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March 31, 2016

New Seismic Brace Connections (OCBF and SCBF)

RISAConnection version 6.0 has introduced the ability to design vertical brace connections per the seismic design provisions of the AISC 341-10 Seismic Design Manual.

Now you can designate Vertical Diagonal Brace Connections and Vertical Chevron Brace Connections as either Ordinary Concentric Braced Frames (OCBF) or Special Concentric Braced Frames (SCBF).

To create the model:

  1. First, select the type of vertical brace connection that you want to use.Seismic Brace_Basics_1
  2. On the General tab of Connection Properties, select your type of Seismic System.Seismic Brace_Basics_2
  3. Enter in the other applicable variables for seismic design.
    1. OCBF: Brace Length, Brace Length Effective Length Factor, K, and the Ca Beam Ratio which is used to calculate the beam width to thickness ratio per AISC 341-10 Table D1.1.
    2. SCBF: Gusset Plate Clearance method, Brace Length Effective Length Factor, K, and the Ca Beam Ratio which is used to calculate the beam width to thickness ratio per AISC 341-10 Table D1.1.Seismic Brace_Basics_3
  4. Once you have designated the connection as seismic, you will also see that you have inputs for Brace Tensile Axial force and Brace Compressive Axial RISAConnection will design braces for both tension and compression forces at the same time.Seismic Brace_Basics_4
  5. The results report will reflect the additional seismic checks.
    1. A new Seismic tab will report the limitations and limit states per the AISC 341-10 Seismic Design Manual:Seismic Brace_Basics_5
    2. The other tabs (ex: Beam/Column) will report the calculated loading (per the Seismic Force Distribution) in both tension and compression. Both tension and compression limit states will be checked.  If a limit state applies to both tension and compression loading, RISAConnection will only check it once, against the larger magnitude required load.Seismic Brace_Basics_6


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This entry was posted by RISA News on Thursday, March 31st, 2016 at 2:36 pm and is filed under Technical Solutions. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

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