Wood Wall Results

Wood Wall results are presented in the Wall Panel Design Spreadsheet and the detail reports.

For additional advice on this topic, please see the RISA Tips & Tricks webpage at risa.com/post/support. Type in Search keywords: Wood Walls.

Wood Wall Results Spreadsheets

Wood Wall Axial Results

The Wall Panel column lists the wood wall panels that you have defined.

The Region column lists the wall panel region that the results are based on.

Note:

• For Perforated or Force Transfer Around Openings design methods, regions are not used. Thus, an N/A will be displayed.

The Stud Size and Spacing columns show the optimum stud size and spacing chosen for your wall, based on the Design Rules you have defined.

The Axial Check value is a code check ratio between the member load and the member capacity. The adjacent Gov LC column shows the governing load combination for the design.

The Chord Size column shows the optimum chord size chosen for your wall, based on the Design Rules you have defined. Note that the chords are the vertical hold-down members/posts at the both ends of the wall.

The Chord Axial Check value is a code check ratio between the member load and the member capacity. The adjacent Gov LC column shows the governing load combination for the design.

Note:

• When running the Segmented design method, the wall panel regions above and below the opening are not considered in design. Thus an NC (no calculation) will be displayed.
• If there are some constraints that will not allow a wall to be designed, an NC (no calculation) will be displayed. Check the Warning Log within the program for more information on this.

Wood Wall In-Plane Results

The Shear Panel Label shows the optimum shear panel arrangement chosen for your wall, based on the Design Rules you have defined.

The Region gives the region for which the design values are being displayed.

Note:

• The Perforated and Force Transfer Around Openings methods do not consider regions in their design, thus N/A is displayed.

The Shear Check value is a code check ratio between the panel shear load and the panel shear capacity. The Shear Force and Gov LC show the values and load combination which governed the design.

The Hold-Down Label shows the optimum hold-down product chosen for your wall, based on the Design Rules you have defined.

The Chord Strap Label shows the optimum strap product chosen for your wall, based on the Design Rules you have defined.

The Tension Check value is a code check ratio between the tension load and the hold-down tensile capacity. This column will only be populated for wood walls at the base level of the structure. The program does not do wall to wall strap design.

The Tie-Down Forceand Gov LC show the maximum value of hold-down/strap and the load combination which produced the highest strap force. This maximum force could occur on either end of the wall/region.

Note:

• When running the Segmented design method, the wall panel regions above and below the opening are not considered in design. Thus an NC (no calculation) will be displayed. If running a combined RISAFloor and RISA-3D model use RISAFloor to get header results.
• If there are some constraints that will not allow a wall to be designed, an NC (no calculation) will be displayed. Check the Warning Log within the program for more information on this.
• If 'default' is shown in the Hold-Down Label column it means that a hold down is not required for this wall/region.

Wood Wall Header Results

The Header Label gives the label of your header. If there is more than one header in a wall you can see which is which in the wall panel editor.

The Design Rule gives the rule that is defining the size and material.

The Size gives the size from the Design Rule.

The Bend UC value is a bending code check ratio. This is given for the load combination from the Gov LC column.

The Shear UC value is a shear code check ratio. This is given for the load combination from the Gov LC column.

The Gov LC gives the load combination that governed the design. The program finds the largest UC value for either bending or shear and reports the associated load combination here.

Note:

• The Bend UC and Shear UC are always given for the SAME load combination. Whichever load combination produced the highest code check for either bending or shear will have its results shown in these columns.
• The program will only design wood headers for non-EL and non-WL load combinations.

Wood Wall Self Weight

The program will calculate the self weight of a wood wall based on the weights of the individual components. Using the material density, the self weight is calculated for the studs, chords, top plates, sill plates, and sheathing. These are all then summed for the total self weight of the wall.

Wood Wall Detail Reports

The detail report gives detailed information about the wall design. The detail reports are specifically molded to the type of design specified. Here we will walk through how to access the different information for each of the types of design: Segmented, Perforated and Force Transfer Around Openings.

