2_Retaining Wall Ashton Lawler.pdf

7/28/2019 2_Retaining Wall Ashton Lawler.pdf

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Retaining Wall 101Retaining Wall 101

D. Ashton LawlerD. Ashton LawlerStructure and Bridge DivisionStructure and Bridge Division

Virginia Department of TransportationVirginia Department of Transportation

1401 E. Broad Street1401 E. Broad Street

Richmond, Virginia 23219Richmond, Virginia 23219

Phone (804)786Phone (804)786--23552355

ee--mail:mail: [email protected]@vdot.virginia.gov


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Learning GoalsLearning Goals

Get reacquainted with basic retainingGet reacquainted with basic retaining

wall designwall design

Brief look at Conventional C.I.P. WallsBrief look at Conventional C.I.P. Walls

Introduction to MSE WallsIntroduction to MSE Walls Learn how to develop plans for MSELearn how to develop plans for MSE

WallsWalls

Check out what not to doCheck out what not to do

Get some good referencesGet some good references


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5Foundation Analysis and Design

J oseph E. Bowles


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6Foundation Analysis and DesignJ oseph E. Bowles


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Typical Section


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Three Basic Components of anMSE wall:

Reinforcing Elements

Select Backfill

Precast Facing Panels


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Courtesy of The Reinforced Earth Company


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Courtesy of The Neel Company


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Why do we use these wall systems?

1. Economical2. Versatile

3. Tolerate settlement well


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Relationship between joint width andRelationship between joint width andlimiting differential settlementslimiting differential settlements

Joint WidthJoint Width Limiting Differential SettlementsLimiting Differential Settlements

1/100 *1/100 *

1/2001/200

1/3001/300

*When significant differential settlements are anticipated*When significant differential settlements are anticipated(greater than 1/100) slip joints must be provided.(greater than 1/100) slip joints must be provided.


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VDOT Approach to MSE Wall Design

External Stability - The Departments (orour Consultants) responsibility.

Internal Stability The WallManufacturers (and the Contractors)responsibility.


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External Stability1. Bearing Capacity

2. Settlement

3. Overturning Resistance

4. Sliding Resistance

5. Global Stability


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Internal Stability1. Pullout Failure of Reinforcement.

2. Breakage of Reinforcement.


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Plan Preparation

Requirements

For Mechanically-Stabilized Earth

(MSE) Walls


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Refer to

Requirements for Preparation ofAlternate Retaining Wall Plans

[Notes To Designer]

Lets look at each of the notes individually.

What appears on these slides is anabbreviated description of each Note.


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v = = Contact pressure generatedby the wall loading

L - 2e

e

R

..2 SF

q

eL

R

vult

=

L


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This is what happens if you dont follow these

guidelines /


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0

5

10

15

20

25

09/30/85 10/30/85 11/29/85 12/29/85 01/28/86 02/27/86 03/29/86 04/28/86 05/28/86

Date

Frequent Rains

Begin Wall

Wall Completed

Washout


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0

2

4

6

8

10

12

14

16

1820

51 52 53

Station No.


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0

2

4

6

8

10

12

51 52 53

Station No.

Base of Wall

Top of Wall


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11"

1.5

1

18"


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2' - Live Load Surcharge

4' Berm

1.5

1 2.3'

3.25 ksf

Height = 17'

SFOT = 3.3

SFsliding = 2.0

SFbearing = 2.5


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4' Berm

1.5

1 2.3'

Good Compaction Low Compaction

= 120 cf; c = 500 sf; = 32.50

= 110 cf; c = 0 sf; = 30.00

SF = 2.5 SF = 1.7

3.25 ksf

Safet Factor for Bearing Capacity

Height = 17'

SFOT = 3.3

SFsliding = 2.0


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4' Berm

1.5

1 2.3'

3.25 ksf

Height = 17'SFOT = 3.3

SFsliding = 2.0

SFbearing = 2.5


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Good Compaction Low Compaction

= 120 cf; c = 500 sf; = 32.50

= 110 cf; c = 0 sf; = 30.00

SF = 2.5 SF = 1.7

SF = 1.9 SF = 0.8

WITHOUT BERM

WITH BERMSafet Factor for Bearing Capacity

Height = 17'

