Computer Modeling/Stiffness

Correctly modeling the SidePlate® connection design stiffness is simple in most analysis programs with built in features.  To better understand modeling implementation refer to Figure Z1, below.

The computer model must reflect the following two items:

  • 100% Rigid Panel Zone
  • Connection Properties Beyond Column Flange

Dimensions, Dim A and Dim B, vary based on beam section, span, and loading.  To define the connection stiffness in the analysis model, SidePlate provides consistent tabulated values for analysis purposes to the various software programmers.

The Stiffness Modifier is calibrated empirically based on full scale testing, and varies based on SidePlate Connection type, as follows:

  • SidePlate: 1
  • SidePlate PLUS SMF, IMF, OMF: 3
  • SidePlate Welded OSHPD: 3

Link to Full Scale Testing Videos

See the following sections on program specific implementation.


Figure Z1 – Connection Stiffness and Strength Modeling 


RAM Structural Systems

Version 16.0 and Newer

Step 1: Select the Connection type

  • Open the Frame Design Module in RAM 
  • Criteria -> SidePlate...
  • Select the appropriate Connection Type

Step 2: Assign SidePlate Frame Beam Connection

  • Assign -> Beam -> Frame Beam Connection Types...
  • Assign SidePlate to Both Ends, Left End, or Right End of lateral frame members

  • Once the beam ends have been assigned, RAM Frame will display a red rectangle symbolizing a SidePlate moment connection as shown below.

Link to detailed SidePlate Modeling Tutorial with RAM 

Link to RAMSS version 15.09 and Older instructions 


Step 1: Group Lateral Members

  • Select all moment frame beams
  • Assign -> Assign Objects to Group...
  • Select FRAME BEAMS group and Replace Group
  • Repeat for moment frame columns


Step 2: Assign Rigid Zone

  • Select Frame Beams and Frame Columns
  • Assign -> Frame -> End Length Offsets...
  • Assign a Rigid-Zone Factor of 1.0

Note: All SidePlate® full-scale steel moment frame testing has demonstrated that the panel zone contributes very little to the total overall drift.  Thus, it has been deemed by the AISC CPRP pre-qualification committee that the flexibility in the panel zone is negligible and can be considered as 100% rigid.  Thus, it would be incorrect to utilize the ETABS Panel Zone feature when modeling SidePlate.  To ensure accurate modeling select all joints and Assign -> Joint -> Panel Zone... -> Select none -> OK.

Step 3: Assign SidePlate® Moment Connection

  • Select Frame Beams
  • Assign -> Frame -> Moment Frame Beam Connection Type...
  • Select SidePlate Option
  • Select the appropriate Connection Type from the drop down menu
    • High Seismic for SidePlate PLUS SMF, IMF, or OMF applications
    • Wind/Low Seismic for SidePlate R=3 applications

  • An SP will show above the frame section of a SidePlate beam in plan or elevation by turning on the Moment Connections in the Set View Options as shown below.

Note: Accurate SidePlate Connection Stiffness can also be modeled using non-prismatic sections with our available non-prismatic section generator tool.  See instructions for SAP 2000 for this modeling technique.  Contact SidePlate via the "Questions, Concerns, Ideas?" button in the header above to receive the tool.

BEFORE YOU BEGIN: It is important to ensure that a "Standard Moment Connection" is applied to all lateral beams and Panel Zones are assigned to "none" before any non-prismatic sections are applied.  To remove any RBS or SidePlate build in features do as follows:  Select all beams -> Assign -> Frame -> Moment Frame Beam Connection Type -> Select Standard Moment Connection -> OK.  To remove any Panel Zone assignments do as follows:  Select all joints and Assign -> Joint -> Panel Zone... -> Select none -> OK.  Missing this step can result in inaccurate stiffness and/or stress results.

