Seismic Performance Assessment of Flat Plate Floor Systems John W. Wallace, Ph.D., P.E. Thomas Hyun-Koo Kang, Ph.D. Student Department of Civil and Environmental.

Seismic Performance Assessment Seismic Performance Assessment of Flat Plate Floor Systemsof Flat Plate Floor Systems

John W. Wallace, Ph.D., P.E.Thomas Hyun-Koo Kang, Ph.D. Student

Department of Civil and Environmental EngineeringUniversity of California, Los Angeles

CUREe-Kajima Joint Research Program: Phase IV

Modeling and Performance IssuesModeling and Performance Issues

• Lateral stiffness and ductility of the column-slab system

• Shear Reinforcement– Conventional Shear Stirrups– Shear Studs

• Punching Failures – Strength and deformation capacity– Stiffness degradation in the connection

region – progessive collapse prevention

Modeling ApproachesModeling Approaches

Effective Beam Width

Column

Slab

- Account for the influence of the concrete cracking (EIeffective)

Modeling ApproachesModeling Approaches

Equivalent Frame Model

Column

Slab

Connection

Performance Issues - PunchingPerformance Issues - Punching

(Hwang)

Performance Issues - PunchingPerformance Issues - Punching

(Hwang)

Performance Issues - PunchingPerformance Issues - Punching

Continuous bottom reinforcement to prevent collapse

(Hwang)

Performance Issues - Gravity StressPerformance Issues - Gravity StressL

ater

al L

oad

Drift

1% 2% 4%

Low Vg/Vo

High Vg/Vo

Connection ModelingConnection Modeling

Effective Beam Width with Rotational Spring

Column

Slab

Connection

1.0

0.04

0.0

Modeling ApproachesModeling Approaches

Displacement-Based Model with Shear strength degradation

Drift derived from Elastic and Inelastic curvature

Vn

d

y

u

Performance Issues - Gravity StressPerformance Issues - Gravity StressDisplacement-Based Model (Moehle)Displacement-Based Model (Moehle)

0.0 0.2 0.4 0.6 0.8 1.0Gravity Shear Ratio

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Dri

ft R

atio

Conventional

Post-Tensioned

Best Fit (Model)

Best Fit (Exp)

Prototype & Test StructurePrototype & Test Structure

Section A-A• Prototype

- Test Structure : 2 Stories, 2 × 2 bays

Earthquake Simulator - Shake TableEarthquake Simulator - Shake Table

• Shake Table Test

(Shahrooz)

• Scale , Span-Depth Ratio- R.C. Flat Plate : 9/20 , 1/30 - Post-Tensioned Flat Plate : 1/3 , 1/33

Shear Reinforcement Shear Reinforcement

• Shear Studs

(Ghali)

R.C. Flat Plate -R.C. Flat Plate - Flexural Reinforcement Flexural Reinforcement (Test Specimen)(Test Specimen)

• Top Reinforcement • Bottom Reinforcement

P.T. flat Plate -P.T. flat Plate - Flexural ReinforcementFlexural Reinforcement(Test Specimen)(Test Specimen)

• Tendon Arrangement

- Scale : 1/3- Span-depth ratio : 1/33- Tendon : 3/8 in diameter seven-wire strands (Grade 270)- Bonded Reinforcement : 3 # 3 in each direction

9/16in

15/16in a1