Retaining Walls

You can create single stem tapered concrete retaining walls or multiple stem non-tapered concrete and masonry retaining walls. These walls can be either cantilevered or restrained and the restraint can be placed at what ever distance below the top of the wall that is required.

Double click anywhere that the cursor turns into a finger pointer to edit the object under the cursor.

Right click over an object to see a menu.

General

  • Use the Straight Stem/Multiple Stem type if you need multiple non-tapered stems or masonry stems. Use the Tapered Stem type for single concrete tapered stems.
  • If you use a wall restraint the wall is considered pinned at the footing. Otherwise, the wall is considered fixed at the footing.
  • If you have more than one stem and wish to delete a stem, double click on the stem and click the Delete Stem button in the dialog box.
  • Equations used in the design are shown as part of the report.
  • The key is used only to resist sliding and is not checked for shear or moment loads.
  • Actual embedment lengths are not compared to the suggested embedment lengths. The user should make sure that there is enough available embedment for the suggested embedment.
  • Concrete rebar spacing and sizes are calculated as follows:If you input a rebar size and set the rebar spacing to Calc, the rebar spacing is determined by the minimum of As req’d, 3 x thickness, or 18″.

    If you input a rebar spacing and set the rebar size to Calc, the rebar size is determined based on the As req’d.

    If you set both rebar spacing and rebar size to Calc, several rebar sizes and spacings are suggested based on the As req’d.

Applied Loads

  • The sign conventions for the external loads are as follows:
    Vertical Point LoadsDown is positive
    Moment LoadsCounter-clockwise is positive
    Horizontal Point LoadsLeft is positive
    Horizontal Distributed LoadsLeft is positive
  • The lateral soil pressure can be calculated using Equivalent Fluid Pressure, Coulomb, Rankine or At-Rest pressures. The total lateral load is calculated as pressure*(depth)2/2.
  • Surcharge loads are divided by the soil density to determine an equivalent soil height. This height is multiplied by the calculated lateral soil pressure to determine the additional lateral pressure due to the surcharge. The total lateral load due to the surcharge is calculated as pressure*(depth)2.
  • The lateral soil pressure can be calculated using Equivalent Fluid Pressure, Coulomb, Rankine or At-Rest pressures. The total lateral load is calculated as pressure*(depth)2/2.
  • Active pressure due to sloping backfill is calculated as follows: depth = tan(slope)*distance from the back side of the wall to the back of the heel. This additional depth is added to the depth of the backfill. If the heel width is zero, the lateral load due to the sloping backfill will be zero.
  • Passive pressures are calculated in the same way as active pressures and are used to resist sliding.

Cantilever Wall Footing Design

  • The left side of footing is considered the toe and the right side is considered the heel.
  • The sum of the overturning moments must be greater than 0 (Counter-clockwise).
  • The heel shear is calculated at the right face of the bottom stem and the toe shear is calculated at a distance d from the left face of the bottom stem.
  • The heel moment is calculated at the centerline of the bottom stem rebar and the toe moment is calculated at the left face of a concrete bottom stem or 1/4 of the nominal stem thickness inside the left face of a masonry bottom stem.

Restrained Wall Footing Design

  • Shear and moment values are calculated for both the left and right sides of the footing and the maximum values are used.
  • Footing shear is calculated at a distance d from the face of the bottom stem.
  • Footing moment is calculated at the face of a concrete bottom stem or 1/4 of the nominal stem thickness inside the face of a masonry bottom stem.

Stem Design

  • Stress reversals are taken into account when calculating stresses. Therefore, when tensile stresses move from one side of the stem to the other, a new d is calculated based on the distance from the rebar centerline to the tension face of the stem. Depending on the location of the rebar, this new d may control the design because this distance may be much smaller than the input value.
  • Passive pressures and surcharge loads over the toe are not included in the stem shear and moment calculations.
  • Axial loads are not considered when designing concrete stems.
  • Building codes call for reinforcement in both faces of concrete walls that are more than 10″ thick except in the case of basement walls. A second layer of reinforcement is not considered in the concrete design because the module considers the walls to be basement walls.
  • Masonry design is based on concrete masonry and Working Stress Design.
  • Section properties for masonry design are based on face shell mortar bed.
  • The height in the h/r calculations of the masonry design are based on the height of each individual stem section and not the total retaining wall height.

