Non-Linear Analysis & Performance-based Design: Current State-of-practice in Earthquake Engineering Short Seminar Universitas Tarumanagara, Jakarta 6 February 2004 Leonardi Kawidjaja Senior Associate PT Rekacipta Kinematika Consulting Engineers www.kinematika.com Current Global Trends • More complex structures • Higher performance requirements • More complete earthquake records • Better understanding of structural non-linear behaviour • Lessons learned from major earthquakes • Advanced earthquake protection technology • Advanced material technology • Public awareness on earthquake hazard Earthquake Engineering in 21st Century towards “Performance-based” Design
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Non-Linear Analysis & Performance-based Design: Current State-of-practice in Earthquake EngineeringShort SeminarUniversitas Tarumanagara, Jakarta 6 February 2004Leonardi KawidjajaSenior AssociatePT Rekacipta KinematikaConsulting Engineerswww.kinematika.com
Current Global Trends• More complex structures• Higher performance requirements• More complete earthquake records• Better understanding of structural non-linear
behaviour• Lessons learned from major earthquakes• Advanced earthquake protection technology• Advanced material technology• Public awareness on earthquake hazard
Earthquake Engineering in 21st Century
towards “Performance-based” Design
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Earthquake Engineering in 21st Century
Traditional Design• Force-based• Force Reduction Factor (R)• Linear Analysis• “Extrapolated” Structural Behaviour
Earthquake Engineering in 21st Century
Nature is Non Linear
Traditional Design• Force-based• Force Reduction Factor (R)• Linear Analysis• “Extrapolated” Structural Behaviour
– plastic hinge rotation, plastic strain, etc• Total Deformation:
– drift, total strain, etc
@ Performance Point !
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Non-Linear Analysis: Dynamic Time History
Earthquake time-history record
Plastic hinge formation in “real time”
Non-Linear Analysis: Dynamic Time History
Scaled Response Spectra
Peak Ground Acceleration
Scaled Time History
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Non-Linear Analysis: Dynamic Time History
Acceptance Criteria?• Inelastic Deformation
– plastic hinge rotation, plastic strain, etc• Total Deformation:
– drift, total strain, etc
Analysis Methodology
Static Pushover• Less complex• Similar to traditional method• “Pushover” force• No dynamic behaviour• No energy dissipation• No cyclic stiffness
degradation• Conventional structure
Dynamic Time History• Very complex• Numerical simulation• Real earthquake input• Non-linear dynamic behaviour• Hysteretic energy dissipation• Cyclic strength & stiffness
Toyota Football Stadium, Toyota, Japan• 40,000 seat stadium• Retractable Roof• Kisho Kurokawa Architects• Cable-stayed Grand Stand Roof• Unbonded Braced Frame• 2-level performance design:
– Level 1: pgv = 25 kine– Level 2: pgv = 50 kine
• Hyotei Special Building Permit Process
LS-DYNA: Performance Based Design
• Tension Cables• Cable Pretension• Unbonded Brace• Steel Moment
Frame• Inelastic Spring• Seismic Beam
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LS-DYNA: Design of Seismic Isolation
San Francisco Civic Center Sculpture, San Francisco, CA• 13 m tall• Light-weight tension wire “wraps”• Slender compression column• UBC Zone 4, EPA = 0.4g• Friction Pendulum base isolation
LS-DYNA: Design of Seismic Isolation
• Wire pretension• Base isolation• Inelastic Springs
• Single-storey cantilever column building• Near fault strong ground motion• Six separate compartments• Insufficient gap to avoid pounding• Mid-level and Roof-level pounding
• Seven-storey steel frame building• FEMA 273 seismic retrofit• Latticed beams & columns• Numerical simulations of cyclic and
monotonic testing of latticed beam & column sub-assemblies
• Ductility parameters
LS-DYNA: Virtual Testing
• Repeated incremental cyclic loading
• Bilinear elastoplastic shell elements
• Non-linear springs for rivet shear & tension
• Contact surface
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CURRENT STATE-OF-PRACTICE
• Not yet required by standard design codes• ALTERNATIVE design methodology• High-Performance or High-Tech structures• Evaluation of Existing Structures• Risk Assessment• Expensive: manhours & software• Limited knowledge on non linear concepts• Limited skills on non linear methodologies
Performance-based Design Exotica
THE FUTURE
• Performance-Based Design Codes• Taller, Bigger, Crooker, Better • “Active” Seismic Protection Device• Advanced Material Technology• Advanced Structural Optimisation• Powerful computing power• Lower computing cost• Advanced, affordable analysis codes• Man (woman) behind the machines• Designer or Operator?