Lee County, Florida - Aspire - The Concrete Bridge Magazine

COUNTYCONCRETE BRIDGESIN LEE COUNTY, FLORIDAby Paul Wingard, Clay Simmons, and Ehab Guirguis, Lee County, Fla.A view from under the Sanibel IslandBridge A revealing its unique piers.Lee County is located along the picturesquesouthwest Gulf Coast of Florida and includesthe famous Sanibel and Captiva Islands. The LeeCounty Department of Transportation (LCDOT) ischarged with the maintenance responsibility of 128bridge structures within Lee County. LCDOT’s bridgesrepresent approximately 1.16% of the total numberof bridges in the state of Florida.The majority of these bridges are located in ahigh humidity, salt-water environment, so corrosionresistance is of utmost importance to the servicelives of our bridges. LCDOT has found that bridgesconstructed of reinforced concrete fulfill these needsnicely and provide reliable service life to supportgrowing traffic demands as our population continuesto increase.Twenty-eight of our 128 bridges, or 22%, areconcrete box culverts crossing small to mediumwidth canals and bodies of water where navigation isnot a consideration.Thirty-nine bridges (31%) are constructed usingprecast, prestressed concrete slabs. These bridges areusually located over medium-width bodies of waterand small navigable canals.Bridges over Lee County’s largest bodies of water,including the newly completed Sanibel CausewayBridges, are constructed with precast, prestressedconcrete piles and beams. This is typical of thepractice for such bridges located across the stateof Florida. These large bridges represent anadditional 19 structures or 15% of Lee County’soverall inventory. Included in this category are threefunctioning drawbridges.The remainder of those qualifying as bridgesaccording to the Federal Highway Administration(FHWA) definition as having an effective span lengthof 20 ft or greater, consist primarily of small concreteculverts providing crossings over such features asdrainage ways. All public bridges in Lee County thatmeet this FHWA bridge definition are inspected bythe Florida Department of Transportation (FDOT) atleast once every 2 years.With an average age of 25.7 years, we are pleasedwith the performance of reinforced concrete asour primary bridge construction material. Noneof Lee County’s bridges are currently classified asstructurally deficient according to FHWA/FDOTcondition inspection and rating guidelines.In addition to material selection, Lee Countybelieves that preventative maintenance routines playa significant role in keeping the county’s bridgesin the best possible condition. LCDOT is fortunateto have in-house bridge repair crews, comprisingseven bridge technicians that handle most requiredmaintenance including concrete spall repairs, jointrepairs, guardrail repairs, vessel fender repairs,routine substructure cleaning, and drawbridgemaintenance. Qualified contractors are procured forlarger repairs and long-term comprehensive bridgerehabilitation projects.In 2007, LCDOT completed construction of theSanibel Causeway Bridges. The three bridges wereconstructed using precast, prestressed concretebulb-tee beams. The bridges have a total length ofapproximately 1.6 miles and contain 6.6 miles ofprecast beams. They use 13,339 yd 3 of concrete inthe superstructure, 14,087 yd 3 of concrete in thesubstructure and 28 miles of 30-in.-square, hollow,precast, prestressed concrete piles. In addition tothe piles and beams, much of the substructure, thefootings and columns, were also precast elements,constructed at a temporary casting yard set up closebywithin Lee County.In the future, LCDOT will continue to use concreteas our primary construction material to build newbridges as an efficient, cost-effective, and timelymaterial for bridge construction along the Gulf Coastregion of Florida.___________________Paul Wingard is deputy director,Department of Transportation, ClaySimmons is division director, Departmentof Transportation Operations, and EhabGuirguis is bridge engineer, all with LeeCounty, Fla.The Midpoint Bridgewas constructed in1997.The three Sanibel Island Bridges werecompleted in 2007 and have a totallength of 1.6 miles. Photo: FloridaAerial Services Inc.

Silica Fume AssociationThe Silica Fume Association (SFA), a not-for-profit corporation based in Delaware, with offices inVirginia and Ohio, was formed in 1998 to assist the producers of silica fume in promoting its usage inconcrete. Silica fume, a by-product of silicon and ferro-silicon metal production, is a highly-reactivepozzolan and a key ingredient in high performance concrete, dramatically increasing the service-life of structures.The SFA advances the use of silica fume in the nation’s concrete infrastructure and works to increase the awareness andunderstanding of silica fume concrete in the private civil engineering sector, among state transportation officials and in theacademic community. The SFA’s goals are two-fold: to provide a legacy of durable concrete structures and to decrease silicafume volume in the national waste stream.Some of the recent projects completed by the SFA, under a cooperative agreement with the Federal Highway Administration(FHWA), include:• The publication of a Silica Fume User’s Manual—the manual is a comprehensive guide for specifiers, ready mixed andprecast concrete producers, and contractors that describes the best practice for the successful use of silica fume in theproduction of high performance concrete (HPC).• The introduction of a Standard Reference Material (SRM) ® 2696 Silica Fume for checking the accuracy of existinglaboratory practices and to provide a tool for instrument calibration. This SRM is available from the National Instituteof Standards and Technology (NIST).A much anticipated research program nearing completion by the SFA is the testing of in-place silica fume concrete underservice conditions. At the conclusion of this research the results will demonstrate the benefit of silica fume concrete’sunparalleled long-term performance. For more information about SFA, visit www.silicafume.org.QAEdison Bridge, Fort Myers, FloridaHow do you connectthe rebar?Use the…NMBSplice-Sleeve ®System.How to do it in Precast…cross-sectionQAHow is the moment connection made?All you need is an emulative detail,reconnect the concrete and rebar.Mill Street Bridge, Epping, New HampshireSPlice Sleeve NortH AMericA, iNc.192 Technology Drive, Suite J • Irvine, CA 92618-2409PHONE: 949-861-8393 • FAX: 949-861-8419 • e-mail: info@splicesleeve.comwww.SPliceSleeve.coM11003_SPLICE_.5bridge_win08.indd 111/30/07 10:51:14 AMASPIRE, Spring 2009 | 47