Building Codes

  • IBC 2012

    Standard Service Load Combinations – Section 1605.3.1

    Alternate Service Load Combinations – Section 1605.3.2

    It is assumed that wind loads used in the alternate service load combinations are calculated by section 1609 or the ASCE 7.

    Standard Design Load Combinations – Section 1605.2.1

    ACI 318-99 Design Load Combinations – ACI 318-99 Section 9.2

    It is assumed that the seismic loads are calculated per the code and are strength level forces.

    The concrete wall and footing maximum reinforcement spacing is 3*thickness with a maximum of 18″. The wall and footing maximum temperature and shrinkage spacing is 5*thickness with a maximum of 18″. The minimum spacing for both is the rebar diameter with a minimum of 1″.

  • IBC 2009

    Standard Service Load Combinations – Section 1605.3.1

    Alternate Service Load Combinations – Section 1605.3.2

    It is assumed that wind loads used in the alternate service load combinations are calculated by section 1609 or the ASCE 7.

    Standard Design Load Combinations – Section 1605.2.1

    ACI 318-99 Design Load Combinations – ACI 318-99 Section 9.2

    It is assumed that the seismic loads are calculated per the code and are strength level forces.

    The concrete wall and footing maximum reinforcement spacing is 3*thickness with a maximum of 18″. The wall and footing maximum temperature and shrinkage spacing is 5*thickness with a maximum of 18″. The minimum spacing for both is the rebar diameter with a minimum of 1″.

  • IBC 2006

    Standard Service Load Combinations – Section 1605.3.1

    Alternate Service Load Combinations – Section 1605.3.2

    It is assumed that wind loads used in the alternate service load combinations are calculated by section 1609 or the ASCE 7.

    Standard Design Load Combinations – Section 1605.2.1

    ACI 318-99 Design Load Combinations – ACI 318-99 Section 9.2

    It is assumed that the seismic loads are calculated per the code and are strength level forces.

    The concrete wall and footing maximum reinforcement spacing is 3*thickness with a maximum of 18″. The wall and footing maximum temperature and shrinkage spacing is 5*thickness with a maximum of 18″. The minimum spacing for both is the rebar diameter with a minimum of 1″.

  • IBC 2003

    Standard Service Load Combinations – ASCE 7, Section 2.4.1

    Alternate Service Load Combinations – Section 1605.3.2

    It is assumed that wind loads used in the alternate service load combinations are calculated by section 1609 or the ASCE 7.

    Standard Design Load Combinations – ASCE 7, Section 2.3.3

    ACI 318-99 Design Load Combinations – ACI 318-99 Section 9.2

    It is assumed that the seismic loads are calculated per the code and are strength level forces.

    The concrete wall and footing maximum reinforcement spacing is 3*thickness with a maximum of 18″. The wall and footing maximum temperature and shrinkage spacing is 5*thickness with a maximum of 18″. The minimum spacing for both is the rebar diameter with a minimum of 1″.

  • IBC 2000

    Standard Service Load Combinations – ASCE 7, Section 2.4.1

    Alternate Service Load Combinations – Section 1605.3.2

    It is assumed that wind loads used in the alternate service load combinations are calculated by section 1609 or the ASCE 7.

    Standard Design Load Combinations – ASCE 7, Section 2.3.3 when seismic loads are not considered, ACI 318 Section 9.2 when seismic loads are considered.

    ACI 318-99 Design Load Combinations – ACI 318-99 Section 9.2

    It is assumed that the seismic loads are calculated per the code and are strength level forces.

    The concrete wall and footing maximum reinforcement spacing is 3*thickness with a maximum of 18″. The wall and footing maximum temperature and shrinkage spacing is 5*thickness with a maximum of 18″. The minimum spacing for both is the rebar diameter with a minimum of 1″.

  • UBC 1997

    Standard Service Load Combinations – Section 1612.3.1

    Alternate Service Load Combinations – Section 1612.3.2

    Standard Design Load Combinations – Section 1909.2 when seismic loads are not considered, Section 1612.2.1 when seismic loads are considered.

    ACI 318-99 Design Load Combinations – ACI 318-99 Section 9.2

    It is assumed that the seismic loads are calculated per the code and are strength level forces.