SAP 2000

Step 1 and 2: Follow Step 1 and 2 on ETABS page

Step 3: Creating Non-Prismatic Sections to Model SidePlate®

Contact SidePlate via the "Questions, Concerns, Ideas?" button in the header above to receive the non-prismatic section generator tool.

Step 3.1

Confirm that the Moment Frame Beam Connection Type is set to Standard Moment Connections, and no Panel Zones are assigned

View -> Set Display Options

If a Panel Zone or a Moment Connection is assigned, the name of that property will show on the screen.

Step 3.2

While keeping SAP or ETABS open, launch the Non-Prismatic Section Generator Tool

  • Note 1: You can only have 1 SAP or ETABS model opened at the time you use the spreadsheet
  • Note 2: SAP or ETABS model must be unlocked

Step 3.3

Click the button "Get List of Materials"

Step 3.4

Use the drop down menu to select the steel material name and the SidePlate connection to use

Step 3.5

Use the drop down menu to select the sections you want to convert to SidePlate

Step 3.6

Once you have entered all the sections you wish to add into your model, click the button “Create new Non-Prismatic Section”

Step 3.7

Verify that the SP Non-Prismatic section were added to your SAP or ETABS Model

Define -> Section Properties -> Frame Sections

Step 3.8

Assign the Non-Prismatic Sections to your SAP or ETABS Building:

Select Moment Frame Beam(s) -> Assign -> Frame -> Section Property -> choose the section ending at “NPSP”

Note: Additional SidePlate non-prismatic sections can be added to an unlocked model at any time.


Step 1: Create Rigid Link Properties

Create General Material Properties of RIGID LINK.


Step 2: Create Rigid Link Section

Create General Section Sets of RIGID LINK. 

Step 3: Determine Rigid Link Lengths

  • RIGID LINK length at beam end is determined by half of column depth
  • RIGID LINK length at column end is determined by beam depth + 3.5"

Step 4: Split Beam and Column Members

  • On the top menu of RISA, go to "Modify -> Split Members..."
  • Input the RIGID LINK length in % or ft, select "Actually Split PHYSICAL Members" and "Apply Entire to All Selected Members", split all beams/columns with the same length and the same RIGID LINK length at once.

Step 5: Assign Fixity of Rigid link

  • Both ends (I End and J End) of RIGID LINK shall be assigned as "Fully Fixed (No Releases)".

Step 6: Create SidePlate® Stiffened Beam Ends for (SMF, IMF, OMF) Connections

  • For SidePlate PLUS SMF, IMF, OMF Connections, create the Stiffened Beam End sections (labeled with NPSP below) at each end of the moment frame beam.  Both ends of the beam is split per STEP 4 with the length "SP Length" or "Dim A". Then assign Section Properties to the split members. See Appendix for examples.
  • Both ends (I End and J End) of Stiffened Beam End Section shall be assigned as "Fully Fixed (No Releases)".

NOTE: To obtain the SidePlate Stiffened Beam End Section Properties and Dimensions, please contact SidePlate at 


Examples of Modeling SidePlate Stiffened Beam End (NPSP Sections) in Risa 3D:

Create and assign SidePlate Stiffened Beam End Properties: “Modify” on the top menu bar, click on “Shape Database...”, in “Shape Selection” window pop-up, click on “Add”.

In “Add Shape” window, create custom Shape Name, and click “OK”. Then re-open “Shape Selection” window, select the custom shape just created and click “Edit”.

In “Edit Shape” window, match the properties with “SidePlate Stiffened Beam End Properties”. For properties not included in “SidePlate Stiffened Beam End Properties”, please refer to AISC Steel Manual.


A. W18x40:

B. W21x50:

C. W24x62:

Assign Stiffened Beam End properties to Risa model: Double click on SidePlate Stiffened Beam End member, in “Information for Member XXX” window, click on “Properties” tab, click on “Shapes List”, in “Shape Selection” window, select the proper custom shape just created, then click “OK” and “OK”.


