Timothy Sass, P.E., MSCE, Civil and Structural Design Expert

Case Summary: A cantilevered section of scaffold collapsed under the weight of a mason. Counsel for the scaffolding rental company retained a Civil and Structural Design Expert with DJS Associates to provide engineering analysis.

Expert Analysis: The cantilevered section of the scaffold was determined to be improperly assembled. Rather than using an outrigger, the cantilever was created using two-foot-long spanners. The scaffold is designed to carry loads like a truss, where each component of the scaffold is either in compression or tension. The improperly assembled scaffold spanner had to carry both tensile and compressive loads, resulting in the cantilever’s failure under regular load conditions. 

Metallographic analysis further confirmed that the failed part had not been properly assembled. Marks on the failed part confirmed it was subjected to bending loads, resulting in compression and tension in the failed member.

Result: The scaffolding rental company had only supplied the scaffold components and was not responsible for assembly. It was determined that appropriate outrigger parts were available on site and that the masons were responsible for assembling the scaffold improperly. Subsequently, the case settled.

Timothy Sass, P.E., MSCE, Civil and Structural Design Expert with DJS Associates, Inc., can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

Categories: Case Studies | Engineering

Tags: Scaffolding | Structural Engineering