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1 Restraining Restraining Thrust Forces Thrust Forces Thrust Forces Thrust Forces Forces Causing Thrust Forces Causing Thrust Static forces Static forces (Internal pressure) (Internal pressure) Dynamic forces Dynamic forces (Fluid velocity) (Fluid velocity) Thrust Force Thrust Force Straight Run Straight Run PA PA PA PA Thrust Force Thrust Force Bend Bend 2PA Sin( 2PA Sin(/2) /2) Resultant Thrust: 90 Resultant Thrust: 90° Bend Bend Nominal Nominal Pipe Size Pipe Size (i ) (i ) Thrust Thrust Force Force (lb ) (lb ) Pressure at 150 psi Pressure at 150 psi (in) (in) (lbs) (lbs) 6 7,932 7,932 12 12 29,030 29,030 24 24 110,901 110,901 36 36 244,396 244,396 48 48 429,956 429,956 64 64 718,506 718,506

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Page 1: Thrust Restraint ISAWWA 1 12 - cdn.ymaws.com · Thrust Restraint Thrust Restraint -- ResearchResearch 12” MJ Pipe and fittings with DI retainer glands Movement sensing Measurement

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RestrainingRestrainingThrust ForcesThrust ForcesThrust ForcesThrust Forces

Forces Causing ThrustForces Causing Thrust

Static forcesStatic forces

(Internal pressure)(Internal pressure)

Dynamic forcesDynamic forces

(Fluid velocity) (Fluid velocity)

Thrust ForceThrust Force

Straight RunStraight Run

PAPA PAPA

Thrust ForceThrust Force

BendBend

2PA Sin(2PA Sin(/2)/2)

Resultant Thrust: 90Resultant Thrust: 90°° BendBend

NominalNominal

Pipe SizePipe Size

(i )(i )

ThrustThrust

ForceForce

(lb )(lb )

Pressure at 150 psiPressure at 150 psi

(in)(in) (lbs)(lbs)

66 7,9327,932

1212 29,03029,030

2424 110,901110,901

3636 244,396244,396

4848 429,956429,956

6464 718,506718,506

Page 2: Thrust Restraint ISAWWA 1 12 - cdn.ymaws.com · Thrust Restraint Thrust Restraint -- ResearchResearch 12” MJ Pipe and fittings with DI retainer glands Movement sensing Measurement

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Restraining TechniquesRestraining Techniques

Thrust blocksThrust blocks

Restrained joint systemRestrained joint system

Tie rodsTie rods

Combined systemsCombined systems

Types of Thrust BlocksTypes of Thrust Blocks

BearingBearinggg

GravityGravity

Bearing Thrust BlockBearing Thrust Block

Undisturbed SoilUndisturbed SoilUndisturbed SoilUndisturbed Soil Bearing AreaBearing AreaBearing AreaBearing Area

4545°°4545°°

Bearing Area (ftBearing Area (ft22) =) =Bearing Area (ftBearing Area (ft22) =) =Safety Factor • Thrust Force (lbs)Safety Factor • Thrust Force (lbs)Safety Factor • Thrust Force (lbs)Safety Factor • Thrust Force (lbs)

Bearing Capacity of Undisturbed Soil (lbs/ftBearing Capacity of Undisturbed Soil (lbs/ft22))Bearing Capacity of Undisturbed Soil (lbs/ftBearing Capacity of Undisturbed Soil (lbs/ft22))

Soil Bearing Strength SSoil Bearing Strength SBB

SoilSoil SSB B (lb/ft(lb/ft22))

MuckMuck 00

Soft claySoft clay 1,0001,000Soft claySoft clay 1,0001,000

SiltSilt 1,5001,500

Sandy siltSandy silt 3,0003,000

SandSand 4,0004,000

Sandy claySandy clay 6,0006,000

Hard clayHard clay 9,0009,000

Bearing Thrust BlockBearing Thrust Block

HHHHtt

hh

h h ≤≤ 1/2H1/2Htt

TT

A = hb =A = hb =TTSSBB

(S(Sff))

