March 14, 2022

Vertical Diagonal Brace Extended Shear Tab Connections in…

RISAConnection Version 13 now includes the ability to define vertical diagonal brace extended shear tab connections both with and without the use of gusset plates. This connection type was highly requested by users due to its usefulness in a variety of situations. For more information about this new connection type, check out the video below:

Tags: New, RISAConnection, Brace Connection

April 19, 2016 | Seismic, New, RISAConnection, Brace Connection

OCBF Seismic Brace Connections

Vertical Diagonal Brace connections and Vertical Chevron Brace connections may be designed as Ordinary Concentric Braced Frame (OCBF) connections in RISAConnection v6. Basis of Design RISAConnection designs OCBF per the provisions found in section F1 of the AISC Seismic Provisions for Structural Steel Buildings (AISC 341-2010). OCBF systems anticipate little inelastic deformation and are designed using a higher seismic force level to account for the limited system ductility. Basic Requirements The requirements for OCBF systems per the AISC 341-10 include the following: Braces are designed as moderately ductile members. Chevron brace members are limited to a slenderness of KL/r ≤ 4*√(E/Fy). Connection strength requirement which ensures that the brace member acts as a ductile link in the frame prior to the connection failing. Design Results RISAConnection calculates the required design strength of the braces in tension and compression and presents the full results on the new Seismic tab of the results report. The results can include the following detailed calculations and checks: Controlling Load Calculation Seismic Loading Combinations Seismic Load Distribution Calculations Seismic Workpoint Limitations Seismic Yield Stress Limitations Seismic Brace Slenderness Seismic Brace Width to Thickness Ratios Seismic Weld Limitations…

July 27, 2016 | Seismic, New, RISAConnection, Brace Connection

Using Eccentric Chevron Brace Workpoints

RISAConnection now offers the ability to enter an eccentric work point for the braces on a Vertical Brace Chevron Connection. Entering the Eccentricity The eccentricity may be horizontal, vertical, or both. These entries are in reference to the origin which lies at the intersection of the beam centerline and the gusset centerline. Work point offsets may be positive or negative, depending on which direction (from the origin) you want to move the work point. Quadrant 1: Positive Horizontal Eccentricity, Positive Vertical Eccentricity Quadrant 2: Positive Horizontal Eccentricity, Negative Vertical Eccentricity Quadrant 3: Negative Horizontal Eccentricity, Negative Vertical Eccentricity Quadrant 4: Negative Horizontal Eccentricity, Positive Vertical Eccentricity Results While the limit state checks will be the same, the calculated loads at the gusset will be different since they now will include the effect of the work point offset…

May 25, 2016 | Seismic, New, RISAConnection, Brace Connection

SCBF Seismic Brace Connections

Vertical Diagonal Brace connections and Vertical Chevron Brace connections may be designed as Special Concentric Braced Frame (SCBF) connections in RISAConnection v6. Basis of Design RISAConnection designs SCBF per the provisions found in section F2 of the AISC Seismic Provisions for Structural Steel Buildings (AISC 341-2010). SCBF systems are very similar to OCBF connections; however they include additional detailing requirements to direct ductile behavior into the braces. These detailing requirements provide for greater energy dissipation and ductility which means SCBF can be designed to a lower force level to that of OCBF connections. Basic Requirements The requirements for SCBF systems per the AISC 341-10 include the following: Columns and Braces are designed as highly ductile members. Beams are designed as moderately ductile members. Brace members are limited to a slenderness of KL/r ≤ 200. Brace connections must be designed to withstand the flexural forces imposed by brace buckling. Connection strength requirement which ensures that the brace member acts as a ductile link in the frame prior to the connection failing. Two analyses must be considered; one where both braces are assumed to resist their expected strength, and the other where the compression brace is assumed to have already buckled. Design…