SFOT = 3.3

SFsliding = 2.0


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SF = 2.5 SF = 1.7 SF = 1.0

SF = 1.9 SF = 0.8 SF = 0.4

Low Compaction

=110 pcf; c =0 psf; =30.00

=120 pcf; c =500 psf; =32.50

WITHOUT BERM

Poor Compaction & Embankment Material

=85 pcf; c =100 psf; =20.00

Safet Factor for Bearing Capacity

WITH BERMGood Compaction

Height = 17'

SFOT = 3.3

SFsliding = 2.0


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FHWA OFFICE OF BRIDGEFHWA OFFICE OF BRIDGE

TECHNOLOGYTECHNOLOGY

www.fhwa.dot.gov/bridge/index.htmwww.fhwa.dot.gov/bridge/index.htm

Click onClick on GeotechnicalGeotechnical

MSEW Version 3 0 SoftwareMSEW Version 3 0 Software


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MSEW Version 3.0 SoftwareMSEW Version 3.0 Software

ADAMA Engineering, Inc.ADAMA Engineering, Inc.Web:Web: www.geoprograms.comwww.geoprograms.com

Email:Email: [email protected]@geoprograms.comPhone: (302) 368Phone: (302) 368--31973197


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Questions?


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Requirements for Preparation ofRequirements for Preparation of

Alternate Retaining Wall PlansAlternate Retaining Wall Plans


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1. Review road plans and cross-sections to estimate approximate wall location,height and length of reinforced soil mass.

a) Check that the entire wall (including the reinforced mass) is located withinthe Departments right-of-way (R/W). If the wall is outside the R/W limits,determine if it is feasible to acquire additional R/W or underground

easement.b) Check if any utilities or obstructions located within the reinforced soil

mass can be adequately accommodated within the requirements andlimitations of the proposed systems allowed for construction.

2. Review the geotechnical information [geotechnical reports, boring logs (geologysheets), laboratory test data, etc.] and estimate the location of the proposedbearing stratum.

3. Perform bearing capacity calculations to determine the maximum allowable soilbearing capacity at the estimated bearing stratum.The maximum allowable soil

bearing pressure must be stated on the plans.

4. Determine the anticipated loading condition (level backfill, level backfill with trafficsurcharge, sloping backfill, or sloping backfill with traffic surcharge, etc.).


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5 Calculate the maximum bearing pressure that the wall will impose on the soil. If

the maximum bearing pressure imposed by the wall is less than the maximumallowable soil bearing capacity calculated in Step 3, the bearing pressurerequirements are satisfied.

6 Perform settlement calculations to determine total and differential settlements. Inaddition to the magnitude of settlement, an estimate of the time-rate of settlement

shall be performed. Wick drains, surcharge loading, or some other method ofground improvement may be required to limit post wall construction settlementsto an acceptable amount. Check the angular distortions to determine if theyappear to be within allowable limits according to AASHTO. Depending on theamount of anticipated settlement, the designer shall implement one of thefollowing actions:

Settlement 2 inches. No action required.

Settlement up to 4 inches and longitudinaldifferential settlement less than 1%

No action required.

Settlement up to 4 inches and longitudinaldifferential settlement greater than 1%

Slip joints to be placed at appropriateintervals in order to limit the longitudinal

differential settlement to less than 1%Settlement 4 inches. Requires approval from State Structure

and Bridge Engineer.


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Estimated settlements along the wall shall be shown in the plans. Method of payment (ifany) for additional square footage of wall created by the settlements should be addressedin the contract documents.

Evaluate whether a waiting period for installing coping, parapet, barrier, moment slab,

piles, paving etc. is required after wall completion.

7 Calculate factors of safety with respect to overturning, sliding, and global stabilityfor the applicable loading conditions. If the factors of safety are greater thanrequired, the overall stability requirements are satisfied.

8 Evaluate the site for potentially deleterious environmental factors such ascorrosive groundwater, seepage forces, stray currents, etc. which may adverselyaffect the wall.

