Post-EQK Damage Assessment of Bridges Marc J. Veletzos, Ph.D., P.E. - PowerPoint PPT Presentation

Post-EQK Damage Assessment of Bridges Marc J. Veletzos, Ph.D., P.E. Merrimack College Post-Earthquake Reconnaissance Workshop 2015 EERI Annual Meeting April 3, 2015

Some Questions for You  Who is…  An Undergraduate Student?  A Graduate Student?  Who has taken…  EQK Engineering Class?  Bridge Design Class?  Concrete Design Class?  Steel Design Class?  Who is from…  West coast?  East coast?  Middle states?

Outline  Current State of Practice  Reinforced Concrete Bridge Behavior  Inspection and Assessment Protocol of RC Bridge Columns  Questions

Current State of Practice A Broad Perspective

ATC-20 (Buildings)  Three placard postings:  No apparent hazard  Hazardous condition exists  Extreme hazard present Source: ATC, 2005

Assessment Procedures (Bridges) ATC-20 equivalent  Indiana DOT and  Kentucky DOT Pre-investigation, , and procedures   Mississippi DOT , , and  New York DOT  Aerial reconnaissance, , , and  Oregon DOT (multi-hazard)  First look, , , and  Utah DOT  Initial reports, , , and  Washington DOT Level I investigation, , , and 

Washington DOT Emergency Response Inspection Procedure Unsafe (red) Forensic (Engineering Unsafe Investigation Evaluation) (red) Collapsed Unsafe (orange) Limited Not Repair/ Level I Level II Level III Event Entry Collapsed Rebuild (yellow) Limited (Rapid (Detailed Entry Evaluation) Evaluation) (yellow) Safe End (green) Safe (green) : Inspection procedure Legend: : Inspection rating Source: Reed and Wang, 1993.

NY DOT Damage Assessment Types - Aerial Reconnaissance

NY DOT Damage Assessment Types

NY DOT Damage Assessment Types - Preliminary Bridge Damage Assessment

NY DOT Damage Assessment Types - Special Post-EQK Bridge Inspection

NY DOT Damage Assessment Types - Further Investigation

NY DOT Process Flowchart (Mobilization of Assets) * In RL1, RSE receives notification EVENT RE receives text message and/or email If you have a M w =4, notification from USGS* do you inspect every No Mw ≥ 3.5? Response Level I: Reports of damage? As directed by RSE. bridge in your state? Yes Affected residency conducts Preliminary Bridge Damage Assessment (PBDA) starting with state bridges on priority routes and reports findings to RSE. No Damage found? Uncertain? Yes RSE arranges for inspection of any critically important bridges within radius of concern (R). Response Level II: Response Level III: Response Level IV: 3.5 ≤ Mw < 4.5 4 .5 ≤ Mw < 5.5 Mw ≥ 5.5 R = 40 miles R = 60 miles R = 80 miles Conduct Aerial Inspect damage bridges Inspect damage bridges Reconnaissance found in PBDA and found in PBDA and seismically vulnerable seismically vulnerable Inspect all bridges in 80 bridges in 40 miles bridges in 60 miles mile radius, starting radius. radius. with damaged and Inspect bridges with Inspect bridges with VR seismically vulnerable VR = 1 or VR =2 = 1 or VR =2 bridges Flag bridges per DOT policy. Call for further investigation if necessary STOP Sources: O’Connor, 2010.

Reinforced Concrete Bridge Behavior A more detailed perspective

Possible Location of Plastic Hinges in Bridge You need to know where to look for damage!

Longitudinal Bar Buckling of Pre '71 Design

Pull Out Failure of Pre '71 Design

Flexural Damage at Base of Column. Note spalling of concrete

Flexural Failure of Post '94 Design

Shear Failure of Pre '71 Design

Shear Failure in Hinge Region

Column Lap Splice Failure

Shear Failure Below Flare

Flexural Failure of Flared Column (Note: Research columns are tested upside down for convenience)

Connection/Joint Shear Failure

Abutment Shear Key Failure

Bearing Failure due to Sliding

Inspection and Assessment Protocol of RC Bridge Columns An approach proposed to Caltrans

PHASE I – DETERMINE PERFORMANCE CURVE How is your column likely to respond? D - Response D - Response X X Lateral Force Lateral Force X X X X SD - Response SD - Response B - Response B - Response Lateral Displacement Lateral Displacement

