by tension braces

• Tension-only braced frames not permitted

• K-bracing not permitted


R. Tremblay, École Polytechnique of Montreal & D. Mitchell, McGill University 46

24

Design – Bracing Members

• Braces must resist gravity + lateral loads

• Pn in tension and compression as per AISC 360-10

• KL/r < 200

• Section must meet seismic hd limits

• For built-up sections, individual components must meet KL/r limits and stitch subjected to shear under buckling must meet minimum shear strength


L

L

H

N

KLout ≈ 0.9 LH

KLin ≈ 0.5 LN

KLout ≈ 0.5 LH

KLin ≈ 0.5 LN


25


Bracing Configuration

Tension-only braced frames permitted

Bracing Members

Section must meets b/t limits that vary with KL/r

C’exp

Cexp


Design – Expected Brace Strengths

P/P

y

Texp

26


0.0 0.5 1.0 1.5 2.0 2.5

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Cu

/ A

gF

y

Cu (S16-01, n = 1.34)

Cu (AISC 1999)

0 50 100 150 200

KL/r

0.0 0.5 1.0 1.5 2.0 2.5

0.0

0.2

0.4

0.6

0.8

1.0

C' u

/ A

gF

y (

Du

cti

lity

= 1

.0)

Cu (S16-01, n = 1.34)

0 50 100 150 200

KL/r

0.0 0.5 1.0 1.5 2.0 2.5

0.0

0.2

0.4

0.6

0.8

1.0

C' u

/ A

gF

y (

Du

cti

ly =

3.0

)

Cu (S16-01, n = 1.34)

C'u (mean)

0.0 0.5 1.0 1.5 2.0 2.5

0.0

0.2

0.4

0.6

0.8

1.0

C' u

/ A

gF

y (

Du

ctil

ity

= 5

.0)

Cu (S16-01, n = 1.34)

C'u (mean)


Texp = A RyFy

Cexp = A (1.12 Fcr) where Fcre = Fcr with RyFy

< A RyFy

C’exp = 0.3 Cexp

C’exp

Cexp

Texp

27

Texp = A RyFy

Cexp = A (1.12 Fcr) ,Fcre = Fcr with RyFy

< A RyFy

C’exp = 0.3 Cexp


Schimdt and Bratlett (2002)


28


Design – Brace Connection

Must resist brace Texp & 1.1 Cexp

Must allow for ductile rotational behavior or resist 1.1 x brace expected flexural strength


29

Kobe 1995

Archambault et al. (1995)Tremblay and Bolduc (2002)

École Polytechnique,Montreal


Yang and Mahin (2004) Univ. of California, Berkeley


30



31


Kobe1995


32

Sabelli (2003) Sabelli (2005)

Sabelli (2003)


Prototype Test Specimen

Attachment to

load frame:

LW

LW

LC-C

LTS

2 t2 t

g

g

Gussetplate

Gussetplate

35O

Coverplate

Coverplate

518

2 (

min

) @

79

37

(max

)

102

290

35O

Elevation

Specimen

End Restraint

Side View

End

Hinge


33



Design – Columns and Beams

Must resist gravity loads plus two brace force scenarios:

• Upon first buckling & yielding (Texp & Cexp)• In post-buckling range (Texp & C’exp)

Beams in V and inverted-V bracing must be continuous between columns

Column sections must meet hd

Beam sections must meet md

34


At Buckling Post-Buckling

T T

T T

T T C’C

C’C

C’Cexp,1 exp,1

exp,2 exp,2

exp,3 exp,3 exp,3exp,3

exp,2exp,2

exp,1exp,1

F3 F3F3

F2 F2F2

F1 F1F1

W W WW W WW W W

Brace force scenarios for columns:

Northridge 1994Photos from Finley 1999(P. Uriz Thesis, 2005)


35

Taiwan 1999



36



F F

F F

F FL,x L,x

L,x L,x

R,x R,x

FR,x

FR,x

C C’

C C’

C C’

C C’

T T

T T

T T

T T

exp,x+1 exp,x+1

exp,x+1 exp,x+1

exp,x exp,x

exp,x exp,x

exp,x+1 exp,x+1

exp,x+1 exp,x+1

exp,x exp,x

exp,x exp,x

1.2 w + 1.0 w 1.2 w + 1.0 w

1.2 w + 1.0 w 1.2 w + 1.0 w

D D

D D

L L

L L

Brace force scenarios for beams:

Note: Redundancy factor, ,and seismic load effectswith overstrength factor, 0,as specified in ASCE 7-10are not considered.