If all of the external stability issues described above (bearing pressure, settlement,overturning, sliding and global stability requirements) are satisfied, alternate walls

may be used at this location. If any of the above is not satisfied, ground modificationor a different type of retaining wall may be required.

9 If an alternate wall is feasible determine the wall geometry (stationing and


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9 If an alternate wall is feasible, determine the wall geometry (stationing andoffsets).

10 Determine the top-of-wall elevations at intervals not exceeding 50 ft. This can beaccomplished using roadway information such as road plans, profiles, cross-sections, and the like. The top of wall shall be either the top of coping or the topof the moment slab (whichever is applicable).

11 Determine the bottom-of-wall elevations at the same locations (stations) that thetop-of-wall elevations were found in Step 10. Check that there is adequateembedment at the toe of the wall in accordance with AASHTO and that theembedment satisfies global stability requirements. The bottom of wall shall betaken to be the top of the leveling pad.

12 Check that the top and bottom elevations of the wall determined in Steps 10 and11 are within the limits assumed in Step 1. If not, recalculate the bearingcapacity, settlement, and the factors of safety with respect to overturning, sliding,and global stability to be sure that the external stability of the wall is adequate.

13 Draw the Elevation View (or Three-Line Drawing) showing the top of wall,bottom of wall, and the approximate finished grade adjoining the front face of thewall. Show the locations of all pipes and utilities that will be penetrating the wallor behind the panels, so the selected alternate wall company can design forthose conditions.


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14 Draw the Plan View. Show stationing, offsets, boring locations, and all pipes and

utilities in the vicinity of the wall.

15 If required, rustication treatment and details shall be included on the drawings.

16 Draw Typical Sections for all significantly different wall sections. For eachsection, show the limits of payment, the required slope in front of the wall, the

required slope of the backfill, and all special loading conditions. The limits ofPayment shall be shown to extend from the top of the wall (top of coping ormoment slab) to the bottom of the wall (top of the leveling pad).

17 Calculate the surface area of the wall based on top and bottom wall elevations

and show this quantity on the plans (Square Feet, Plan Quantity Item). Whenrequired, the traffic barrier/parapet shall be listed as a separate payment item

(Linear Feet, Plan Quantity Item).

18 The plans shall clearly indicate whether some method of ground improvement isrequired and the manner in which the Contractor will be paid for this work. If

overexcavation and replacement is required, these items shall be listed asseparate payment items [Undercut Excavation, (Cubic Yards)] and [SelectMaterial Type I, Minimum CBR of 30 (tons)]. The estimated limits of undercutand backfilling shall be indicated on the Elevation View and the Typical Sections.


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19 List the approved wall companies with their addresses and telephone numbers

on the plans so the Contractor can contact them to request bids. Some projectshave geometric constraints (e.g., walls that wrap around bridge abutments) thatpreclude the use of some wall systems. Wall systems that cannot conform to thegeometrics of the project shall not be included on the plans as an allowable wallsystem.

20 Include the boring logs (Geology Sheets) in the plans.

21 Place appropriate General Notes on the Plans.


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General Notes for Alternate RetainingGeneral Notes for Alternate Retaining

Wall PlansWall Plans

These are suggested wordings for notes that are regularly or occasionallyneeded. Where these notes are fully applicable, there may be no need to change


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their wording. They should be changed, however, or other notes added,

wherever they are not adequate.

Notes should line up with the GENERAL NOTE on the Alternate Retaining WallPlan.

Notes in the single parentheses indicate alternate wordings to be selected by the

designer. Notes in the double parentheses((italics))

are explanations andinstructions to the designer. Skip a line between paragraphs.

Specifications:

Construction: Virginia Department of TransportationRoad and Bridge Specifications, 2002.

Design: AASHTO Standard Specifications for Highway Bridges, 1996; 1997and 1998 Interim Specifications; and VDOT Modifications.(Structure(s) is (are) designed for Seismic Performance Category B).((Use note only when designing for Seismic Performance Category B.Do not show note when designing for Seismic Performance Category

A.))

Standards: Virginia Department of TransportationRoad and Bridge Standards, 2001.

