OSHA: Design flaws caused Hurricane Irma crane collapses
- According to a recent OSHA report, three hammerhead tower cranes that collapsed last year when Hurricane Irma rolled through Miami did so because of wind turbulence, which U.S. and European manufacturers do not have to take into consideration when designing cranes.
- The three tower cranes that OSHA studied were SK-315 models — one manufactured by Terex Peiner GmbH and two by Noell Service and Maschinenetechnick GmbH. These were the only cranes to fail during the storm and were designed for maximum wind speeds of 95 mph, not for the lateral and upward wind loads that the agency said caused the jibs to separate from the equipment's turntables and collapse. The cranes fell despite following manufacturers' instructions to place the cranes out of service and allow them to weathervane, or spin freely.
- OSHA's recommendations include that building officials in coastal areas conduct wind simulation tests if there are tall buildings and frequent turbulent winds in their jurisdictions for more realistic evaluations; that crane manufacturer Terex re-evaluate its jib-to-turntable connection design to prevent crane-jib detachment in turbulent winds plus consider adding jib pendants to the SK-315 model in order to provide more stability; and that the design of crane tower tops be evaluated for higher safety and with counterjib loads in mind.
A spokesman for Terex told Engineering News-Record that the SK-315 model had been in use for more than 20 years and was not designed to withstand the wind forces generated by Irma. OSHA's report could play a role in post-Irma litigation brought against Terex and other crane companies by property owners who claim they sustained damage as a result of the collapses. Greg Teslia, president of Crane Safety & Inspections, told ENR that there is nothing contractors could have done to prevent the collapses and that "cranes aren’t made out of armor, and wind is their enemy.”
One of OSHA's focus areas is crane safety, and the agency, after periods of industry input and delays, is set to introduce revised crane operator rules next month. Currently, operators are only required to provide evidence that they are certified, which OSHA maintains does not establish an acceptable level of experience or competence. OSHA said the new rules will also clarify the controversial "type and capacity " requirements. In May, the agency said it would not require operators to be certified based on rated lifting capacity — a provision that received industry pushback — but left open the possibility that operators would have to be certified according to type.
- Occupational Safety and Health Administration Investigation of the Failures of Three Hammerhead Cranes on September 10, 2017, in Miami and Fort Lauderdale in the Wake of Hurricane Irma
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