Dimaggio

Practical Implementation of LRFD for Geotechnical Engineering Features

Design and Construction of Driven Pile Foundations Wednesday, June 22, 2011PDCA Professors WorkshopByJerry A. DiMaggio, PE, D. GE, M. ASCE

E-Mail: [email protected]

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ASCE LRFD Webinar Series** Check ASCE website for latest information

#Topic20092010201120121Fundamentals of LRFD Part 1 1/16, 8/76/301/18, 10/132Fundamentals of LRFD Part 2 1/30, 9/87/152/4, 10/213Subsurface Explorations6/30, 11/54/152/17, 8/18 2/34Shallow Foundations7/241/6, 5/7, 11/85/20, 12/125Deep Foundations Piles1/25, 6/1, 12/146/21, 11/76Deep Foundations Shafts2/8, 6/111/7, 7/81/237Deep Foundations Micropiles9/103/3, 7/291/128Earth Retaining Structures Fill8/203/11, 9/123/99Earth Retaining Structures Cut 10/219/302/2810MSE Walls4/4, 12/211Ground Anchors5/2 3/29

Presnetation Assumptions/ReferencesBasic knowledge of:LRFD (previous webinars)Basic Deep Foundation Design and Construction

Primary References:Section 10 of AASHTO (2010, 5th Edition)List of other references provided at end

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Driven Pile Foundations*

TopicSlidesGeneral (Section 3, Section 10.4, 10.7.1) 4 1810.5 Limit States and Resistance Factors19 2210.7.2 Service Limit State 23 3110.7.3 Strength Limit State32 5810.7.4 Extreme Event Limit State59 6510.7.5 Corrosion and Deterioration66 6910.7.8 Drivability Analysis70 73

Section 10 Contents*

ArticleTopic10.1Scope10.2Definitions10.3Notation10.4Soil and Rock Properties10.5Limit States and Resistance Factors10.6Spread Footings10.7Driven Piles10.8Drilled Shafts10.9MicropilesRefer to Section 3 for Loads and Load Factors

Deep Foundation Types*

MaterialDriven PilesDrilled Shafts/ MicropilesJacked/ SpecialPrestressed concreteXXPost-tensioned concreteXXPre-cast concreteXCast-in-place concreteXXXSteelXXXWoodXSpecialty/CompositesXXX

Section 10.7 Driven Piles*

ArticleTopic10.7.1General10.7.2Service Limit State Design10.7.3Strength Limit State Design10.7.4Extreme Event Limit State Design10.7.5Corrosion and Deterioration10.7.6Minimum Pile Penetration10.7.7Driving Criteria for Bearing10.7.8Drivability Analysis10.7.9Test Piles

Professional Discipline CommunicationGeotechnical, Structural, Hydraulic, and Construction specialists all play an important role and have different responsibilities on deep foundation projects.Project specific loads, extreme events, performance requirements, scour, pile cap details, specifications, plans construction, pile damage are ALL KEY issues for a successful project!The Geotechnical Design Report is a key communication tool. *

10.7.1 GENERAL

Consider spread footings first.Basic guidelines for driven pile configurationsMinimum spacing 2.5 pile diameters or 30 inches.Minimum of 9 inches pile cap edge and be embedded 12 inches into the pile cap or if with strands or bars then the pile embedment should be 6 inches.Piles through embankments should extend 10 ft into original ground or refusal on rock. Maximum of 6 inch fill size.Batter Piles: stiffness, dont use in downdrag situations, concern in seismic situations.

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Comparison of LRFD and ASD approaches for Deep Foundations

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SameDifferentDetermining resistanceComparison of load and resistanceDetermining deflectionSeparation of resistance and deflection

AASHTO Table 3.4.1-1*

DCDWEHEVESLLWAEQCTDD*

Load Factors for Permanent Loads, gpAASHTO Table 3.4.1-2*

Load Type and Direction*

StructuralGeotechnicalVertical or horizontalPermanent/TransientVertical/HorizontalDowndrag/Setup/Relaxation

Downdrag*Geotechnical loadCan be significant particularly given the max load factorsArticles 3.4.1 and 3.11.8

