performance limits for structural walls

Performance Limits for Structural Walls

P. Gülkan1 and İ. Kazaz2

1Başkent University, 06790 Ankara, Turkey2Erzurum Technical University, 25100 Erzurum, Turkey

1

Math

SkillsProblem

Solving

People

Skills

Drinking

Disorder

Heartless

Obsessive

Compulsive

Disorder

Engineer

Lawyer

Management

SalesHuman

resources

Accountant

Selecting the Right Profession Was

Never Easier

2

Institutional building near Erzincan

where an M7.9 earthquake occurred

in 1939, virtually destroying the city.3

Street scene following the M6.8

earthquake in Erzincan, 1992.

4

One of about twenty bare-frame school buildings

that were retrofitted at great cost. (Erzincan, 1992).

5

Outline

• Performance limits for structural walls

• Component (local) vs system (global) response

• Tests vs calculations

• The need for investigating full range of parameter variations

• Synthesis of analytical experiments

• Conclusions

6

Investigation of performance limits of structural walls

is required to:

Improve the limit state definitions and corresponding values

too conservative?

very generous, possibly unsafe, limits?

Examine the validity of recently adopted strain limit definitions

(TSRB* 2019) compared with conventional rotation limits (FEMA

356)

inadequate experimental verification of proposed strain limits, i.e., do

strain limits and damage states match?

Does the plane section analysis for walls work?

The gap is mainly due to

Limitations in the experimental setups and the range of variables

that dictate the outcome. Numerical experiments involving a range

of parameters may prove to be illuminating.

Accuracy of analytical procedures in predicting reinforced concrete

response under varying loading and stress conditions.* Turkish Seismic Regulation for Buildings, sometimes elevated, incorrectly, to the status of «code.» It is not. 7

Attempting to predict the real behavior of reinforced concrete systems in the

advanced inelastic range can be an experience that teaches humility.

8

(TSRB-19)

ASCE/SEI 41IO: Immediate OccupancyLS: Life SafetyCP: Collapse Prevention

TSRB-19MD: Minimum Damage LimitSL: Safety LimitCL: Collapse Limit

Eurocode 8 (EC8)DL: Damage LimitationSD: Significant DamageNC: Near Collapse

Component performance levels for flexural members

(TSRB-19)

(TSRB-19)

No unanimity in designation of limit states. No change between TSRB (2007) and (2019).

9

Plastic rotation limits for shear wall members controlled by

flexure in ASCE/SEI 41

Acceptable Plastic Hinge

Rotation (radians)

Performance Level

IO LS CP

Shear walls and wall segments

'

')(

cww

yss

flt

PfAA '

cww flt

ForceShear Confined

boundary

≤ 0.10 ≤ 0.25 (3)* Yes 0.005 0.010 0.015

≤ 0.10 ≥ 0.50 (6)* Yes 0.004 0.008 0.010

≥ 0.25 ≤ 0.25 (3)* Yes 0.003 0.006 0.009

≥ 0.25 ≥ 0.50 (6)* Yes 0.0015 0.003 0.005

≤ 0.10 ≤ 0.25 (3)* No 0.002 0.004 0.008

≤ 0.10 ≥ 0.50 (6)* No 0.002 0.004 0.006

≥ 0.25 ≤ 0.25 (3)* No 0.001 0.002 0.003

≥ 0.25 ≥ 0.50 (6)* No 0.001 0.001 0.002

*The values in parentheses are in psi

10

0.225 0.35'

100v1 max(0.01; )0.016 0.3 25 1.25

max(0.01; )

ywsx

c d

f

fv

um c

el

Lf

h

0.3 0.35'

1000.2 v1 max(0.01; )0.0145 0.25 25 1.275

max(0.01; )

ywsx

c d

f

fpl v

um c

el

Lf

h

Eurocode 8:

0.002 1 0.125 0.133

b yv vy y y

v c

d fL z h

L f

• Limit State of Damage Limitation (DL):

• Limit State of Near Collapse (NC):

Total chord rotation:

Plastic component:

Regressed equations aren’t all

seeing.