Note:

• RISAFloor only considers the Segmented design method. If using RISAFloor together with RISA-3D, simply taking your model into RISA-3D will open up the Perforated and Force Transfer Around Openings design methods.
• Many of the values for design checks seen below are not performed in RISAFloor as it is strictly a gravity design program.

Accessing the Detail Reports and the Specific Windows

Once you have a solved model, the detail reports become available. They are accessible in two ways:

1. If you have the Wall Panel Design spreadsheet open, you can right-click on a line in the spreadsheet and select Detailed Report. there will be a button at the top of the screen:. This will open up the detail report window.
2. If you are in a graphic view of your model, there is a button that will open up the detail report window.

Note:

• Detail report information is not available for an envelope solution.

Once the detail report window is open, you will see a dialog area at the top.

• - Allows you to click between the different wall panels in your model.
• - This button will allow you to take a snapshot of the current detail report you are viewing so that it can be added to a report. View the Printing topic for more information.
• - This dropdown list allows you to select between the three different parts of the wood wall panel detail report. Below we will explain the importance of each of these sections.
• - This dropdown list allows you to select between different regions or headers defined within the individual wall panel.

The Wall detail report gives an overall summary of your wall, complete with governing code checks and opening information. The Opening detail report gives information to the header design for the opening as well as detailed information for the Force Transfer Around Openings method. The Region detail report only applies for Segmented walls. Below we have give detailed information on each type of design: Segmented, Perforated and Force Transfer Around Openings.

Segmented Method

The Segmented design method uses each of the three detail report windows to give design information.

Wall Window

This window gives an overview of the wall, giving controlling region information and deflection information. Note that this window only gives information on the full-height segments in your wall, as this is the basis of the Segmented method.

Input Echo

This lists information about the wall, similar to the Region report and also gives an image of the wall. The image shows the location of hold-downs/straps, regions and headers.

Design Details

The Enveloped Results gives the code checks for all of the controlling elements in the wall and their associated load combinations.

The Region Information gives the tabulated results of all of the full-height regions in your wall.

The Opening Information simply states that header design cannot be completed with the Segmented method. The regions above and below the opening have their shear stiffnesses set to be zero and this causes the header forces to be invalid.

The Deflection Results gives both the calculated NDS deflection (Maximum Region Deflection) and the FE deflection for use as a means of comparison. Because the NDS/CSA O86 equations are empirical and take into account many non-elastic considerations such as nail slip, these two values may not be the same. The use of the SSAF helps to make these two values similar.

Opening Window

This window defines the openings in the wall. The segmented wall design method assumes zero stiffness over the opening, therefore, there is no header design for a Segmented wall with openings. Walls specified as a Perforated or FTAO can be analyzed for a header design.

Region Window

This window gives information for your wall on a region by region basis. Note that only full-height regions of the wall panel will have a region detail report. The Segmented method only considers these full height segments in the design of the wall.

The region detail report is split into four portions: input echo, diagrams and design, design details, and cross section detailing. Note that in RISAFloor the detail reports are less detailed because RISAFloor does not consider lateral forces which RISA-3D does.

Input Echo

Below is the input echo portion of the detail report.

Diagrams and Design

Envelope Diagrams

These diagrams show the axial forces, in-plane shear, and in-plane moments of the wall, as well as the maximum and minimum forces and their locations.

Note:

• The diagrams are not actually enveloped.
  • The Axial diagram shown is the diagram from the governing load combination for Stud design.
  • The Shear diagram is the diagram from the governing load combination for Shear Panel design.
  • The Moment diagram is the diagram from the governing load combination for Hold-Down design.

Design Summary  

This portion gives you the capacity and strength values at the section in the wall where the combined check is maximum, as well as the governing load combination. Much of this information is also reported in the Wood Wall Panel Design spreadsheets.

Shear Panel

The provided capacity of the shear panel is taken from the Shear Capacity column of the panel database. This is the allowable shear value from Table 2306.4.1 from the 2006 IBC (for NDS design) or Table 9.3A, 9.3B, and 9.3C from the CSA O86-14 (for Canadian design). This capacity automatically considers whether the loading is based on wind or seismic loads. The Governing LC explicitly states if the controlling load combination was based on Wind or Seismic. The program does a unity check for all LCs that are being solved, finds the maximum value and reports that information.

