NONSTRUCTURAL DAMAGE ASSESSMENT AND ITS IMPACT IN TALL BUILDINGS Naveed Anwar, Vice President, Knowledge Transfer Nwe Ni Sein Toe, Graduate Catherine B. Diaz, Graduate May 30 – June 1, 2019 Manila, Philippines 19th ASEP International Convention “Structural Engineering for Infrastructure Resilience” Main Structural Performance Concerns in Tall Buildings 01 02 03 04 05 06 07 Stability and integrity Strength and Servivbility Deformation Drift Ductility Energy Dissipation Motion Perception 2 To limit the structural damage and ensure public life safety Traditional Intent of Structural Design It does not concern itself with cost of “limited damage” It does not concern itself on economic loss to public 3 Is this acceptable? Even though it satisfies CBD and PBD 4 5 6 Lesson Related to Nonstructural Damage 2010 and 2011 Christchurch, New Zealand Earthquakes • • • • • • Magnitude 7.1 and 6.3 respectively Good structural behavior Small number of collapses or fatalities Large amount of Nonstructural damage Economical loss = US$17 billion Long-lasting effect for the economy 7 Report of the Earthquake Engineering Research Institute (2011) Exterior Glazing Lesson Related to Nonstructural Damage Eastern Japan Earthquake, March 11, 2011 ❖ Very little major structural damage ❖ Majority of nonstructural damage in large cities including Tokyo and Sendai For example, ❖ Ceiling damage or collapse ❖ Overturning of contents ❖ Damage or collapse older facade panels Source: Report of the Building Research Institute of Japan Fallen exterior wall panels Fallen ceiling 8 Risk posed by Nonstructural Damage in Previous Earthquakes 1989 Loma Prieta Earthquake, (Robert Reitherman) Fallen ceiling and flexible ducts 1994 Northridge Earthquake. (Wiss, Janney, Elstner Associates ) Fallen light fixtures, 1994 Northridge Earthquake(Wiss, Janney, Elstner Associate) 1994 Northridge Earthquake (Wiss, Janney, Elstner Associates) Compressor overturning (Wiss, Janney, Elstner Associates) Broken sprinkler pipe, Olive View Medical Center, 1994 Northridge Earthquake . Risk posed by Drift, Acceleration and Velocity Demand Parameters Drift sensitive damage The SPONSE Workshop in China, 2014 Acceleration sensitive damage Velocity sensitive damage 10 Seismic Risk Prediction in Bangkok Earthquake levels Loss distribution of each building component type (in % of total loss) Structural components • • • • • Nonstructural components Total loss (Million baht) No: of expected Earthquake levels collapsed buildings Building contents SLE 1 75 24 318 DBE 15 68 17 8,402 MCE 16 65 19 23,325 SLE 0 DBE 0-4 MCE 4 - 17 A total of 1433 buildings were assessed Buildings are 12 to 88-story high SLE: Service Level Earthquake (43-year return period) DBE: Design Based Earthquake (475-year return period) MCE: Maximum Considered Earthquake (2500-year return period) The Disaster Prevention and Mitigation Department of the Bangkok Metropolitan Administration (BMA) 11 Importance of Nonstructural Components Cost breakdown of sample buildings Total cost of building 120% 100% 20% 17% 44% 80% 60% 62% 20% Nonstructural component 70% 40% Content 48% Structural component 20% 13% 8% 0% Office (Whittaker and Soong, 2003) Hotel Hospital 12 Assessment of Non Structural Damage is Important • It is therefore important to Estimate the non structural damage, even though structure has been designed to Code or even if Performance Based Design has been carried out 13 Design Approaches Code Based Design Performance Based Design Consequences and Risk Based Design Resilience Based Design 14 Resilience Based Earthquake Design Economic Loses Go Beyond Life Safety! Loss of Quality of Life Loss of Community and Culture 15 Link Performance to other Indicators Restaurant Restaurant Re Operational (O) 0% sta ura nt Immediate Occupancy (IO) Life Safety (LS) Damage or Loss Collapse Prevention (CP) 99 % Lowest Casualties Highest Lowest Downtime for Rehab Highest Lowest Rehab Cost to Restore after event Highest Highest Retrofit Cost to Minimize Consequences Lowest Lowest Impact on Sustainability of Community Highets 16 Ref: FEMA 451 B Green Buildings Main authors : Arup, Supported by USRC and many others Resilient Buildings 17 ARUP 18 Methodologies for Performance Assessment of Nonstructural Components 19 Seismic Losses a) Repair cost (direct economic cost): This is the cost required to repair or replace the physical damage of nonstructural components and bring their performance back to pre-earthquake condition. b) Serious injury and casualty: It is the number of serious injuries (requiring hospitalization) or loss of life inside the building envelop. c) Downtime: It is the required time to recover the damaged nonstructural components back to pre-earthquake condition. d) Business interruption cost (indirect economic cost): It is the loss (in terms of cost) due to interruption of business or the building’s serviceability due to the damage of nonstructural components. 