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Design MethodLoad FactorsMaximum MinimumPilesa-method1.400.25l-method1.050.30ShaftsReese & ONeill (1999)1.250.35

AASHTO Section 10.4 Soil and Rock PropertiesDISCUSSED IN PREVIOUS WEBINAR ON SUBSURFACE INVESTIGATIONS Next Offering on August 18, 2011

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ArticleTopic10.4.1Informational Needs10.4.2Subsurface Exploration10.4.3Laboratory Tests10.4.4In Situ Tests10.4.5Geophysical Tests10.4.6Selection of Design Properties

Deep Foundation SelectionMethod of supportBearing material depthLoad type, direction and magnitudeConstructabilityCostExpressed in $/kip capacityInclude all possible costs*

Pile Types Based on Soil Displacement During Driving*

Low DisplacementHigh Displacement

Strength Limit State Driven Piles ARTICLE 10.5.3.3Axial compression resistance for single pilesPile group compression resistanceUplift resistance of single pilesUplift resistance of pile groupsPile punching failure in weaker stratumSingle pile and pile group lateral resistance Constructability, including pile drivability

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SPECIAL DESIGN CONSIDERATIONSNegative shaft resistance (downdrag)Lateral squeezeScourPile and soil heaveSeismic considerations

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10.5LIMIT STATES AND RESISTANCEStrength Limit State (will be discussed later)Structural ResistanceGeotechnical ResistanceDriven ResistanceService Limit StateResistance Factor = 1.0 (except for global stability)Extreme Event Limit StateSeismic, superflood, vessel, vehicleUse nominal resistance

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Service Limit State Checks*

Global StabilityVertical and Horizontal Displacements

Settlement of Pile GroupsArticle 10.7.2.3.1 [Hannigan (2006)]Treat as equivalent footingsCategorize as one of the 4 cases shown here*

10.7.2.4 Horizontal Loads and Pile Moments*

Horizontal ResponseAssumes nominal resistance is adequateNo consideration of possible brittle response of geomaterialLPILE type p-y model or Strain Wedge MethodIsolatedGroup*

P-y Results for Single Element*

10.1 k

1740 k

8000 in-k

Depth, ft

50

40

30

20

10

-0.2

0

0.2

0.4

0.6

0.8

0

20

40

60

80

-60

-40

-20

0

20

Deflection, in.

Moment, in. -kx102

Shear, k

0.84

8640

65.5

P-y Results for Pile GroupsAASHTO Figure 10.7.2.4-1*

Spacing (S)P-multiplier (Pm)Row 1Row 2Row 33B0.80.40.35B1.000.850.7

DxDxPile Head Fixity**

Tolerable Movements and Movement Criteria 10.5.2.2

Service loads for settlements, horizontal movements and rotations. Omit transient loads for cohesive soilsReference movements to the top of the substructure unit. Angular Distortion (C10.5.2.2)

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STRENGTH LIMIT STATESStructuralAxialDriven (Assess Drivability)FlexureShearGeotechnicalAxial

Axial compressionCombined axial and flexureShearLRFDSpecificationsConcrete Section 5Steel Section 6Wood Section 8Methods for Determining Structural Resistance*

Factors AffectingAllowable Structural Pile StressesAverage section strength (Fy, fc, wood crushing strength)Defects (knots in timber)Section treatment (preservation for timber)Variation in materialsLoad factor (overloads or pile damage)*

Concrete (5.5.4.2)Axial Comp. = 0.75 Flexure = 0.9 (strain dependent)Shear = 0.9

Steel (6.5.4.2)Axial = 0.5-0.7CombinedAxial= 0.7-0.8Flexure = 1.0Shear = 1.0Timber (8.5.2.2 and .3)Compression = 0.9Tension = 0.8 Flexure = 0.85Shear = 0.75LRFDSpecifications

Structural Resistance Factors10.7.3.13 Pile Structural Resistance

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Field methodsStatic load testDynamic load test (PDA)Driving FormulaeWave Equation AnalysisStatic analysis methodsDetermining Nominal Axial Geotechnical Resistance of Piles*

