October 30, 2020

Inclusion of RSA Results in RISAFoundation

With the release of RISAFoundation v13, you now have the ability to transfer Response Spectra Analysis reactions from RISA-3D v19. RISAFoundation now also includes additional seismic options that can be considered in the generation of Load Combinations.

Tags: Seismic, RISAFoundation, New, Loading

September 4, 2025 | Featured, RISA-3D, RISAFloor, RISAFoundation

Understanding Sign Conventions for Members Across RISA Software

RISA software products use different sign conventions depending on the product’s purpose and typical use case. While the conventions are logical within each program, they may appear inconsistent when moving between tools like RISA-3D, RISAFloor, RISAFoundation, and RISAConnection. This article consolidates the sign convention rules for common forces and moments across these programs, so users have a single reference point for interpretation. Overview Table of Sign Conventions Program Positive Moment (M) Shear (V) Direction Axial (P) Direction Display Notes RISA-3D Top fiber in tension (sagging) → Negative Bottom fiber in tension (hogging) → Positive Downward on right face = Positive Tension = Negative Global/local directions shown in results grids RISAFloor Top fiber in tension (sagging) → Positive Bottom fiber in tension (hogging) → Negative Downward on right face = Positive Tension = Positive Matches common AISC/textbook convention RISAFoundation Top fiber in tension (sagging) → Positive Follows structural sign convention Tension = Positive Matches RISAFloor convention RISAConnection Based on free body diagram convention (force direction matters, not internal sign) Force arrows into member = Compression Force arrows away = Tension Force direction shows magnitude/type Blue arrows clarify direction of loads ⚠️ Important: The “top fiber” is always the side of the…

October 17, 2025 | Featured, RISA-3D

The Hidden Tension Tie: When Rigid Diaphragms Meet Sloping Members

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…

December 16, 2016 | RISA-3D, RISAFloor, RISAFoundation, New, Modeling

Viewing Coordinates in Cursor Display

In RISA-3D, RISAFloor, and RISAFoundation the cursor now provides additional information regarding the cursor coordinates. As you move your cursor around on your screen, a box adjacent to your cursor will appear and populate with the coordinates of the cursor. The mouse coordinates that are displayed are the coordinates of the grid point or joint that is nearest to the cursor. These are the same coordinates displayed in the Status Bar. If you would like to view the coordinates using your cursor then you can toggle this new feature by going to File-Application Settings and on the General tab check click the check box to Show current location coordinates next to cursor…