Quantifying Seismic Bridge Performance in Terms of Loss and Sustainability

Quantifying Seismic Bridge Performance in Terms of Loss and Sustainability From Earthquake Image Information System, University of California Berkeley! Kevin Mackie Visiting Professor - ETH Zurich Associate Professor - University of Central Florida Kevin.Mackie@ucf.edu mackie@ibk.baug.ethz.ch Aristotle University March 20, 2013

2 Seismic vulnerability: Collapse Bridge is not safe No traffic Detours, delays Questions: Rebuild/repair costs? Traffic routing? How long will it take?

3 Seismic vulnerability: Damage, no collapse How safe is the bridge for traffic? How quickly can repairs be made? Load rating?

4 Seismic vulnerability: Slight damage Repair? Disregard?

5 Economic decisions for bridges Total Losses Life cycle cost analysis (LCCA) perspective of post-earthquake losses Direct Losses repair replacement Repair cost Replacement cost Repair time Indirect Losses loss of traffic function closure Immediate access Emergency only Closed Component Level Bridge Level But how to quantify the environmental cost/losses?

6 PBEE: Overview & motivation Performance-based earthquake engineering Trend away from prescriptive approaches Performance metrics meaningful to engineers, stakeholders, practitioners, and owners alike Repair Cost Repair Time Carbon Footprint Focus on quantifying damage and consequences, not only demand Requires multi-disciplinary view of seismic risk assessment for bridge-ground systems

7 A roadmap to PBEE for bridges Local Linearization Repair Cost and Time (LLRCAT) methodology: Seismic Hazard Analysis Response Analysis Damage Analysis Repair Estimates Repair Cost Loss Analysis RC: repair cost decision variable UC: unit repair cost IM: intensity measure EDP: engineering demand parameter DM: damage measure Q: repair quantity Repair Time Loss Analysis RT: repair time decision variable PR: labor production rate Demand models Damage models Sustainability Loss Analysis CF: carbon footprint decision var. Scope multipliers Repair models Loss models Hazard characterization Demand Simulation Damage & Loss Estimation Mackie, et al (2010). Post-earthquake bridge repair cost and repair time estimation methodology." Earthquake Engineering and Structural Dynamics, 39(3): 281-301.

8 Loss modeling Probabilistic loss/decision model Separate the repair model from the loss model Becomes an assembly-based procedure (vector) Divide bridge-ground system into performance groups (PGs) or repair groups (RGs) Contains a collection of components that reflect global-level indicators of structural performance and that contribute significantly to repair-level decisions Need to reassemble losses from PG to get total (requires correlation)

9 Damage & loss models 1.) Define Performance Groups (PG) and response metric (EDP) that captures behavior of PG P[DS > ds j ] DS1 DS3 EDP Repeat for each PG 2.) Define discrete Damage States (DS) for each PG. Each DS has a fragility function 4.) Perform cost and schedule estimation 3.) Define a repair method for each DS that specifies material quantities Item! Repair Item Description! Unit! Unit Cost! Q1! Replace column! SF! $ 120! 80! Q2! Inject cracks with epoxy! LF! $ 80! 3! Q3! Steel column casing! LF! $ 2,000! 45! Q4! Bridge bar reinforcement! KG! $ 2! 5! Q5! Replace joint seal assemblies! LF! $ 900! 7! Q6! Replace elastomeric bearing! EA! $ 3,000! 2! Q7! Replace abutment back wall! LF! $ 1,000! 15! Q8! Replace abutment shear key! EA! $ 2,000! 12! Q9! Remove and replace approach slab! SF! $ 30! 6! Q10! Refinish bridge deck! SF! $ 13! 2! Prod. Rate! DS1 DS2 DS3 9

10 Outcomes Possible outcomes of performance assessment Fragilities P[EDP] P[DM] P[DV] Demand fragility Damage fragility Decision fragility IM IM IM Hazard curves λ λ λ Demand hazard Damage hazard Decision hazard EDP DM DV Response as function of intensity DM, DV, etc. IM

11 Procedure for bridge-specific data 1. Define performance groups (PG) PGs are collections of structural components that are grouped by engineering demands and related repair methods. 2. Define damage states (DS) Each PG has 1 or more discrete damage states with a repair method (and a fragility). 3. Create damage scenarios Scenarios provide specificity needed to estimate quantities, costs, and time for repairs among various damage states. 4. Estimate damage scenarios Repair estimates for the damage scenarios provide cost and repair time data. 5. Perform life-cycle analysis (LCA) Repair model and initial construction data used to generate carbon footprint or embodied energy.

