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ACTT Workshop: Minnesota
June 14-16, 2004, Minneapolis, Minnesota

Appendix C (continued): Skill Set Report Forms

Structures Team
Facilitator: Paul Kivisto, Mn/DOT
Note Taker: Kevin Hagen, Mn/DOT
FHWA National Experts: Steve Stroh, URS Corporation
Vasant Mistry, FHWA, BT
Michael P. Culmo, CME Engineering
Mn/DOT, Local FHWA, or Local Experts: Romeo Garcia, FHWA
Dan Dorgan, Mn/DOT
Kevin Western, Mn/DOT
Keith Molnau, Mn/DOT
Larry Erickson, SRF Consulting Group, Inc.
Ron Berg, J&L Steel
Mark Panek, Mn/DOT
Nelson Canjura, HDR Engineering
Tom Jerde, C.S. McCrossan Construction
Idea (Short Name) Idea (Detailed Description) Implementation Details (Barriers, Skill Set Coordination, etc.)
Staging and early contracts.
  • Getting work done earlier by starting earlier.
  • Early steel contracts.
  • Letting bridges on north end of project earlier (if money is available).
  • Using steel in cold weather.
  • Cold weather epoxy with precast boxes.
  • 8 to 9 months to get segments.
  • 170,000 to 190,000 ft2 of segmental bridges.
  • Possibly change a segmental to steel.
  • Need 100,000 ft2 of segmental to be economical - could change one ramp.
  • Precast Segmental hasn't been done in MN yet - competition not there yet (more expensive).
  • Takes a while to set up for segmental suppliers but goes good when set up.
  • Precast piers.
  • Ideas to get walls built faster.
  • Tiebacks into R/W no good.
  • Cast-in place (CIP) footing with precast stem.
  • Emulation = CIP design converting to precast.
  • Could go up to 30 ft.
  • With CIP, footings easy, stems take longer.
  • Secant walls (expensive, large quantity).
  • Local precasters share responsibility with contractors.
  • No room on project for casting yard.
  • Set up precasting to be competitive.
  • Enough volume on this project to bury cost of forms.
  • Aesthetics with precast walls?
  • Can precast anything that can be CIP (counterforts included).
  • Precast counterfort walls done on 394.
  • Give contractors option of CIP or alternate.
  • Contractors required to design alternates.
  • Alternates = CIP, MSE, MBW, tiebacks, crib.
  • Just give the contractor the ground rules for walls then let them finalize design and const. (not sure of what you'll get in end - maybe allow only one type of wall).
  • Have contractors submit designs for options before letting.
  • Giving options may make for a crunch with design later. At this stage we'd want value engineering option.
  • West wall on north segment will be critical - 1 mile on piles.
  • With precast panels, could set up to 20 a day.
  • Battered forms take extra time.
  • Aesthetic of PC walls could be a tough sell (full height vertical joint ~ every 10 ft).
  • MSE issues - temp sheeting retaining 8 ft' at abutments - ½ price of CIP - ½ time of CIP.
  • How is sheeting pulled at MSE/abutment joint? Use temporary block out from abutment.
  • MSE strap length = 0.7H - utility conflicts, settlement issues.
  • Running long lengths of sheeting (only 8 ft high)? Good for contractor? Sheeting may not be needed if slopes are shallow enough.
  • In Florida MSE walls cost $20/vertical sq ft.
  • MSE walls good for different settlements, get costly when forming at top of wall, cast in place or precast option at top of wall.
  • Slip form rail on top of MSE wall.
  • Drainage considerations in MSE walls should not be a problem.
  • Right now one large contract.
  • May eliminate some small contractors.
Small overpass bridges on north end (not on critical path).  
  • Precast slab structures to speed construction.
  • Superstructures only being replaced.
  • Stay in place precast deck panels on PCB, not on steel (reflective cracking)?
Commons bridges.  
  • MSE wall abutments.
  • Pile footing, Spread footing.
  • Close rail line for a while - side walls.
  • Precast panels - need neoprene pad to set on, then make sure grout gets underneath to provide a solid bearing (solid bearing most important - need gap over beam from edge of neoprene to edge of panel).
  • Decking a bridge doesn't take that long if there aren't traffic issues. Time of pulling forms would be saved.
  • Monolithic, precast decks prefabricated on beams (German construction).
  • Stage the Lyndale Bridge so that it can all be built at once - may not be an issue because there will be a lot of room to work (100 ft) - may be better for traffic if built all at once.
Segmental bridges.  
  • Segment weight = 55T - 60T, 250T crane to lift.
  • Placed by crawler crane.
  • 1 to 2 hours to get one segment placed.
  • Four segments during 8 hour shift, temporarily constructed - need to post-tension later.Traffic OK with temp PT installed.
  • The more segmental bridges, the better for the segmental contractor.
Afternoon Session
Bridge type specifics.  
  • Br 27V73 - make it segmental to match 27V66?
    • Need to widen retaining walls.
    • Too small to make same size segmental as other five.
  • High performance concrete and steel.
  • Self-compacting concrete (no vibration needed, give up strength, tougher for field applications).
  • Use 12 in CIP, try to get 75T.
  • Shallow foundations may not work because of future excavations.
  • Sheeting incorporated into foundations to be left in place - tie into footing.
    • Slurry trench - more expensive, harder.
    • Why design for worst case? H-pile in front of footing, lagging later if excavation needed. Drilled shafts for piers - possibly 1-8-footer for each pier, soil may be better for shafts on east end of commons.
    • Works for segmental.
    • Need temporary footing of bracket off column for temporary erection.
  • Driven piles (18 in).
    • Load tests prior to letting.
    • Huge point loads in footings (not always economical - tougher design).