These plans are incomplete unless accompanied by the SupplementalSpecifications and Special Provisions included in the contract documents.

The minimum design life of MSE wall shall be (75-year) (100-year).


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The maximum allowable foundation bearing pressure shall be _____ tons/sq. ft.

((Add table if allowable bearing pressure varies along wall alignment.))

The anticipated MSE wall total settlement is ____ inches and differentialsettlement is _____. ((Add table if settlement varies along wall alignment.))

Vertical slip joints shall be placed in the wall at intervals not to exceed ____ ft.between Stations __________ and _________.

Prior to wall construction, the foundation shall be compacted with a smoothwheel vibratory roller. The drums of the roller should be ballasted and each passof the roller should overlap one half the width of the previous pass. The rollershall make at least ten passes over the proposed wall foundation zone. Nodensity test will be required. Any foundation soils found to be unsuitable shall beremoved and replaced with select material Type I minimum CBR of 30. ((Usenote where marginal foundation conditions exist or zones of unsuitable materialmaybe encountered.))

The minimum required depth of undercut shall be _____ ft. between Stations_________ and _________. ((Add table if undercut depth varies along wallalignment.))

Remove unsuitable or unstable foundation material below the bottom of the wall

and replace with select material prior to wall construction. Compact thefoundation area according to the VDOT Specifications.

The estimated required depth of unsuitable material to be removed is shown onthe plans. The lateral limits of excavation are dependent on the depth at aparticular location below the wall. Additional localized excavation may berequired depending on the site conditions at the time of construction.

Rustication treatment shall be ______________. Forms and liners shall beapproved by the Engineer.


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Concrete surface coating shall be _______, similar to Federal Standard Color

No. _______.

Minimum panel design thickness is _____ inches. Thickness of concrete mustincrease to accommodate any architectural surface finish that may be specified.

An impervious membrane shall be placed below the pavement and just abovethe first row of reinforcement to intercept any flows containing deicing chemicals.The membrane shall be sloped to drain away from the facing to an intercepting

longitudinal drain outletted beyond the reinforced zone. ((Used when theextensive use of deicing chemical may cause accelerated corrosion problems)).

A geotextile shall be used as a separator between the mechanically stabilizedearth mass and the subbase. ((Used where the potential for the subbasemigration into an oversized selected material may occur)).

Epoxy coated reinforcement steel shall be used in (copings) (facing panels)(parapets) (moment slabs) (traffic barriers) and __________. ((Epoxy coatedsteel is required in area of heavy salt or chemical spray)).

(Coping) (Parapet) (Barrier) (Moment slab) (Piles) (Paving) shall not be placeduntil _____ days after wall completion have elapsed.

The selected wall supplier will submit a detailed design and shop drawings for

approval.

Provide drainage details such as perforated pipe underdrain and/or drainageblanket based upon field conditions. For wall installation at stream crossing,provide adequate drainage so the difference between streambed and saturatedbackfill is not greater than what is considered in the design.

All panel types and other related elements shall be detailed on shop drawings.

This worksheet checks the external stability (i.e. eccentrici ty, slid ing, and bearing pressure)

of MSE walls based on the strength limit state requirements in AASHTO LRFD 4th Edition


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Version 2-1, 2/08

Project Name: Test

Project Number: 123456

Designer: KL

INPUT (Yellow Colored Cells)

Total Wall Height, H (ft) 30.00

Reinforcement Length, L (ft) 21.00

Backslope Height, h (ft) 0.00Backslope Run, r (ft) 100.00

Wall Embedment, Df(ft) 2

* For level backslope, enter zero for backslope height.