12 Calibration study Ketchum, et al. (2004). Influence of Design Ground Motion Level on Highway Bridge Costs, Report No. Lifelines 6D01, Pacific Earthquake Engineering Research Center, University of California, Berkeley. Testbed Type 1A bridge from Ketchum (2004) Potentially liquefiable layer

13 1. Define Performance Groups (PG) Each performance group is related to an engineering demand parameter (EDP) that characterizes earthquake performance 9 categories, total of 27 PGs Columns Maximum Drift Columns Residual Drift Bearings Shear Keys Column Foundations Abutment Foundations Abutments Deck and Superstructure Approaches

14 2. Define Damage States (DS) Each performance group has one or more discrete damage states. Each damage state also has a specific repair method with material quantities dependent on bridge information. DS0 DS1 DS2 DS Onset of damage Maximum possible damage

15 3. Damage and repair scenarios Mackie et al. (2011). "Bridge damage and loss scenarios calibrated by schematic design and cost estimation of repairs." Earthquake Spectra, 27: 1127-1145.

16 3. Damage and repair scenarios Mackie et al. (2011). "Bridge damage and loss scenarios calibrated by schematic design and cost estimation of repairs." Earthquake Spectra, 27: 1127-1145.

17 4. Repair cost and time estimation Schedule and cost estimate for minor damage scenario Contract Item! Unit! Quantity! Price! Amount! Temporary Support! SF! 7,605! $38.00! $288,999.00! Clean Bridge Deck! SF! 26,910! $0.40! $10,764.00! Bridge Removal (Portion)! CY! 30.3! $2,355.00! $71,238.75! Structure Excavation (Bridge)! CY! 189! $165.00! $31,185.00! Structure Backfill (Bridge)! CY! 114! $220.00! $25,080.00! Aggregate Base (Approach Slab)! CY! 10! $325.00! $3,250.00! Furnish Piling (Class 140) (Alternative W)! LF! 840! $55.00! $46,200.00! Drive Pile (Class 140) (Alternative W)! EA! 14! $9,000! $126,000.00! Structural Concrete (Bridge Footing)! CY! 75! $520.00! $39,000.00! Structural Concrete (Bridge)! CY! 30.3! $2,225.00! $67,306.25! Structural Concrete, Approach Slab! CY! 43! $2,625.00! $69,875.00! Bar Reinforcing Steel (Bridge)! LB! 20,186! $1.35! $27,251.10! Column Casing! LB! 10,540! $10.00! $105,400.00! Furnish Bridge Deck Treatment Material! GAL! 299! $85.00! $25,415.00! Treat Bridge Deck! SF! 26,910! $0.55! $14,800.50! Replace Bearing! EA! 3! $1,500.00! $4,500.00! Inject Crack (Epoxy)! LF! 12! $215.00! $2,580.00! Repair Spalled Surface Areas! SF! 23! $300.00! $6,900.00! Joint Seal Assembly (MR 4)! LF! 78! $275.00! $21,450.00! Drill and Bond Dowel! LF! 50! $55.00! $2,750.00! Subtotal! $989,936.00!

18 Outcomes: Repair cost model Total repair cost ratio (%) 40 35 30 25 20 15 Fixed mean Springs mean Fixed + / 1 Springs + / 1 P[RCR < rcr] Mackie et al. (2008). "Integrated probabilistic performance-based evaluation of benchmark reinforced concrete bridges." PEER Report No. 2007/09, Pacific Earthquake Engineering Research Center, University of California, Berkeley. 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 10 0.2 Fixed 2% in 50 yr Springs 2% in 50 yr 5 0.1 Fixed 50% in 50 yr Springs 50% in 50 yr 0 0 0 5 10 15 20 0 20 40 60 80 100 120 140 160 180 200 Total repair cost ratio (%) 25 30 IM = PGV SRSS (cm/s) Repair Cost Ratio (RCR) = repair cost / construction cost Can integrate with site hazard to get MAF of exceeding RCR For hazard levels, also defines RCR probability distribution

