Cantilever steel post damaged by wind

• Zinc layer on the fracture surfaces would suggest that they were not fresh fracture.
• That the failure planes were straight would point to the previously existing cracks.
• Cut surfaces are heavily corroded compared to the fracture surfaces that have zinc.
• Delamination near fracture surface formed long before fracture or during fracture.
• Fracture was along a previously existing surface or interface jointed together.

An analysis for the cause of fracture failure of a cantilever steel sign post damaged by wind has been carried out. An unusual cause of failure has been identified, which is the subject of this paper. Microscopy and microanalysis of the fracture surface showed that the failure was due to pre-existing cracks, from the fabrication of the post. This conclusion was reached after detecting and analysing a galvanised layer on the fracture surfaces.