Curved or Skewed Moment Frames
The SidePlate® connection adds torsional capacity to the frame beam and therefore curved moment frames may be used without compromising performance. To achieve a skewed moment frame, the side plates or beams can be skewed, the column can be rotated, or a subtle skew can be applied to the cover plates and angle details. Examples of skewed beam configurations are shown in Figure M1 below. Please contact SidePlate® Systems if you have further questions or require specific details.
Figure M1 - Plan Views of Skewed and Subtle Skewed SidePlate® SMF Field Bolted – Standard Connection
Sloping beams can easily be incorporated into the design of the SidePlate® connection. An example of a sloped condition is shown in Figure M2 below. Any combination of slopes can be accommodated (i.e. both sides sloped, one side sloped, etc.). For beam slopes greater than 1” per foot, contact SidePlate® Systems for more details.
Figure M2 - Sloped SidePlate® Field Bolted Special Moment Frame Connection
Steps At Moment Frames
Steps and differing beam depths of a two-sided SidePlate® connection can easily be accommodated. Sea Figure M3 below for guidelines. Note the connection shown is the field-bolted connection, and the field-welded connection is similar. Larger steps than those shown below can also be accommodated. Please contact SidePlate® Systems for details.
Figure M3 Standard Field-Bolted SidePlate® Connection with a Step.
Slab Depression at Moment Frames
The top of a SidePlate® connection may extend vertically above the top of steel which may need coordination at slab depressions. For the field bolted - standard configuration, the top cover plate and bolts will extend into the slab, typically on the order 2-3". For the field bolted - narrow configuration the side plate may extend approximately 4.5" into the slab. For the standard field welded configuration the top cover plate on the beam, side plate, and the horizontal shear plate extend into the slab roughly 2.5-3.5" depending on member size. See the illustrations in Figure M4 below. For larger slab depressions, consider using a Stepped Moment Frame. Please contact SidePlate® Systems for details.
Figure M4 - Standard SidePlate® Connections at concrete over metal deck, a) field bolted and b) field welded
Openings in Moment Frame Beams
Openings in moment frame beams are not generally recommended. As with typical gravity framing, any openings in steel moment frame beams should be carefully coordinated and designed by the engineer. For situations where openings occur in non-seismic moment frame beams, we recommend that the opening occur within an area made up of the intersection of the middle third of the beam depth and length. The opening should also not be wider than the depth of the beam. All beam openings should be reinforced for shear, bending, and serviceability requirements as needed. See Figure M5 below.
For Special Moment Frame (SMF) projects, we do not recommend openings in moment frame beams. Special Moment Frames rely on the ability of the beam to form a hinge at a specific and predictable location under seismic load. Adding openings to an SMF beam may lead to unexpected hinging at or near the opening location. If there is no other alternative and an opening must occur, please contact SidePlate® Systems.
Figure M5 - Beam Penetrations for Low Seismic
SidePlate® connections may be used in biaxial configurations with either built-up column sections (cruciform or boxed) or HSS columns. Biaxial configurations with WF columns require an extension of 6-8” above the roof. For biaxial connections, please contact SidePlate® Systems for further coordination.
Cap plate detailing will require coordination with the SidePlate® connection detailing only if the cap plate is located at the top of the side plate and takes the place of the horizontal shear plate. For the field bolted connection, it is preferable to extend the column above the side plate and add a cap. If a cap plate is placed at the top of side plate, the cap plate will need to be 1 inch thick to match the top of steel. For the field welded connection, the top of side plate is typically about 3 inches above the top of steel. See Figure M6 below.
Figure M6 - SidePlate® Connections with Cap Plate; a) field bolted and b) field welded
In some cases, such as at cantilevered columns with high moments, stiffeners below the cap plate will provide the most efficient design and performance. Note that the minimum thickness of any column cap plate acting as the SidePlate® horizontal shear plate will be 3/8”. Also note that for most SidePlate® connections, welding the cap plate “all around” will not be permitted. Please coordinate the attachment of posts, davits, and column lifting lugs to the cap plate with SidePlate® Systems.
Although the curtain wall and façade detailing is often left until the end of the design process, it may be important to think through how these elements will be detailed at the SidePlate® connections. At perimeter moment frame columns, the top of the horizontal shear plates may not be at the top of steel and should be coordinated with the façade manufacturer. On Special and Intermediate Moment Frame (SMF and IMF) projects, protected zones are required on the side plate and the beam where welded attachments are not permitted. Areas outside of the protected zones may be used for the attachment of these systems. If the loading of the curtain wall or façade is heavy (greater than 25 psf) and the attachments occur at the SidePlate® connections, contact SidePlate Systems to coordinate the detailing.
Open Web Steel Joists
Open web steel joists are fairly common at roof conditions in steel buildings and are often spaced closely enough that one or more may require the support of a SidePlate® connection. The type of SidePlate® connection will once again affect how the joist is supported. For the SidePlate® Field Bolted – Narrow and SidePlate® Field Welded Connections, the side plate is taller than the top of steel by 3 or more inches. In this configuration, provide a joist seat off of the face of the side plate which avoids any bolts. For the SidePlate® Field Bolted – Standard Connection, the joist seat may either rest on the top cover plate and avoid the horizontal rows of bolts or use an extended seat off of the face of the side plate. Joist bracing may be connected to the SidePlate® connection outside of the protected zones.