(pcf) ' (deg.) c' (psf)Reinforced Soil 125.00 34.00 0.00

Retained Soil 125.00 30.00 0.00

Foundation Soil 125.00 30.00 0.00

100Depth of Groundwater Below Grade in Front of MSE Wall, Dw(ft)

g q

(2007)

Soil Parameters:

Wall Geometry:H

h

Reinforced

Soil

L

Retained

Soil

Foundation Soil

Df


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Traffic Live Load, LS (psf) 250.00 (See Tables below for guidelines)

Load Factors:

Different combinations of maximum and minimum values of load factors, p, is considered as follows:

Group EV LSV LSH EH

Strength I-a 1 1.75 1.75 1.5

Strength I-b 1.35 1.75 1.75 1.5

Resistance Factors at Strength Limit States:

Resistance factor for sliding resistance of foundation, is = 0.9

(See AASHTO Table 10.5.5.2.2-1)

Resistance factor for bearing resistance, b = 0.45(See AASHTO Table 10.5.5.2.2-1)

Vehicular Live Load

External Stability Results Summary:


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Eccentricity:

Group e (ft)Result

Strength I-a 4.40 OK

Strength I-b 3.26 OK

Sliding

Group Rr (kips/ft)Htotal

(kips/ft)Result

Strength I-a 40.92 32.50 OKStrength I-b 55.24 32.50 OK

Bearing Resistance

Group qR (ksf/ft)

qmax

(ksf/ft) Result

Strength I-a 10.33 6.71 OK

Strength I-b 11.52 7.70 OK

* Performance Ratio 1 means factored resistance factored load OK

Performance Ratio < 1 means factored resistance < factored load NG

y y

Performance Ratio*

1.261.70

5.25

5.25

1.19

Performance Ratio*1.54

1.49

Allowable max.e, emax(ft)

Performance Ratio*

1.61

CALCULATIONS


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Back Slope Angle (deg,) = 0.00

Broken Slope Equivalent Angle (deg.) eq = 0.00 (Art. 3.11.5.8.1)

Active Lateral Pressure Coeff. for Ext. Stability* Ka = 0.333

Additional Height from Backslope h (ft) = 0.00

Total Design Height for External Stability H+h (ft) = 30.00

*For equation of Ka, see Articles 3.11.5.3 & 11.10.5.2

(A) Unfactored Loads

Horizontal Components

PEH = 0.5KaH2cos(eq) = 18.75 k/ft

P(LS)H = Ka(LS)Hcos(eq) = 2.50 k/ft

Vertical Components

PEV1 = HL = 78.75 k/ft

PEV2 = 0.5hL = 0.00 k/ft

P(LS)V1 = (LS)L = 5.25 k/ft

P(EH)V = 0.5KaH2sin(eq) = 0.00 k/ft

P(LS)V2 =Ka(LS)Hsin(eq) = 0.00 k/ft

CALCULATIONS


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where:

EH is lateral earth pressure acting at eq from horizontal

EV1 and EV2 are vertical earth pressures

LSH is lateral live load acting at eq from horizontal

H

h

EV1

LS

EHLSH

Toe

eq

Equivalent

Backslope

(H+h)/3(H+h)/2

EV2

L

Summary of Unfactored Horizontal Loads


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Items

Horizontal

Loads

(kips/ft)

Moment

Arm about

Toe (ft)

Moment

about Toe

(k-ft/ft)

PEH 18.75 10.00 187.50

PLSH 2.50 15.00 37.50

Items

Vertical

Loads

(kips/ft)

Moment

Arm about

Toe (ft)

Moment

about Toe

(k-ft/ft)

PEV1 78.75 10.50 826.88

PEV2 0.00 0.00 0.00

P(LS)V1 5.25 10.50 55.13P(EH)V 0.00 21.00 0.00

P(LS)V2 0.00 21.00 0.00

y

and Overturning Moments

Summary of Unfactored Vertical Loads and

Resisting Moments


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(B) Load Factors

The following strength limit states are not considered in the analysis:

In theory, structures should be evaluated for each of the strength limit states. However, depending

on the particular loading conditions and performance characteristics of a structure, only certain

controlling strength states need to be evaluated for MSE wall.

Strength II: for Owner specified special design vehicles and/or evaluation permit vehicles, without

wind. Not applicable for typical MSE wall unless special vehicle loading is specified.

Consequently, only Strength I loading applies to MSE wall analysis.

Strength III: for structure exposed to wind of velocity of exceeding 55 mph. Not applicable to MSE

wall because wall is not subjected to other than standard wind loading.Strength IV: load combination relating to very high dead load to live load force effect ratio ratios.

