FEMA 356 Evaluation
PEER Van Nuys Testbed
May 23, 2002
by: Jon Heintz, S.E. & Robert Pekelnicky
Van Nuys Holiday Inn
Van Nuys Holiday Inn
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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
Typical Floor Plan
Exterior Frame Elevation
North Elevation
South Elevation
Evaluation Methodology
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Perform ASCE 31 (FEMA 310) Tier 1
screening.
Create 3-D linear dynamic model.
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Determine Modes & Periods
Evaluate Torsion
Perform 2-D nonlinear pushover of
longitudinal exterior and interior frame.
Tier 1 Deficiencies
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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
3-D Model
Elastic Model Assumptions
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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:
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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
Transverse Fundamental Mode
T = 1.27 sec.
PMR = 85%
Longitudinal Fundamental Mode
W/O Infill: T = 1.20 sec.
PMR = 89%
W/ Infill:
PMR = 77%
T = 1.12 sec.
Plan Torsion Fundamental Mode
W/O Infill: T = 1.03 sec.
PMR = 0%
W/ Infill:
PMR = 8%
T = 1.00 sec.
Comparison with Recorded
Periods (longitudinal)
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Pre-1971 T=0.52 sec
San Fernando
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Northridge
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early T=0.7 sec
peak response T=1.5 sec
early T=1.5 sec
Elastic model
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FEMA 356 empirical equation T=0.73 sec
T=1.2 sec w/o infill
Plan Torsional Irregularity
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Torsion triggers amplified target disp.
Infill has 1” expansion gap between frame.
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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
2-D Nonlinear Pushover
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Model longitudinal direction as critical
Include both exterior and interior frames.
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2 exterior frames = 40% of stiffness
2 interior frames = 60% of stiffness
2-D Nonlinear Pushover
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Place hinges at all member ends
Use criteria in FEMA 356 for hinge properties
Flexural hinges limited by:
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flexural strength
shear strength
lap splice strength
embedment (development)
Include two load patterns
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Uniform based on floor mass
Modal based on CQC combination of Modes
Degenkolb Engineers
225 Bush Street, Suite 1000
San Francisco, CA 941044207
Phone: 415.392.6952
Fax: 415.981.3157
Pushover Curves
Subject: Pushover Curves
Job: PEER Van Nuys
Job Number: A2162007.00
By: RGP
Checked By:
Date: 4/29/02
Section:
Page: ___
of ___
600
Ground Fl. Column Bot. Lap
500
2nd Fl. Int. Columns Shear Hinge
Ext. Beams
+
M Hinge
400
Uniform
Base Shear [kips]
2nd Fl. Ext. Columns Shear Hinge
Modal
300
Target dt= 29 inches
(10%/50)
Target dt= 7 inches
(50%/50)
200
100
0
0
2
4
6
8
Roof Displacement [in.]
10
12
14
16
Hinge locations
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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:
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shear in columns
shear in joints
local hinge rotation limits
slab punching shear on interior frames
Degenkolb Engineers
Response Spectra
Subject: Site Response Spectra
Job: PEER Van Nuys
Job Number: A2162007.00
By: RGP
Checked By:
225 Bush Street, Suite 1000
San Francisco, CA 941044207
Phone: 415.392.6952
Fax: 415.981.3157
Date: 4/29/02
Section:
Page: ___ of ___
2.5
2% in 50 Years
2
1.5
Sa/g
1994 Northridge
10% in 50 Years
1
0.5
50% in 50 Years
0
0.00
0.20
0.40
0.60
0.80
1.00
Period [sec]
1.20
1.40
1.60
1.80
2.00
Roof Displacement
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Peak displacement during Northridge
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9.2 inches
Calculated displacement capacity is
significantly less. Why?
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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?
Summary
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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?