performance-based seismic design of structures...

PESDES 2017 International Workshop on Performance-Based Seismic Design of Structures

Prediction of the Lateral Load Displacement Curves for RC Squat Walls Failing in Shear

DirectorNational Center for Research on Earthquake Engineering

ProfessorNational Taiwan University

Shyh-Jiann Hwang

October 14, 2017

Mission of NCREE

• Established at National Taiwan University in 1990• Mission:

2

· Pre-quake preparation – Disaster prevention· Emergency response – Disaster reduction· Post-quake recovery – Disaster relief

l Introductionl Proposed Load Deflection Curvel Test Verificationl Conclusions

Outline

Seismicity in Taiwan (1900-2014)

5

Vulnerable Low-rise RC Buildings

Most Vulnerable Buildings under Chi-Chi Earthquake

Collapse of School Building

Collapse of Street Townhouse

Low-rise Reinforced Concrete Buildings

• Tax Information of Taiwan (2011)• Total: 54 million buildings，1,651million m2

• RC Buildings with 7 stories and below : 61.4%

RC Steel Brick Else

Tota

l Flo

or A

rea

Performance Based Engineering

Seismic EvaluationCapacity

Spectrum MethodPushover Analysis

Performance-Target Ground Acceleration Ap

Ap

RC

Short Column Shear Wall Column

Skeleton Curves

2010 Chile Earthquake

Damage of RC Walls

2016 Meinong Earthquake

1999 Chi-Chi Earthquake

Damage of Short Columns

Objective

Ø Propose the lateral-load displacement curves of shear wall and short column subjected to shear failures

Ø Considering:l crackingl strengthl shear deformationl collapse


Outline

2.Shear deformation

1.Shear cracking

4. gradual process

3. Strut-and-tie action

Li, Y. A., Huang, Y. T., and Hwang, S. J., (2014) “Seismic Response of Reinforced Concrete Short Columns Failed in Shear,” ACI Structural Journal, V. 111, No. 4, July-August, pp. 945-954.

Test Observation on Short Column

Proposed Curve

Weng, P. W., Li, Y. A., Tu, Y. S., and Hwang, S. J., (2017) “Prediction of Lateral Load Displacement Curves for Reinforced Concrete Squat Walls Failed in Shear,” Journal of Structural Engineering, ASCE, 143(10), DOI: 10.1061/(ASCE)ST.1943-541X.0001872, 04017141.

(ACI 318-14 Code)web shear cracking

flexural shear cracking

Cracking Point

wwccr

NddtfV4

27.0

dt

VM

tNf

fV ww

wwcw

ccr

2

2.01.005.0

effc

wcrcrf IE

hV12

3

,

, ,, slipc f c csr cr rr

dtEhV

wc

wcrcrs 4.0,

ws

yb

y

crcrslip h

kddufd

VV

1E8

2

,

Flexure

Shear

Slip

Cracking Point

Proposed Curve

v

d r

v

h

NormalStrain

2

h

Shear Strain 2

d

d

cf

cf

o o

HognestadParabola

d

d

d

r

Crackedreinforcedconcrete

vf

hf

Cylinder

d

d

d

Equilibrium

Diagonal Compression

Compatibility

Softening

Diagonal Comp. Failure

Hwang, S. J., and Lee, H. J., (2002) “Strength Prediction for Discontinuity Regions by Softened Strut-and-Tie Model,” Journal of Structural Engineering, ASCE, Vol. 128, No. 12, pp. 1519-1526.

Softened Strut-and-Tie Model

Hwang, S. J., Tsai, R. J., Lam, W. K., and Moehle, J. P., (2017) “Simplification of Softened Strut-and-Tie Model for Strength Prediction of Discontinuity Regions,” ACI Structural Journal, V. 114, No. 5, pp.

1239-1248.

cos strcn AfKV

wcww ft

Nkd

85.025.0

wstr tkdA

46.114.01cottan BK AA

112

c

y

ff

A

130

c

y

ff

B

52.035.3

MPafc

Strength PointSoftened Strut-and-Tie model

Shear Deformation due to Strain Field of Shear Element

1DL - 1.5% 1DH – 0.75% rd

v

h

Formulation of Strut-and-Tie Mechanism

Tests of Short Columns

※ Approximation of @ Vmax is preferred.

Vmax : convergent @Vmax : divergent

Characteristics of Strength Point

r

vd

h

0020.yh

0020.yv

0010.d

r d

0.005r

vh

Approximation of Strain Field

(Mohr’s Compatibility)

2sindrvh

wwvhs hh 2sin006.0

2sin006.0vh

005.0r 001.0d

Shear Deformation

sn ipf sl

ws h 2sin006.0

Flexure

Shear

Slip

Lateral Displacement

effc

wcrf IE

hV12

3

ws

yb

y

crslip h

kddufd

VV

1E8

2

Proposed Curve

(Referred to ASCE 41-13 Table 10-20)

Collapse Point

Condition Strength ratio ( )

Drift ratio ( )

0.2 2.0%

0.0 1.0%

na VV wa h

05.0

cww

yss

ftNfAA

05.0

cww

yss

ftNfAA


Outline

• Hidalgo et al. (2002)Test Data of Shear Walls

Weng, P. W., Li, Y. A., Tu, Y. S., and Hwang, S. J., (2017) “Prediction of Lateral Load Displacement Curves for

Reinforced Concrete Squat Walls Failed in Shear,” Journal of Structural Engineering, ASCE, 143(10), DOI:

10.1061/(ASCE)ST.1943-541X.0001872, 04017141.

00

h

v

Verification

0v

0h

38.1w

H

00.1w

H

70.0w

H

Verification

AVG : 1.34COV : 0.16

AVG : 0.77COV : 0.37

Statistics

• Hidalgo et al. (2002)

Test Data of Shear Walls

Comparison of Failure Mechanisms coscos, strcdSSTn AfKCV Proposed

ACI 318-14 , 0.83n ASCE c c y w wt w c wV f f t f t

Crushing of concrete

Widening of Diagonal crack

1.64 11

64%steel contributionconcrete contribution

232%0.83 10.25

steel contributionconcrete contribution

ACI 318-14

Proposed

Comparison with ACI 318-14 Code

Li, Y. A., and Hwang, S. J., (2017) “Prediction of Lateral Load Displacement Curves for Reinforced Concrete Short Columns Failed in Shear,” Journal of Structural Engineering, ASCE,

143(2), DOI: 10.1061/(ASCE)ST.1943-541X.0001656, 04016164.

Speci. H/h[MPa] [MPa]

1DL

1

0.09 281.27% 430

1DH 0.29 25

1NL 0.10 230.24% 458

1NH 0.29 25

2DL

2

0.09 261.27% 430

2DH 0.30 24

2NL 0.10 230.24% 458

2NH 0.29 26

1

20.3

36 1.21% 300

3 391.88% 305

4 35

2 0.6 48 1.21% 300

cf cg fA

N

ytfs

Test of Short Columns

Compared with Test Results

AVG : 1.21COV : 0.15

AVG : 1.33COV : 0.29

Statistics


Outline

1. Proposed curve is trilinear, consisting of shear cracking, shear strength and collapse point

2. Proposed curve is suitable for shear walls and short columns

3. Approximation of strain field to calculate shear deformation is feasible

Conclusions

p Funded by Ministry of Science and Technology and National Center for Research on Earthquake Engineering (NCREE)

Acknowledgement

Thanks for Your Attention

performance-based seismic design of structures...

Documents