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Precast Box Culverts & Crown-Span

Design Criteria: AASHTO Section17 Materials and Purchasing Criteria: ASTM C1433 or as appropriate. Installation Criteria: AASHTO Division 11, section 27 and state modifications thereto. Concrete Cover Over Reinforcement (CCOR): AASHTO Divisi

0' to 2' fill: CCORto, Top-Outside = 2.0 in. CCORti, Top-Intside = 1.0 in. CCOR, All other = 1.0 in. 2' Fill. CCORto, CCORti, CCOR, Top-Outside = 1.0 in. Top-Inside = 1.0 in. All Other = 1.0 in.

Material Properties:

Design Concrete Strength .................................. fc ...................... 5 ksi ....................................... AASHTO 17 . 7 . 2 . 1 Reinforcement Yield Stress ............................... fy .................... 85 ksi ....................................... AASHTO 17 . 7 . 2 . 2 Concrete Density ............................................... rhoc .......... 150 pcf ....................................... AASHTO 3 . 3 . 6

Load Factors:

Dead Load Factor for Moment and Shear ......... DLFmv ........... Dead Load Factor for Thrust .............................. DLFn .............. Live Load Factor for Moment and Shear ........... LLFmv ............ Live Load Factor for Thrust ................................ LLFn ............... 1.3 ....................................... AASHTO 3 . 22 . 1 1.0 ....................................... N/A 2.17 ........ (Betol = 1.67) ...... AASHTO 3 . 22 . 1 1.0 ....................................... N/A

Capacity Reduction Factors:

Shear ................................................................. phiv .............. 0.90 ....................................... AASHTO 17 . 7 . 4 . 6 Flexure ............................................................... phif ............... 1.00 ....................................... AASHTO 17 . 7 . 4 . 6

Soil Properties:

Soil Density ........................................................ rhoE ......... 120 pcf ....................................... AASHTO Minimum Laterial Soil Pressure Coefficient ....... CoMin .......... 0.250 ...................................... AASHTO Maximum Laterial Soil Pressure Coefficient ...... CoMax ......... 0.500 ...................................... AASHTO Soil Structure Interaction Factor ........................ SIF .............. 1.0 .......................................... AASHTO (Alter required height of fill for SIF not equal to 1.0, if needed.) (CoMin - Used to determine negative moments in slabs and positive moments in walls.) (CoMax - Used to determine positive moments in slabs and negative moments in walls.) 6.2.1 6 . 2 . 1 & 3 . 22 6.2.1 17 . 4 . 4 . 2

Live Load Data:

Live Load ........................ HS-20 and Alt-1 (Alternate Interstate Fig. 3.7.7A) AASHTO 3 . 7. 6 Tire Contact Area, Lwh = 8 in. x BetoL: 2' : Wwh = 20 in., Wwh = 20 in., <2' : Wwh = 4 + FT. AASHTO 3 . 30 & 3 . 24 . 3 . 2 Live Load Distribution ........................................ 1.75 x H ........................................................ AASHTO 6 . 4 . 2 & 3 . 24 . 3 . 2

Allowable Reinforcement Spacing:

Circumferential wire spacing to be not less than 2 in., nor more than 4 in. Circumferential wire spacing of As1 to be not more than s1. Circumferential wire spacing of As2 to be not more than s2. Circumferential wire spacing of As3 to be not more than s3. Longitudinal wire spacing to be not less than 2 in., nor more than 8 in. using welded wire fabric. Longitudinal distribution reinforcement may be welded wire fabric and / or deformed bars.

Depth to Reinforcement:

d = h - CCOR - dw / 2 dw = SQR(As / NLAY x s l / b) x [NLAY + .4 x (NLAY - 1)] d - Depth to reinforcement. dw - Diameter of reinforcement wire. CCOR - Concrete cover over reinforcement at tension face section. h - Section thickness: Includes haunch, H, for sections at face of supports. (Except in calculation of minimum reinforcement). Two layers of reinforcement, NLAY, presumed for depth calculation except for crack control design where 1 layer is more conservative. (Multiple layers increase the number of wires.) Smooth welded wire fabric presumed for crack control.

Design Designation: Box Span (ft.) Crown-Span (If Applicable)

Example - 1006A215

Design Specification:

A - AASHTO Fill Range: 02 0' - 2' 05 2' - 5' 10 5' - 10' 15 10' - 15' Remainder in 5' increments

CS

10

06 A 2 15

Live Load: 1 - HS 20 - 44 2 - AASHTO Alternate Interstate 7 - AASHTO HS - 27 8 - A. R. E. A. Cooper E80

Box Rise (ft.)

Expanded: 10' x 6' AASHTO / ASTM alternate interstate for 10' to 15' fill.

TITLE NEW ENGLAND SECTION PAGE

.

DATE

AASHTO / ASTM Precast Section Design Parameters

8.12

05-15-08

HEIDELBERGCEMENT Group

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