Geotechnical Safety Factors for Piles (ASD)*

Basis for Design and Type of Construction ControlIncreasing Design/Construction ControlSubsurface explorationXXXXXStatic analysisXXXXXDynamic formulaXWave equationXXXXCAPWAP analysisXXStatic load testXXFactor of Safety (FS)3.502.752.252.001.90

Pile Testing Methods*

Geotechnical Nominal Resistance of Piles: Static Load Tests ASTM D1143 (10.7.8.2)*

Test SetupResults and Definition of Failure

Dynamic Load Test (PDA) ASTM D494510.7.3.8.3*

Wave Equation Driven Resistance10.7.3.8.4*

Drivehead

Ground Surface

Ram

vo

Cushion

Soft Layer

Dense Layer

(a)

(b)

(c)

Permanent Set(d)

Pile

elastic

elastic

c

c

c

c

Compressive Force Pulse (Incident)

Compressive Force Pulse (Attenuated)

Compressive Force Pulse

Tensile or Compressive Force Pulse (Reflected)

Wave Equation Applications*

ItemUseDevelop driving criterionBlow count for a required nominal resistanceBlow count for nominal resistance as a function of energy/strokeCheck drivabilityBlow count vs penetration depthDriving stresses vs penetration depthDetermine optimal driving equipmentDriving timeRefined matching analysisAdjust input values based on dynamic measurements

68 blows / 0.25 m195 MPa1480 kN2.6 mWave Equation Results*

Driving Formulas (Article 10.7.3.8.5)*

Pile Testing Methods*

Calculate pile length for loads Determine number of piles Determine most cost effective pile type Calculate foundation settlement Calculate performance under uplift and lateral loads Static analysis methods and computer solutions are used to: *

Static Analysis MethodsPrimary use is for pile length estimation for contract drawings and feasibility.Secondary use for estimation of downdrag, uplift resistance and scour effectsShould rarely be used as sole means of determining pile resistance. ONLY IN SPECIAL SITUATIONS!

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Side ResistanceTip ResistanceTotal ResistanceABCDRPRSRR = fRn = fqpRp + fqsRsVertical DisplacementResistanceLarge Pile Diameter Resistance*

Computation of Static Geotechnical ResistanceAASHTO 10.7.3.7.5-2RPRS*

Nominal Resistance: Rn = Rs1 + Rs2 + Rs3 +RtFactored Resistance: RR = fRn= f(Rs3 + Rt)Soil Resistance to Driving (SRD):SRD = Rs1 + Rs2 + Rs3 +RtEXAMPLE SOIL PROFILESRD = Rs1 + Rs2 / 2 + Rs3 +Rt (with clay soil strength change)((with no soil strength changes)*

Static Analysis Methods a methodb methodl methodNordlund -Thurman methodSPT-methodCPT-methodDriven Piles*

Resistance Factors Static Analysis MethodsAASHTO Table 10.5.5.2.3-1*

MethodResistance Factor, fCompressionTensiona- method0.350.25b- method0.250.20l- method0.400.30Nordlund- Thurman0.450.35SPT0.300.25CPT0.500.40Group0.600.50

Combining Geotechnical Resistance FactorsC10.7.3.3 fdyn x Rn = f stat x Rnstat

The length predicted by this method may be overly conservative and need to be adjusted to reflect experience.Local experience replaces this suggested relationship.

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Driven Pile Time Dependent Effects(Article 10.7.3.4)SetupRelaxationRPRSRPRSRPRSRPRS*

SOIL SETUPSoil setup is a time dependent increase in the static pile resistanceLarge excess positive pore pressures are often generated during pile drivingSoil setup frequently occurs for piles driven in saturated clays as well as loose to medium dense silts and fine sands as the excess pore pressure dissipateMagnitude of setup depends on soil characteristics and pile material and type

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Point Bearing on Rock(Article 10.7.3.2)

Soft rock that can be penetrated by pile driving may be treated similar to soils.Steel piles driven into soft rock may not require tip reinforcement.On hard rock the nominal resistance is controlled by the structural capacity. See Article 6.9.4.1 and the driving resistances in 6.5.4.2 and 6.15 for severe driving. PDA should be used when the nominal resistance exceeds 600 kips.C10.7.3.2.3 Provides qualitative guidance to minimize pile damage when driving piles on hard rock.*

Pile Group Resistance 10.7.3.9 & 11 Static Geotechnical ResistanceFigures 10.7.3.11-1 and -2 for group uplift resistance for cohesionless and cohesive soils respectively.