19 Outcomes: Repair time model Mackie et al. (2008). "Integrated probabilistic performance-based evaluation of benchmark reinforced concrete bridges." PEER Report No. 2007/09, Pacific Earthquake Engineering Research Center, University of California, Berkeley. Total repair time (CWD) 200 180 160 140 120 100 80 60 Fixed mean Springs mean Fixed + / 1 Springs + / 1 40 20 0 0 20 40 60 80 100 120 140 160 180 200 IM = PGV SRSS (cm/s) Repair quantity used as trigger only, uncertainty from PR Repair time (CWD) = total crew working day effort (not critical path)

20 Cost disaggregation by repair quantity Contribution to expected repair cost ($) 2.5 2 1.5 1 0.5 3 x 105 Fixed-base case 0 0 50 100 150 200 IM = PGV SRSS (cm/s) Structure excavation Structure backfill Temporary support (superstructure) Temporary support (abutment) Structural concrete (bridge) Structural concrete (footing) Structural concrete (approach slab) Aggregate base (approach slab) Bar reinforcing steel (bridge) Bar reinforcing steel (footing, retaining wall) Epoxy inject cracks Repair minor spalls Column steel casing Joint seal assembly Elastomeric bearings Drill and bond dowel Furnish steel pipe pile Drive steel pipe pile Drive abutment pipe pile Asphalt concrete Mud jacking Bridge removal (column) Bridge removal (portion) Approach slab removal Clean deck for methacrylate Furnish methacrylate Treat bridge deck Barrier rail Re center column Contribution of repair quantities to expected repair cost as a function of intensity

21 Cost disaggregation by repair quantity Fixed-base case Contribution of repair quantities to expected repair cost as a function of intensity

22 Cost disaggregation by PG 3 x 105 Contribution to expected repair cost ($) 2.5 2 1.5 1 0.5 Fixed-base case Max tangential drift ratio col 1 SRSS Max tangential drift ratio col 2 SRSS Max tangential drift ratio col 3 SRSS Max tangential drift ratio col 4 SRSS Residual tangential drift ratio col 1 SRSS Residual tangential drift ratio col 2 SRSS Residual tangential drift ratio col 3 SRSS Residual tangential drift ratio col 4 SRSS Max long relative deck end/abut disp left Max long relative deck end/abut disp right Max absolute bearing displ left abut Max absolute bearing displ right abut Max shear key force left abut Max shear key force right abut Residual vertical disp left abut Residual vertical disp right abut strain at roadway surface span 1 strain at roadway surface span 2 strain at roadway surface span 3 strain at roadway surface span 4 strain at roadway surface span 5 Residual pile cap displ left abut SRSS Residual pile cap displ right abut SRSS Residual pile cap disp col 1 SRSS Residual pile cap disp col 2 SRSS Residual pile cap disp col 3 SRSS Residual pile cap disp col 4 SRSS 0 0 50 100 150 200 IM = PGV SRSS (cm/s) Contribution of PGs to expected repair cost as a function of intensity

23 Global response including soil Lateral spreading condition with non-uniform layers Δ Δ Second order Third order 40 cm -20 cm 20 cm Shin et al. (2008). "Seismic response of a typical highway bridge in liquefiable soil." In Proceedings of 4th decennial Geotechnical Earthquake Engineering and Soil Dynamics Conference, May 18-22, 2008. Sacramento, CA. 40 cm 20 cm 60 cm

24 Comparison with fixed-base case Repair cost ratio models Same response (as fixed-base) at small intensities Foundation and residual drift column repairs govern 0 60 10 20 30 40 50 60 70 mean + 1 50 1 IM = PGV SRSS (in/s) Total repair cost ratio (%) 40 30 20 10 0 0 20 40 60 80 100 120 140 160 180 200 IM = PGV SRSS (cm/s) Kramer et al. (2008).Using OpenSees for Performance-Based Evaluation of Bridges on Liquefiable Soils, Report No. 2008/07, Pacific Earthquake Engineering Research Center, University of California, Berkeley.

