ASPIRE Summer 08 - Aspire - The Concrete Bridge Magazine
ASPIRE Summer 08 - Aspire - The Concrete Bridge Magazine ASPIRE Summer 08 - Aspire - The Concrete Bridge Magazine
For both bridges, the piers were locatedoutside the 100-year flood levels.Looking south at segmental constructionof the south bridge pier 2 cantilever withform travelers. Abutment 1 can be seenin the background. Photo: © Jon Hirtz,Caltrans.The superstructure varies in depth from31.5 ft at the piers to 11.5 ft at theends and midspan. The single cell, boxgirder cross section has vertical websand is post-tensioned longitudinallyand transversely. The box girder has adeck width of 42.8 ft and a bottomslab width of 23.8 ft. The bridge isbeing built by the balanced cantileverconstruction method from each pierand casting on falsework near theabutments. The contractor is utilizingone set of conventional form travelers,constructing the pier 2 cantilever firstand then moving the travelers over topier 3 to construct the final cantilever.The cantilevers on each side of thepiers consist of 17 segments. The firstfour heavier segments are 13.1 ft longwhile the remaining 13 segments ofeach cantilever are 15.4 ft long. Theclosure segments are 12.5 ft long. Theheaviest segment weighs 200 tons. Thepier table length is 45 ft and is 7.5 ftout of balance toward the center spanside of the pier so that during segmentproduction the cantilever will not bemore than one-half of a segment out ofbalance. The first segment cast is on theend span side of the piers.The heights of the piers from top of thefooting to the top of the bridge deckare 200 ft. Because of this height, it wasdetermined that it was more economicalto use a hollow pier section. Thehollow piershave heavilyconfined cornerelements usingw e l d e d N o .10 reinforcinghoops spacedat 4-3/8 in.o n c e n t e r sto get the necessary ductility to meetthe California Seismic Design Criteria.The solid pier footings and caps wereclassified as mass concrete and requiredchilled water to be pumped through theelements to keep the heat of hydrationbelow specified limits. The footingsincorporated eleven 5-ft-diameter castin-drilledhole piles. The piles are upto 136 ft deep and have a nominalcompression resistance of 4382 tons perpile. The footing dimensions are 36 ftlong by 49 ft wide by 10.5 ft deep.Construction of the superstructurebegan at the pier 2 table in October2007. Early on, the contractor was ableto achieve two segments per week perpair of travelers on the first cantilever.The contractor has plans to increasesegment production to three segmentsper week prior to completing this firstcantilever. The bridge deck incorporatesan integral overlay in which an additional1 in. of cover has been provided to thedeck reinforcement for profile grinding.The bridge has also been designed tocarry a future wearing surface.The design of the bridge utilized the1990 CEB-FIP Model Code for ConcreteStructures to model the time-dependentcreep and shrinkage characteristics ofthe bridge. Testing of the contractorsmix surprisingly showed that the actualshrinkage was twice that predicted in theTypical section for the cast-on-falsework north bridge.The depth varies from 13.8 ft at the piers to 5.9 ft atthe ends and midspan. Photo: © Caltrans.Rendering of thecompleted south bridge.Pier 2 is on the right side of photo. Photo: © Caltrans.
