PRECAST CONCRETE BOX CULVERTS

1 PRECASTCONCRETE BOXCULVERTSOUTLINE Introduction Applications Manufacturing Methods Design Procedures &Joints Installation Quality SummaryINTRODUCTIONFour-sided culvertsare typically referredto as box Standard box sizes: 3 x 2 to 12 x 12 in 1 span and rise increments. Typically come in 6 and 8 lengths. Custom box sizes: Nonstandard sizingis permissible and must be designedper project design Three-sided structures are U-shapedstructures that may or may not have acrown in the center. Standard three-sided structures rangefrom 8 to 48 span lengths. Custom sizes are available and mustbe designed per project CULVERTS Short-span bridges (over highways, waterways,railways, for golf courses, etc.) Conveyance of stormwater, sewage or industrialwastes (storm drains) Tunnels (to house conveyers, utilities, etc; to provideaccess, escape routes, etc.)

2 DetentionThree-sided CULVERTS Short-span bridges (flat and arched)APPLICATIONSAPPLICATIONSB enefits: Box CULVERTS can be made in large sizes toaccommodate increased flow rates and capacities. Boxes can be set with 0 feet to 100 feet of smallstream CONVEYANCEFast andeconomicalmethod fortunnels underroadways, as inthis golf foremergencyegress, as withthis tunnelunderneath awarehouse & ESCAPE ROUTESM ulticell boxculvertinstallation toeconomicallyprovidestorage ofstorm DETENTIONC ustomdesigned andmanufacturedbox CULVERTS areavailable, aswith thismonolithic triplecell BOX SIZESBENDS CAN BE DESIGNEDMITERS & SIDE OPENINGS Placed on stripfooting and used forshort span bridges. They allow fornatural stream bedsto remain intact andcan meet STRUCTURESL arge 3-sidedstructurew/precastheadwalls andwing STRUCTURESR oadway overroadwayapplications can beaccomplished withlong-span BRIDGESWet-Cast Typically cast on end using an inner and outer form.

3 Blockouts / hole formers can easily be incorporated. Cast with conventional CONCRETE or self-consolidatingconcrete. Product cured in the form. Wet-cast is commonly used for sanitary METHODSDry-Cast (Machine Made) Product cast using mechanized equipment. Form vibrators consolidate zero-slump CONCRETE betweencore and jacket. Hole formers may be incorporated, or coring is done asneeded. The product is immediately stripped and the form isreused. Products typically cured in a kiln, or a combination oftarps and moisture curing is used. Surface may appear textured due to METHODS Designs are dependent on projectspecifications and applications. This includes hydraulic design for fluidconveyance Conveyance Hydraulic design and sizing are usually performedusing Manning's n for open channel flow(typical values for n are for wet-cast for dry-cast).

4 This work is usually performed by the owner sengineer, who then supplies the precaster with thesize design is performed based onapplication After determining the size required, use applicablestandards for the box or three-sided structure design. This work is usually performed by the precaster or theprecaster s of common design standards: ASTM C 1433 Box CULVERTS , for conveyance ofstormwater, industrial wastes and sewage. ASTM C 1504 Three-sided structures, forstormwater conveyance and CULVERTS . AASHTO Standard Specification for Highway Bridgesfor short-span of common design standards: ACI 318, for tunnels and special design. ACI 350R, for wastewater Box CULVERTS are subject to: Lateral earth loads from soil and hydrostatic loadsfrom ground water. Vertical loads from the cover soil and live loadsabove. Surcharge loads from nearby impact loads.

5 Seismic loads where NOTESBox culvert design for stormwaterconveyanceProject data:Flow rate, Q = 1000 ft3/secLength, L = 800 feetInitial slope, So = Head Water, HW = 15 feetManning's, n= EXAMPLE After calculations, it was determinedthat a 9 x 7 box culvert will handle therequired flow. The box will supportHS20 loads: Use ASTM C 1433. Box to be set at 8 depth, use table EXAMPLE9 x 7 x 9 CircumferentialReinforcement Areas, in2 < <2 MAs8As7As6As5As4As3As2As1 Depth, ftDESIGN EXAMPLEDESIGN < <2 MAs8As7As6As5As4As3As2As1 Depth, ftDESIGN EXAMPLELess than 2 Cover - 9 x 7 x 9 Circumferential Reinforcement Areas, in2/ftDESIGN EXAMPLE ASTM C 877 JOINTS EXTERNAL WRAP ASTM C 990 JOINTS MASTIC/BUTYL Closed cellular rubber (vinyl & nitrile elastomers). Physical properties of ASTM D1056 Type 2C-1 &chemical resistance requirements of AASHTOM198.

6 Requires a joint gap. Soil tight JOINTSF emale (groove) endMale (tongue) endJOINTS Trench must remain dry during the installationprocess, dewater if necessary. Bedding must be compacted, set to grade andmeet specifications. Place groove end section first. Set subsequent boxes with the tongue end beingset into the groove to reduce bedding Backfill shall be placed uniformly on each side ofthe PRECAST CONCRETE box sections. The backfillmaterial to be placed, the percent of compaction,the depth of layers, etc., shall be as required bythe contract When purchasing andspecifying box or three-sidedprecast CONCRETE structures,you should specify certifiedplants. NPCA Certification