SCBF

5500

EBF BRBF

2 @ 4000= 8000

[mm]ELEVATIONS

MR

F (

typ

.)

BF (typ.)

5 @ 9000 = 45 000

[mm]PLAN

300(slab edge)

5 @

90

00

= 4

5 0

00

Gravity loads: Roof: Dead = 3.2 kPa Live = 1.0 kPa Floor: Dead = 3.5 kPa Partitions = 1.0 kPa Live = 3.8 kPa Exterior walls = 1.5 kPa

Seismic Load Data (NCh433): Zone 2 Soil Type C A= 0.30 g In-plane torsion omitted

Load Combinations: 1.2D + 1.6L 1.2D + 1.0L + 1.4E 0.9D + 1.4E

Seismic weight: P = 7720 kN (Level 9) 12635 kN (Levels 2-8) 12840 kN (Level 1)

Steel: BRB cores: Fyc = 260-290 MPa Other members: Fy = 345 MPa

37



Static method of analysis

38


Brace Design


At Buckling

Column Design

1103

4890

4092 47492492

7916 7916

25914437

+ 1.2 x 644 (D)+ 1.0 x 372 (L)= 5893

-0.9 x 644 (D)= 1913

1103

4092

2001 4890

29072907

70077007

599

169 169169

599599 599

1692001

39


Post-Buckling

Column Design

1103

4890

1227 5136662

6085 6086

7774437

+ 1.2 x 644 (D)+ 1.0 x 372 (L)= 6280

-0.9 x 644 (D)= 82

331

1227

600 4890

29072907

70077007

856

812 812812

856856 856

812600



Beam Design

1103 331

4092 1227

2001 600

2001 600

1103 331

1498 1210

939 556

1498 1210

939 556

1077 842

2907 2907

7007 7007

4890 4890

4890 4890

2907 2907

-1498 -1210

-939 -556

-2800 -2565

M = 243 M = 243

M = 759 M = 3896

M = 2785 M = 3939

1498 1210

939 556

1077 842

1.2 w + 1.0 w = 8.71

1.2 w + 1.0 w = 24.0

1.2 w + 1.0 w = 24.0

1.2 w + 1.0 w = 8.71

1.2 w + 1.0 w = 24.0

1.2 w + 1.0 w = 24.0

D

D

D

u u

u u

u u

D

D

D

L

L

L

L

L

L

[kN,m]

40

Consider more realistic brace KL

9000

O41.6

W610 Beam

Bolted EndPlate Connection

750 +

/-

4500

+/-60

21

Hinge

4000


Brace sizes are reduced, increasing T*, reducing seismic loads …

T* = 0.55 s -> 0.65 sC = 0.119 -> 0.093 (22% decrease in seismic loads)


41


SCBF

5500

2 @ 4000= 8000

Eccentrically Braced Frames


Energy is dissipated through shear or flexurein link beams

Connections and other members (including beams outside links) expected to remain essentially elastic


Shearyielding

e

42


Filiatrault et al.

Residential buildingsMontrealMartoni Cyr


43

Hockey Canadian, MontrealR. Tremblay, Polytechnique Montreal, Canada 85

Wellington, New-Zealand 2013


44

Built-up rectangular tubular link beams

Contreventement non requispour le segment ductile !

Berman, J.W, and Bruneau, M. 2008. Tubular Links for Eccentrically Braced Frames I: Finite Element Parametric Study. ASCE J. Struct. Eng., Vol. 134, No. 5, pp. 692-701.


Takanashi &Roeder1976 Roeder

1977

Kasai1986

Malley1983

Engelhardt1989

Ricles1987

System originally developed by Prof. Povov with …

+ othersR. Tremblay, Polytechnique Montreal, Canada 88

45



• Symmetrical• Pf ≅ 0 in ductile links• Pinned beam-to-column joints

• Shorter beam spans• Good clearance

Rigidconnection(typ.)

