Specifying and Designing SidePlate® Moment Frames in the RAM Structural System

Comprehensive analysis and design of moment frames using SidePlate® connection technology are now available in the RAM Structural System. This document describes the use of this feature.

Modeling

Create the model as customary for any project using steel moment frames.  When selecting preliminary lateral beam and columns sizes in RAM Modeler, it is important to keep in mind the following two rules:

1) Geometric Compatibility: bf-bm + Geometric Compatibility Limit ≤ bf-col

Note that Geometric Compatibility Limit is a function of member sizes and is specified in the SidePlate property table, but for this purpose it can be roughly estimated as 1.1tf-bm + 1/2" 

Background: The SidePlate connection typically consists of cover plates at the beam ends to bridge the difference between the beam flange width and the wider column flange width.  The cover plates are fillet welded to the beam flange edges of which the top cover plate is detailed to be approximately the same width as the column flange width.

Note that RAM Frame will check geometric compatibility each time Analysis is run when moment connections have been assigned as SidePlate. If there is a problem, the program will give a warning

2) Strong Column – Weak Beam Compliance for SMF designs only:

∑ (Zx,col) > 1.7*∑ (Zx,bm)   for 1-12 stories (rule of thumb)

Background: The above approximate equation takes into account the latest Seismic Provisions equation for SCWB compliance of SMF connections, including an approximate allowance for reduction in column capacity due to axial loads as well as the pushing out of the plastic hinge into the beam.

Note that RAM Frame Steel - Seismic Provisions includes the actual SCWB checks for SidePlate moment connections.

Criteria

In RAM Frame, the Criteria for these moment connections can be specified using the Criteria – SidePlate command.

The connection properties are different for high seismic (inelastic) applications versus wind (elastic) and low seismic applications.  Previously the engineer had the choice of selecting either R=8 or R=3. Now users can select from a list of connection types. Select the criteria that will most likely govern the sizing of the moment frames. For R=8 designs, seismic displacement will typically govern.  For R=3 designs, wind displacement will typically govern.

Note that SidePlate 100% rigid end zone (i.e., panel zone) properties are now built-in automatically and accounted for when SidePlate is assigned as a moment connection and will be considered as such regardless of what option is specified for Rigid End Zones in the Criteria – General command.

Assign

In RAM Frame, Assign the moment connection type using the Assign – Beams – Connection command.

Selecting “Both Ends” and “All” will assign a SidePlate connection at both ends of every lateral frame beam.  If there are lateral beams that are fixed-pinned as shown below, select the “Left End” or “Right End” and Assign those specific beams using the Single command. Generally the beams will have SidePlate connections on both ends.

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

Close up of moment frame above

To maintain the SidePlate moment connection symbol display, simply check the Connection box on the Frame Beam / Horiz Brace tab of the View – Members command:

Analysis

When the Analysis is performed, the appropriate SidePlate connection criteria properties are applied accordingly. A frame beam-to-column geometric compatibility check is performed each time an Analysis is performed to confirm compliance: bf-bm + Geometric Compatibility Limit ≤ bf-col. The Geometric Compatibility Limit is a function of the member size, and is given in the SidePlate property table.

If any particular combination of beam and column sizes does not satisfy this relationship, the following error will be displayed:

The Member Forces report has been enhanced to include pertinent SidePlate information such as beams being identified as having SidePlate connections with forces reported at key points along the beam. Such added locations are used for stress checks in the beam as well as information for connection designs used by SidePlate.  Column rigid end zones reflect the geometry of SidePlate connections, including appropriate depths of side plates.

A new section has been added to the Frame Takeoff report to include the plate weight of the SidePlate connection, the number of beam end connections and the total number of SidePlate connections.

Steel – Standard Provisions

The Design moment and shear for the beams are taken at the face (end) of the SidePlate connection. The unbraced length of the beam is measured from end of SidePlate to end of SidePlate. No design is performed for the beam within the connection, nor for the connection itself.  Connection designs are provided by SidePlate Systems, Inc. (www.sideplate.com).

The Design moment and shear for the columns are taken at the face (top and bottom edges) of the SidePlate.  The unbraced length (both x and y) is taken as the clear height between SidePlates.

The Member Code Check report for the beams indicates that the beam has SidePlate connection(s):

Steel – Seismic Provisions

In the Steel – Seismic Provisions mode the seismic provision requirements for AISC 341-05, 341-10 and 341-16 ASD and LRFD have been implemented for SidePlate connections. Select one of the codes in the Criteria – Codes command.

It is necessary to assign a frame type to each member, used by the program to determine which seismic provisions are pertinent. This is done using the Assign – Frame Type command. Select Special Moment Resisting Frame, Intermediate Moment Resisting Frame or Ordinary Moment Resisting Frame as appropriate. The Frame Type selection should be consistent with the Design Methodology selected during the Analysis under Criteria – SidePlate… Frame Type assignments not consistent with the methodology selected during the analysis will be ignored during the Seismic Provisions Code Check.

The Frame Type assignment on each member can be displayed by selecting the Frame Type labels option on the Frame Beam and Frame Column tabs in the View – Members command.

The text on the display should show SMRF, IMRF or OMRF.

Select the Process – Member Code Check command to have the code check performed on all of the members, and select the Process – Member View/Update command to select and view the results for an individual member.

Select the Process – Joint Code Check command to have the code check performed on all of the joints and select the Process – Joint View/Update command to select and view the results for an individual member.

The Seismic Provisions Member Code Check and Joint Code Check reports show the results of all the checks, including compliance that structural framing does not occur within the beam’s protected zone as defined for SidePlate connections

Note: Designs using the SidePlate connection should be reviewed and verified by SidePlate Systems, Inc. To assist in this process, upon completion of preliminary and/or final lateral designs using SidePlate connection technology, users should send their RAM model (e.g. “xxx.rss” file), including any customized beam, column or deck tables, to SidePlate Systems, Inc. (1-949-305-7889) at solutions@sideplate.com for verification and validation of the computer model.  Upon completion of model review, SidePlate Systems will provide structural drawings (notes and details), including stamped/signed calculations for each SidePlate moment connection for the specific project.