Residual fire resistance of steel frames assessed using a multi-hazard analysis framework in OpenSees
- 1. Residual Fire Resistance of Steel Frames Assessed using A Multi-hazard Analysis Framework in OpenSees Mian Zhou Brunel University London, UK Email: mian.zhou@brunel.ac.uk - A Case Study OPENSEES DAYS EUROPE 2017 Porto, Portugal, 19-20,June
- 2. Co-authors: Liming Jiangb;Suwen Chenc;Asif Usmanib b Department of Building Services Engineering, Hong Kong Polytechnic University Emails: liming.jiang@polyu.edu.hk, asif.usmani@polyu.edu.hk c College of Civil Engineering, Tongji University,Shanghai,China swchen@tongji.edu.cn
- 3. Outline Case Study: Seismic Steel Frames Using Cementitious Passive Fire Protection Capacity: Post-earthquake fire analysis Application: Residual fire resistance assessment OpenSees Multi-hazard Analysis Framework
- 4. Seismic Analysis of Steel Frame Structures Fig1: Steel Moment Resisting Frame (SMRF) N-S Direction Fig2: Steel Concentrically Braced Frame (SCBF) N-S Direction Penthouse not Shown Two Equivalent Designs, FEMA P-751 Seven-story Office Building, Los Angeles California
- 5. Gravity Loads Earthquake Loading: 1994 Northridge Earthquake, Canoga Park Record Recorded Peak Ground Acceleration (PGA) =0.42g ; Reduction Factor = 0.65 Northridge 94 Acceleration History of Canoga Park Record Continued...
- 6. Cementitious PFP Damage Brittle; Fragile Inaccessible Post-Earthquake Residual Fire Resistance Capacity? Where is the Damage?? Building Safe for Fire?
- 7. Damage Index Interface Tensile Strain Lower Bound: 0.135% Upper Bound :0.198% YC Cementitious Coating Material
- 8. SCBF: No Damage in PFP Identified SMRF: Damages in Piers & Beams Moment Frame Beams Behave Like Beam- Columns Seismic Analysis Results & Modelling Sensitivity SCBF Model Strain Developments in Floor Beams, SMRF
- 9. Continued... Damage Scale Sensitive to Beam/Column Stiffness Ratios Model 1: Central line to central line model Model 2: Panel zone design included model Model 1 Model 2
- 10. Model 3 Model 3: Panel zone + Reduced beam section design Model 4: Leaning columns Model 2
- 11. Damage in Piers Model 3: Panel Zone + Reduced Beam Section Damage Length≈ 400 mm (16 inches) Continued... Model 3
- 12. Damage Map Schematic Damage Location Map
- 13. Thermo-mechanical Analysis of Steel Moment Frame Protected Nodal Thermal Loading Unprotected Nodal Thermal Loading0.4 m(16”) 1m (39”) Protected Nodal Thermal Loading 7m(268”) (0.0) (0.06) (0.20) (1.0) Heat Transfer Analysis Thermo-mechanical Analysis Same Seismic Analysis Model Thermal Action Wrapper for Thermal Loading Application Damage Length and Transition Length Transition Unprotected Protected W24x207 ProtectedW24x146 Pier 3Pier 2 Protected Temperature Loading at Fibres Section
- 14. Analysis Results Deformed Shape Column Failure Leads to Progressive Collapse No Longer 2 hr Fire Resistant! Global Structure Deformation History (a) T=0s, Scale =250 (b) T=1200s, Scale =250 (c) T=1545s, Scale =250 (d) T=2300s, Scale =30 Pier 3 Pier 3 Pier 3 Pier 3
- 15. Conclusions Steel Moment Frame Design Susceptible to Fire Damage Integrated Multihazard Analysis using OpenSees Effective, Efficient Development: o New Materials o Realistic Fire Scenarios Procedure to evaluate post-earthquake fire performance of steel frames: 1. Select an earthquake 2. Perform seismic structural analysis 3. Fire protection evaluation 4. Select a fire scenario 5. Perform heat transfer analysis 6. Perform thermo-mechanical analysis for the structure