Pinned connection(typ.)

e

e

= L/ep

= L/ep

p

p

L

L

L

e

L

M

MVV

V

V = 2 M / e

M


Design – Link BeamsResistance can be governed by shear (short links) or flexure (long links). Resistances affected by axial load:

Section must meet hd (md for flanges if e < 1.6 Mp/Vp )

e > d; upper limit on e applies in presence of axial load

Must meet limits on plastic rotation (p): from 0.02 rad for e < 1.6 Mp/Vp to 0.08 rad for e > 2.6 Mp/Vp

Need for end and intermediate stiffeners; depend on yielding mechanism & p

46


For center links (M = 0 at e/2):

e/2 e/2

M

M

V

V

M

L

L

L

L

L

For shear yielding: Vn = Vp

For flexural yielding: Vn = 2 Mp/e

e

Shorter links generally preferred:

• Higher lateral frame stiffness• Higher energy dissipation capacity• Less stringent (md for flanges)• Easier to design beams outside links

hp

s

= L/ep p ph

p

s

= L/e

p

p p


47


Design – Adjusted link shear strength

Vadj = 1.25 RyVn (I-shaped links)= 1.40 RyVn (built-up tubular links)

May be multiplied by 0.88 for beams outside links and for columns in structures more than 3 storeys



Must resist gravity loads plus Vadj

Column sections must meet hd. Beam outside links and braces must meet md section requirements

e/2e/2 L/2- /2e

adj

adj

adj

adj

adj

beam

beam

beam

brace

col

L/2

V

V

V

V

V

P

V

M

P

P

48



Must resist gravity loads plus Vadj

Column sections must meet hd. Beam outside links and braces must meet md section requirements

e/2e/2 L/2- /2e

adj

adj

adj

adj

adj

beam

beam

beam

brace

col

L/2

V

V

V

V

V

P

V

M

P

P

SCBF

5500

EBF BRBF

8 @

4

00

0 =

32

00

0

[mm]ELEVATIONS

MR

F (

typ

.)

BF (typ.)

5 @ 9000 = 45 000

[mm]PLAN

300(slab edge)

5 @

90

00

= 4

5 0

00

Gravity loads: Roof: Dead = 3.2 kPa Live = 1.0 kPa Floor: Dead = 3.5 kPa Partitions = 1.0 kPa Live = 3.8 kPa Exterior walls = 1.5 kPa

Seismic Load Data (NCh433): Zone 2 Soil Type C A= 0.30 g In-plane torsion omitted

Load Combinations: 1.2D + 1.6L 1.2D + 1.0L + 1.4E 0.9D + 1.4E

Seismic weight: P = 7720 kN (Level 9) 12635 kN (Levels 2-8) 12840 kN (Level 1)

Steel: BRB cores: Fyc = 260-290 MPa Other members: Fy = 345 MPa


49

EBFs – Modular Linkswith N. Mansour & C. Christopoulos, Univ. of Toronto



50



51


102

52

Repair using Self-compacting concrete(Sikacrete-08 SCC)Repair of main transverse surface

cracks using Low-viscosity injection resin (Sikadur 52)



53

Comparisons for cycles at 0.08 rad.:

(¼’’ reinforcement plates)(3/16’’ reinforcement plates)



54

Buckling Restrained Braced Frames

Energy dissipated in bracing members through tensile and compression axial yielding


P

P

PP

P

Cross-Section

SteelCore

MortarFill

SteelTube

UnbondingMaterial


Wakabayashi et al. (1973)

Watanabe et al. (1988)


55

École Polytechnique 1998 Québec City (1999)

Buckling Restrained Braced Frames

-4.0 -2.0 0.0 2.0 4.0-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

V /

V

/

y

y



56

Québec City (1999)

Vancouver (RJC)

Montreal (Canam)


0 5 10 15 20 25Time (s)

-0.2

0.0

0.2

Ac

cel.

(g)

-0.8-0.40.00.40.8

R

oo

f / h

n

-0.8-0.40.00.40.8

R

oo

f / h

n

-0.8-0.40.00.40.8

R

oo

f / h

n

-20000

-10000

0

10000

20000

V B

ase

(k

N)

-20000

-10000

0

10000

20000

V B

as

e (

kN

)

-1.0 0.0 1.0

1/ hs (%)

-20000

-10000

0

10000

20000

V B

as

e (

kN

)

BRB-L

CBF

BRB-L

CBF

.

BRB-S

BRB-S


57

PP

L

EI , d

a Core

Concrete Fill r r

0

PPGap

PP

Global buckling:

Local (core) buckling:


-10 -8 -6 -4 -2 0 2 4 6 8 10

y

-2.0

-1.0

0.0

1.0

2.0

V/V

y

All-steel BRBs


58


Eryasar & Topkaya 2010Usami et al. 2008


59



60



61

http://www.corebrace.com/

http://www.starseismic.net/

http://www.unbondedbrace.com/

Specialized suppliers (U.S.)