20 Performance Assessment Methodologies (PEER)’s Performance-based Earthquake Engineering Methodology (FEMA P-58)’s Performance Assessment Methodology Component-based Loss Estimation Method Downtime Assessment Methodology by REDi™ 21 (PEER)’s Performance-based Earthquake Engineering Methodology IM EDP DM DV • Select representative ground motion sets NOTE: • Simulate nonlinear dynamic structural response to collapse, uncertainty in response • Calculate probabilities of being in each damage state for each component and assembly IM = Intensity Measure EDP = Engineering Demand Parameters DM = Damage Measure DV = Decision Variable • Calculate repair cost for each component and assembly 22 Performance Earthquake Engineering Research Center (Keith A.Porter, 2003) (FEMA P-58)’s Performance Assessment Methodology FEMA P-58 (Volume-1) , 2012 23 Component-based Loss Estimation Method Data collection program Earthquake scenario selection Structural modeling and analysis Damage analysis Loss analysis Kanokwan Artudorn (2016) 24 Downtime Assessment by REDi™ Utility Disruption Earthquake Occurrence Impeding Factors Utility Disruptions Impeding Factors ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ ▪ Electricity Water Gas REDi™ Rating System Building repair Post-earthquake Inspection Engineering Mobilization and Review Financing Contractor mobilization Permitting Long-lead time components 25 A Typical Performance Based Evaluation and Loss Estimation Framework 26 Performance Based Evaluation Framework Collect building data Review hazard Analysis Review structural analysis Determine nonstructural damage Determine nonstructural performance Direct economic loss * Repair cost Direct social loss *Serious injury and casualty Downtime * Downtime Indirect economic loss * Business interruption cost 27 Overall Process • Determine demand parameters (Drift, velocity, acceleration ..) • Determine damage due to these demands on corresponding components (using fragility or other measures) • Determine repair/replacement cost implication of each damage • Determine downtime to carryout repairs • Determine business intruption cost • Determine casualty and injury 28 Classification of Nonstructural Component based on Demand Sensitivity Drift-Sensitive component Architectural component Nonstructural components Mechanical and Electrical component Building Content Acceleration-Sensitive component Drift-Sensitive component Acceleration-Sensitive component Acceleration-Sensitive component Velocity-Sensitive component 29 Nonstructural Damage Assessment Quantify nonstructural component Assign Component fragility Damage state-i Quantity of component Probability of damage state-1 No: of component being in damage state-1 Total number of damaged component being in n-damage states FEMA-P-58 Ceramic wall fragility (FEMA-P-58) P (DS ≥ Dsi ) 1 0.8 0.6 0.4 0.2 0 0 0.005 0.01 Drift 0.015 0.02 30 Downtime Assessment Framework Utility disruption Delay time Impeding factors Interior repair Downtime Exterior repair Repair time Mechanical repair Electrical repair Elevator repair Utility Disruptions Impeding Factors ❖ Electricity ❖ Water ❖ Gas ❖ ❖ ❖ ❖ ❖ Stair repair Post-earthquake Inspection Engineering Mobilization and Review Financing Contractor mobilization Permitting 31 Business Interruption Cost Framework Business interruption cost Downtime x Breakdown area x Rental cost per area 32 Some limitations of the Approach The collapse mode may not be determined in buildings under different earthquake scenarios. The casualties or serious injuries which could occur outside the building envelope may not be predicted. Uncertainty involved in specified component fragility functions according to FEMA fragility specifications 33 Determine Non Structural Loses A Case Study Structural Responses under Level Seismic Hazard Acceleration under SLE level 0 0.002 0.004 0.006 55 50 45 40 35 30 25 20 15 10 5 0 0.008 0 0.5 drift Drift-Y No: of story No: of story 0.01 Drift Drift-X 2 0 0.2 0.015 0.5 1 acceleration (g) Drift-Y Acceleration 0.6 0.8 1 velocity Velocity under MCE 55 50 45 40 35 30 25 20 15 10 5 0 0 0.4 velocity (m/sec) Acceleration under MCE 55 50 45 40 35 30 25 20 15 10 5 0 0.005 1.5 Acceleration Drift under MCE 0 1 55 50 45 40 35 30 25 20 15 10 5 0 Acceleration (g) No: of story Drift-X Velocity under SLE