Note:

• A shear panel design will be chosen for the worst-case region in a segmented wall. That panel will then be used for all regions in that wall. The worst-case region is the one that has the highest Shear UC value.
• Because wind and seismic loading allows for different design capacities, the highest shear in the wall may not be the governing shear (if that highest shear was due to wind).

Chords, Studs

The provided capacities of these members are calculated using the standard provisions for tension/compression members. These members are assumed to be fully braced in the weak axis, and unbraced in the strong axis. For more information on the chord force calculations, see the Wood Wall - Design topic.

Note:

• For chord results, the tension/compression capacity is computed using the reduced cross-sectional properties caused by the hold-down bolt hole.

Hold-Downs

The provided capacity of the hold-down is taken from the Allowable Tension column of the hold-down database. This is information supplied by the manufacturer. Note that we are modifying the Cd value for the hold-down based on taking a ratio of the assumed Cd values from the database and the Cd called for in the Load Combinations spreadsheet.

Chord Straps

The provided capacity of the chord strap is taken from the Allowable Tension column of the chord strap database. This is information supplied by the manufacturer. Note that we are modifying the Cd value for the chord strap based on taking a ratio of the assumed Cd values from the database and the Cd called for in the Load Combinations spreadsheet.

Deflections

The deflection listed in the detail report is based on an approximation from the design code.:

NDS Design Deflection

Per the NDS 2015 Special Design Provisions for Wind and Seismic, Equation 4.3-1:

The first term of the above equation determines the Bending Component of the deflection.

The second term of the above equation determines the Shear Component of the deflection.

The third term of the above equation determines the Hold-Down Elongation Component, which causes additional deflection.

Note

• This is the theoretical deflection of the wall. This may differ from the deflection of the wall as performed by finite element analysis within RISA. Therefore, this deflection value may not coincide with the reported deflection value in the deflections spreadsheets. For information on making the FEM deflections similar to the reported deflections from the NDS calculated deflections, see the Shear Stiffness Adjustment Factor information.
• For Perforated design deflections, the total deflection is to be divided by C_oper section 2305.3.8.2.9 of the IBC 2006. Because the unit shear values have already been amplified by C_o, the only portion of the deflection that needs to be divided is the hold-down portion.
• The hold-down deflection is reported for the maximum shear LC, which may not result in the largest hold-down component, but typically results in the highest total deflection.

CSA O86 Design Deflection

Per the CSA O86-14 clause 11.7.1.2 (or CSA O86-09 clause 9.7.1.1):

The first term of the above equation determines the Bending Component of the deflection.

The second term of the above equation determines the Shear Component of the deflection.

The third term of the above equation determines the Hold-Down Elongation Component, which causes additional deflection.

Note

• This is the theoretical deflection of the wall. This may differ from the deflection of the wall as performed by finite element analysis within RISA. Therefore, this deflection value may not coincide with the reported deflection value in the deflections spreadsheets. For information on making the FEM deflections similar to the reported deflections from the CSA calculated deflections, see the Shear Stiffness Adjustment Factor information.
• The hold-down deflection is reported for the maximum shear LC, which may not result in the largest hold-down component, but typically results in the highest total deflection.

Design Details

The Selected Shear Panel gives the call-out from the shear panel database. The information below it is the information describing the call-out.

Note:

• There will also be an "Adjusted Shear Capacity" that takes the given shear capacity from the design code and divides it by any appropriate adjustment factors from the Geometry section at the top of the report.

The Selected Hold-Down gives the call-out from the hold-down database. The information below it is the information describing the call-out. The "Base Capacity" is the capacity from the manufacturer divided by the assumed Cd value from the database. The "CD factor" that is displayed is the value from the load combinations spreadsheet for the controlling load combination. The actual capacity of the hold-down is the Base Capacity*CD factor.