    • Use heavy wall sections (3/8 in wall on Wakota).
    • Drive 12 in heavy wall to more than 96T
    • Geotech.
    • Use prestressed piles with steel prices on the rise.
    • Augercast piles - no vibrations, no problem with water table, just very messy when close to water, need computer automated monitoring, increased inspection demands, 100T at 18 in.
    • For speed of construction use high capacity piles and pour cap quickly.
    • Precast piles may not be ideal for MN with varying depths of soil layers.
    • Room for pile load test?
    • $60K - $80k for auger pile test.
    • Deep soil mixing?
    • Micro-piles (5-8 in diameter) $100/lf - too expensive.
    • Drilled shafts have been done in MN recently - could be cost effective, some don't like crosshole sonic logging (CSL), $1K to $2K per test, doesn't replace testing.
    • Waiting period on fills - no, maybe 72 hours at the most.
    • Light weight fill to eliminate settlement periods.
Retaining walls.  
  • Construction questions:
    • Consider other types of walls.
    • Bringing in fill may limit rate of construction - incentives for speed of construction.
    • MSE walls are quickest and cheapest.
    • R/W not an issue on fill situations, other options considered in cut situations.
    • Utilities can't be under MSE straps, transverse crossing wouldn't be an issue.
    • Also no trees on top of MSE walls.
    • Use soil nailing under frontage road near 46th Street.
    • Walls on north end.
    • Precast wall types.
    • Stability of foundations for future excavations.
    • 1 mile of walls on piling - may control rate of work.
  • Final Recommendations:
    • Contractors would need list of acceptable wall types in proposal.
    • WY tee detailed to 30 ft.
    • High cost, $80/sq ft (high because of long hauling).
    • Glen Canyon.
    • Michael Culmo has sketches - will be quicker but not cheaper than CIP.
    • Aesthetic considerations.
    • MSE = $25/sq ft.
    • CIP = $50/sq ft.
    • Precast = $50/sq ft.
Design-Build (DB).  
  • Staging is the issue.
  • Project must be all DB or none.
MSE walls.  
  • Use at abutments to shorten span lengths.
Bridge 27V68.  
  • Shorten east end span and put another span on the east end?
  • Can't lengthen because we'll get into exiting ramp too much.
  • Split bridge along gore area, stagger abutment.
Bridge 27V75.  
  • Precast box vs. steel.
  • Issues:
    • Future painting of steel.
    • Fracture critical steel cap.
    • PT Concrete cap.
    • Redecking segmental is an issue, not an issue with beam bridges.
    • Erection not an issue for either.
    • Consider weathering steel.
    • Need to paint too.
    • Removal of precast segments - the whole thing may come down if things go wrong, with beams can better control things.
    • Aesthetics issues with mixed superstructure types on flyovers.
    • If bridge needs to open in spring 2007, bridge may need to be steel.
    • May need early steel contract.
    • Steel tub section vs. steel I-section.
  • North end of bridge controlled by retaining wall heights (approaching 50 ft).
  • Make other flyovers steel if this one needs to be steel.
  • Construction questions:
    • Use steel for this bridge?
    • When does it need to be done? - Stage 0 (says construction staging).
    • Can't start till 2007 now, could start a year earlier if steel used.
    • Could also benefit by changing location of piers for bridge 27V79 - get farther from travelways (reduce lane closures).
    • Bridge open by spring 2007 to save the time.
    • Use CIP box superstructure.
    • More money than early steel because have to pay for whole bridge.
  • Steel box cost 20 percent more than steel I-girders, and more difficult to erect.
  • Steel box may end up being economical with less steel because of torsional resistance.
  • Approximately two tubs would be required if tubs are to be used.
  • With tubs, lose deck inspection access.
  • Recommendation: When could seg bridge realistically be opened?
    • Cast Jan, Feb., March, April.
    • Erect March to June.
    • Deck, railing - June, July.
    • Open August 1, 2007.
  • Steel bridge be opened.
    • Piers and abuts July, August, September.
    • Questionable to open by fall 2006.
  • Let this bridge on its own.
Bridge 27V73.
  • See bridge type specific notes.
  • Widen out to use precast section?
  • Would have two small cores and four large cores for casting.
  • If made segmental - Stage 1 - four bridges (180 large segments, 91 small segments - could this be done), Stage 2 - two bridges.
  • 6-8 months lead time to cast stage one segments, first segment comes off in 6 months.
  • Number of different sections (two) is not an economic issue.
  • Load restrictions, onsite casting maybe at a location where weight restrictions are an issue.
  • Spend first year doing substructures then ready for segments (do-able).
  • Geotech questions:
    • Shorten bridges by eliminating cross slopes.
    • Use MSE walls to do this.
    • Drive piles so beams can be set before MSE walls built.
    • Use 30 ft approach panels for compaction issues behind MSE walls.
    • Spread footings on bridges.
General bridge.  
  • Self compacting concrete - works best in precasting yards where there is more control.
    • Usually lose strength.
    • OK for drilled shafts.
    • No real advantage for field applications.
  • High performance steel - silent in new code.
  • High performance concrete.
    • High fly ash.
    • Silica fume.
    • Already used by Mn/DOT.
RR Bridge (27V74).  
  • Build bridge off site then haul into place.
  • Salvage existing substructures.
  • Rigid frame structure.
  • Conspan structure.
Final Recs.
  • See bridge type specific notes.
  • Bridge 27V75.
  • Steel:
    • Needs to be steel only 8 months prior.
    • Probably done by fall 2006.
    • Box vs. I-girder.
  • Segmental:
    • Done by July/Aug 2007.
    • What really is the critical path?
  • Retaining Walls.
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Updated: 10/27/2015
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