Take lesser of*

EXTREME EVENT LIMIT STATES10.5.5.3 ScourVessel and Vehicle collisionSeismic loading and site specific situations.

(Uplift Resistance should be 0.80 rather than 1.00 for all extreme checks.)

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Piles Subject to Scour 10.5.5.3.2*

Seismic Articles 10.7.4, 10.5.5.3.3Liquefaction: Neglect axial resistance in liquefiable zoneLateral Spreading: Either consider forces due to lateral spreading or improve ground; reduce P-y curve based on duration of strong shaking and ability of the ground to fully liquefy during strong shakingDowndrag: Do not combine seismic downdrag with static downdrag*

10.7.5 Corrosion and DeteriorationIdentified by soil resistivity & pH testing

If pH < 4.5, design should be based on an aggressive environment

Corrosion of steel pile foundations, particularly in fill soils, low pH soils and marine environments

Sulfate, chloride, and acid attack of concrete pile foundations

Decay of timber piles from wetting and drying cycles from insects and marine borers

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Aggressive Subsurface EnvironmentsResistivity < 2000 ohms-cmpH < 5.5pH between 5.5 and 8.5 in soils with high organic contentSulfates > 1,000 ppmLandfills and cinder fillsSoils subject to mine or industrial drainageAreas of mixed resistivity (high and low)Insects (wood piles)

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Pile Driving Induced VibrationsSee Hannigan (2006)Vibration induced damage

Vibration induced soil densification

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Section 10.7.8 Driven PilesRequirements for drivability analysis have been added and clarified*

Comp Str

ksi

30

20

10

Ult Cap

200

400

600

800

kips

0

160

320

480 Blows/ft

4.0

8.0

12.0

16.0

ft

Stroke

Tens Str

ksi

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Pile TypeLoading TypeLimiting Driving StressSteelCompression/TensionConcreteCompressionTensionPrestressedCompressionTensionTension (in severe corrosion)TimberCompression/Tension

Concrete piles, = 1.00AASHTO Article 5.5.4.2.1Steel piles, = 1.00AASHTO Article 6.5.4.2Timber piles, = 1.15AASHTO Article 8.5.2.2Driven Resistance Factors*

5th Edition 2010 Changes Sec 10.5 Specification references to changes in resistance factors based on pile group size moved to the commentary.

The definition of foundation redundancy (in commentary) was simplified.

Tables relating resistance factor to site variability were removed from the specifications and decisions were deferred to the engineer. The site variability method was retained as an acceptable option to aid in engineering judgment.

Precaution for static analysis predictions for piles greater than 24 was added.

The resulting changes based on the above was a modest increase for several resistance factors. *

5th Edition 2010 Changes Sec 10.7Use of dynamic tests with signal matching to estimate side friction were added as a reasonable alternative to static analysis methods or load testing.

Table 10.7.2.4-1, small adjustments in the p-multipliers for group lateral load analysis.

Provisions for piles driven to hard rock (Article 10.7.3.2) were made more complete.

Article 10.7.3.3 changed to clarify the use and potential pitfalls of the approaches provided to estimate the pile length required.

Article C10.7.3.4.3, guidance added regarding the length of time needed for various soil conditions before a restrike should be attempted. *

Table 10.5.5.2.3-1 Resistance Factors for Driven Piles

Static Load Test with Dynamic Tests 0.80 (minimum test number 2 and minimum percentage 2% of tests)Static Load Test without Dynamic Tests 0.75Dynamic Testing 100% production piles 0.75Dynamic Tests 0.65 (minimum test number 2 and minimum percentage 2% of tests)Wave Equation 0.50*

For More Information on Driven Piles*

REFERENCESAllen, T. M. 2005. Development of Geotechnical Resistance Factors and Downdrag Load Factors for LRFD Foundation Strength Limit State Design, FHWA-NHI-05-052, FHWA, Wash. DC.

Barker, R. M. et al 1991. Manuals for the Design of Bridge Foundations NCHRP Report 343. Transportation Research Board, NRC, Wash., DC.