No special requirements (BRB have nearly symmetrical response)

May be controlled by drift limit or available BRB capacities



62

Select Ac:

BRB assumed not resist gravity loads=> required axial strength from lateral loads only

Pn = AcFyc (compression & tension) with = 0.9

Notes: use lower bound for Fyc

round-off Ac

Verify availability of BRB and test data

Determine stiffness factor KF for analysis

= KBrace / (EAc/Lc/c)

Design – BRB members


9000

O41.64500

+/-

6021

L

L

c/c

c

4000


63

Two cyclic tests: individual BRB + sub-assemblage

Specimen Pysc within 50-120% of prototype

Specimen design, fabrication and quality control as for prototype

Test displacements based on design storey drift bm

Tests used to demonstrate performance of the member and connections and to provide design data

Qualification tests of BRBs:


Adjusted (max) brace strengths from tests:

Tadj = AcFyc

Cadj = AcFyc

with and from C and T at the maximum testdeformations

Note: use upper bound for Fyc

Design – BRB adjusted axial strength

-8.0 -4.0 0.0 4.0 8.0 y

-2.0

-1.0

0.0

1.0

2.0

P/P

y

Tmax

Cmax


64

Must resist gravity loads plus forces induced when the braces reach their adjusted strengths

Section must meet hd (md for flanges if e < 1.6 Mp/Vp )



C

C

C

C

T C

adj

adj

adj

adj

adj adj

Beam Design

Column Design

ChevronBRB

F

F

C

C

T

T

F

F

L,x

L,x

R,x

R,x

C

C

C

C

T

T

T

T

and

adjx+1

adjx+1

adj,x

adj,x

adj,x

adj,x

u

u

u

u

adj,x

adj,x

0.9 w

1.2 w + 1.6 w

D

D L


65

• At design stage, verify:

– Range of Fyc

– Strength factors &

– Stiffness factors KF

– Py range for which test data is available

• On drawings, specify:

– Minimum Py (or Ac & Fyc), with tolerances

– Factors , and KF

– Req’d test brace axial deformations

Communication with BRB suppliers


Fyc = 260-290 MPaKF = 1.5

R = 6.0 (as EBF)T = 0.99 sQ0 = 871 kN / Frame

BRBF


66

BRBFSCBF


Moment Resisting Frames

Energy dissipated by plastic hinging in beams and limited shear yielding in column panel zones. Plastic hinging in columns permitted at the base and in single-storey structures.



67

Section must meet hd

Must resist expected shear demand upon hinging

Must be laterally braced

Design – Beams

L'

L

L' = L - 2 x - d c

w

pb

1.1 R My pb

1.1 R My pb

V = wL' / 2 + 2.2 R M / L'h y pb

Vh Vh


Section must meet hd

Must satisfy “weak beam-strong column” criteriaexcept for:

Columns with Puc < 0.3 AcFy in single-storey buildings or at the top storey of multi-storey buildings;

Columns with Puc < 0.3 AcFy when their total shear contribution < 20% of total storey shear resistance and 33% of storey shear resistance along their MF line; or

Columns that have shear capacity to demand ratio 50% gretaer than in the storey above.

Design – Columns


68

L'

L

L' = L - 2 x - d c x + d /2c x + d /2c

w

w w

1.1 R My pb

1.1 R My pb

1.1 R My pb

1.1 R My pb

V = wL' / 2 + 2.2 R M / L'h y pb

Vh Vh

Vh

Vh

M'rc, i+1

M'rc, i

Cf, i

Cf, i+1

“Weak beam-strong column” criteria:

M*: projected at membercenter lines


x + d /2c x + d /2c

1.1 R My pb

1.1 R My pb Vh

Vh

V

V

Must meet: t > (dz + wz)/90

Shear strength, Rn:

Design – Column panel zone


69

L/2

V

L/2

h /2s

h /2s

Design – Beam-to-column connections

Must accommodate 4% storey drift angle

Measured flexural resistance at column face at 4% storey drift angle > 80% Mpb

Performance considered as demonstrated if pre-qualified connections are used; otherwise must be demonstrated through physical cyclic testing


http://www.aisc.org

• Design requirements

• Welding requirements

• Bolting requirements

• Requirements for 6pre-qualified connections


70

Welded Unreinforced Flange

Welded Web

Bolted End Plate

Kaiser Bolted Bracket

Bolted Flange PlateReduced Beam Section

Conxtech Conxl



71

MRF

Example



72

At Level 1:

M*pb = 656 + 738 = 1394 kN-m



73


Steel Plate Shear Walls

Energy dissipated through web plate (infill panel) yielding and plastic hinging in beams and at the base of columns



74

ING St-HyacintheQuirion Metal


Louis Crépeault Groupe Technika R. Tremblay, Polytechnique Montreal, Canada 148

75

University of Alberta (1997)


Work by Bruneau, Tsai et al.

-5000

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

5000

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3

Interstory Drift (%)

Ba

se S

hea

r F

orc

e (k

N)

-5000

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

5000

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3

Interstory Drift (%)

2F

Sh

ea

r F

orc

e (

kN

)


76

MF + web plate

V

+ ==

mf

wV

V

Distribution of Vx from analysis

Infill panel designed for 100% Vx

Beams Mpb such that VMF = 2 Mpb/hs > 0.25 Vx


Design of web plate


77

M' M'

M'

V

V

V

C C F

C

q

h

h

i

i+1 i

w,i yi2 2

i+1

i

i+1

ipb,i

pb,i

pb,i

b,ib,i

r,i

br,i

br,i

c

c

b,i

bl,i

b,i

L - 2 x - d

x + d /2

C (T h sin ) (T h sin ) ] = [ + / 2

T = t F

(T sin )(T cos )

(T cos ) (T sin )

i+1i+1

i i

L

Design of beams (HBE)and columns (VBE)


Beam-to-Column Connections

M'

M'

Beam

V

V

PP

q

i

i+1

i

pbr,i

pbl,i

br,i

br,i

c

bl,i

bl,i

L - 2 x - d

i+1

i

Columns:Class 1, W Shapes

Beams:Class 1 or 2

CP groove weldsBacking bar removedRun-off tabs removedReinforcing fillet weldsTr = 60% Tr in Cl. 21.3

Type LD MRF


78

Corner cut-outs

Vian, D. and Bruneau, M. 2004. Testing of Special LYS Steel Plate Shear walls. Proc. 13th WCEE,

Vancouver, BC. Paper No. 978.

Purba, R. and Bruneau, M. 2007. Design Recommendations for Perforated Steel Plate Shear Walls. Report MCEER-07-0011, SUNY Buffalo, NY.


Berman, J.W. and Bruneau, M. 2005. Experimental Investigation of Light-Gauge Steel Plate ShearWalls. ASCE J. of Struct. Eng., 131, 2, 259-267.

Optimization of infill plates

Use of thin infill plates

0.9 mm thick ASTM A1008 (cold-rolled, carbon, commercial steel sheet)


79

Perforated infill plates

Vian, D. and Bruneau, M. 2004. Testing of Special LYS Steel Plate Shear walls. Proc. 13th WCEE,

Vancouver, BC. Paper No. 978.

Purba, R. and Bruneau, M. 2007. Design Recommendations for Perforated Steel Plate Shear Walls. Report MCEER-07-0011, SUNY Buffalo, NY.


Perforation(typ.)

V

D

* D * D + 0.7 S< <

D / S > 0.6

diag

diag

*

V> 4 rows

iL

> 4 rows

4545oo

diag

diag

S

S


80



81


Warning!

Only basic design requirements have been discussed; several other requirements must be applied including those related to loads and load combinations, demand critical welds, protected zones, bracing, quality control, etc.

Only the systems designed and detailed for high ductility have been introduced; provisions also exist for other systems exhibiting moderate and limited ductility that may be more appropriate for some applications.