11

Turkish Seismic Regulation for Buildings (TSRB, 2019) limit states

Concrete and steel strain limits at the fibers of a cross section for

minimum damage limit (MD, implying Immediate Occupancy) are given as

(εcu)MD = 0.0025 ; (εs)MD = 0.0075

Concrete and steel strain limits at the fibers of a cross section for safety

limit (SL, limited damage, or controlled damage) are

(εcg)SL = 0.75 (εcg)CL ; (εs)SL = 0.75 (εs)CL

and for collapse limit (CL newly collapse prevention) they are specified as

(εcg)CL = 0.0035 + 0.04 √ωwe ≤ 0.018 ; (εs)CL = 0.4εsu

No explicit guidelines are provided for how these strains are

to be calculated. Section analysis?

12

The test specimen

14

•Numerical simulations of the test specimen were carried out with

ANSYS

•Two sets of models generated

3D model = 3464 elements and

6047 nodes

2D model = 1966 elements and

3728 nodes

17

Boundary conditions at the wall-table connection

Steel anchor bars were modeledwith tension only elements

Spring elements allocatedK=20000 N/mm

Filled with elastic mortar (unknownproperties)

18

Displacement

19

Pushover Curve for One Wall

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

0 5 10 15 20 25 30 35 40 45

Displacement (mm)

Ba

se

Sh

ea

r (k

N)

Pushover

Run1 Experimental

Run2 Experimental

Run3 Experimantal

Run4 Experimental

Run5 Experimental

Linear Static Analyses

Run1 Computed

Run2 Computed

Run3 Computed

Run4 Computed

Run5 Computed

pushover_1.6g

only wall

pushover_rectangular

pushover_fixed_table

20

-40

-30

-20

-10

0

10

20

30

40

50

0 5 10 15 20 25 30 35 40 45 50

Time (sec)

Dis

pla

ce

me

nt (m

m)

experiment

computed

Run1 Run2

Run3Run4

Run5

Satisfactory global results!!!

21

Top Horizontal Displacement _ Run4

-15

-10

-5

0

5

10

15

4 6 8 10 12 14 16Time (sec)

Dis

pla

ce

me

nt (m

m)

experiment

computed

Shear at Level1 _ Run4

-100

-75

-50

-25

0

25

50

75

100

4 6 8 10 12 14 16Time (sec)

Sh

ea

r F

orc

e(k

N)

experiment

computed

22

Crack pattern before Run 3

Crack pattern after Run 3

Yielding of reinforcement occurred at levels

2, 3 and 4. The trend was the same as the

experiments.

Local Results

Run3= Non-linearity initiated

23

PowerPoint Poisoning

28

Computational Tests Are Required

This would serve two purposes: (1) the range and number of parameters

would be increased, and (2) the power of our computational tools would be

assessed.

29

The parameters were

• Wall width (Lw): 3 m, 5 m and 8 m.

• Effective shear span (Lv): 5 m, 6 m, 9 m, 15 m, 24 m.

• Boundary element longitudinal reinforcement ratio (b): 0.5, 1, 2, 4%.

• Wall axial load ratio at the base (P/fc/Aw): 0.02, 0.05, 0.1, 0.15, 0.5.

• Horizontal web reinforcement ratio (sh): whatever design requires.

A parametric study was conducted.

Typical wall section:

30

Wall finite element model:

31

Material models used in the FE model:

32

Results of one of several verification examples:

33

• Static monotonic loading was applied on wall models.

• As a general rule the overall deformation capacity under a realistic

ground motion could be expected to be over 75 percent of the

deformation capacity under monotonic loading conditions (Vallenas et

al., 1979).34

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0.05

0 244 488 732 976 1220

Bir

im ş

ek

ild

eğ

işti

rme

Gövde yatay uzunluğu (mm)

Test %1 ötelenme oranı

Test %2 ötelenme oranı

SEM %1 ötelenme oranı

SEM %2 ötelenme oranı

Çekme kenarı

Kesit analizinden eşdeğer eğrilik için elde edilen birim şekildeğiştirme dağılımları

Basınç kenarıa)

