Reinforced Concrete Pipe Structural Design Overview Jason Kruger

Reinforced Concrete Pipe Structural Design Overview Jason Kruger CPAM Engineer www. concrete-pipe. org © 2007

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

RCP strength design ¡ Pipe Classes l l Class II – least strong III – stronger than Class II IV – stronger than Class III V - strongest 4 4

RCP manufacturing ¡ Prescriptive requirements (C 76, M 170) l Steel reinforcing cage ¡ Area ¡ Yield strength l Concrete strength Wall thickness l 5 5

Three-edge bearing test (3 -EB) ¡ 3 -EB is a proof test l l 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 6

7 3 -EB Test 7

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Three-edge bearing test (3 -EB) ¡ 3 -EB history l l l “Gold Standard” Since 1930’s Relates pipe strength to the bedding factor, Bf 9 9

Three-edge bearing test (3 -EB) ¡ 3 -EB test load is dependent on l l Pipe class Inside diameter Pipe length Loading condition (D. 01 or Dult) 10 10

Three-edge bearing test (3 -EB) ¡ D-Load l Each pipe class is associated with a specific “D-Load” l Definition: ¡ 11 “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 l There are two D-Loads that define the strength of a given concrete pipe 12 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 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 Dload” NOTE: D. 01 is the basis for concrete pipe strength design 14 14

Three-edge bearing test (3 -EB) ¡ D-Loads for each pipe class 15 15

Three-edge bearing test (3 -EB) ¡ 3 -EB test load – SAMPLE CALCULATION l l l Test pipe: 36” 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 16

Three-edge bearing test (3 -EB) ¡ 3 -EB test: passing criteria: l Cracks are no wider than. 01” l . 01” cracks less than 12” in length are considered passing 17 17

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ASTM C 76 - Tested pipe allowable for project 22 22

AASTHO Section 27 23 23

State crack specifications assessed 24 24

Discussion 26 26