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CUREe-Kajima Joint Research Program: Phase IV
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 Engineering
University of California, Los Angeles
Modeling 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 Approaches

Effective Beam Width
Column
Slab
- Account for the influence of
the concrete cracking (EIeffective)
Modeling Approaches

Equivalent Frame Model
Connection
Slab
Column
Performance Issues - Punching
(Hwang)
Performance Issues - Punching
(Hwang)
Performance Issues - Punching
Continuous bottom
reinforcement to
prevent collapse
(Hwang)
Performance Issues - Gravity Stress
Lateral Load
Low Vg/Vo
High Vg/Vo
1%
Drift
2%
4%
Connection Modeling

Effective Beam Width with Rotational
Spring
Connection
0.04
Column
0.0
1.0
Slab
Modeling Approaches

Displacement-Based Model with
Shear strength degradation
Drift derived from
Elastic and Inelastic
curvature
fy
fu
Vn
d
Performance Issues - Gravity Stress
Displacement-Based Model (Moehle)
0.07
Conventional
0.06
Post-Tensioned
Best Fit (Model)
Drift Ratio
0.05
Best Fit (Exp)
0.04
0.03
0.02
0.01
0.00
0.0
0.2
0.4
0.6
Gravity Shear Ratio
0.8
1.0
Prototype & Test Structure
• Prototype
- Test Structure : 2 Stories, 2 × 2 bays
Section A-A
Earthquake Simulator - Shake Table
• Shake Table Test
• Scale , Span-Depth Ratio
- R.C. Flat Plate : 9/20 , 1/30
- Post-Tensioned Flat Plate : 1/3 , 1/33
(Shahrooz)
Shear Reinforcement
• Shear Studs
(Ghali)
R.C. Flat Plate - Flexural Reinforcement
(Test Specimen)
• Top Reinforcement
• Bottom Reinforcement
P.T. flat Plate - Flexural Reinforcement
(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