-200

-150

-100

-50

0

50

100

150

200

-100 -75 -50 -25 0 25 50 75 100

Yan

al yü

k (

kN

)

Tepe noktası ötelemesi (mm)

Deneysel

ÇevrimselhesaplananMonotonikhesaplanan

Loading

-3

-2

-1

0

1

2

3

0Dri

ft (

%)

Total # of Cycles = 20

F

P

b)

Thomsen ve Wallace [31]

tarafından test edilen RW2 perde

elemanı için deneysel ve sonlu

eleman hesabı sonuçlarının

karşılaştırılması a) perde alt

noktasından itibaren 229 mm

yüksekliğinde bölge üzerinde

ölçülen ve hesaplanan birim şekil

değiştirme dağılımları, b) yük-

deformasyon eğrileri.

35

Determination of Performance limits:Performance levels-Damage states

Life Safety (LS) at ¾ of Dult

Collapse Prevention (CP) at Dult

Immediate Occupancy (IO)

at es = 0.01 or ec = 0.0035whichever occurs first

Drift ratio (%)

0 1 2 3 4 5

No

rma

lize

d S

hea

r

0.0

0.1

0.2

0.3

0.4

0.5Lw = 3m ; b = 0.01 ; M/V = 5m

P/Po = 0.02

P/Po = 0.05

P/Po = 0.10

P/Po = 0.15

P/Po = 0.25

36

Calculation of the Curvature, Plastic rotation and Strains

• The strain limits given in TSC-07 and in other documents (such as

Priestley et al., 2007) are compatible with the (iffy) section (moment-

curvature) analysis!

• But section-based analytical procedures may underestimate the actual

concrete compression strains.

• Instead of using strains from FE analysis, strains from section analysis

were used by matching the two different analyses results on the basis of

curvatures.37

Şekil 9. a) Plastik mafsal boyunun perde boyuna göre normalleştirilmiş değerlerinin beton

dayanımına göre normalleştirilmiş kesme gerilmelerine karşı gösterimi, b) (10) bağıntısı ile

tahmin edilen plastik mafsal boyunun gerçek değerlerle korelâsyonu

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

Lp /

Lw

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Lw = 8 m

Lw = 5 m

Lw = 3 m

cww fLtVmax Lp (m) - SEM

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Lp (

m)

- B

ağ

ıntı

(1

0)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

R2 = 0.94

a) b)

(a) Plastic hinge length normalized with respect to wall width (b) Plastic hinge

length as predicted by FEM and the expression

38

Şekil 10. Perde modelleri için Kesit Hesabı(KH) ve Sonlu Eleman Metodu (SEM)

kullanılarak hesaplanan perde taban kesiti eğrilik kapasitelerinin karşılaştırılması

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

KA /

S

EM

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Lw = 3 m

Lw = 5 m

Lw = 8 m

cww fLtVmax

Ratio of ultimate curvature capacities obtained from section ΦKA and finite element

analysis ΦFEM

39

Şekil 13. İki farklı yöntem kullanılarak perde uç bölgelerinde elde edilen beton birim

kısalması (ec) karşılaştırması

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

c

0.000

0.002

0.004

0.006

0.008

0.010

MN

0.000 0.002 0.004 0.006 0.008 0.010

(c) S

EM

0.000

0.002

0.004

0.006

0.008

0.010

MN

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

c

0.00

0.01

0.02

0.03

0.04(

c)KA

(c)SEM

DBYBHY-07

GV

0.00 0.01 0.02 0.03 0.04

(c) S

EM

0.00

0.01

0.02

0.03

0.04

GV

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

c

0.00

0.02

0.04

0.06

0.08

GÇ

cw fAVmax(

c)KA

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

(c) S

EM

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

GÇ

(c)SEM

=2.11(c)KA

(c)SEM

=1.78(c)KA

(c)s

SEM =1.63(

c)KA

Comparison of extreme fiber compressive strains in the concrete and damage

states from section and finite element analysis

40

Şekil 14. İki farklı yöntem kullanılarak perde uç bölgelerinde elde edilen çelik birim

uzaması (et) karşılaştırması

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

t

0.000

0.005

0.010

0.015

0.020

0.025

0.030

(c)KA

(c)SEM

DBYBHY-07

MN

0.000 0.005 0.010 0.015 0.020 0.025

(t)