R. Tremblay, Polytechnique Montreal 162

82

Bruneau, M., Sabelli, R., and Uang C.-M. (2003) Ductile Design of Steel Structures, 2nd

ed., Wiley

AISC. (2013) Seismic Design Manual, 2nd ed., AISC

Filiatrault, A., Tremblay, R., Christopoulos, C., Foltz, B., and Pettinga, D. (2013)Elements of Earthquake Engineering and Structural Dynamics, 3rd ed.,Presses Internationales Polytechnique (PIP)

R. Tremblay, Polytechnique Montreal 163


83


Seismic Design of Heavy Industrial Buildings : Challenges


84

• Structures are not buildings:– Irregular structures with heavy point masses and loads

and low damping

– Design is process driven and structure will likely be modified to accommodate changes to the process

– Equipment may interact with the structure

– …

• Structures may have limited redundancy

• Damage under severe earthquakes must be limited:

– Structures may contain hazardous material

– No or short downtimes

• Application of ductile seismic systems not practical, often impossible

• Current building code provisions not suitable

Observations / Issues:


1. Simple code provisions to control inelastic demand: low R factors , use of dynamic analysis, etc.

2. Use of ductile anchorage systems with minimum stretch lengths in combination with shear keys

3. Use ductile fuses in key structural elements to control the force demand

4. Where applicable, use sliding or rocking systems to control input

Possible avenues:

Above avenues are listed in order of ease of implementation implementation and flexibility for future process changes;

however, the latest ones could be more effective

Ductility (or alternative similar approach) needed to accommodate uncertainty in ground motions and seismic response


85

In Canada, industrial structures are buildings and National Building Code (NBCC) applies.

New Annex proposed for inclusion in CSA S16-14 and which would be referenced in NBCC 2015:


1. Demand prediction from RS analysis

2. Use/design of ductile anchorage

3. Ductile structural fuses

4. Multi-tiered braced frames

Recent related research work:


86

Demand Prediction from RS Analysis


• Plan dimensions: 36 m x 60 m x 40 m

• Heavy equipment, including 1200t & 750t tanks

• Irregularities in mass and stiffness

• Montreal Site Class C

• Static, Response Spectrum & Linear response history analyses


87

Structure has a large number of contributing modes


0

20

40

60

80

100

120

140

Dis

pla

cem

ent (

mm

)

Level

STAT-CNBCSTAT-ASCESPECTRALETH-MÉDIANETH-84e CEN


88

Use & Design of Ductile Anchors

22 4

00

16 8

00

5600

25 000 1675 1675

2 x 40t cranes

3 sites: Montreal, Vancouver & Seattle

Seismic force demand from linear response history analysis

Ductile anchors at column bases


-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2

Strength ( = 1)

Strength ( = -1)

Stability ( = 1)

Stability ( = -1)

P/RyPy

M/RyMp


89

Elastic time history analysis

0.71

%

0.70

%

0.67

%

0.87

%

0.67

%

0.66

%

0.63

%

0.81

%

0.0%

0.2%

0.4%

0.6%

0.8%

1.0%

STAT SPEC TH-MedTH-84th

c/h

,

r/h (%

)

Analysis method

Crane levelRoof level

0.44

0.37

0.51

0.42

0.42

0.52

0.0

0.2

0.4

0.6

STAT SPEC TH-Med TH-84th

Acc

eler

atio

n (g

)

Analysis method


n.a. 120%

121%

115%

149%

107%

106%

102%

120%

0%

50%

100%

150%


Stre

ss R

atio

(%)

Analysis method

Ext. base col.

Top column

Seattle (Site Class D)

0.46

0.44

0.57

0.53

0.52

0.72

0.0

0.2

0.4

0.6

0.8


Acc

eler

atio

n (g

)

Analysis method

)


n.a.1.00

%

0.88

%

0.78

%

1.01

%

0.91

%

0.79

%

0.70

%

0.93

%

0.0%

0.2%

0.4%

0.6%

0.8%

1.0%

1.2%

STAT SPEC TH-MedTH-84th

c/h

,

r/h (%

)

Analysis method

)


Vancouver (Site Class C)

160%

142%

115%

156%

94%

86%

76%

93%

0%

50%

100%

150%

200%


Stre

ss R

atio

(%)

Analysis method

)

Ext. base col.

Top column


Ductile anchorage at column bases

total = e + i

e = total/Ri = total/(1 ‐ R)

e i

total = e + i

e = total/Ri = total/(1 ‐ R)i = x H/h

= i x h/H

L = / = /0.03

H

h

e i

,

verticalfuse

sh y fuse

FA

R F


90

Anchor rodSpring for stability of analysis

1

2 3

4

5

6

7 8

Inelastic time history analysis



91

1.40%

1.56%

1.14%

1.77%

1.24%

1.38%

1.14%

1.77%

0.0%

0.5%

1.0%

1.5%

2.0%

TH-MÉD TH-84e CEN TH-MÉD TH-84e CEN

c/h

, r

/h (

%)


With anchor yielding

Without anchor yielding


NCh2369 (2003)

Is 8db or 250 mm suitable for all applications?


