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 CUREe-Kajima Joint Research Program: Phase IV

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 (EI effective )

Modeling Approaches Equivalent Frame Model Column Slab Connection

Performance Issues - Punching (Hwang)

Performance Issues - Punching (Hwang)

Performance Issues - Punching Continuous bottom reinforcement to prevent collapse (Hwang)

Performance Issues - Gravity Stress Lateral Load Drift 1% 2% 4% Low V g /V o High V g /V o

Connection Modeling Effective Beam Width with Rotational Spring Column Slab Connection

Modeling Approaches Displacement-Based Model with Shear strength degradation Drift derived from Elastic and Inelastic curvature VnVn dd yy uu

Performance Issues - Gravity Stress Displacement-Based Model (Moehle)

Prototype & Test Structure Section A-A Prototype - Test Structure : 2 Stories, 2 × 2 bays

Earthquake 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 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