level No: of story 55 50 45 40 35 30 25 20 15 10 5 0 No: of story No: of story Drift under SLE level 1.5 2 55 50 45 40 35 30 25 20 15 10 5 0 0 0.5 1 1.5 2 2.5 velocity (m/sec) velocity 35 Overall Nonstructural Damage under both SLE and MCE 25.0% 23.17% 19.32% Percentage of damage 20.0% 15.0% 10.0% 5.0% 4.7% 3.9% 3.01% 0.6% 0.2% 0.0% Total damage Architectural damage Service level earthquake 0.84% Mechanical and electrical damage Building content damage Maximum considered earthquake 36 Repair Cost of Nonstructural Damage under both SLE and MCE Direct economic cost (Million-peso) 200 183.61 160 120 108.19 80 58.11 40 35.48 17.31 22.95 6.36 6.17 0 Total damage Architectural damage Service level earthquake Mechanical and electrical damage Maximum considered earthquake Building content damage 37 Total Nonstructural Repair Cost Service Level Earthquake Maximum Considered Earthquake Architectural repair cost 17% Content replace cost 65% Mechanical and electrical repair cost 18% Architectural repair cost 32% Content replace cost 59% Mechanical and electrical repair cost 9% 38 Nighttime population distribution Daytime-HAZUS population distribution model Daytime-FEMA population distribution model Serious Injury and Casualty Total population 716 Serious injury (People) 1 7 Casulty (People) 0 1 Total population 403 Serious injury (People) 1 4 Casulty (People) 0 1 Total population 1432 1 13 Serious injury (People) 0 1 Casulty (People) 0 200 400 Service level earthquake 600 800 1000 POPULATION (PEOPLE) 1200 1400 1600 Maximum considered earthquake 39 Downtime Assessment Downtime Method Repair Time REDi™ Guideline(1) ❖ Repair in series ❖ Repair sequence by sequence ❖ Recommended no: of labor by REDi™ REDi™ Guideline(2) ❖ Repair in parallel ❖ Maximum no: of worker by REDi™ REDi™ Guideline(3) ❖ Repair in parallel ❖ Half of maximum worker by REDi™ REDi™ Guideline(4) ❖ Repair in parallel ❖ Maximum no: of worker by REDi™ ❖ 12 hour per a day (Overtime work) REDi™ Guideline(5) ❖ Repair in parallel ❖ Half of maximum worker by REDi™ ❖ 12 hour per a day (Overtime work) 5.6 REDi™ guideline (1) 17.7 2.7 REDi™ guideline (2) 3.9 2.8 REDi™ guideline (3) 5.5 2.5 3.3 REDi™ guideline (4) 2.6 REDi™ guideline (5) 4.5 0 Service level earthquake 5 10 Downtime (Months) 15 Maximum considered earthquake 20 40 Improving Resilience • If we know the non structural damage, we can determine and improve Resilience by enhancing Non Structural Components • A Case study 41 Baseline Resilience Objectives for Design Level Earthquakes Rating Platinum Downtime Immediate Re-Occupancy (Green Tag expected) and Functional Recovery < 72 hours Direct Financial Loss Scenario Expected Loss < 2.5% Occupant Safety Physical injury due to failure of building components unlikely Gold Immediate Re-Occupancy (Green Tag e xpected) and Scenario Expected Loss < 5% Functional Recovery < 1 month Physical injury due to failure of building components unli kely Silver Re-Occupancy < 6 months (Yellow Tag p ossible) and Scenario Expected Loss < 10% Functional Recovery < 6 months Physical injury may occur fro m falling components (but n ot structural collapse), fatalit ies are unlikely 42 Resilience Earthquake Design Initiative Rating System Before No rating – Code Level Direct Financial Loss – 13.96% Downtime assessment = 1.2 years Scenario Expected Loss – mean estimated direct financial loss (50% confidence level) suffered by the facility for a given earthquake intensity level Almufti and Willford, 2013 ENHANCED PARTITION WALL 44 Gerardo Araya-Letelier et al., 2012 45 ENHANCED SUSPENDED CEILING Hanger suspension wires FEMA P-58 Effect of Enhancement Percentage of total component Overall Damage Comparison 11.4% 20.00% 18.82% 9.9% 18.00% 16.00% 14.00% 1.5% 11.32% 12.00% 10.00% 8.00% 6.00% 7.42% 6.92% 5.42% 4.00% 1.42% 2.00% 0.57% 0.57% 0.00% Mechanical and Electrical Architectural Conventional Structural Total Enhanced 46 Improving Rating Through Non-structural Enhancement 47 After - ATTAINED SILVER RATING Direct financial loss = 4.14% Downtime = 4 months Before No rating – Code Level Direct Financial Loss – 13.96% Downtime assessment = 1.2 years Almufti and Willford, 2013 Non Structural Damage Assessment Impacts • Help to differentiate between structural and non-structural damage • Understand and mitigate causes of damage beyond structure • Inform the clients and public of nature damage due to earthquakes • Help to determine building resilience • Increase public confidante and significance of structural designers profession • Can be used to enhance resilience of tall buildings and communities 48 Thank You View publication stats