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

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. Designed in 1965 & Constructed in 1966 Seven Stories, 65’ Height 150’ x 61’ Approximate Plan Non-Ductile Exterior Concrete Frame

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

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  1. 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?

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