Prokon SUMO stands out as one of the most user-friendly structural analysis tools available, at least in my experience. Beyond its intuitive interface, it offers impressive functionalities, including the calculation of Wood & Armer bending moments, which account for twisting moments, and the determination of required reinforcing steel in concrete elements.
In a recent webinar, Investigating Slab Moments Calculated using FEA versus Code-Based Values – Part 01, we explored how results from SUMO’s finite element analysis (FEA) compare to hand-calculated, code-based values. While direct comparisons aren’t always possible, in certain cases, results align within 1%—depending largely on how the SUMO model is configured. The closer the model aligns with code assumptions, the more comparable the results become.
Building on that, I recently examined whether SUMO alone (without additional design modules) could be used to analyze and design a concrete beam, and how its results compare with hand calculations. Instead of using traditional line elements, I modeled the beam as a plane shell. In the Z-X plane, the shell measured 250mm in width, with a thickness parameter set to 500mm to simulate a 250mm × 500mm beam. A mesh size of 125mm was used, and 25MPa concrete was assigned as the material. The beam, spanning 7 meters, was supported at three points on either end with no rotational rigidity. Two area loads were applied:
- DL = 5kN/m²
- LL = 2,5kN/m²
For the hand calculations, I converted the area loads into equivalent line loads by multiplying them by 0.25m, then applied the ultimate limit state (ULS) load using 1.2DL + 1.6LL. Using the SAISC Red Book formula, I determined the critical moment at mid-span, with detailed calculations shown in the accompanying image.
Next, I checked SUMO’s output. Running a standard linear-elastic analysis and navigating to the Results Workspace under the Shells tab, I selected Load Combination 1 (C1), Plate Category, and the Mx component. The moment at the center of the span was 61.255 kNm/m. Multiplying this by the beam width, the critical bending moment came to 15.314 kNm—a strong validation of the hand calculations.
To take it further, I recreated the scenario in Single Span Beam to compare the calculated moment there.
With the moment confirmed, the next step was calculating the required reinforcement. Assuming a 40mm cover, I simplified the effective depth calculation by subtracting the cover from the beam depth.
SUMO’s reinforcement results were then checked under the Results Workspace → Shells tab → Reinforcement Category, focusing on the Asy’ bot component. The value at mid-span was 358.217 mm²/m, which, when multiplied by the beam width, gave 89.554 mm²—once again closely matching hand calculations.
To refine the output further, I introduced an Integration Strip in the model. This allowed for a more direct reading of the design moment and reinforcement values via the Strips tab in the Results Workspace. For a deeper understanding of this feature, check out the Prokon Know-How: SUMO Integration Strips video on YouTube.
Overall, SUMO’s results align impressively with hand calculations, reinforcing confidence in its accuracy and efficiency in the design process.
In Part 02, I’ll explore the impact of increasing the span, modifying the cross-section, and adjusting loads, followed by another comparative analysis.