Bearing Block ConstructionBearing Block Construction

RightRight WrongWrong

4545°°4545°°

TT TT

Page 3: Thrust Restraint ISAWWA 1 12 - cdn.ymaws.com · Thrust Restraint Thrust Restraint -- ResearchResearch 12” MJ Pipe and fittings with DI retainer glands Movement sensing Measurement

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Thrust RestraintThrust Restraint

Gravity Thrust BlockGravity Thrust Block

Gravity Block Size (ftGravity Block Size (ft33) =) =Gravity Block Size (ftGravity Block Size (ft33) =) =Safety Factor • Thrust Force (lb)Safety Factor • Thrust Force (lb)Safety Factor • Thrust Force (lb)Safety Factor • Thrust Force (lb)

Density of Block Material (lb/ftDensity of Block Material (lb/ft33))Density of Block Material (lb/ftDensity of Block Material (lb/ft33))

Gravity BlockGravity BlockGravity BlockGravity Block

Page 4: Thrust Restraint ISAWWA 1 12 - cdn.ymaws.com · Thrust Restraint Thrust Restraint -- ResearchResearch 12” MJ Pipe and fittings with DI retainer glands Movement sensing Measurement

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Restrained Joint Force SystemRestrained Joint Force System

PAPA

PA Tan(PA Tan(/2)/2)

FFff + ½ R+ ½ Rss

L =L =

LL

FFff

RRss

PA Sin(PA Sin(/2)/2)

[F[Fff + ½ R+ ½ Rss]LCos(]LCos(/2)/2)

LL

Mechanical Joint Retainer GlandsMechanical Joint Retainer Glands

SetSet--ScrewScrewMechanical JointMechanical JointRetainer GlandRetainer Gland

WedgeWedge--actionactionMechanical JointMechanical JointRetainer GlandRetainer Gland

Restrained JointsRestrained Joints

Page 5: Thrust Restraint ISAWWA 1 12 - cdn.ymaws.com · Thrust Restraint Thrust Restraint -- ResearchResearch 12” MJ Pipe and fittings with DI retainer glands Movement sensing Measurement

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Designing Thrust SystemsDesigning Thrust Systems

Thrust Restraint BrochureThrust Restraint Brochure

A brochure outlining design theoryA brochure outlining design theoryand a design aid of restrainedand a design aid of restrained

joint systems for ductile iron pipe.joint systems for ductile iron pipe.

Restrained Joint Force SystemRestrained Joint Force System

PAPA

PA Tan(PA Tan(/2)/2)

FFff + ½ R+ ½ Rss

L =L =

LL

FFff

RRss

PA Sin(PA Sin(/2)/2)

[F[Fff + ½ R+ ½ Rss]LCos(]LCos(/2)/2)

LL

Restrained Length Dependant UponRestrained Length Dependant Upon

Pipe sizePipe size

Type of fittingType of fitting

Internal pressureInternal pressure

Depth of coverDepth of cover

Soil characteristicsSoil characteristics

Laying conditionsLaying conditions

Suggested Values for Soil PropertiesSuggested Values for Soil Propertiesand Reduction Constantand Reduction Constant

Soil Soil DesignationDesignation

Soil DescriptionSoil Description

(deg)(deg)ff

CCss

(psf)(psf)ffcc

γγ(deg)(deg)

K K nn

A21.50 Laying A21.50 Laying ConditionCondition

2*2* 33 44 55

Clay 1Clay 1Clay of medium to low plasticity, Clay of medium to low plasticity, LL<50, <25% coarse particlesLL<50, <25% coarse particles

