SEISMIC RESPONSE OF LOW ASPECT RATIO REINFORCED CONCRETE

SHEAR WALLSBismarck Luna

Ph.D. CandidateCivil, Structural and Environmental Engineering, University at Buffalo

2Quake Summit 2012, Boston, Massachusetts

• National Science Foundation Dr. Joy M. Pauschke, NEESR Program Director

• Project team members University at Buffalo

Jonathan Rivera, Joshua Rocks, Dr. Caglar Goksu (ITU), Emma Lejeune (Cornell REU), Prof. Andrew Whittaker (PI)

University of California, BerkeleyCatherine Whyte, Prof. Bozidar Stojadinovic (Co-PI)

University of WashingtonJoshua Pugh, Anna Birely, Prof. Laura Lowes (Co-PI)

California Polytechnic State University, San Luis ObispoProf. Abraham Lynn (Co-PI)

• LPCiminelli, Inc. • MCEER (http://mceer.buffalo.edu/)

Acknowledgement

• Goals• Specimen details• Test setup• Instrumentation• Global response• Peak shear strength• Lateral stiffness• Strength degradation• Future work

3

Outline of presentation

Quake Summit 2012, Boston, Massachusetts

• Acquire robust information on the seismic behavior of low aspect ratio rectangular RC shear walls

• Provide simulation tools as needed• Revise predictive equations for shear strength and

stiffness• Understand force transfer in walls at different levels of

drift• Develop macro-level hysteretic models • Update fragility functions and damage states• Response modification factors

4

Goals

Quake Summit 2012, Boston, Massachusetts

Wall hw/lwWeb Boundary

Elementρl

(%)ρt

(%)ρl

(%)ρt

(%)SW1 0.94 0.67 0.67 - - 3600 67 102SW2

0.541.0 1.0 - - 7000 63 87

SW3 0.67 0.67 - - 7800 63 87SW4 0.33 0.33 - - 4200 67 102SW5

0.331.0 1.0 - - 4300 67 102

SW6 0.67 0.67 - - 3800 67 102SW7 0.33 0.33 - - 3800 67 102SW8

0.54

1.5 1.5 - - 3500 67 102SW9 1.5 0.67 - - 4300 67 102SW10 1.5 0.33 - - 4600 67 102SW11 0.67 0.67 1.5 1.5 4800* 67* 102*SW12 0.33 0.33 2.0 2.0 5000* 67* 102*

SW9

SW12

5

Specimen details

Quake Summit 2012, Boston, Massachusetts

Test fixture setup Specimen SW2

6

Test setup

Quake Summit 2012, Boston, Massachusetts

• In-plane string potentiometers and temposonics

• Out-of-plane string potentiometers

• Krypton system

• Strain gages

7

Instrumentation

Quake Summit 2012, Boston, Massachusetts

Gigapan system

8

Instrumentation

Quake Summit 2012, Boston, Massachusetts

SW3

9

Global response

SW4

SW6 SW7

Quake Summit 2012, Boston, Massachusetts

SW3

-3 -2 -1 0 1 2 3-800

-600

-400

-200

0

200

400

600

800

Drift Ratio (%)

Forc

e (k

ips)

SpecimenC1 C2

C2/C1Measured(kips)

ACI 318§21.9 (kips)

SW1 253 576 2.28SW2 563 803 1.43SW3 468 660 1.41SW4 226 400 1.77SW5 726 630 0.87SW6 571 592 1.04SW7 317 386 1.22SW8 623 592 0.95SW9 633 622 0.98

10

Peak shear strength

Quake Summit 2012, Boston, Massachusetts

11

Peak shear strength

Quake Summit 2012, Boston, Massachusetts

1 2 3 4 5 6 7 8 90

200

400

600

800

1000

1200

Specimen (SW) number

Pea

k sh

ear s

treng

th (k

ip)

ACI 318 Chapter 11ACI 318 Chapter 21Barda (1977)Wood (1990)Gulec (2009)Measured

SW3

12

Lateral stiffness

0 0.5 1 1.5 20

100

200

300

400

500

Disp (in)

Forc

e (k

ips)

SpecimenMeasured

initial stiffness (kips/in)

Theoretical‘uncracked’

(kips/in)

ASCE 43-05‘cracked’(kips/in)

Secant stiffness at peak resistance

(kips/in)

Col. 5 /Col. 4

SW1 2400 4886 2443 172 0.07SW2 3400 19709 9855 693 0.07SW3 3900 20805 10403 344 0.03SW4 3000 15267 7634 322 0.04SW5 8900 30527 15264 1682 0.11SW6 10100 28697 14349 1719 0.12SW7 15800 27931 13966 1757 0.13SW8 3700 14522 7261 1369 0.19SW9 5020 15488 7744 1014 0.13

0 0.5 1 1.5 20

100

200

300

400

500

Disp (in)

Forc

e (k

ips)

13

Lateral stiffness

SW3

14

Strength degradation

Quake Summit 2012, Boston, Massachusetts

Specimen

SW1 0.84 0.79 0.41

SW2 0.79 0.70 -

SW3 0.60 0.44 0.14

SW4 0.72 0.63 0.3

SW5 0.42 0.22 -

SW6 0.87 0.81 0.53

SW7 0.86 0.8 0.51

SW8 0.80 0.68 0.45

SW9 0.85 0.74 0.42SW8

15

Future work

• Testing of the remaining two specimens• Data reduction• Processing Krypton data• Analysis of cracks and strain gage data• Processing Gigapan images

Quake Summit 2012, Boston, Massachusetts

THANK YOUbismarck@buffalo.edu

Quake Summit 2012, Boston, Massachusetts