25 Comparison with fixed-base case Disaggregation by PG Contribution to expected repair cost (thousand $) 0 10 20 30 40 50 60 70 300 Max tangential drift ratio col 1 SRSS Max tangential drift ratio col 2 SRSS Max tangential drift ratio col 3 SRSS Max tangential drift ratio col 4 SRSS 250 Residual tangential drift ratio col 1 SRSS Residual tangential drift ratio col 2 SRSS Residual tangential drift ratio col 3 SRSS Residual tangential drift ratio col 4 SRSS Max long relative deck end/abut disp left 200 Max long relative deck end/abut disp right Max absolute bearing displ left abut Max absolute bearing displ right abut Residual pile cap displ left abut SRSS Residual pile cap disp col 2 SRSS 150 Residual pile cap disp col 3 SRSS Residual pile cap disp col 4 SRSS 100 50 IM = PGV SRSS (in/s) 0 0 20 40 60 80 100 120 140 160 180 200 IM = PGV SRSS (cm/s)

26 Challenges Everyone focuses on components of interest (soil, column, abutment, etc.) Need a way to consider bridge-ground system response FE models produce deterministic output Need many runs to vary ground motions or other model parameters Mountains of data produced (nodal displ. of mesh, soil stresses, etc.) Need to identify response measures that can be related to consequences Structural and geotechnical engineers not typically experts in post-earthquake response and repair Need expertise of maintenance, construction, and emergency response personnel

27 Challenges to Action Expert knowledge required in each area Problem not tractable for more common bridges Need a way to move PBEE forward beyond academic exercise:

28 http://peer.berkeley.edu/bridgepbee BridgePBEE Graphical interface for integrated performance-based earthquake engineering (PBEE)

29 BridgePBEE Graphical interface for integrated PBEE Handle the input ground motion ensemble and computing the corresponding intensity measures Automatically generate user-defined bridge-ground FE models Build the post-processing capability to display seismic response ensembles, and to display PBEE outcomes

30 Ground Motion Module Graphical interface for integrated PBEE Handle the input ground motion ensemble and computing the corresponding intensity measures

31 Meshing, Soil, & Bridge Graphical interface for integrated PBEE Automatically generate user-defined bridge-ground FE models

32 Meshing, Soil, & Bridge Graphical interface for integrated PBEE Handle the input ground motion ensemble and computing the corresponding intensity measures

33 PBEE Quantities Graphical interface for integrated PBEE Handle the input of PBEE quantities Post-processing capability to display PBEE outcomes

34 BridgePBEE case study Typical 2-span California highway overpass Four ground profiles considered Rigid base (Case 1), benchmark (Case 2), soft shallow strata (Case 3), and stiff upper strata (Case 4) 0 m 5 m 10 m 15 m 20 m 25 m 30 m CASE 2 G = 45 MPa, ρ = 1500 kg/m 3 Su = 41.5 kpa G = 113 MPa, ρ = 1500 kg/m 3 Su = 74.5 kpa G = 170 MPa, ρ = 1500 kg/m 3 Su = 108 kpa G = 275 MPa, ρ = 2000 kg/m 3 Su = 142 kpa G = 325 MPa, ρ = 2000 kg/m 3 Su = 175 kpa G = 375 MPa, ρ = 2000 kg/m 3 Su = 208 kpa 2x2 CIDH Equivalent single pile CASE 3 G = 45 MPa, ρ = 1500 kg/m 3 Su = 30.0 kpa G = 45 MPa, ρ = 1500 kg/m 3 Su = 30.0 kpa G = 45 MPa, ρ = 1500 kg/m 3 Su = 30.0 kpa same as Case 2 same as Case 2 Mackie et al. (2012). ``Performance-based same as Case 2 earthquake assessment of bridge systems including ground-foundation interaction.' Soil Dynamics and Earthquake Engineering, 42: 184-196.

35 Demand assessment THA and ensemble response outputs (Case 3) 1000 100 LMLR LMSR Near SMLR SMSR Mean -1 Sigma +1 Sigma Lateral deformed shape during THA PGV cm/sec 10 Vertical deformed shape during THA PSDM for residual pile cap displacement 1 0.0001 0.001 0.01 0.1 1 Displacement (m)

36 Repair cost ratios Mackie et al. (2012). ``Performance-based earthquake assessment of bridge systems including ground-foundation interaction.' Soil Dynamics and Earthquake Engineering, 42: 184-196. Comparison of 4 bridge-ground scenarios Soil may isolate or amplify shaking felt by superstructure Reduction in column losses often offset by increased abutment and foundation losses Soft shallow strata (Case 3) highest Foundation repair governs, but columns isolated

