Design of New Steel Moment Framed Buildings With Dampers Using ASCESEI 7 Methodology

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Design of New Steel Moment Framed Buildings With
Dampers Using ASCE/SEI 7 Methodology
H. Kit Miyamoto Amir S.J. Gilani Miyamoto
International, Inc.
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Overview

• Design Methodology
• ASCE/SEI 7-05
• Case study Moderate Seismic Hazard
• Case study High Seismic Hazard
• Life-Cycle Evaluation
• Confidence Levels

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PBD Approach

• Design Structural Members to Meet The Code
  Strength Requirements
• Provide Supplementary Damping (VDD) to Limit
  Displacement
• Produce Highly Damped Low Frequency Structure

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ASCE 7/ IBC

• Chapter 18
• Design for 75 of V
• Linear Analysis is ok if DCRlt 1.5

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Medical Office Building

• Central Valley California Moderate Seismicity
• Five-Story,
• 21 m Tall
• 13,000 m2

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Damper Frames
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Moderate Seismic Demand
Maximum Considered EQ (MCE) 2,500-Year
Event Design Basis EQ (MCE) 500-Year Event
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Performance Goals

• Enhanced Performance
• Design Basis EQ
• Immediate Occupancy
• Max. Considered EQ
• Life Safety

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Evaluation Procedure

• NL Analysis
• Suite of Site Specific Motions
• Maxima of Responses
• Compare Performance Based Design (PBD) And
  Conventional Design (CD)

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Base Shear Coefficient, MCE
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Steel Stress, MCE
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Summary of Results
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Laboratory Tests of Dampers

• Capacity Stroke
• Force-Velocity Relation
• Others

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Production Tests
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Construction Cost Evaluation

• Damper Cost Offset by Reductions in Materials

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Construction Photos
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Commercial Building

• LA Area High Seismicity
• Four-Story, Office Building
• 18.5 m Tall
• 8,000 m2

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PBD Lateral Load Components

• Viscous Damper

• Ductile Slotted Web Connection

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Performance Goals

• Design Basis EQ
• Life Safety
• Max. Considered EQ
• Collapse Prevention

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High Seismic Demand
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Base Shear Coefficient, DBE Event
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Plastic Hinge Formations, MCE Event

• CD

• PBD

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Summary of Results
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Dissipation of EQ energy

• CD
• Ductile Yielding of Members

• Damper
• Energy Dissipation Devices

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EQ Performance

• Damper
• Protect Non structural Components
• Less Damage

• CD
• Protect Connections
• Will See Damage
• Permanent Offset

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Anticipated Life-Cycle Cost Performance
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Quantitative Resiliency
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Confidence Level Calculations

• FEMA 350 Methodology
• Confidence Level f(l, k, bUT)
• l Confidence Index Depends on
• Demand Variability
• Analysis Uncertainty
• f Factor
• DCR
• bUT Uncertainty Measure

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Evaluation

• PBD Building no Column Hinge
• Even Though CD Building Meets Performance Point
  Lower Confidence

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Confidence Level For MCE Performance
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Conclusions

• Damped Structures Provide Higher Performance
• Damped Structures Provide a Less Cost Solution
• Damped Structures Provide Higher Confidence Level
• Life Cycle Performance of Damped Building is
  Superior
• A Great Communication Tool