Hannigan P.J. et al, 2005. Design and Construction of Driven Pile Foundations, FHWA-HI-05, FHWA, Wash. DC

Paikowsky S. G. et al, 2004. Load and Resistance Factor Design (LRFD) for Deep Foundations, NCHRP Report 507. Transportation Research Board, NRC, Wash. DC.*

Practical Implementation of LRFD for Geotechnical Engineering Features

Design and Construction of Driven Pile Foundations Wednesday, June 22, 2011PDCA Professors WorkshopByJerry A. DiMaggio, PE, D.GE, M. ASCE

E-Mail: [email protected]

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February 08, 2010Developed by NCS Consultants, LLCASCE Drilled Shaft Webinar*CE 464-564A*CE 464-564A*12th Bridge Design WorkshopLRFD Specifications for Foundation DesignPage *Printed: October 7, 2005Slide controlBullets appear one at a time or other appropriate slide control.

This information is Arial 14 pt. font in text box on the notes view page.

Key MessageSummarize the point that you want everyone to remember from slide.

Background InformationExplain any background or related information to support the slide that may be used to answer questions or to elaborate, if necessary. This is in 12 pt Arial font

InteractivityIf there are special comments, or facilitation techniques, that are recommended for the instructors to use, they should be stated here. It is important, that the instructional methodology supports the Learning Outcomes (LOs).

NotesDescribe any factors that might make it difficult for learners to understand/accept a key message, identifying typical questions, regional, political or demographic issues and possible solutions.

This is a Power point slide inserted in the notes view. This description was placed in the file outside the printable area of the motes pages*NO open end pipe and composite driven pile guidance.12th Bridge Design WorkshopLRFD Specifications for Foundation DesignPage *Printed: October 7, 2005Slide controlBullets appear one at a time or other appropriate slide control.






This is a Power point slide inserted in the notes view. This description was placed in the file outside the printable area of the motes pages***ASCE Drilled Shaft WebinarJune 11, 2010Developed by NCS Consultants, LLC*Permanent Loads

DC = dead load of structural components and nonstructural attachments DW = dead load of wearing surfaces and utilities EH = horizontal earth pressure load ES = earth surcharge load EV = vertical pressure from dead load of earth fill

Transient Loads

LS = live load surcharge WA = water load and stream pressure

ASCE Drilled Shaft WebinarJune 11, 2010Developed by NCS Consultants, LLC*ASCE Drilled Shaft WebinarJune 11, 2010Developed by NCS Consultants, LLC**12th Bridge Design WorkshopLRFD Specifications for Foundation DesignPage *Printed: October 7, 2005Slide controlBullets appear one at a time or other appropriate slide control.






This is a Power point slide inserted in the notes view. This description was placed in the file outside the printable area of the motes pages***CE 464-564A****CE 464-564A**12th Bridge Design WorkshopLRFD Specifications for Foundation DesignPage *Printed: October 7, 2005Slide controlBullets appear one at a time or other appropriate slide control.






This is a Power point slide inserted in the notes view. This description was placed in the file outside the printable area of the motes pages***12th Bridge Design WorkshopLRFD Specifications for Foundation DesignPage *Printed: October 7, 2005Strain Wedge Method does not use p-multipliers.Slide controlBullets appear one at a time or other appropriate slide control.






This is a Power point slide inserted in the notes view. This description was placed in the file outside the printable area of the motes pages**CE 464-564A*****Resistance factors dependent upon:Type of materialType of stressPlacement conditions (confidence)10.7.3.13 Pile Structural ResistanceSteel Piles: See Article 6.9.4.1 for noncomposite piles and Article 6.9.5.1 for composite piles. For unsupported noncomposite piles see Eqs. 6.9.4.1-1 or 6.9.4.1-2 and 6.9.5.1-1 an d-2 for composite piles. The effective unsupported length is determined by Article 10.7.3.13.4. Resistance factors for the compresssion limit state are specified in Article 6.5.4.2Concrete Piles: See Article 5.7.4.4 nominal compressive resistance of precast and prestressed concrete piles. Unsupported pile compressive resistance is provided in Articles 5.7.4.3 and 4.5.3.2 and the effective length is as determined in Article 10.7.3.13.4. Resistance factors for the compression limit state is given in Article 5.5.4.2.1 Article 5.7.4 includes limits on longitudinal reinforcements, spirals and ties. This Article includes methods for determining nominal compression but not for prestressed members.Timber Piles: See article 8.8.2 for both laterally supported and unsupported piles. Article 8.5.2.3 requires a reduction for long term loads of 0.75 for the Strength Load Combination IV.Buckling and Lateral Stability: For stability the effective is equal to the unsupported length plus the embedded depth to fixity. Potential for buckling should be as in Article 10.7.3.12. Preliminary design for the depth to fixity for clays and sands are provided by 2 equations in 10.7.3.13.4.