37 Cost disaggregation Disaggregation of expected costs By major performance group By repair quantity Right abutment (PG4) Right bearings (PG6)

38 Repair times Mackie et al. (2012). ``Performance-based earthquake assessment of bridge systems including ground-foundation interaction.' Soil Dynamics and Earthquake Engineering, 42: 184-196. Comparison of 4 bridge-ground scenarios Loss models (RT) Mean annual frequencies (RT) Stiff ground cases govern Furnishing times for column repairs

39 Ideas for thought Original D-D-D Never considered downtime Focused entirely on component system damage mapping, should be considering functionality Limited DV to direct costs Need to consider broader consequences for design Sustainability Carbon footprint, embodied energy API to enable Resiliency through performanceenhanced elements End-user focuses on innovation in individual components

42 Sustainability Increasing societal interest on economic and environmental impacts of construction Carbon footprint emissions of carbon dioxide (CO 2 ), or GHG expressed in terms of CO 2 equivalents, directly and indirectly caused by an activity Life cycle assessment (LCA) considers whole life cycle (construction -> demolition) The Greenhouse Gas Protocol Year: 1000 1500 2000 390 370 350 330 310 290 270 ppm A Corporate Accounting and Reporting Standard W O R L D R E S O U R C E S I N S T I T U T E R E V I S E D E D I T I O N Emission scopes and accounting described by World Resources Institute and World Business Council for Sustainable Development (2004)

43 Additional LCA steps Hybrid LCA methodology Economic input-output (EIO) LCA Process-based LCA (P-LCA) Emission scopes Scope%1% Scope%2% Scope%3% Scope 1 direct emissions on site Scope 2 indirect emissions from purchased electricity Scope 3 indirect upstream emissions (suppliers, transportation Life-cycle phases Material extraction & processing Construction Material transportation Total Carbon Footprint by Scope 1,2 and 3! 0.00E+00% 2.00E+05% 4.00E+05% 6.00E+05% 8.00E+05% 1.00E+06% 1.20E+06% 1.40E+06% 1.60E+06% 1.80E+06% 2.00E+06% Total Carbon Footprint (g CO2-eqv)! 0.00E+00% 2.00E+05% 4.00E+05% 6.00E+05% 8.00E+05% 1.00E+06% 1.20E+06% 1.40E+06% 1.60E+06% 1.80E+06% 2.00E+06% Manufacturing% Transporta:on% Construc:on%

44 Sustainability results Carbon footprint model Similar trends with IM as cost model, but 2500 mean + 1 Mackie et al. (in progress). ``Sustainability metrics for performance-based seismic bridge response.' TBD Total carbon footprint (Mg CO 2 equiv.) 2000 1500 1000 500 1 0 0 20 40 60 80 100 120 140 160 180 200 IM = PGV SRSS (cm/s)

45 Sustainability results Different drivers for PG and Q Disaggregation by repair quantity for Scope 3 Contribution to expected carbon footprint S3m (Mg CO 2 equiv.) emissions in the manufacturing phase 400 350 300 250 200 150 100 50 Temporary support (superstructure) Temporary support (abutment) Structural concrete (bridge) Structural concrete (approach slab) Aggregate base (approach slab) Bar reinforcing steel (bridge) Epoxy inject cracks Column steel casing Joint seal assembly Elastomeric bearings Mackie et al. (in progress). ``Sustainability metrics for performance-based seismic bridge response.' TBD 0 0 20 40 60 80 100 120 140 160 180 200 IM = PGV SRSS (cm/s)

46 Conclusions Performance metrics for bridges that transcend demand Repair cost and time Carbon footprint BridgePBEE: Enabling tool for research, assessment, etc. Direct integration with NGA motions Automatic 3D SFSI meshing Automatic linking to performance groups and generation of PBEE quantities

47 Conclusions Bridges are coupled bridge-ground systems Difficult to assess demands and losses without proper consideration of soil domain/boundaries with structure Many limitations/opportunities for development Studies limited to certain classes of bridges (singlebent, straight RC overpasses) Lack of PBEE data for other bridges and systems Basically ignoring indirect costs/functionality LCCA and LCA should consider maintenance/ degradation Ultimately this is all assessment: need to decide what s important for design

48 Thank You! For more information: Kevin.Mackie@ucf.edu mackie@ibk.baug.ethz.ch