92


Other buildings to be examined

HeadFrame (Mining)

Chemical Industry


93

Conveyor Towers

Pipe Racks


Tank Supporting Structures


94

Ductile

Structural

Fuses


-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0

/ h (%)

-0.5

0.0

0.5

1.0

1.5

V /

Vy

Brace Fuse Test 3CTWithout Fuse

With Fuse

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0

/ h (%)

-0.5

0.0

0.5

1.0

1.5

V /

Vy


With Fuse

HS 102x102x4.8

280

200

200

40(typ.)

25.4 bolts@ 80x80 (typ.)

133

133271

64 hole(4 sides)

64 x 335 slotted hole(4 sides)

PL 6x63x250(2 sides)1

4

3


95

Fuses forHSS braces

P

P

P

P

C

C

C

C

T

T

T

T

C

C

C

C

T

T

T

T

T

L

L

L

T

C

F

F

c

C

u

uF

u

u

u

uF

uF

u

f

f

f

f

f

f

f

f

Section A

A

Steel Core

Mortar Fill

Steel Tube

T

C

C/TC/T


0 5 10 15 20

Time (s)

-1.0

0.0

1.0

/

hn (

%)

Without Brace FusesWith Brace Fuses

-0.2

0

0.2

ag (

g)

M7.0 1989 Loma PrietaStandford Univ. 360o

-2.0 -1.0 0.0 1.0 2.0

/ y

-1.0

-0.5

0.0

0.5

1.0

P /

Tu

-1.0 -0.5 0.0 0.5 1.0

B / hn (%)

-0.5

0.0

0.5

V /

W

Without Brace Fuses

With Brace Fuses

V NBCC

V NBCC


96

L

b

Angle withreduced section

Cut inHSS

HSS brace

Bucklingrestraining box

L Lf

f

t w

Typ.

A


1000 kNDynamicactuator

3.75

m

Loadingarm

W36

0x34

7 (t

yp.)

W310x179 (typ.)

Horizontalreaction block

6.0 m

Bracestudied

Bracefuse

Frame support(typ.)

Pin(typ.)

Pin(typ.)


97

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0

/ h (%)

-0.5

0.0

0.5

1.0

1.5

V /

Vy

Brace Fuse Test 5CCWithout Fuse

With Fuse

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0

/ h (%)

-0.5

0.0

0.5

1.0

1.5

V /

Vy


With Fuse

280

280

40(typ.)

25.4 bolts@ 80x80 (typ.)

1034

Cut

BraceFuse

PL 6x63x250(2 sides)1

5-6



98


Fuses in W-Shapes (Canam Group, Montreal)


99



100


-5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0

/ hs

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

P /

AF

y

Design

Design

Cu

Tu

Test 1 - LF/LH = 0.11

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0

/ hs

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

P /

AF

y

Design

Design

Cu

Tu

Test 3 - LF/LH = 0.07


101

Multi-Tiered Braced Frames


= 6.8

= 1.6

= 4.2

0.0 5.0 10.0 15.0 20.0Time (s)

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

Dri

ft (

% h

n)

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

Dri

ft (

% h

n)

Drift at h = 10.0 mDrift at h = 6.8 m

-1.0

-0.5

0.0

0.5

1.0

Ac

cel.

(g)

X-braced CBF vs Multi-tiered CBFs


102

2-tiered CBFsDesigned in accordance with AISC 341-10SCBF – R = 6.0Los Angeles, CA - Site class D

Design Storey Drift (Cd∆/H) = 0.86% < 2%

Braces: HSS 102x102x6.4Columns: W310x174

Strut: W250x58



103

Design Storey (Cd∆)

1

2

Frame LateralDeformation

Column Shear &Bending Moment

Member Forces(axial loads in columns not shown)

u1

u2 u2

u1

1

c1c1

c2 c2

c1c1

c1c1

T

T C

C’

VV

V V

MM

M M

H

2

c1

c2

c1

H

M

M

V

V

Vc c

1

2



104

Conclusions

• Design provisions to achieve ductile seismic performance for building steel structures are now available for application in practice

• Design objective is to prevent structural collapse and structural damage & residual deformations are expected

• Some issues still need to be addressed

• Application of this design approach not suitable for heavy industrial applications; specific design provisions needed for these structures


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