****Static load tests as per ASTM D1143, Quick Load Test Method: Davisson 24in and less; larger than 36 diameter s = QL/12AE + B/2.5 (B is in ft.)*Dynamic Testing 10.7.3.8.3: follow ASTM D4945. Testing should be performed by certified and experienced testers.

10.7.3.8.3 Dynamic TestingAdded commentary on restrike capacity matching with PDA from Hannigan.

*Note that the static analysis resistance factors are much less than the field tested resistance factors.Ask Participants why (answer less uncertainty from fielded tested resistance)*****12th Bridge Design WorkshopLRFD Specifications for Foundation DesignPage *Printed: October 7, 2005Slide controlBullets appear one at a time or other appropriate slide control.






This is a Power point slide inserted in the notes view. This description was placed in the file outside the printable area of the motes pages****Note that the static analysis resistance factors are much less than the field tested resistance factors.Ask Participants why (answer less uncertainty from fielded tested resistance)*Static analysis resistance factors reflect an average value since research has indicted that the static analysis vary depending on pile type.

**Add relaxation discussion***Resistance of Pile Groups in CompressionPile Groups in Clay = 0.65 for soft soil and cap contact at 2.5 diameters and 1.0 at 6.0 diameters. No reduction is applied in clays if the cap is in contact with the soil and the soil is stiff. In cohesionless soils regardless of the cap condition = 1.0 provided the pile spacing is 2.5 or greater. If the group is tipped in a strong deposit overlying a weaker deposit the block bearing resistance should evaluated as to the pile group punching into the weaker deposit.

10.7.3.10 and 11 Uplift Resistance of Single Piles and Pile GroupsUplift test ASTM D 3689 and evaluated as stated in Hannigan.Resistance factors for single piles are reduced to 0.80 of static compressive resistance.

CE 464-564A***10.5.5.3.2 ScourThe provisions of Articles 2.6.4.4.2 and 3.7.5 shall apply to the changed foundation conditions resulting from scour. Resistance factors at the strength limit state shall be taken as specified herein. Resistance factors at the extreme event shall be taken as 1.0 except that for uplift resistance of piles and shafts, the resistance factor shall be taken as 0.80 or less.

CE 464-564A**General guidance on minimizing corrosion and deterioration in Section, page 118 but in general it directs you to Hannigan for detailed guidance in the specification commentary.**CE 464-564A*12th Bridge Design WorkshopLRFD Specifications for Foundation DesignPage *Printed: October 7, 2005Slide controlBullets appear one at a time or other appropriate slide control.






This is a Power point slide inserted in the notes view. This description was placed in the file outside the printable area of the motes pages**CE 464-564A*12th Bridge Design WorkshopLRFD Specifications for Foundation DesignPage *Printed: October 7, 2005Slide controlBullets appear one at a time or other appropriate slide control.






This is a Power point slide inserted in the notes view. This description was placed in the file outside the printable area of the motes pages12th Bridge Design WorkshopLRFD Specifications for Foundation DesignPage *Printed: October 7, 2005Slide controlBullets appear one at a time or other appropriate slide control.






This is a Power point slide inserted in the notes view. This description was placed in the file outside the printable area of the motes pages**12th Bridge Design WorkshopLRFD Specifications for Foundation DesignPage *Printed: October 7, 2005Slide controlBullets appear one at a time or other appropriate slide control.






This is a Power point slide inserted in the notes view. This description was placed in the file outside the printable area of the motes pages

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