Not applicable to MSE wall.

Strength V: load combination relating to normal vehicular use of the bridge with wind velocity of 55

mph. Not applicable to MSE wall because wind load is not a design factor.

(C) Factored Loads

GroupPEH PLSH Total

Factored Horizontal Loads


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Group

(kips/ft) (kips/ft) (kips/ft)Unfactored Hori. Load, H 18.75 2.50 21.25

Strength I-a 28.13 4.38 32.50

Strength I-b 28.13 4.38 32.50

Group

PEV1

(kips/ft)

PEV2

(kips/ft)

PLSV1

(kips/ft)

PEHV

(kips/ft)

PLSV2

(kips/ft)

Total

(kips/ft)Unfactored Vert. Load, V 78.75 0.00 5.25 0.00 0.00 84.00

Strength I-a 78.75 0.00 9.19 0.00 0.00 87.94

Strength I-b 106.31 0.00 9.19 0.00 0.00 115.50

Group PEH(kips/ft)

PLSH(kips/ft)

Total(kips/ft)

Unfactored Moment from

Horizontal Load, Mh 187.50 37.50 225.00

Strength I-a 281.25 65.63 346.88

Strength I-b 281.25 65.63 346.88

GroupPEV1

(kips/ft)

PEV2(kips/ft)

PLSV1(kips/ft)

PEHV(kips/ft)

PLSV2(kips/ft)

Total

(kips/ft)

Unfactored Moment from

Vertical Load, Mv 826.88 0.00 55.13 0.00 0.00 882.00

Strength I-a 826.88 0.00 96.47 0.00 0.00 923.34

Strength I-b 1116.28 0.00 96.47 0.00 0.00 1212.75

Factored Moments from Horizontal Loads

Factored Vertical Loads

Factored Moments from Vertical Loads


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(D) Eccentricity Check

Eccentricity, e = L/2 - Xo where: L/2 = 10.5 ft

Allowable max. e, emax = L/4 for MSE wall on soils (see Article 10.6.3.3)

emax = 5.25 ft.

GroupMv, dead load

(k-ft/ft)

MH, total(k-ft/ft)

Vdead load(kips)

Xo (ft) e (ft) Result

Strength I-a 826.88 346.88 78.75 6.10 4.40 OK

Strength I-b 1116.28 346.88 106.31 7.24 3.26 OKNote: OK if e emax; NG if e > emax.

deadload

totalHdeadloadV

oV

MMX

,,

=


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(E) Base Sliding Check

Assumptions: 1. Passive earth resistance from soils in front of wall is ignored.

Factored Resistance against Base Sliding Failure on Cohesionless Soils, Rr = x V tan'

Factored Resistance against Base Sliding Failure on Cohesive Soils, Rr = x Su

where: is resistance factor for sliding resistance of foundation on soil

(from Table 10.5.5.2.2-1)

V is total vertical loads, excluding traffic live load.' is the lesser ofr of reinforced fill andfof the foundation soil.

Su is undrained shear strength.

Group/Item V (kips/ft) tan' Su (ksf) Rr (kips/ft)Htotal

(kips/ft)Result

Strength I-a 78.75 0.58 0.00 40.92 32.50 OK

Strength I-b 106.31 0.58 0.00 55.24 32.50 OK

Note: OK if Rr Htotal; NG if Rr < Htotal.

2. For clay foundation soils and a layer of compacted granular

material is placed between the MSE mass and foundation soil, refer

to Article 10.6.3.4 for sliding resistance calculations.

(F) Bearing Pressure Check

Equivalent footing width, B' = B - 2e'


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Applied Bearing Pressure, qmax = (Vtotal)/B'

Eccentricity to calculate equivalent footing width:

e' =(B/2) - X'o

where: 10.5 ft.

