i-5, skagit river bridge collapse first annual missouri bridge conference april 9, 2015 columbia, mo...
TRANSCRIPT
I-5, Skagit River Bridge Collapse First Annual Missouri Bridge Conference
April 9, 2015 Columbia, MO
Jugesh Kapur, PE, SE
I-5, Skagit River Bridge Collapse• Bridge collapses on May 23,
2013• Struck by over height truck• I-5 the only N-S interstate in WA
state w/ ADT = 71,000• $14 billion of US-Canada
commerce passes thru I-5 annually
Courtesy: WSDOT
I-5, Skagit River Bridge Collapse
Courtesy: WSDOT
First Steps
1. Within 24 hrs – Assembled team to evaluate replacement options
2. Within 24 hrs – Selected contractor (force acct.) to remove debris
3. Within 48 hrs – Options for temp. bridge alternatives evaluated – 30 day emergency contract executed
4. Within 72 hrs – Governor and Secretary of Transportation announce plans to install temp. span w/in 30 days and reopen I-5
Courtesy: WSDOT
Next Steps
• Coordination w/ NTSB investigation
• Inspection of remaining trusses & piers
• Repairs to remaining trusses• ACROW temp bridge ordered
and pier supports modified
Courtesy: WSDOT
Temp. Span Details• Acrow panels – arrived w/in 5
days• Two temp. bridges placed side by
side using launching technique• Speed reduced to 40 mph• Opened to traffic in 27 days
Courtesy: WSDOT
Perm. Span Contract Details
1. Accelerated RFP Process
2. A+B+C = Best Value Approach
A= # hours of total closure x $660K/day B= Days past Sept 4th x $50K C= Price proposal
3. Two week proposal period – from RFP to award
4. Best value award $6.9M – Max J. Kuney & PB team
5. Anticipated opening of Sept 5th w/ 12 hr. total closure Courtesy: WSDOT
Perm. Span Options
1. Precast, prestressed deck bulb tee girders (59” deep)
2. Lightweight concrete deck bulb tee girders (65” deep)
3. Steel girders (6’ deep) w/ 3.5” precast stay-in-place panels w/ 5” CIP concrete topping
4. Steel plate girders (5’-6” deep) with CIP slab
5. WSDOT obtained all environ. permits, ROW , detour permits, etc.
Courtesy: WSDOT
Preferred Alternate
Modified deck bulb tees (lightweight concrete) chosen for:
1. Shorter fabrication time2. Greater schedule control3. Conventional construction4. Concrete wt. = 133pcf
Challenges :
1. Concrete superstructure weight less than 915 tons
2. Weight for shipping and erection
Courtesy: WSDOT
Girder Connection Details
1. Headed bars used between girders (first use in WA, based on NCHRP 12-69 research); staggered between girders
2. Full moment connection
Courtesy: WSDOT
Camber Challenges
1. Predicted camber – 5.5”
2. Vertical profile - 1.5”
3. Pre-cambered the girder forms - 4.375”
4. Used 1.5” modified concrete overlay
Courtesy: WSDOT
Perm. Span Details
Replacement Scheme – Lateral Slide
Courtesy: WSDOT
Lateral Slide Details1. Push & reset system2. 2 – 150 M-ton jacks one on each side for lateral move; 4 –
150 M-tons for vert. movement 3. Total lateral move – 75 ft4. Skid beam w/ clad stainless steel sheets; support beams w/
Teflon surface
Courtesy: WSDOT
Temp. Bents – Special Feature
Special truss span = 77 ft.
Courtesy: WSDOT
Skid Track Details
Courtesy: WSDOT
1 7
Modified Concrete Overlay
• 1 ½” modified concrete overlay• 42 hours cure time• Deck temperature between 450-750F
Courtesy: WSDOT
Placement Details
Courtesy: WSDOT
Lowering Span To Final Position
Courtesy: WSDOT
Bridge Move Summary
1. 19 hours full road closure2. Temp. span out in 25 minutes3. Permanent span into place in 45 minutes4. Superstructure lowering in 30 minutes
Courtesy: WSDOT
2 1
NTSB’s Findings (failure mechanism)
1. Truck hits the sway brace2. Vertical member L4-U4 is deformed3. Upper chord U3-U5 pulled downward4. Bucking failure in upper chord at node U4
NTSB’s Findings
1. Load 2” taller than permitted.2. Pilot car distracted by cellphone (although hands-free);
claimed that clearance pole never struck the bridge.3. Insufficient distance between pilot car and truck (less than
1/2 of what it should be).4. States should have better warnings for low-clearance
bridges.5. Provide lane specific guidance for bridge clearance.
Vertical Clearance Upgrade
Courtesy: WSDOT
Thank you.