October 28, 2025

Why Maximum Moment Graphs Differ from Flexural Demand in RISA-3D

When the Graphs Don’t Match: Understanding the Controlling Case A common question from users is why the maximum moment shown in the Detail Report graphs doesn’t match the required flexural moment reported in the design results. At first glance, this difference can be confusing — but it comes down to how RISA determines the controlling condition for design. Each member design is based on the governing load combination and the controlling location along the member where the combined effects of bending and axial forces produce the highest demand-to-capacity ratio (DCR). The graphs, on the other hand, show the pure bending moment diagram, which does not include these combined effects. To fully understand the calculation behind the flexural demand (and shear), expand the Applied Loading section of the Detail Report. There you’ll see how RISA combines: Bending + Axial forces for flexural checks Shear + Torsion forces for shear checks By reviewing both the governing load combination (Gov LC) and the location of the controlling results within the expanded sections, you can pinpoint exactly where and why your member design is governed by interaction effects rather than just the maximum moment value from the diagram. When Torsion is Involved: Considering Warping…

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