Factored Bearing Resistance =qR =b x qnwhere: b = Resistance Factor for Bearing Resistance

qn = Nominal Bearing Resistance (calculated in Bearing Resistance Worksheet)

Group/ItemMv,total(k-ft/ft)

MH,total(k-ft/ft)

Vtotal(ki s/ft)

X'o (ft) e' (ft) B' (ft)

Strength I-a 923.34 346.88 87.94 6.56 3.94 13.11

Strength I-b 1212.75 346.88 115.50 7.50 3.00 14.99

Group/Item qmax (ksf/ft) qR (ksf/ft) Result

Strength I-a 6.71 10.33 OK

Strength I-b 7.70 11.52 OK

Note: OK if qmax qR; NG if qmax >qR.

Note: The values of e' for calculating equivalent footing width and bearing pressure are different

from the e for eccentricity check.

B/2 = L/2 =

total

totalHtotalV

o

V

MMX

,,'

=


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Version 2-1, 2/08

Project Name: Test

Project Number: 123456

Designer: KL

INPUT (Yellow Colored Cells)

30.00

21.00

0.00

100.00

* For level backslope, enter zero for backslope height.

Calculated backslope angle, (deg) = 0.00

This worksheet checks the internal stabil ity of steel strip MSE walls based on the strength l imit

state requirements in AASHTO LRFD 4th Edi tion ( 2007)

Wall Height, H (ft)

Reinforcement Length, L (ft)

Backslope Height, h (ft)

Wall Geometry:

(Orange Cells are Input Imported from

MSE Ext. Stabili ty Worksheet

Backslope Run, r (ft)

H

h

Reinforced

Soil

L

Retained

Soil

Foundation Soil

r

z


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(pcf) ' (deg.) c' (psf)125.00 34.00 0.00

125.00 30.00 0.00125.00 30.00 0.00

Traffic Live Load, LS (psf) 250.00

Panel and Strip Properties

MSE Wall Design Life (yr.) = 75 (From Contract Document)Effective Panel Width, (ft) = 4.92 (From MSE wall plans)

Width of Strip, b (in) = 2 (From MSE wall plans)

Nominal long-term strip design strength, Tal (kips/strip) = 7.2 (From MSE wall vendor)

Nominal long-term connection design strength, Tcon (kips/conn) = 8.4 (From MSE wall vendor)

Soil Parameters:

Vehicular Live

Reinforced Soil

Retained SoilFoundation Soil

Calculations


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A. Factored Tensile Resistance of Strip Reinforcement and Connect ion

Resistance factor for strip tension, = 0.75 for static loading (Per AASHTO Table 11.5.6-1)

Factored tensile resistance of strip,Tal = 5.4 kip/strip

Resistance factor for connection, = 0.75 for static loading (Per AASHTO Table 11.5.6-1)Factored tensile resistance of connection, Tcon = 6.3 kip/strip

B. Factored Load on Strip Reinforcement

The factored horizontal stress, H, at each strip level

= p(vkr+H)

where: p = the load factor for vertical earth pressure EV from Table 3.4.1-2

p, EV = 1.00 (min)

1.35 (max)

The load factor that produces the largest strip tensile force is p, EV = 1.35. Therefore,

only p, EV = 1.35 is considered in the following calculations.


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kr = reinforced fill horizontal pressure coefficientkr = (kr/ka)x ka

ka, active lateral pressure coefficient = (C11.10.6.2.1)

= 0.28

kr/ka , coefficient multipler, refers to Figure 11.10.6.2.1-3

v =rZ + 0.5Lr(tan) + LS

Z is depth of reinforced fill at strip layer measured from top of MSE wall.

Factored load on strip reinforcement, Tmax =H x Sv x (width of 2 panels/#of strips in 2-panel)

where: Sv = tributary height of strip reinforcement.

v = pressure from soil self weight within and immediately above the reinforced wall backfill, and

any surcharge loads present (ksf)

H = horizontal stress at the reinforcement level resulting from any applicable concentrated

horizontal surcharge load as specificed in Article 11.10.10.1 (ksf), such as "true" MSE

abutment.H is not consiidered in this spreadsheet.

2

'45tan

2 f

C. Strip Reinforcement Tensile Strength and Connection Checks

Number of strip reinforcement layers, N = 8 (From MSE wall shop plans)


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Reinf.

Layer

Depth, Z

(ft)

Total

Vert.

