Weld capacity estimation (AISC)
Improvements from the Previous Weld Utilization Check (Ut)
Traditional weld checks focus on the highest-stress elements, meaning engineers would see high utilization percentages at certain spots and assume the weld was close to its limit. As a result, engineers sometimes overlook the available capacity in less-stressed regions of the weld.
With the Weld capacity estimation (UtC) feature, IDEA StatiCa now displays an overall utilization percentage that reveals how much of the weld length’s capacity is engaged at each load level. This view helps engineers see how welds respond to increasing loads, adding clarity to design decisions.
To illustrate this, the following table shows an analysis progression for a beam-to-column moment connection:
| My (kip.ft) | Max. stress, ksi | Ut % | UtC % |
| 15 | 3 | 9.6 | 0 |
| 30 | 6.1 | 19.2 | 7.3 |
| 60 | 12.1 | 38.5 | 17.9 |
| 100 | 20.2 | 64.1 | 36.2 |
| 150 | 23.7 | 75.3 | 46.9 |
| 200 | 23.9 | 76.5 | 55.1 |
| 250 | 24.2 | 76.9 | 58.3 |
| 300 | 25.2 | 80.1 | 71.9 |
| 325 | 26.0 | 82.6 | 80.1 |
| 350 | 27.2 | 86.3 | 86.3 |
| 375 | 28.7 | 91.1 | 91.1 |
As shown, at a low moment of 15 kip.ft, Ut is 9.6% while UtC is 0%, indicating that only a small section of the weld is stressed. At 200 kip.ft, the Ut and UtC values are 76.5% and 55.1%, respectively, showing that the full weld length is not yet fully engaged. Finally, at a moment of 375 kip.ft, both Ut and UtC converge at 91.1%, demonstrating uniform stress distribution and optimal weld utilization. This behavior aligns with AISC standards and reassures engineers that the entire weld length achieves even stress distribution under higher loads.
IDEA StatiCa’s Weld capacity estimation feature enhances weld evaluations by presenting both localized Utilization (Ut) and overall utilization for the full weld length (UTC). This dual approach allows engineers to maximize weld efficiency confidently, knowing that UtC reflects a comprehensive assessment of weld behavior under various loading conditions.
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