1. Reinforced Concrete Pipe
Structural Design Overview
Jason Kruger
CPAM Engineer

2. RCP strength design Concrete pipe strength Bedding Factor, Bf
Fill height
Traffic loads

3. RCP strength design Pipe Classes Class II – least strong
Class III – stronger than Class II
Class IV – stronger than Class III
Class V - strongest

4. RCP manufacturing Prescriptive requirements (C76, M170)
Steel reinforcing cage
Area
Yield strength
Concrete strength
Wall thickness

5. Three-edge bearing test (3-EB)
3-EB is a proof test
Obtain piece of pipe from production run
Insert pipe in 3-EB test machine
Load it to pre-determined value
Inspect loaded pipe for compliance

6. 3-EB Test

8. Three-edge bearing test (3-EB)
3-EB history
“Gold Standard”
Since 1930’s
Relates pipe strength to the bedding factor, Bf

9. Three-edge bearing test (3-EB)
3-EB test load is dependent on
Pipe class
Inside diameter
Pipe length
Loading condition (D.01 or Dult)

10. Three-edge bearing test (3-EB)
D-Load
Each pipe class is associated with a specific “D-Load”
Definition:
“The D-Load is the supporting strength of a concrete pipe loaded under three-edge bearing test conditions, expressed in pounds per linear foot per foot of inside diameter”

11. Three-edge bearing test (3-EB)
D-Load
There are two D-Loads that define the strength of a given concrete pipe

12. Three-edge bearing test (3-EB)
D-load.01 (or simply D.01)
“the maximum three-edge bearing test load supported by a concrete pipe before a crack occurs having a width of .01” measured at close intervals throughout a length of at least one foot, expressed as D-load”

13. Three-edge bearing test (3-EB)
D-loadult (or simply Dult)
“the maximum three-edge bearing test load supported by a concrete pipe, expressed as D-load”
NOTE: D.01 is the basis for concrete pipe strength design

14. Three-edge bearing test (3-EB)
D-Loads for each pipe class

15. Three-edge bearing test (3-EB)
3-EB test load – SAMPLE CALCULATION
Test pipe: ” i.d. Class III
Required D.01 = 1,350
Total 3-EB test load = Pipe i.d. X Length X D.01
= (36/12) X 8 X 1350
= 32,400 lbs

16. Three-edge bearing test (3-EB)
3-EB test: passing criteria:
Cracks are no wider than .01”
.01” cracks less than 12” in length are considered passing

19. ASTM C76
- Tested pipe allowable for project

20. AASTHO Section 27

21. State crack specifications
assessed

23. Discussion