Presentation on theme: "Material Selection Central Office Hydraulics"— Presentation transcript:
1Material Selection Central Office Hydraulics Culvert DesignMaterial SelectionCentral Office Hydraulics
2Steps for Material Selection Field ReviewCulvert HydraulicsStructural StrengthService LifeMaterial AnalysisPlan Alternates
3Field Review Determine pH of the water Use an instrument that is capable of accuracy of 0.1Use Figures through only if no flow is present when performing the field check
4Do not use unless there is no flow when performing the site visit.
5Field Review Determine if there is a presence of abrasive material. Abrasive Material – Presence of gravel, stones, or a course sand in the barrel of an existing conduit (or in the existing stream bed) that has a stream gradient or flow sufficient to cause movement of the abrasive material.Assume abrasive conditions if there is any question about the bed material.
8Field Review Investigate the condition of existing structures. If a replacement structure, look at the existing structure.If a new structure look at any adjacent existing structures.
9Culvert HydraulicsUse approved methods outlined in the Location and Design, Volume 2 Manual
10Structural StrengthStructural strength for Metal Conduits (steel and aluminum)Select the gauge thickness and corrugation profile that is adequate (based upon fill height).Figures through (steel)Figures through (aluminum) (NOT Aluminized)
19Material AnalysisFor metal conduit, choose the higher gauge thickness from the structural design, or the durability analysis.When durability thickness is higher than structural thickness, provide the 1-inch corrugation profile for pipe diameters over 48 inches.
20Plan AlternatesPlace all available material options in the plan (all metal alternatives and concrete).In some cases, only one material may be specified in the plan:If the outlet velocity in a concrete pipe requires a ring chamber and the velocity of the metal alternative is below 20fps, then metal may be used exclusively.When encountering excessive cover for a concrete pipe.
21Plan AlternatesWhere a larger corrugated metal pipe would require a higher pavement grade to satisfy minimum cover requirements, concrete may be used exclusively.Where a metal pipe arch is required hydraulically and a round concrete pipe would work, concrete may be used exclusively.Do not need to specify minimum D-loads or minimum gauge thicknesses in the item call-out.
22Plan Alternates Show the following in the plan: D-load or gauge thickness if it is above the minimum shown in the specifications.The conduit shown in the plans should be the longest length pipe (the smallest diameter).Hydraulic Design InformationOther information (see L&D, Vol. 3, Section )
23Example Problem Given: Hydraulic design requires 96 inch corrugated or 90 inch smooth linedOutlet velocities:Corrugated: V=17.0 fps & Smooth lined: V=21.0 fpsHeight of cover = 18 feetUnder a new alignment (minor state route)pH was measured and found to be 7.5
24Design ExamplePhoto from creek:Is this Abrasive?
25Example Problem Select the appropriate design alternatives. As per L&D, we will exclude concrete conduit in the design due to the velocity of 21 fps.Durability DesignSite was determined to be abrasive in natureA design service life of 75 years will be used due to the high fill height.Use Figure (75) for the durability design
27Example Problem Options from figure & notes are: 10 gauge Aluminum Coated12 gauge Aluminized & Asphalt Coated & Paved14 gauge Polymer Coated with 1” corrugations16 gauge Polymer Coated & Asphalt Coated & Paved16 gauge with Concrete Field Paving1 gauge12 gauge with Concrete Field Paving(aluminum pipe) with Concrete Field Paving(aluminum structural plate) with Concrete Field Paving
28Example Problem Structural Design of Metal Conduit Use Figure & to check for maximum height of cover:
31Example ProblemA gauge thickness of (16 gauge) will be satisfactory up to a fill height of 31 feet for all steel options except for (structural plate).A gauge thickness of (12 gauge) will be satisfactory up to a fill height of 29 feet for steel structural plate.A thickness of (the minimum for this size) will be satisfactory up to a fill height of 20 feet for aluminum pipe.A thickness of (the minimum for this size) will be satisfactory up to a fill height of 20 feet for aluminum structural plate.
32Example Problem Specifying in the Plan Specify the alternative as per L&D, Volume 3, SectionFor this example it would be as follows:603 – 180 L.F. 96” Conduit, Type A (0.138) Aluminized, with CFP, (0.280), with CFP, (1”) (0.079) Polymer Coated, (1”) Polymer Coated Asphalt Coated and Paved, (0.109) Aluminized Asphalt Coated and Paved, with CFP, with CFP