May 1, 2020
Video: Steel Member Design in RISACalc
Learn how to load and design individual beam and column steel members in RISACalc.
Rigid diaphragms in RISA-3D are a powerful way to model how floor systems distribute lateral loads. By forcing all connected nodes to move together in-plane, they effectively capture the stiffness of a concrete slab or diaphragm deck—often simplifying analysis without sacrificing accuracy. However, when rigid diaphragms are combined with sloping members, they can introduce unexpected behavior that changes how the structure resists loads—sometimes creating a hidden “tension tie” that doesn’t exist in the real system. When Rigid Diaphragms Alter the Model’s Behavior Consider a simple moment frame with sloped beams under gravity loads—common in pre-engineered metal buildings. Model 1: No rigid diaphragm applied Model 2: Identical frame, but with a rigid diaphragm located at the eaves When reviewing the strong-axis bending moments, column base reactions, and thrust forces: The first frame behaves as expected. The second frame (with the rigid diaphragm) shows reduced bending moments and smaller thrust reactions at the column bases. At first glance, this might seem like an improvement—but it’s actually unrealistic behavior caused by the diaphragm. Why It Happens: The “Hidden Tension Tie” In the model with the rigid diaphragm, the diaphragm prevents the eaves from moving apart under load. This effectively turns the diaphragm into…
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Learn how to load and design individual beam and column steel members in RISACalc.
In RISA-3D when drawing members you must start with initial sizes. After loading and load combinations are completed the model is solved and then member design must be done, making sure that members pass for both strength and serviceability considerations. For both strength and serviceability...
RISA-3D includes the ability to design steel structures for seismic provisions found in AISC 341 and AISC 358 including moment frames and braced frames. For more information, review the video below.
Connection design according to the new AISC 360-16 (15th Ed.) Steel Manual has now been implemented in RISAConnection. To select this code for your design, simply choose either LRFD or ASD from the Solution tab within the Global Project Settings. The addition of the new 15th Edition code, includes...
The most recent release of AISC 360-16 (15th Edition) includes changes to connection design for rectangular HSS shapes with applied concentrated forces. These changes are now included in RISAConnection v10.
The release of RISAConnection v10 incorporates updates according to AISC 360-16 (15th Edition) including changes to HSS provisions as well as improved design for column webs subject to out-of-plane loading, in addition to other enhancements.
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