    The concrete wall and footing maximum reinforcement spacing is 3*thickness with a maximum of 18″. The wall and footing maximum temperature and shrinkage spacing is 5*thickness with a maximum of 18″. The minimum spacing for both is the rebar diameter with a minimum of 1″.

    Masonry Fa, Fb, and Fv are reduced by 1/2 is there is no special inspection.

Menus

File Menu

Revert to Saved Version…
Reload your last saved version from the server. This will remove any changes that you have made since your last save.

Save
Save your calculation to the server overwriting any previously saved version on the server.

Save As
Save a copy of your current calculation to the server and make the copy your current calculation.

Return to Projects
Return to the Projects page.

Geometry Menu

Add/Edit Stem…
If your calculation is a Tapered Stem type this option will open a dialog box where you can edit the stem. If your calculation is a Straight Stem/Multiple Stem type this option will open a dialog box where you can add a stem to the design.

Set or edit the stem height, thickness, rebar size and spacing. If your calculation is a Tapered Stem type then the material defaults to concrete. Otherwise you are able to set your material type.

If you wall is cantilevered the stem rebar centerline is measured from the right side of the stem. Otherwise it is measured from the left side.

If your material is masonry your rebar centerline can be set to Edge, Center or you may input your own dimension by choosing Other and entering the dimension. Please see the Rebar Depth table on the Properties page for the Edge and Center dimensions.

If you have more than one stem, a Delete Stem button will be available to delete the stem.

Wall Restraint…
Turn the wall restraint on or off and set the distance below the top of wall.

Footing…
Set your footing thickness, toe and heel width, rebar size and spacing, and key usage.

If your wall is cantilevered, the toe rebar centerline is measured from the bottom of the footing and your heel rebar centerline is measured from the top of the footing. Otherwise, your footing rebar centerline is measured from the bottom of the footing.

Loads Menu

Soil Load…
Set the soil height, slope, density and analysis type.

If your analysis type is Coulomb, Rankine or At Rest you have the option of applying the vertical component of the load to resisting Overturning and/or Sliding. You also have the option of using the vertical component to redistribute the bearing pressures.

Please see the Definitions page for definitions of values used in this dialog box.

Vertical Point Loads…
Moment Loads…
Horizontal Point Loads…
Horizontal Distributed Loads…
Toe Surcharge Loads…
Heel Surcharge Loads…
Set the loads for your wall. Use the arrow buttons to indicate the load direction.

The Ecc From CL distance in the Vertical Point Loads dialog is measured from the centerline of the top stem.

The Top Location and Base Location in the Horizontal Distributed Loads dialog are measured from the top of the footing.

Passive Pressure…
Set the toe soil height, density and analysis type.

If you check the Restrained From Sliding check box then no calculation will be made for sliding.

The Height To Ignore For Sliding value will be subtracted from the Height Above Footing value for the Passive Pressure calculation but not for the Toe Soil Weight calculation.

Please see the Definitions page for definitions of values used in this dialog box.

Design Menu

Calculate Now…
Analyze and design the retaining wall and view the report.

The Show Controlling Load Combinations Calculations Only check box in the Report Options dialog controls whether only the controlling load combination calculations are shown or whether all load combination calculations are shown. Unchecking the check box will show all load combinations but will make for a long report.

Heading…
Enter heading information that will be shown at the beginning of the report.

Material Properties…
Set the concrete, masonry, steel and soil properties. Please see the Definitions page for the definitions for this dialog box.

Design Criteria…
Set the service and design load combinations, safety factors and steel ratios.

If the Neglect Heel Bearing check box is checked, any bearing under the heel will be used to reduce the shear and moment in the heel.

Select Service Load Combinations…
Select Design Load Combinations…
Select the service and design load combinations that you wish to apply to the retaining wall. Only the checked combinations will be used. If you change the building code or load combination types in the Design Criteria dialog, these combinations will change.

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Toolbar
You can use the buttons on the toolbar to speed up access to some commonly used commands. Hold your mouse over an icon for about 1/2 second to see a pop-up of what the icon does.

Buttons from left to right:
Save
Add/Edit Stem…
Wall Restraint…
Footing…
Soil Load…
Vertical Point Loads…
Moment Loads…
Horizontal Point Loads…
Horizontal Distributed Loads…
Toe Surcharge Loads…
Heel Surcharge Loads…
Passive Pressure…
Calculate Now