Bent Caps - By Elements and Systems - Innovative Projects - Projects - PBES - Management - Bridge

PBES

Innovative Projects

By Elements and Systems: Bent Caps

Beaufort and Morehead Railroad Trestle Bridge
Location	Over Newport River between Morehead City and Radio Island
State	NC
Completion Date	1999
Contact Person	John Frye P.E. Project Group Engineer Structure Design Unit North Carolina Department of Transportation Phone: (919) 250-4049 Email: jfrye@dot.state.nc.us
Description	A design-build project consisting of ballasted, precast prestressed T-girders spanning transverse, precast reinforced concrete caps, supported on composite piles (24-inch steel pie piles protected by 36-inch concrete cylinder pile sleeves), this project replaced 2,298 feet of trestle-span approaches on existing alignment on each side of a single-leaf rolling bascule span. Trestle spans were replaced during weekly track outages of 4-day duration. The bridge was designed and constructed to AREMA standards and to meet NCDOT's highly-corrosive coastal environment criteria. All environmental documentation and permits, design, construction, and construction engineering and inspection were done by the design-build team.
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Prefabricated Elements	Bent caps
Other Keywords	Steel pipe piles, concrete cylinder piles, prestressed girders,precast prestressed cylinder piles,prestressed 'tee' girders,speed of construction
Advantages	Speed of construction: The trestle was replaced while serving rail traffic, with individual spans replaced between scheduled trains, Minimized traffic disruption, Improved constructibility.
Contract Elements	Lump-sum design-build project
Related Document 1	Photographs (PDF, 0.7 mb) HTML Version
Photo Credits	North Carolina Department of Transportation
I-45/Pierce Elevated
Location	Downtown Houston
State	TX
Completion Date	1997
Contact Person	Kenneth L. Ozuna P.E. Texas Department of Transportation Phone: (713) 802-5435 Email: kozuna@dot.state.tx.us
Description	When a 113-span section of IH 45 in Houston's central business district needed replacing, designers estimated that a conventional bridge system would require more than a year and a half of construction. Estimating user delay costs at $100,000 a day, TxDOT opted to speed construction by using precast bent caps on the existing columns. The bridge consists of twin structures, one northbound and one southbound, and each structure was completed in 95 days, a total of 226 spans replaced in 190 days. To connect the precast caps to the existing columns, the precast caps were anchored with post-tensioning bars and hardware.
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Prefabricated Elements	Bent caps; decks
Other Keywords	Precast bent caps; precast prestressed deck panels; precast prestressed I-beams,precast deck panels with topping slab,precast pretensioned partial-depth deck panels,speed of construction
Advantages	Minimized traffic disruption: construction time was reduced from an estimated 1.5 years to 190 days, with user delay costs estimated at $100,000/day.
Related Document 1	Cap-to-Column Connection Detail Drawings (PDF, 0.5 mb) HTML Version: Sheet 1 Sheet 2 Sheet 3
Photo Credits	Texas Department of Transportation
IH80/Carquinez Strait Bridge
Location	IH80 across the Sacramento River between Crockett and Vallejo
State	CA
Completion Date	2003
Contact Person	California Department of Transportation
Description	This single bridge is 3,465 ft. long with 3 spans. This new Carquinez Strait bridge carries IH80 across the Sacramento River between Crockett and Vallejo and is an important link between Sacramento and the Bay Area. It is the first suspension bridge in the US with concrete towers. The bridge has two batter-leg concrete frame towers with classic draped cables and vertical suspender ropes to support the steel box girder deck. Each tower is supported by 12 drilled shafts that terminate in pile caps below sea level. The high cap position and deep water precluded use of conventional cofferdams, so the contractor provided a prefabricated, float-in cofferdam system. Designed as thin precast concrete shells in the shape of the specified pile caps, the cofferdams had corrugated block-outs in the bottom to allow the drilled shaft to fit up into the cap while remaining water-tight during the float-in. While the drilled shafts were installed, the cofferdams were cast on a barge deck and launched. Crews then cut the drilled shaft casings off underwater and floated the cofferdams into place. After sealing the cofferdams to the shaft casings, crews dewatered the cofferdam to allow extension of the drilled shaft reinforcing cages and then cast the pile caps. Construction completed in late 2003. This project used prefabricated cofferdams that functioned as float-in pile-cap shells. For the California Department of Transportation, use of prefabricated cofferdams expedited construction of the bridge and will increase the service life of the IH80 crossing. For the contractors, FCI Constructors and Cleveland Bridge California, use of prefabricated cofferdams greatly improved constructibility and work-zone safety.
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Prefabricated Elements	Bent caps
Other Keywords	Cofferdam system,precast bent caps
Advantages	Constructibility
Photo Credits	FCI Constructors, Inc.