SE

M

0.000

0.005

0.010

0.015

0.020

0.025

MN

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

t

0.00

0.02

0.04

0.06

0.08

0.10

GV

0.00 0.02 0.04 0.06 0.08

(t)

SE

M

0.00

0.02

0.04

0.06

0.08

GV

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

t

0.00

0.02

0.04

0.06

0.08

0.10

0.12

GÇ

cw fAVmax(

t)KA

0.00 0.02 0.04 0.06 0.08 0.10 0.12

(t)

SE

M

0.00

0.02

0.04

0.06

0.08

0.10

0.12

GÇ

Comparison of extreme fiber tensile strains in the steel and damage states from

section and finite element analysis

41

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

SE

C /

S

IM

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Lw = 3 m

Lw = 5 m

Lw = 8 m

cww fLtVmax

Curvature- (1/m)

0.000 0.005 0.010 0.015 0.020 0.025 0.030

M (

kN

-m)

0

10000

20000

30000

40000

FEM Analysis

Section Analysis(SEC)

Comparison of typical moment-curvature relationships obtained from section

and finite element analysis

Ratio of ultimate curvature capacities obtained from section (SEC) and finite element

analysis (SIM)

42

Comparison of extreme fiber compression strains at global yield and

ultimate limit states for section and finite element analyses.

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

c

0.000

0.001

0.002

0.003

0.004

(c)SEC

(c)FEM

a) Global Yield

0.000 0.001 0.002 0.003 0.004

(c) F

EM

0.000

0.001

0.002

0.003

0.004

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

c

0.00

0.02

0.04

0.06

0.08

(c)SEC

(c)FEM

b) Ultimate

cw fAVmax (c)SEC

0.00 0.02 0.04 0.06 0.08

(c) F

EM

0.00

0.02

0.04

0.06

0.08

(c)FEM

=2.11(c)SEC

(c)FEM

=1.56(c)SEC

43

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

t

0.000

0.002

0.004

0.006

0.008

(t)SEC

(t)FEM

a) Global Yield

0.000 0.002 0.004 0.006 0.008

(t)

FE

M

0.000

0.002

0.004

0.006

0.008

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

t

0.00

0.02

0.04

0.06

0.08

0.10

0.12

(t)SEC

(t)FEM

b) Ultimate

cw fAVmax (t)SEC

0.00 0.02 0.04 0.06 0.08 0.10 0.12

(t)

FE

M

0.00

0.02

0.04

0.06

0.08

0.10

0.12

Comparison of extreme fiber steel tensile strains at global yield and

ultimate limit states for section and finite element analyses.

44

Variation of different deformation

parameters with normalized wall

shear stress and axial load ratio.

0.0 0.4 0.8 1.2 1.6

DR

0

1e-3

2e-3

3e-3

4e-3

5e-3

0.0 0.4 0.8 1.2 1.6

.L

w

0

1e-3

2e-3

3e-3

4e-3

5e-3

6e-3

0.0 0.4 0.8 1.2 1.6

t (r

ad

)