Protecting the EnvironmentThe project is located at the northend of Mendocino County. It is withinthe majestic redwood forests nearStandish-Hickey State Recreation Area,approximately 10 miles north of thetown of Leggett where State Route 1terminates and joins U.S. Route 101.Several tourist attractions are nearbyincluding the adjacent Confusion HillMystery Spot from which the landslidegets its name.The South Fork Eel River is federallydesignated as a “Wild and Scenic River.”Because of this designation, all bridge pierswere required to be outside of the “ordinaryhigh water” level of the river in order toexpedite the environmental process on thisemergency project. This requirement causedthe bridges to have relatively large centerspans over the river. Both bridges are threespanstructures that carry two lanes of trafficand have see-through concrete barriersalong each edge of the deck.Advertisers IndexAVAR........................ 39Bentley/LEAP .. . . Inside Front CoverCampbell Scientific.. . . . . . . . . . . 51DSI. ........................ 43Eriksson Technologies.....Back CoverFinley Engineering.. . . . . . . . . . . . 29FIGG .. . . . . . . . . . . . . . . . . . . . . . . . 3Gerdau Ameristeel.............. 4Hatch Mott MacDonald ........ 33Lehigh Cement................ 25PB . ......................... 7PCAP—CABA..... Inside Back CoverSplice Sleeve. ................ 33Stalite....................... 49Standard Concrete Products..... 21T.Y. Lin International .. . . . . . . . . . . 5VSL .. . . . . . . . . . . . . . . . . . . . . . . . 38CEB model. Consequently, a shrinkagereducingadmixture was added to themix to cut the concrete drying shrinkagein half. The shrinkage results of the mixat the Devil’s Slide segmental bridgeswere similar (see article in Winter 2008ASPIRE), and a shrinkage-reducingadmixture had to be incorporated intothat mix as well.The project is progressing on scheduleand within budget. The north bridgewas completed in January 2008.The contractor is currently truckingexcavated material from the large cutsbetween the two bridges over thenorth bridge. The south bridge pier 2cantilever is expected to be completedin July, at which time the form travelerswill be moved over to pier 3. The closurebetween the cantilever tips is scheduledto be placed in early 2009._______________________Kevin Harper is a senior bridge engineerwith the California Department ofTransportation, Sacramento, Calif.For more information on this or otherprojects, visit www.aspirebridge.org.SPIRE_adfinal.indd 1ASPIRE, Summer 3/3/08 2008 6:43:22 | PM 29
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- Page 32 and 33: ECONOMICAL BRIDGEWIDENINGby Craig A
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- Page 66 and 67: South fork eel river Bridges / cali
- Page 68 and 69: Photo: Michael Baker Jr. Inc.Pomero
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Protecting the Environment<strong>The</strong> project is located at the northend of Mendocino County. It is withinthe majestic redwood forests nearStandish-Hickey State Recreation Area,approximately 10 miles north of thetown of Leggett where State Route 1terminates and joins U.S. Route 101.Several tourist attractions are nearbyincluding the adjacent Confusion HillMystery Spot from which the landslidegets its name.<strong>The</strong> South Fork Eel River is federallydesignated as a “Wild and Scenic River.”Because of this designation, all bridge pierswere required to be outside of the “ordinaryhigh water” level of the river in order toexpedite the environmental process on thisemergency project. This requirement causedthe bridges to have relatively large centerspans over the river. Both bridges are threespanstructures that carry two lanes of trafficand have see-through concrete barriersalong each edge of the deck.Advertisers IndexAVAR........................ 39Bentley/LEAP .. . . Inside Front CoverCampbell Scientific.. . . . . . . . . . . 51DSI. ........................ 43Eriksson Technologies.....Back CoverFinley Engineering.. . . . . . . . . . . . 29FIGG .. . . . . . . . . . . . . . . . . . . . . . . . 3Gerdau Ameristeel.............. 4Hatch Mott MacDonald ........ 33Lehigh Cement................ 25PB . ......................... 7PCAP—CABA..... Inside Back CoverSplice Sleeve. ................ 33Stalite....................... 49Standard <strong>Concrete</strong> Products..... 21T.Y. Lin International .. . . . . . . . . . . 5VSL .. . . . . . . . . . . . . . . . . . . . . . . . 38CEB model. Consequently, a shrinkagereducingadmixture was added to themix to cut the concrete drying shrinkagein half. <strong>The</strong> shrinkage results of the mixat the Devil’s Slide segmental bridgeswere similar (see article in Winter 20<strong>08</strong><strong>ASPIRE</strong>), and a shrinkage-reducingadmixture had to be incorporated intothat mix as well.<strong>The</strong> project is progressing on scheduleand within budget. <strong>The</strong> north bridgewas completed in January 20<strong>08</strong>.<strong>The</strong> contractor is currently truckingexcavated material from the large cutsbetween the two bridges over thenorth bridge. <strong>The</strong> south bridge pier 2cantilever is expected to be completedin July, at which time the form travelerswill be moved over to pier 3. <strong>The</strong> closurebetween the cantilever tips is scheduledto be placed in early 2009._______________________Kevin Harper is a senior bridge engineerwith the California Department ofTransportation, Sacramento, Calif.For more information on this or otherprojects, visit www.aspirebridge.org.SPIRE_adfinal.indd 1<strong>ASPIRE</strong>, <strong>Summer</strong> 3/3/<strong>08</strong> 20<strong>08</strong> 6:43:22 | PM 29
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