Route 57 over Wolf River
Location	Fayette County
State	TN
Completion Date	1999
Contact Person	Edward P. Wasserman P.E. Tennessee Department of Transportation Phone: (615) 741-3351 Email: Ed.Wasserman@state.tn.us
Description	The Wolf River Bridge in Fayette County, Tennessee, crosses sensitive wetlands and carries the only east-west route through its geographic region. For the 20-span replacement bridge, the Tennessee Department of Transportation chose staged construction, maintaining one lane of traffic with timed signals. TDOT designers selected precast prestressed beams to facilitate speedy construction and allowed optional stay-in-place precast prestressed concrete deck forms. TDOT and the contractor developed details for precasting bent caps in two pieces to suit staged construction. Construction of the 1,408-foot long, 46-foot wide bridge was completed in eleven months without putting any equipment in the surrounding wetlands.
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Prefabricated Elements	Bent caps; decks
Other Keywords	Precast bent caps; precast prestressed concrete stay-in-place deck forms; precast prestressed I beams; steel pipe piles,precast deck panels with topping slab,precast prestressed I-beams,precast pretensioned partial-depth deck panels
Advantages	Minimized environmental disruption by eliminating the need to place equipment in surrounding wetlands, and minimized traffic disruption of an important east-west corridor.
Contract Elements	"A" plus "B" format was used. The "A" portions of the bids reflected prices for construction items. The "B" portion required the contractor to identify the number of calendar days needed to complete construction, which was then multiplied by a pre-determined price per day established by the owner.
Photo Credits	Tennessee Department of Transportation
SH 36 over Lake Belton
Location	Near Waco
State	TX
Completion Date	2004
Contact Person	Lloyd M. Wolf P.E. Design Branch Manager Bridge Division Texas Department of Transportation 125 E. 11th Street Austin TX 78701 Phone: (512) 416-2279 Fax: (512) 416-2557 Email: lwolf@dot.state.tx.us
Description	Because of fluctuating water surface elevations on the lake and uncertainties about performance of underwater precast column joints, designers chose a cast-in-place twin-column arrangement for replacement of the Lake Belton bridge. Twin bridges will be 3,840 feet long with 62 identical precast interior bent caps. The hammerhead bents will be some of the highest-moment-demand cap-to-column connections used yet with precast caps in Texas, presenting new design challenges. TxDOT bridge designers are developing design procedures extended for high-moment-demand connections. TxDOT has funded a 2002 Research Implementation Project to adapt and implement guidelines for multi-column bent cap connections to single-column, high-moment-demand connections and to continue development of specifications addressing grout placement, segregation, and durability.
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Prefabricated Elements	Bent caps; decks
Other Keywords	Precast bent caps; precast prestressed deck panels; precast prestressed U-beams,precast deck panels with topping slab,precast pretensioned partial-depth deck panels
Advantages	Constructibility: A primary source of water for Waco and an important flood control resource for the area, Lake Belton's water level is highly variable, as much as 48 ft, reaching as high as the bottom of the bridge's beams on occasion. Using precast components limits construction dependence on the lake level.
Related Document 1	Interior Bent with Precast Cap and High-Moment Connection (PDF, 1.1 mb) HTML Version: Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5
Photo Credits	Texas Department of Transportation
SH 361 over Redfish Bay and Morris-Cummings Cut
Location	Aransas County
State	TX
Completion Date	1994
Contact Person	Lloyd M. Wolf P.E. Design Branch Manager Bridge Division Texas Department of Transportation 125 E. 11th Street Austin TX 78701 Phone: (512) 416-2279 Fax: (512) 416-2557 Email: lwolf@dot.state.tx.us
Description	This project required construction of two bridges over Redfish Bay (2,020 ft.) and the Morris-Cummings Cut (415 ft.), posing the challenge of over water work on the Texas Gulf Coast. The design included precast piling as well as a precast double-tee superstructure with 44 identical bent caps, which the contractor requested to precast. Bent caps were fabricated in Corpus Christi and used epoxy-coated reinforcing to protect against corrosion in the marine environment. They were transported by barge to the bridge site and then lifted into place over epoxy-coated reinforcing steel hairpin bars embedded in the piling to form the connections. The interface between pile and the bottom of the cap was sealed, and concrete was placed through the slot in the top of the cap to complete the connection.
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Prefabricated Elements	Bent caps
Other Keywords	Precast bent caps; precast piling,precast concrete piles/columns,precast deck panels with topping slab,precast pretensioned partial-depth deck panels
Advantages	Constructibility: Using precast caps limited the amount of time required for over water work on the Texas Gulf Coast. Minimized Traffic Disruption: Using precast caps reduced project duration by about 40%.