The Selected Chord Strap gives the call-out from the strap database. The information below it is the information describing the call-out. The "Base Capacity" is the capacity from the manufacturer divided by the assumed Cd value from the database. The "CD factor" that is displayed is the value from the load combinations spreadsheet for the controlling load combination. The actual capacity of the chord strap is the Base Capacity*CD factor.

The above section of the report echoes the database information for the selected shear panel and hold-down. For more information on these properties refer to Appendix F-Wood Shear Wall Files.

Cross Section Detailing

The last section of the detail report consists of the wall detailing information. This information is provided as a visual confirmation of the wall design. The wall thickness, and stud spacing are shown as dimensions. The triangle shows sheathing on one side of the wall, with the abbreviated panel designation. The chord sizes/forces and hold down or strap designations/forces are shown at either end. If either chord is only experiencing a compression force, the hold down or strap will not be drawn.

Note:

• The displayed chord force is not necessarily the force used in the hold-down design because hold-down optimization only considers the governing tension LC.

Perforated Method

Opening Window

This window is identical to the Segmented Window information.

Wall Window

This is where the majority of the information is located for the perforated method.

The General information gives some of the important parameters in designing the wall.

The Geometry section gives dimensions and ratios for the wall panel.

• The Wall H/W Ratio is checked against the aspect ratio limits given in Table 4.3.4 of the NDS 2015 Special Design Provisions for Wind & Seismic (SDPWS).
• The Max Opening Ht is used in the calculation of C_o.
• The % Full Ht Sheathed is used in the calculation of C_o.
• The Full Ht Sheathed is the Sum Li value for C_o.

The Materials information just gives the sizes of the members that are not explicitly talked about in the detail report.

Note:

• The top plate, sill plate and trimmer sizes are used only for the Material Take Off.

The Design Details section gives adjustment factors and some other values used to calculate C_o. See the Wall Panels topic for more information on the Shear Stiffness Adjustment Factor. See the Wood Wall - Design topic for more information on C_o.

The Deflections section gives the calculated deflection for the three term shear wall equation from the NDS. See above for more information on deflections.

The Wall Results section gives:

• The Governing LC is the load combination that produced the highest allowable code check. This will also state if this load combination was a wind or seismic LC.
• The Total Shear is the total shear in the wall for the governing LC.
• The Max. Unit Shear is the maximum shear in the shear panel and it is what is used to optimize the sheathing/nailing selection from the shear panel database. Note that the Max Unit Shear may not be the absolute maximum, because shear walls governed by wind are allowed a 40% stress increase. Thus, a wind Max Unit Shear would need to be 40% higher than a seismic Max Unit Shear to govern.
• The Shear Ratio is a ratio of the Max Unit Shear over the Shear Capacity of the shear panel selected from the database.

The Selected Shear Panel , Selected Hold-Down, and Selected Strap section gives the same hold down, strap, and shear panel information that was given in the Segmented region report.

There is then the chord, stud, hold-down, and strap design section that has the same information as given in the Segmented region report.

The Cross Section Detailing section gives a detailed view of the wall. For more information see the Segmented section.

Force Transfer Around Openings (FTAO)

Wall Window

This is the overall wall information and is essentially identical to the Perforated method wall window information. There is some geometry information that is not necessary for FTAO that is omitted.

Opening Window

The Criteria section gives the code being used and which design method used.

The Geometry section gives the opening dimensions and the h/w ratio.

The Materials section gives dimensions for some of the members in the wall.

The Envelope Diagrams give the enveloped shear and moment diagrams for the header beam above the opening.

The FTAO graphic shows the design block numbers around the wall panel opening along with the strap numbers.

The Design Details section is split into two different tables: Opening Straps and Analysis Summary. The opening straps information gives the location, direction, force in the strap and the load combination that caused that force.

Note:

• For more information on how the strap forces and unit shears are calculated, see the Wood Wall - Design topic.
• The program does not design the straps around the opening, just presents the forces.

The analysis summary gives the unit shear and the h/w ratio for each of the blocks.

The information below is the code check information for the header member. This is identical to the information given for Segmented Window information.