0

1e-4

2e-4

3e-4

4e-4

5e-4

0.0 0.4 0.8 1.2 1.6

0.00

0.01

0.02

0.03

0.04

0.05

P / Aw fc <= 0.10

P / Aw fc = 0.15

P / Aw fc = 0.25

0.0 0.4 0.8 1.2 1.6

0.00

0.02

0.04

0.06

0.08

0.10

0.0 0.4 0.8 1.2 1.6

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.0 0.4 0.8 1.2 1.6

0.00

0.01

0.02

0.03

0.04

0.05

0.0 0.4 0.8 1.2 1.6

0.00

0.02

0.04

0.06

0.08

0.10

0.0 0.4 0.8 1.2 1.6

0.00

0.01

0.02

0.03

0.04

0.05

0.06

At global yield 3/4 of Ultimate Ultimate

0.0 0.4 0.8 1.2 1.6

c)S

EC

0.0

5.0e-4

1.0e-3

1.5e-3

2.0e-3

2.5e-3

0.0 0.4 0.8 1.2 1.6

0.000

0.005

0.010

0.015

0.020

0.025

0.0 0.4 0.8 1.2 1.6

0.000

0.005

0.010

0.015

0.020

0.025

0.0 0.4 0.8 1.2 1.6

t)S

EC

0

1e-3

2e-3

3e-3

4e-3

cww fLtVmax

0.0 0.4 0.8 1.2 1.6

0.00

0.02

0.04

0.06

0.08

cww fLtVmax

0.0 0.4 0.8 1.2 1.6

0.00

0.02

0.04

0.06

0.08

cww fLtVmax

a) b) c)

d) e) f)

g) i)h)

j) l)k)

m) o)n)

ASCE 41flexural

limit

ACI 318upper limit

c = 0.0135

c = 0.018

t = 0.04t = 0.06

yL

w = 2

sy

ult Lw = 0.072

Lw = 3 m

Lw = 5 m

Lw = 8 m

Drift

Rota

tion

Concre

te

str

ain

Curv

atu

reS

teel

str

ain

45

Comparison of calculated plastic rotation limits at specific performance levels with

the limits available in ASCE/SEI 41.

(p)

SIM (rad)

0 2e-3 4e-3 6e-3 8e-3 1e-2

(p) A

SC

E 4

1 ( r

ad

)

0

2e-3

4e-3

6e-3

8e-3

1e-2

(p)

SIM (rad)

0.00 0.01 0.02 0.03 0.04 0.05

0.00

0.01

0.02

0.03

0.04

0.05P / Aw fc <= 0.10

P / Aw fc = 0.15

P / Aw fc = 0.25

(p)

SIM (rad)

0.00 0.01 0.02 0.03 0.04 0.05

0.00

0.01

0.02

0.03

0.04

0.05Immediate Occupancy Life Safety Collapse Prevention

a) b) c)

46


the plastic chord rotation limits in EC8.

(y)

SIM (rad)

0 2e-3 4e-3 6e-3 8e-3 1e-2

(y)

EC

S ( r

ad

)

0

2e-3

4e-3

6e-3

8e-3

1e-2

(p)

SIM (rad)

0.00 0.01 0.02 0.03 0.04 0.05

(p) E

CS ( r

ad

)

0.00

0.01

0.02

0.03

0.04

0.05P / Aw fc <= 0.10

P / Aw fc = 0.15

P / Aw fc = 0.25

(p)

SIM (rad)

0.00 0.01 0.02 0.03 0.04 0.05

a) b) c)

For damage limitation

EC8 uses yield rotation

Damage Limitation Significant Damage Near Collapse

M/V/Lw > 3.5

47


the limits available in TSC-07.

(p)

SIM (rad)

0 2e-3 4e-3 6e-3 8e-3 1e-2

(p) T

SC

( r

ad

)

0

2e-3

4e-3

6e-3

8e-3

1e-2

(p)

SIM (rad)

0.00 0.01 0.02 0.03 0.04 0.05

0.00

0.01

0.02

0.03

0.04

0.05

P / Aw fc <= 0.10

P / Aw fc = 0.15

P / Aw fc = 0.25

(p)

SIM (rad)

0.00 0.01 0.02 0.03 0.04 0.05

0.00

0.01

0.02

0.03

0.04

0.05a) c)b)

Minimum Damage Safety Limit Collapse Limit

Plastic hinge length was taken as Lp=0.5Lw

48

Lower bound plastic rotation limits at different performance levels

49

The proposed plastic rotation limits for shear wall members controlled by flexure

(underlined values are ASCE/SEI 41 limits)

