1. by: Jon Heintz, S.E. & Robert Pekelnicky
FEMA 356 Evaluation
PEER Van Nuys Testbed
May 23, 2002
by: Jon Heintz, S.E. & Robert Pekelnicky

2. Van Nuys Holiday Inn

3. Van Nuys Holiday Inn Designed in 1965 & Constructed in 1966
Seven Stories, 65’ Height
150’ x 61’ Approximate Plan
Non-Ductile Exterior Concrete Frame
Interior Slab-Column Frames
Masonry infill in four bays
Building Instrumented

4. Typical Floor Plan

5. Exterior Frame Elevation
North Elevation
South Elevation

6. Evaluation Methodology
Perform ASCE 31 (FEMA 310) Tier 1 screening.
Create 3-D linear dynamic model.
Determine Modes & Periods
Evaluate Torsion
Perform 2-D nonlinear pushover of longitudinal exterior and interior frame.

7. Tier 1 Deficiencies Soft First Story (44% of 2nd story)
Quick Check Column Shear >> Capacity
Members Shear Controlled
Weak Column / Strong Beam (Mc=0.8Mb)
Inadequate Lap Splices
Minimal confinement reinforcement
Stirrups & Ties w/o seismic hooks

8. 3-D Model

9. Elastic Model Assumptions
Concrete strength f’ce 150% of specified
Frame beams modeled with ACI effective slab widths
Interior flat slabs modeled as effective beams (Luo et. al. 1994, Pecknold 1975)
Effective stiffnesses used:
Columns = 50% of Gross (FEMA 356)
Beams = 50% of Gross (FEMA 356)
Slabs = 33% of Gross (Vanderbilt 1983)
Beam-Column Joints partially rigid
Columns fixed at pile cap

10. Transverse Fundamental Mode
T = 1.27 sec.
PMR = 85%

11. Longitudinal Fundamental Mode
W/O Infill: T = 1.20 sec. PMR = 89%
W/ Infill: T = 1.12 sec. PMR = 77%

12. Plan Torsion Fundamental Mode
W/O Infill: T = 1.03 sec. PMR = 0%
W/ Infill: T = 1.00 sec. PMR = 8%

13. Comparison with Recorded Periods (longitudinal)
Pre-1971 T=0.52 sec
San Fernando
early T=0.7 sec
peak response T=1.5 sec
Northridge
early T=1.5 sec
Elastic model
FEMA 356 empirical equation T=0.73 sec
T=1.2 sec w/o infill

14. Plan Torsional Irregularity
Torsion triggers amplified target disp.
Infill has 1” expansion gap between frame.
Two models used: one with infill panels and one without infill panels.
Models compared to determine whether presence of infill has dramatic effect.
3-D model results did not trigger 
3-D model results did not show significant response modification for higher modes

15. 2-D Nonlinear Pushover Model longitudinal direction as critical
Include both exterior and interior frames.
2 exterior frames = 40% of stiffness
2 interior frames = 60% of stiffness

16. 2-D Nonlinear Pushover Place hinges at all member ends
Use criteria in FEMA 356 for hinge properties
Flexural hinges limited by:
flexural strength
shear strength
lap splice strength
embedment (development)
Include two load patterns
Uniform based on floor mass
Modal based on CQC combination of Modes

17. Pushover Curves Target dt= 29 inches (10%/50) Target dt= 7 inches
(50%/50)

18. Hinge locations
Flexural hinges at base of columns (lap-splice controlled)
Flexural hinges below 2nd floor beams
Shear controlled hinges in 1st, 2nd, 3rd floor beams
Still need to check:
shear in columns
shear in joints
local hinge rotation limits
slab punching shear on interior frames

19. Response Spectra

20. Roof Displacement Peak displacement during Northridge
9.2 inches
Calculated displacement capacity is significantly less. Why?
Conservative hinge assumptions? (actual elements can go farther)
Conservative limitations on lap splice capacities?
Conservative accounting for degradation (C3)
Higher Mode Effects? (not a factor based on our linear model results)
Plastic hinge not a reliable EDP?

21. Summary
ASCE 31 Tier 1 does a good job of predicting possible deficiencies
FEMA 356 does reasonable job of predicting cracked stiffness, in lieu of more detail
FEMA 356 NSP yields very conservative results for this building
Can PEER Methodology more accurately predict recorded response?