Limitations of 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. .
The new UtC feature in IDEA StatiCa now estimates the entire weld’s utilization, not just the concentrated stressed areas. This view reflects the gradual engagement of weld length under increasing loads, showing engineers how forces distribute along the weld as load increases. This capability provides engineers with a more comprehensive view of how welds perform under different load levels:
To illustrate this, the following table shows an analysis progression for a beam-to-column moment connection (Column: W14x120, Beam: W18x97, Weld: Top flange to column, size 3/8"):
| 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 |
These results reveal the difference in utilization along the weld as loading increases. For instance, 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. As the moment reaches 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 new weld capacity feature significantly improves the evaluation of weld capacity by presenting both localized and full-length utilization data. This dual approach allows engineers to maximize weld efficiency confidently, knowing that UtC reflects a comprehensive assessment of weld behavior under various loading conditions.
With UtC, engineers can make more informed decisions and optimize designs for safe, reliable, and cost-effective connections. Ready to see these advancements in action? Try IDEA StatiCa’s latest release and discover how IDEA can improve your workflow.
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