Version 2019 and Newer

Step 1: Assign Moment Frame Columns and Beams

  • Select SidePlate Moment Frame Columns and Beams in one direction
  • From the Properties Window expand Seismic:
  • In a seismic force resisting system - Check Box
  • SFRS direction - Choose "Dir 1" or "Dir 2" as appropriate
  • SFRS type - Choose applicable frame type to match Side Plate Connection for your project
    • Other SFRS type:  SidePlate; R=3; steel systems not specifically detailed for seismic resistance
    • Special moment frame:  SidePlate PLUS; R=8; SMF
    • Intermediate moment frame:  SidePlate PLUS; R=4.5; IMF
    • Ordenary moment frame:  SidePlate PLUS; R=3.5; OMF
  • Select SidePlate Moment Frame Columns and Beams in other direction and repeat steps above

Note: This step must be performed even in non-seismic regions.

Step 2: Assign SidePlate Beams

  • Select SidePlate Moment Frame Beams
  • From the Properties Window:
  • Expand End 1 and/or End 2:
  • Apply SidePlate connection - Check Box
  • Connection type:  choose appropriate connection type

Step 3: Activate the SidePlate Connections

  • Design Settings - Analysis - First-order analysis 

  • Run - Design Steel (Static)  

Note: A second-order analysis will still need to be performed for the final design, when required by code, and will also activate the SidePlate connection stiffness when it completes properly.  However, since it often takes longer, it is easier to use a first-order initially to activate the SidePlate connection stiffness.

Step 4: Validate SidePlate Connections

  •   Validate Model - Review errors and warnings in Status Window
  •   Review - Show/Alter State
    • In the Properties Window - General - [A]ttribute - choose SidePlates from the dropdown
    • Verify all of the Side Plate beams are green (pass)

Note: Step 3 and 4 must be complete before accurate drift results are produced.


Step 1: Create General Material Properties of RIGID LINK

Under the General -> Material tab, create an Isotropic Material "RIGID"

Step 2: Create General Section of RIGID LINK in the User Provided Table

Under the "Tools" drop down list, click on "Create User Table...". Create a New Table with General Section Type, assign the section name as RIGID and the parameters shown in the picture below.

Step 3: Determine the Length of RIGID LINK

  • RIGID LINK length at beam end is determined by half of column depth
  • RIGID LINK length at column end is determined by beam depth + 3.5"

Step 4: Split Beam and Column Members

  • Select the lateral beam or column member, right click and choose "Insert Node".
  • Input the RIGID LINK and SP length in ft, select "Add New Point" and click on "OK".

NOTE: To obtain the SidePlate Stiffened Beam End Section Properties and Dimensions, please contact SidePlate at 

Step 5: Assign RIGID LINK and Non-Prismatic SidePlate® Section Property

  • Under the General -> Property tab, highlight the RIGID section, select all the RIGID LINKS in the model, choose the Assignment Method "Assign To Selected Beams", and click on "Assign". Repeat the same procedure for assigning NON-PRISMATIC SIDEPLATE BEAMS.
  • Keep all the RIGID LINKS and NON-PRISMATIC SIDEPLATE BEAMS Fixed and no Release.
  • See Appendix for examples.



Examples of Modeling SidePlate Non-Prismatic Beam in STAAD PRO:

Create and assign Non-Prismatic SidePlate Beam Properties: “Tools” on the top menu bar, click on “Create User Table...”, in “Create User Provided Table” window pop-up, click on “New Table”, choose WIDE FLANGE in the "Select Section Type" drop down, then click on "Add New Property".

In the “Wide Flange” window, input NPSP property values, and click “OK”.

Below is the W33X130NPSP example shown:

Assign NPSP beam properties to STAAD Pro model: Click on "User Table..." button in the "Properties" window, add the NPSP property to the "Properties - Whole Structure" table.


Select the NPSP member(s), then click on "Assign" button to change the member properties.