The Case of the Precast Panel Collapse

Figure 1.  Aerial Site View – Precast Building OpeningThe Problem:

The final, tilt-up, precast panel, weighed 40,000 lbs and collapsed unexpectedly during field erection.  The incident caused the death of 3 landscape workers at ground level, working outside the building.

My Assessment:

Figure 2.  Wall Precast Embed, Missing Welds.Forensic Engineer (FE) assessed the contractors’ non-compliance with the contract for temporary wall braces, and code compliance for welding, welder certifications, and welding inspections.  Reviews included the building permit, field weld inspection reports, welding procedures, welder certifications, and OSHA training about workplace hazards.

Managers did not heed the Third Party Inspection reports about deficient welds and missing embeds needed to support the precast panel.  Welding inspectors incorrectly reported all field welds were installed and accepted.  An obsolete welding code was specified.  The result was inadequate precast panel support after temporary bracing supports were removed and the precast panel collapsed.

Figure 3. Deficient Truss Welds-to-Precast Embed.The Consequences:

The FE determined that field welds were rejectable and missing from required locations.  Aggressive management overlooked compliance to welding inspections and safety.  Premature removal of temporary wall and floor braces resulted in failures at panel supports and death to 3 landscape workers.

The Lesson Learned:

Inexperienced management placed budget and schedule before code compliance and safety.  The contractors’ negligence toward field welding resulted in three wrongful deaths.

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Welding Failures I Have Known, Interesting cautionary tales from Metals & Welding  expert, Dr Jesse A Grantham, PE