[CL & CL[CL & CL ML]ML]00 00 300300

.50.50

.80.809090 .20.20 .40.40 .60.60 .85.85

[CL & CL[CL & CL--ML]ML] .80.80

CohCoh--grangranCohesive granular soils,Cohesive granular soils,

> 50% coarse particles [GC & SC]> 50% coarse particles [GC & SC]2020

.40.40

.65.65200200 .40.40 9090 .40.40 .60.60 .85.85 1.01.0

Sand SiltSand SiltSand or gravel w/silt,Sand or gravel w/silt,

> 50% coarse particles [GM & SM]> 50% coarse particles [GM & SM]3030

.50.50

.75.7500 00 9090 .40.40 .60.60 .85.85 1.01.0

Good SandGood SandClean sand, >95% coarse particles, Clean sand, >95% coarse particles,

[SW & SP][SW & SP]3636

.75.75

.80.8000 00 100100 .40.40 .60.60 .85.85 1.01.0

Consult Table 3 of thrust brochure for pertinent notes.Consult Table 3 of thrust brochure for pertinent notes.

Laying ConditionsLaying Conditions

Type 1Type 1

Type 4Type 4

Type 2Type 2 Type 3Type 3

Type 5Type 5

Thrust Restraint Thrust Restraint -- ResearchResearch

12” MJ Pipe and fittings12” MJ Pipe and fittingswith DI retainer glandswith DI retainer glands

MovementMovementsensingsensing

Measurement TrenchMeasurement Trench

sensingsensingprobesprobes

Railroad CrossRailroad CrossTie BulkheadTie Bulkhead

MeasuringMeasuringFrameFrame

ProbeProbe

BackfilledBackfilled ApproximatelyApproximately3’ of cover3’ of cover

Bedding compactionBedding compactionvaried during testvaried during test

Section “ASection “A--A”A”

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Designing Thrust SystemsDesigning Thrust Systems

t i

Thrust Restraint Computer ProgramThrust Restraint Computer Program

A computer program to aid inA computer program to aid inthe design of restrained jointthe design of restrained jointsystems for ductile iron pipe.systems for ductile iron pipe.

Table BTable B--55

A21 50A21 50 L i C ditiL i C diti

22 33 44 55

ff 0.400.40 0.650.65 0.650.65 0.650.65

ff cc 0.400.40 0.400.40 0.400.40 0.400.40

KK nn 0.400.40 0.600.60 0.800.80 1.001.00

A21.50 A21.50 –– Laying ConditionsLaying ConditionsSoil Type: CohSoil Type: Coh--grangranSoil ParametersSoil Parameters

CCss

= 20 degrees= 20 degrees= 200 psf= 200 psf= 90 pcf= 90 pcf

SizeSize

(in)(in)

DepthDepth

(ft)(ft)

A21.50 A21.50 –– Laying ConditionsLaying Conditions

22 33 44 55

RestrainedRestrained

Length (ft)Length (ft)

RestrainedRestrained

Length (ft)Length (ft)

RestrainedRestrained

Length (ft)Length (ft)

RestrainedRestrained

Length (ft)Length (ft)

3030 2.52.5 97 97 (112)(112) 69 69 (79)(79) 56 56 (62)(62) 50 50 (55)(55)

3030 3.03.0 91 91 (105)(105) 65 65 (74)(74) 52 52 (58)(58) 47 47 (51)(51)

3030 4.04.0 81 81 (93)(93) 57 57 (65)(65) 46 46 (51)(51) 41 41 (45)(45)

3030 6.06.0 66 66 (76)(76) 46 46 (52)(52) 37 37 (41)(41) 33 33 (36)(36)

3030 8.08.0 56 56 (64)(64) 38 38 (44)(44) 31 31 (34)(34) 28 28 (30)(30)

3030 10.010.0 48 48 (56)(56) 33 33 (38)(38) 26 26 (30)(30) 24 24 (26)(26)

Horizontal Bend MultiplierHorizontal Bend Multiplier

Tan(Tan(/2)/2)

9090°° 1 0001 0009090 1.0001.000

4545°° 0.4140.414

2222½½°° 0.1990.199

1111¼¼°° 0.0980.098

Vertical Down BendVertical Down Bend

/2/2 2PA Sin(2PA Sin(/2)/2)

