PEER Van Nuys TestbedPEER Van Nuys TestbedMay 23, 2002May 23, 2002

by: Jon Heintz, S.E. & Robert Pekelnickyby: Jon Heintz, S.E. & Robert Pekelnicky

FEMA 356 EvaluationFEMA 356 Evaluation

Van Nuys Holiday InnVan Nuys Holiday Inn

Van Nuys Holiday InnVan Nuys Holiday Inn

Designed in 1965 & Constructed in Designed in 1965 & Constructed in 19661966

Seven Stories, 65’ HeightSeven Stories, 65’ Height 150’ x 61’ Approximate Plan 150’ x 61’ Approximate Plan Non-Ductile Exterior Concrete FrameNon-Ductile Exterior Concrete Frame Interior Slab-Column FramesInterior Slab-Column Frames Masonry infill in four baysMasonry infill in four bays Building InstrumentedBuilding Instrumented

Typical Floor PlanTypical Floor Plan

Exterior Frame ElevationExterior Frame Elevation

North Elevation

South Elevation

Evaluation MethodologyEvaluation Methodology

Perform ASCE 31 (FEMA 310) Tier Perform ASCE 31 (FEMA 310) Tier 1 screening.1 screening.

Create 3-D linear dynamic model.Create 3-D linear dynamic model. Determine Modes & PeriodsDetermine Modes & Periods Evaluate TorsionEvaluate Torsion

Perform 2-D nonlinear pushover of Perform 2-D nonlinear pushover of longitudinal exterior and interior longitudinal exterior and interior frame.frame.

Tier 1 DeficienciesTier 1 Deficiencies

Soft First Story (44% of 2nd story)Soft First Story (44% of 2nd story) Quick Check Column Shear >> CapacityQuick Check Column Shear >> Capacity Members Shear ControlledMembers Shear Controlled Weak Column / Strong Beam Weak Column / Strong Beam

(Mc=0.8Mb)(Mc=0.8Mb) Inadequate Lap SplicesInadequate Lap Splices Minimal confinement reinforcementMinimal confinement reinforcement Stirrups & Ties w/o seismic hooksStirrups & Ties w/o seismic hooks

3-D Model3-D Model

Elastic Model AssumptionsElastic Model Assumptions Concrete strength f’Concrete strength f’cece 150% of specified 150% of specified Frame beams modeled with ACI effective slab Frame beams modeled with ACI effective slab

widthswidths Interior flat slabs modeled as effective beams Interior flat slabs modeled as effective beams

(Luo et. al. 1994, Pecknold 1975)(Luo et. al. 1994, Pecknold 1975) Effective stiffnesses used:Effective stiffnesses used:

Columns = 50% of Gross (FEMA 356)Columns = 50% of Gross (FEMA 356) Beams = 50% of Gross (FEMA 356)Beams = 50% of Gross (FEMA 356) Slabs = 33% of Gross (Vanderbilt 1983)Slabs = 33% of Gross (Vanderbilt 1983)

Beam-Column Joints partially rigidBeam-Column Joints partially rigid Columns fixed at pile capColumns fixed at pile cap

Transverse Fundamental Transverse Fundamental ModeMode

T = 1.27 sec.

PMR = 85%

Longitudinal Fundamental Longitudinal Fundamental ModeMode

W/O Infill: T = 1.20 sec. PMR = 89%

W/ Infill: T = 1.12 sec. PMR = 77%

Plan Torsion Fundamental Plan Torsion Fundamental ModeMode

W/O Infill: T = 1.03 sec. PMR = 0%

W/ Infill: T = 1.00 sec. PMR = 8%

Comparison with Recorded Comparison with Recorded Periods (longitudinal)Periods (longitudinal)

Pre-1971 T=0.52 secPre-1971 T=0.52 sec San Fernando San Fernando

early T=0.7 secearly T=0.7 sec peak response T=1.5 secpeak response T=1.5 sec

NorthridgeNorthridge early T=1.5 secearly T=1.5 sec

Elastic modelElastic model FEMA 356 empirical equation T=0.73 sec FEMA 356 empirical equation T=0.73 sec T=1.2 sec w/o infillT=1.2 sec w/o infill

Plan Torsional IrregularityPlan Torsional Irregularity Torsion triggers amplified target disp.Torsion triggers amplified target disp. Infill has 1” expansion gap between Infill has 1” expansion gap between

frame.frame. Two models used: one with infill panels and Two models used: one with infill panels and

one without infill panels.one without infill panels. Models compared to determine whether Models compared to determine whether

presence of infill has dramatic effect.presence of infill has dramatic effect. 3-D model results did not trigger 3-D model results did not trigger 3-D model results did not show significant 3-D model results did not show significant

response modification for higher modesresponse modification for higher modes

2-D Nonlinear Pushover2-D Nonlinear Pushover

Model longitudinal direction as criticalModel longitudinal direction as critical Include both exterior and interior frames.Include both exterior and interior frames.

2 exterior frames = 40% of stiffness2 exterior frames = 40% of stiffness 2 interior frames = 60% of stiffness2 interior frames = 60% of stiffness

2-D Nonlinear Pushover2-D Nonlinear Pushover

Place hinges at all member endsPlace hinges at all member ends Use criteria in FEMA 356 for hinge propertiesUse criteria in FEMA 356 for hinge properties Flexural hinges limited by:Flexural hinges limited by:

flexural strengthflexural strength shear strengthshear strength lap splice strengthlap splice strength embedment (development)embedment (development)

Include two load patternsInclude two load patterns Uniform based on floor massUniform based on floor mass Modal based on CQC combination of ModesModal based on CQC combination of Modes

Pushover CurvesPushover Curves

Target t= 29 inches(10%/50)Target t= 7 inches(50%/50)

Hinge locationsHinge locations

Flexural hinges at base of columns (lap-splice controlled)Flexural hinges at base of columns (lap-splice controlled) Flexural hinges below 2nd floor beamsFlexural hinges below 2nd floor beams Shear controlled hinges in 1st, 2nd, 3rd floor beamsShear controlled hinges in 1st, 2nd, 3rd floor beams Still need to check:Still need to check:

shear in columnsshear in columns shear in jointsshear in joints local hinge rotation limitslocal hinge rotation limits slab punching shear on interior framesslab punching shear on interior frames

Response SpectraResponse Spectra

Roof DisplacementRoof Displacement Peak displacement during Northridge Peak displacement during Northridge

9.2 inches 9.2 inches Calculated displacement capacity is Calculated displacement capacity is

significantly less. Why?significantly less. Why? Conservative hinge assumptionsConservative hinge assumptions? ? (actual (actual

elements can go farther)elements can go farther) Conservative limitations on lap splice Conservative limitations on lap splice

capacities?capacities? Conservative accounting for degradation (CConservative accounting for degradation (C33)) Higher Mode Effects?Higher Mode Effects? (not a factor based on (not a factor based on

our linear model results)our linear model results) Plastic hinge not a reliable EDP?Plastic hinge not a reliable EDP?

SummarySummary

ASCE 31 Tier 1 does a good job of ASCE 31 Tier 1 does a good job of predicting possible deficienciespredicting possible deficiencies

FEMA 356 does reasonable job of FEMA 356 does reasonable job of predicting cracked stiffness, in lieu of predicting cracked stiffness, in lieu of more detailmore detail

FEMA 356 NSP yields very conservative FEMA 356 NSP yields very conservative results for this buildingresults for this building

Can PEER Methodology more Can PEER Methodology more accurately predict recorded response?accurately predict recorded response?