Pressure,

v (ksf)

Hori.

Pressure

Coeff. kr

Factored

Hori.

Pressure,

H (ksf)

#of

Strips Per

2 Panels

Tributary

Height, Sv(ft)

Factored

Load on

Strip for

Rupture,

Tmax(kips)

Factored

Tensile

Resist. of

Strip,

Tal(kips)

Strip

Tensile

Strength

Check

Connection

Rupture

Check

1 1.25 0.41 0.47 0.26 6.00 2.50 1.06 5.40 OK OK

2 3.75 0.72 0.45 0.44 6.00 2.50 1.81 5.40 OK OK

3 6.25 1.03 0.44 0.61 6.00 2.50 2.49 5.40 OK OK

4 8.75 1.34 0.42 0.76 6.00 2.50 3.11 5.40 OK OK

5 11.25 1.66 0.40 0.90 6.00 2.50 3.68 5.40 OK OK6 13.75 1.97 0.38 1.02 6.00 2.50 4.18 5.40 OK OK

7 16.25 2.28 0.37 1.13 6.00 2.50 4.62 5.40 OK OK

8 18.75 2.59 0.35 1.22 6.00 12.50 24.99 5.40 NG NG

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10

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13

14

15

16


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D. Strip Pullout Resistance

Width of active zone for pullout calculation = 0.3xH1

H1 = 30.00 ft.

0.3H1 = 9.00 ft.

30.96 Deg.

Only the effective pullout length (Le) which

extends beyond the theoretical failure

surface is considered in pullout resistance

calculations.

tan3.013.0tan1

+= HHH

L

0.3H1

La Le

Zone of max. stress

or potential failuresurface

H1

H1/2

H1/2

H


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Nominal Pullout Resistance, Pr (kips/strip) =F*vCbLe

where:

F* = Pullout friction factor at top of wall = 2.0

= Scale effect correction factor = 1.0

v = Unfactored vertical stress at the strip level (ksf)

C = Overall strip surface area geometry factor = 2 for strip reinforcementb = Width of strip (ft)

Le = Length of strip in resistant zone (ft)

Pullout Resistance Factor, = 0.9

Factored Pullout Resistance =Pr (kips/strip)

Vertical pressure, v = rZp.where Zp is depth of soil at strip layer at beginning of resistance zone (See AASHTO Fig. 11.10.6.2.1-2)

For strip reinforcement pullout resistance computation, traffic live load (LS) is neglected in computing the

vertical stress and pullout resistance at strip level (See AASHTO Fig. 11.106.2.1-1 and -2).

Factored tensile load on strip, Tmax, is calculated in Section C and is used to compare with the factored

pullout resistance..

E St i P ll t Ch k


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E. Strip Pullout Checks

Reinf.

Layer

Depth, Z

(ft)

Zp(ft)

Total

Vert.

Pressure,

v (ksf)

Length of

Strip

Beyond

Failure

Surface,

Le (ft)

Pullout

Resist.

Factor, F*

Nominal

Pullout

Resist. Pr(kip)

Factored

Pullout

Resist.,

Pr (kips)

Factored

Load on

Strip for

Pullout,

Tmax

(kips)

Strip

Pullout

Check(PrTmax)

Strip

Pullout

Check(Le3')

1 1.25 1.25 0.16 12.00 1.92 1.20 1.08 0.41 OK OK

2 3.75 3.75 0.47 12.00 1.75 3.28 2.96 1.18 OK OK

3 6.25 6.25 0.78 12.00 1.59 4.96 4.46 1.89 OK OK

4 8.75 8.75 1.09 12.00 1.42 6.21 5.59 2.54 OK OK

5 11.25 11.25 1.41 12.00 1.25 7.06 6.35 3.12 OK OK

6 13.75 13.75 1.72 12.00 1.09 7.48 6.74 3.65 OK OK7 16.25 16.25 2.03 12.75 0.92 7.97 7.17 4.11 OK OK

8 18.75 18.75 2.34 14.25 0.76 8.43 7.59 22.58 NG OK

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2_Retaining Wall Ashton Lawler.pdf

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