Column Failure Mode and Performance Curve Decision Making Flowchart 1. Column Retrofits 1. Column Retrofits F-F F-F Yes Yes Yes Yes “DUCTILE” “DUCTILE” column column column column End End End End Start Start jacket jacket flexure failure flexure failure jacket jacket retrofit retrofit retrofit retrofit No No No No Check for Check for “STRENGTH “STRENGTH Column Column DEGRADING” flexural DEGRADING” flexural Retrofits Retrofits P-F P-F Yes Yes failure but the column failure but the column column jacket column jacket End End End End will retain vertical load will retain vertical load retrofit retrofit capacity  capacity  collapse possible collapse possible “BRITTLE” “BRITTLE” No No Check “2. Aspect Ratio” Check “2. Aspect Ratio” Shear Shear End End End End and “3. Transverse and “3. Transverse dominated dominated failure failure Reinforcement”. This Reinforcement”. This column may be moved column may be moved P P Yes Yes or or to “BRITTLE” but will to “BRITTLE” but will column jacket column jacket be no better than be no better than retrofit retrofit “STRENGTH “STRENGTH “STRENGTH “STRENGTH End End End End DEGRADING” DEGRADING” DEGRADING”. DEGRADING”. 2. Aspect Ratio 2. Aspect Ratio Flexural failure Flexural failure “BRITTLE” “BRITTLE” Yes Yes Check Aspect Check Aspect L/D < 2 L/D < 2 Shear Shear End End End End Ratio Ratio Dominated Dominated Failure Failure No No 3. Column 3. Column Reinforcement Splices Reinforcement Splices “BRITTLE” “BRITTLE” Are hoops Are hoops No No Shear Shear 3a. Check 3a. Check or spirals or spirals End End End End Dominated Dominated TRANSVERSE TRANSVERSE continuous continuous Failure Failure Reinforcement for Reinforcement for Lap Splices Lap Splices Yes Yes

Column Failure Mode and Performance Curve Decision Making Flowchart “BRITTLE” Shear failure. “BRITTLE” Shear failure. Any Any Column Column 3b. Check 3b. Check Yes Yes Yes Yes The column may not retain The column may not retain longitudinal longitudinal trans rebar trans rebar End End End End LONGITUDINAL LONGITUDINAL vertical load capacity vertical load capacity splices in splices in spacing spacing Reinforcement for Reinforcement for  collapse possible  collapse possible column column > 8” > 8” Lap Splices Lap Splices “STRENGTH DEGRADING” Flexure “STRENGTH DEGRADING” Flexure failure. Regardless of column failure. Regardless of column No No No No reinforcement, under extreme cycles the reinforcement, under extreme cycles the End End End End splice may slip and act more like a splice may slip and act more like a Splicing not an issue. Splicing not an issue. strength degrading column. The column strength degrading column. The column Check Column Transverse Check Column Transverse may retain vertical load capacity. may retain vertical load capacity. Reinforcement Reinforcement  collapse is unlikely  collapse is unlikely 4. Column Transverse 4. Column Transverse Reinforcement Reinforcement #4 @ 12” #4 @ 12” Yes Yes “BRITTLE” “BRITTLE” 4a. Check Column 4a. Check Column (typ. of pre ‘72) (typ. of pre ‘72) End End End End Shear Shear TRANSVERSE TRANSVERSE or spacing or spacing Dominated Dominated Reinforcement Reinforcement > 12” > 12” Failure Failure Spacing Spacing No No Yes Yes s >= s >= “STRENGTH “STRENGTH 4b. Check Confinement 4b. Check Confinement End End End End min(6d b , 8”) min(6d b , 8”) DEGRADING” DEGRADING” of Plastic Hinge Regions of Plastic Hinge Regions Flexural failure Flexural failure (adjacent to fixed (adjacent to fixed connections at footing connections at footing and/or bent cap) and/or bent cap) No No s <= min(6d b , 8”) s <= min(6d b , 8”)  “DUCTILE”  “DUCTILE” Flexural failure Flexural failure 5. Comments 5. Comments Make note of inadequate Make note of inadequate Check Check development of column development of column Yes Yes Development of Development of l < l d l < l d End End End End long. rebar. Use this long. rebar. Use this Column Column information to assess the information to assess the Longitudinal Longitudinal bridge system bridge system Reinforcement Reinforcement No No End End End End

PHASE II – DETERMINE DAMAGE LEVEL Where is your column on each curve? Level IV Level IV Level III Level III Ductile Curve Ductile Curve Ductile Curve X X X X X X Lateral Force Lateral Force Lateral Force Level V Level V X X X Level V Level V Strength Degrading Curve Strength Degrading Curve Strength Degrading Curve Level II Level II Level I Level I Brittle Curve Brittle Curve Brittle Curve Lateral Displacement Lateral Displacement Lateral Displacement