FFss

FFss

PA Tan(PA Tan(/2)/2)

FFff

L =L = SSff

LL

TeeTee

PAPAbb

LLrr

PAPAbb --1/2 R1/2 RssLLrr

(F(Fff ))bb

LLbb == SSff

LLbb

LLbb(F(Fff))bb

Extend Restrained Joints at:Extend Restrained Joints at:

CasingsCasings

Bridge crossingsBridge crossingsBridge crossingsBridge crossings

Aboveground applicationsAboveground applications

Poor soil conditionsPoor soil conditions

Closely located fittingsClosely located fittings

Page 7: Thrust Restraint ISAWWA 1 12 - cdn.ymaws.com · Thrust Restraint Thrust Restraint -- ResearchResearch 12” MJ Pipe and fittings with DI retainer glands Movement sensing Measurement

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Combined Horizontal BendsCombined Horizontal Bends

RRssRRss

2PA Sin(2PA Sin(/2)/2) 2PA Sin(2PA Sin(/2)/2)

FFffFFff

2PA Tan(2PA Tan(/2)/2)

FFf f ++ 1/2R1/2Rss

LL11 == SSff -- LL

LL11 LL11

LLLL

KnownKnown KnownKnown

Vertical OffsetVertical Offset

FFff

2PA Tan(2PA Tan(/2)/2)

FFf f ++ 1/2R1/2Rss

LL22 == SSff -- LL

2PA Sin(2PA Sin(/2)/2)

FFff

LL11 LL

LL22LL

RRss

2PA Tan(2PA Tan(/2)/2)

FFff

LL11 == SSff -- LL

2PA Sin(2PA Sin(/2)/2)

Combined Vertical Equal Angle OffsetsCombined Vertical Equal Angle Offsets

FFffFFff

2PA Tan(2PA Tan(/2)/2)

FFff

LL11 == SSff -- LL

LL

LL11LL11

LL

LLLL

Page 8: Thrust Restraint ISAWWA 1 12 - cdn.ymaws.com · Thrust Restraint Thrust Restraint -- ResearchResearch 12” MJ Pipe and fittings with DI retainer glands Movement sensing Measurement

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Thrust Restraint Thrust Restraint -- ClosuresClosures

LL

LL22

ClosureClosure

LL11LL11

LL22

ClosureClosure

Thrust Restraint Thrust Restraint –– Deflected JointsDeflected Joints

Second unrestrained jointSecond unrestrained jointbegin deflectbegin deflect

First unrestrained jointFirst unrestrained jointdo not deflectdo not deflect

Horizontal Bend / Vertical Up BendHorizontal Bend / Vertical Up Bend

PAPA

LL

PA Tan(PA Tan(/2)/2)

FFff + ½ R+ ½ Rss

L =L = SSff

FFff

RRss

PA Sin(PA Sin(/2)/2)

[F[Fff + ½ R+ ½ Rss]LCos(]LCos(/2)/2)

LL

TieTieRodsRods

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Calculating Number of Tie RodsCalculating Number of Tie Rods

F = SAF = SA

N = N = SSff TT(X or Y)(X or Y)

FFFFWhere:Where:

F = Force Developed per Rod (lbs.)F = Force Developed per Rod (lbs.)

S = Tensile Strength of Rod Material (psi)S = Tensile Strength of Rod Material (psi)

A = Cross Sectional Area of Rod (in.A = Cross Sectional Area of Rod (in.22))

N = Number of Rods RequiredN = Number of Rods Required

TT(X or Y)(X or Y) = Thrust Force Component (lbs.)= Thrust Force Component (lbs.)

SSff = Safety Factor (usually 1.5)= Safety Factor (usually 1.5)

CombinedCombinedSystemsSystems

DUCTILE IRON PIPEDUCTILE IRON PIPETHE RIGHT DECISIONTHE RIGHT DECISION