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Advanced RCP Design

ACPA 2016 Pipe School – Arlington, TX. Advanced RCP Design. Matthew Jackson, P.E. Forterra Pipe & Precast. Direct Design Approach. Direct Design vs. Indirect Design Concrete Design vs. D-Load Design. 2. www.concretepipe.org. Indirect Design Method.

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Advanced RCP Design

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  1. ACPA 2016 Pipe School – Arlington, TX Advanced RCP Design Matthew Jackson, P.E. Forterra Pipe & Precast www.concretepipe.org

  2. Direct Design Approach Direct Design vs. Indirect Design Concrete Design vs. D-Load Design 2 www.concretepipe.org

  3. Indirect Design Method Analyze Pipe Installation and Support Conditions Calculate Total Load on Pipe Calculate and Apply Bedding Factors Determine Pipe Class / D-Load 3 www.concretepipe.org

  4. 4 Direct Design Method • Define Pipe Material Properties • Specify Installation Conditions • Calculate Total Load on Pipe • Calculate Design Forces • Design Pipe to Resist Design Forces www.concretepipe.org

  5. References • AASHTO LRFD Bridge Design Specifications, 7th Ed., American Association of State Highway and Transportation Officials, 2014. • Standard Practice for Direct Design of Buried Precast Concrete Pipe Using Standard Installations (SIDD), ASCE 15-98, American Society of Civil Engineers, 2000. • Concrete Pipe Technology Handbook, American Concrete Pipe Association, 2001. www.concretepipe.org

  6. Installation Methods Embankment Trench Tunnel

  7. AASHTO LRFD 12.10.2.1 “Standard installations for both embankments and trenches shall be designed for positive projection, embankment loading conditions where Fe shall be taken as the vertical arching factor, VAF, specified in Table 12.10.2.1-3 for each type of standard installation.” www.concretepipe.org

  8. Loads Earth Load Internal Fluid Load Pipe Weight Surcharge Load Live Load

  9. Earth Load ( ) é ù - æ ö B 4 π = + ç ÷ c PL w H B ê ú c 8 è ø ë û Final Grade Prism Load (PL) H Where: Bc (O.D.) • WE = w x Bc x H x Fe (AASHTO LRFD 12.10.2.1-1) WE = PL x Fe

  10. Fluid Load Effects are of little significance in small diameter pipe. Fluid weight is calculated as:

  11. Pipe Weight Always included in direct design. Pipe weight is given by:

  12. Live Loads Highway Live Load Railroad Live Load Aircraft Live Load

  13. AASHTO HL-93 Live Load

  14. Tire Contact Area LRFD (3.6.1.2.5) 10”x20” Footprint

  15. Live Load Distribution “Live load shall be distributed to…concrete pipe with less than 2.0 ft. of fill as specified in Article 4.6.2.10.” – LRFD 3.6.1.2.6a E = 96 + 1.44S (for Axle Load) E = in. S = Span (ft.)

  16. Live Load Distribution Factor (LLDF) 2 ft. of Cover or Greater

  17. Live Load Distribution – LRFD 3.6.1.2.6b Live Load Applied From “Interacting Wheels” As Opposed to Axles. Axle Load Interaction Depth

  18. Live Load Distribution • Previously: Le = L + 1.75(¾ Bc) • For 36” RCP, Le = L + 4.8125’ • Currently: Le = L + 0.06 Di • For 36” RCP, Le = L + 0.18’

  19. Live Load Distribution For single-span culverts, the effects of live load may be neglected where the depth of fill is more than 8.0 ft and exceeds the span length;” – LRFD 3.6.1.2.6a

  20. AASHTO LRFD – Lane Load “Where the slab spans primarily in the transverse direction…[and] where the slab spans primarily in the longitudinal direction…only the axle loads of the design truck or design tandem of Articles 3.6.1.2.2 and 3.6.1.2.3, respectively, shall be applied.” – LRFD Article 3.6.1.3.3

  21. Calculate Design Forces Uniform Load System Radial Load System SIDD Pressure Distribution

  22. Uniform Load System Rational Approximation Also Allowed per LRFD 12.10.4.2.1 Uniformly distributed vertical and horizontal components of pressure. First proposed by J.M. Paris in the early 1920’s.

  23. Radial Load System Pressures act normal to the pipe surface and vary as a trigonometric function. First presented by H.C. Olander in 1950.

  24. SIDD Pressure Distribution Resulted from a long range research program initiated by the ACPA in the 1970’s. Commonly referred to as the Heger Pressure Distribution.

  25. Vertical Arching Factors (SIDD) INSTALLATION Fe TYPE 1 1.35 TYPE 2 1.40 TYPE 3 1.40 TYPE 4 1.45

  26. SIDD Pressure Distribution The following equations are used to calculate the internal pipe moments, thrusts, and shears:

  27. SIDD Pressure Distribution Type 1 Installation

  28. SIDD Pressure Distribution Type 2 Installation -.437

  29. SIDD Pressure Distribution Type 3 Installation

  30. SIDD Pressure Distribution Type 4 Installation

  31. SPIDAFinite Element Analysis Soil Pipe Interaction Design Analysis

  32. Pipe Wall Design “The procedures for analysis and design are similar to those used for other reinforced concrete structures.” – LRFD C12.10.4.2.1 Design procedure is based on “limit states” criteria to ensure adequate pipe strength and serviceability.

  33. Direct Design – Articles 12.5.3 & 12.10.4.1 • Flexure & Thrust • Steel • Concrete • Crack Control • Diagonal Tension (Shear) • 7 ksi Max. Conc. Comp. Strength • Radial Tension

  34. Radial Tension

  35. Pipe Wall Design Steps: Determine required reinforcement areas based on the tensile yield strength limit. Check radial tension. Check compressive strains. Check shear. Modify design if any strength limit is exceeded. Design stirrup reinforcement (if req’d.). Check crack width.

  36. Example:

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