IO LS CP P

/Po ≤

0.1

0

< 0.33

= 0.33

0.005 - 0.0106

0.0015 / 0.005§

0.018 - 0.02420.01 / 0.01

0.025 - 0.03030.015 / 0.015

0.33 < < 0.50 0.0015 0.0139 - 0.0118 0.0247 - 0.0294

> 0.50

= 0.50

0.0015

0.0015 / 0.004 0.012 - 0.0080.008 / 0.008

0.015 - 0.010.01 / 0.01

P/P

o =

0.1

5

< 0.33

= 0.33

0.005 - 0.00450.0025 / 0.0043

0.018 - 0.02730.009 / 0.0087

0.025 - 0.03940.012 / 0.013

0.33 < < 0.50 0.0035 - 0.0029 0.0148 - 0.0176 0.016 - 0.012

> 0.50

= 0.50

0.0025 - 0.0010.002 / 0.0032

0.0085 - 0.005(0.006 / 0.0063

0.016 - 0.0120.01 / 0.0083

P/P

o ≥

0.2

5

< 0.33

= 0.33

0.004 - 0.00450.0025 / 0.003

0.015 - 0.02420.007 / 0.006

0.02 - 0.03330.009 / 0.009

0.33 < < 0.50 0.0035 - 0.0029 0.0118 - 0.0109 0.012 - 0.009

> 0.50

= 0.50

0.0025 - 0.0010.002 / 0.0015

0.007 – 0.0040.005 / 0.003

0.012 – 0.0090.0075 / 0.005

1.75

(1.90 1.47 / )

(0.031 0.053 / ). / 0.10

(0.031 0.053 / ). / 0.10o

o o

p P P

o o

P P e if P P

P P e if P P

§(This study / ASCE/SEI 41)

50

( ). w

B C DL

p b pA e

0.014 0.1429 0.0005

0.014 0.03 0.0025

0.03 0.038 0.8125 0.0219

0.038 0

pp

p

p

pp

p

if rad

if rad rad

if rad rad

if rad

P/Po A B C D

≤ 0.10 0.138 0.220 1.814 0.071

= 0.15 0.087 0.148 1.779 0.066

= 0.25 0.034 0.037 1.485 0.037

A more accurate plastic rotation expression is given by:

Coefficients of the equation

51

Correlation of predicted plastic rotations with analysis results

52

(ec)GVmaks = 0.010 – 0.005 (17)

(ec)GÇmaks = 0.0135 – 0.006 (18)

Şekil 16. Güvenlik ve göçme sınır durumları için davranışı beton basınç birim kısalması

tarafından kontrol edilen iyi sargılanmış perde elemanları birim kısalma kapasiteleri

0.000

0.005

0.010

0.015

0.020

0.025

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

Be

ton

bri

m k

ısa

lma

sı

=

GV

GÇ

(ec)GÇ = 0.018

cw fAVmax

(ec)GV = 0.010 - 0.005

(ec)GÇ = 0.0135 - 0.006

(ec)GÇ = 0.0135

Limiting concrete compressive strains for code-conforming walls for Life Safety

(GV) and Collapse Prevention (GC) limit states

53

Conclusions

• Accuracy in predicting local strains or curvatures is very difficult to

achieve. Global parameters vary less rapidly.

• Among the documents evaluated, ASCE/SEI 41 limits were observed to be

the most accurate ones yielding conservative results at all levels except

the low axial load levels.

• Neither EC8-3 nor TSR-07 (or -19?) specify consistent deformation limits.

TSC-07 suggests un-conservative limits at all performance levels, and it

appears to fall short of capturing the variation reflected in the calculated

values.

54

Conclusions (Cont.)

• Likewise EC8-3 seems to fall short of representing the variation in plastic

rotation in contrast to several parameters employed in the calculation. The

estimations are un-conservative at damage limitation. Although conservative

estimations are obtained at life safety and collapse prevention levels, the

values are not logical.

• Calibration of local or global response parameters against different ground

motion levels proved to be difficult.

• Expressions for plastic rotations that expand and improve ASCE/SEI 41 limit

states are proposed. These expressions are adjusted to err on the safe side,

and represent an improvement over existing provisions.

55

Kazaz, I., Gülkan, P. and Yakut, A. (2012): «Performance limits for structural walls: An analytical perspective,» Engineering Structures, 43: 105–119 .

Kazaz, I., Gülkan, P. and Yakut, A. (2012): «Deformation Limits for Structural Wallswith Confined Boundaries,» Earthquake Spectra, 28(3), pp. 1019–1046.

56

performance limits for structural walls

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