Related Document 1	Precast Bent Caps for SH 361 over Redfish Bay and Morris-Cummings Cut (PDF, 0.5 mb) HTML Version: Sheet 1 Sheet 2 Sheet 3
Photo Credits	Texas Department of Transportation
SH 66 over Lake Ray Hubbard
Location	Near Dallas
State	TX
Completion Date	2002
Contact Person	Lloyd M. Wolf P.E. Design Branch Manager Bridge Division Texas Department of Transportation 125 E. 11th Street Austin TX 78701 Phone: (512) 416-2279 Fax: (512) 416-2557 Email: lwolf@dot.state.tx.us
Description	After 40 years of service, the narrow two-lane crossing of SH 66 over Lake Ray Hubbard had become a congested route for commuters in the suburbs east of Dallas and needed to be replaced. In 2000, construction began on a pair of conventional prestressed concrete I beam bridges with lengths of 10,280 and 4,360 feet. After the project was let for construction, the contractor asked to precast the substructure bent caps as an alternative to the original design of cast-in-place multi-column bents to reduce the amount of time the workers would need to operate near power lines. TxDOT designed a precast bent cap option that included a cap-to-column connection and a specific construction procedure that allowed early placement of caps and prestressed beams based on achieved cap concrete and cap grout connection strength. The connection design included reinforcing steel dowel bars that protrude from the columns into the precast caps via open plastic ducts that are grouted after cap placement. On this project a total of 43 bent caps will be precast.
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Prefabricated Elements	Bent caps; decks
Other Keywords	Precast bent caps; precast prestressed deck panels; precast prestressed I-beams
Advantages	Work zone safety: reduced amount of time required for work near power lines and reduced work time overwater (80% of work on caps was done on the ground).; Minimized traffic disruption: Using precast caps produced a saving of 5-7 days per cap, distributed across activities associated with formwork, curing, steel, inspection, and bearing seats.; Improved constructibility.
Related Document 1	Precast Bent Cap Column (Square and Round) Drawings (PDF, 0.6 mb) HTML Version: Sheet 1 - Square Sheet 2 - Round
Related Document 2	Precast Bent Cap Detail Drawings (PDF, 0.9 mb) HTML Version: Sheet 1 Sheet 2 Sheet 3
Photo Credits	Texas Department of Transportation
SH 66 over Mitchell Gulch
Location	SH 66 over Mitchell Gulch between Franktown and Castle Rock
State	CO
Completion Date	2002
Contact Person	Wes Goff P.E. Phone: (303) 757-9116 Email: wes.goff@dot.state.co.us
Description	Originally designed as 3 box culverts, the Colorado Department of Transportation accepted a value-engineering proposal for this replacement bridge to minimize traffic impact. The alternate structure has a single span with side-by-side precast slab girders welded onto precast abutments and wings welded to driven-steel H piles. Piles were driven in advance outside the existing bridge. Railing was precast into the outside girders. Except for the steel H-pile supports, the entire bridge substructure was composed of precast concrete elements. Each abutment consisted of a lower and upper backwall unit. Each of the four wingwalls for the bridge was a separate precast piece. The precast substructure units were attached in the field by welding together embedded plates precast into the elements. The bridge superstructure consisted of eight precast deck girder units each 5'-4" wide, 1'-6" deep, and 38'-4" long. The deck girders were placed on the completed abutments and then transversely post-tensioned and grouted together. The outside deck girders were constructed with integrated bridge railing to avoid the need for a separate railing installation operation in the field. Construction detours as a result of this project were reduced by the value-engineering proposal from an estimated two-to-three months to less than 48 hours.
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Prefabricated Elements	Total superstructure systems; bent caps
Other Keywords	Precast railing, precast retaining walls,totally prefabricated bridges
Advantages	Minimized traffic impact, improved work-zone safety by reducing work-zone time from several months to a weekend.
Related Document 1	Construction Photos (PDF, 0.4 mb) HTML Version
Photo Credits	Colorado Department of Transportation
US 290 Ramp E-3
Location	Austin
State	TX
Completion Date	1996
Contact Person	Gregg A. Freeby P.E. Design Branch Manager Bridge Division Texas Department of Transportation 125 E. 11th Street Austin TX 78701 Phone: (512) 416-2192 Fax: (512) 416-2557 Email: gfreeby@dot.state.tx.us
Description	After the contract had been let and work started, it became clear that formwork for the proposed cast-in-place cap would interfere with traffic and require closing of the ramp for an estimated 7 days. With TxDOT's approval, the contractor instead precast the straddle bent cap at the work site and lifted it into position. When it was in place, workers post-tensioned bars and grouted the cap-to-column connections. The time necessary for closure of the ramp was reduced from an estimated 7 days to 4 hours.
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Prefabricated Elements	Bent caps
Other Keywords	Precast bent cap,precast bent caps
Advantages	Minimized traffic disruption: The time necessary for closure of the ramp was reduced from an estimated 7 days to 4 hours.
Photo Credits	Texas Department of Transportation