Issue #7

This week’s StructEd Bulletin highlights a new experimental study showing how thin‐walled open‐section steel beams resist “pure bending” far less cleanly than theory suggests. Even with shear‐center loading, small geometric imperfections and gravity‐induced torsion drove coupled local and global buckling, underscoring the limits of idealized bending‐only models. RISAConnection v17 also arrives with AISC 360‐22 support, expanded shape libraries, and improved HSS and base‐plate workflows. The featured case study reviews several welded‐steel failures where brittle fracture, hydrogen embrittlement, and heat‐affected‐zone microstructures dominated behavior — a reminder that modern alloys demand more careful weld preparation than traditional mild steels. Rounding out the issue are three free upcoming PDH sessions covering mass timber construction types, project‐management fundamentals, and advanced fire‐life‐safety design.

1. Code & Standards Watch

Updates & New Releases:

• AISC/RCSC Design Guide 41 Released: Design guidance for stainless steel bolts, used to connect stainless or carbon steel components.

Working Sessions, Public Comment, & Balloting:

• NFPA 5000-2024 & Proposed 2027 Editions: Proposed Tentative Interim Amendment (TIA) No 1870 Seeking Public Comments through Apr 24, 2026
• AISC Code of Standard Practice for Steel Buildings and Bridges (AISC 303): Draft available for public review & comment March 6th through April 20th
• TMS 405 “Mini Summit”: Existing Masonry Standards Committee formal working session as part of the 2026 TMS Spring Meeting, April 21-23 in Denver
• 2026 ICC Leadership Week + Hearings: 2027 I-Code development | Public Comment Hearings – Groups A & B | April 18 – 24 | Connecticut Convention Center | Hartford, CT

Latest Errata:

AISC Steel Construction Manual, 15th Edition:

• Table 3-23 - Beam Case 7 - Point load at midspan of simply supported beam, diagram and M3 equation updated.
• Revised L.c to 60 from 70 in penultimate row of Y-Y Axis table on 4-140
• And a few other small updates to graphics and callouts

2. Research Snapshot

Experimental investigation of four-point bending of thin walled open section steel beam loaded and set in the shear center

Researchers took on the challenge of trying to isolate pure bending (no torsion) in a thin-walled, open steel section, and experienced some difficulties.  Despite a custom test rig intended to carefully load the section exactly in line with its shear center, minor imperfections in the material of the beam still presented noticeable torsional impacts.

Owing in part to the incidental torsion, the beam exhibited combined local & global buckling, and was very sensitive to boundary conditions and geometric accuracy.  Sensitivity was so high, in fact, that torsion induced by the eccentricity of the self-weight of the section dominated behavior.

Key Takeaways: Any assumptions of pure bending should be taken skeptically when it comes to thin-walled, open sections, regardless of material.  Idealized bending-only models with no consideration for torsion simply do not reflect reality in such sensitive situations, even under lab conditions.

3. Tools & Workflow

RISAConnection v17 Released

• Added Code Support: AISC 16th Edition (360-22) and CSA S15-19
• New Features: HSS beam-to-HSS Column connection design per CSA S16-19 | Expanded shape coverage using the AISC historical shape database | Enhanced base plate and anchorage workflows

4. Case Study of the Week

Case studies of steel structure failures

Several real failures of welded steel structures, summarized in one convenient spot.  Major recurring themes are hydrogen embrittlement from poor weld preparation, stresses induced by rapid heating/cooling of high-strength (higher carbon) alloys, and stress concentrations coinciding with these critical flaws

Key takeaways: AISC (and other prevalent steel codes) principally is calibrated for very mild steel alloys which are specifically formulated to be very ductile and forgiving of heat treatment abuses.  Once more complex alloys are introduced, careful weld preparation is necessary, and stress concentration factors we otherwise can ignore (due to ductility) emerge to dominate behavior.

5. Upcoming Free Live PDH

Selecting a Mass Timber Construction Type: Balancing Design Vision and Structural Reality

• 1.0 PDH, Wednesday, April 15 @ 12 pm Central
• Presented by WoodWorks
• Speakers: Michael Scancarello, P.E. + Christopher Angelakis Christopher Angelakis AIA, LEED AP BD+C
• Bonus Session - Smartlam North America manufacturer Q&A after completion of the accredited portion of the session

Project Management: Critical Path Scheduling And How To Conduct Effective Kick-off Meetings

• 1.0 PDH, Wednesday, April 22 @ 11 am Central
• Presented by NoonPi | Free PDH for Engineers

Rethinking Fire Life Safety Design Beyond the Code

• 1.0 PDH, Friday, April 24 @ 11 am Central
• Presented by SGH
• Speakers: Qianru Guo & Tom Jaleski

6. Quick Hits

• FEMA remains unfunded in the longest partial government shutdown in US history

👋 From the Editor

I’m Eric, the engineer behind the StructEd Bulletin.  I dig through stacks of journal articles and software patch notes to find useful information for practicing engineers and keep an eye on the scattered code updates & errata for you. I’m just getting started, so if you find this useful, the best way to support the newsletter is to share it with a colleague or post it on LinkedIn. It helps more than you’d think!

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