Wind Damage

A single grain silo, under construction, at a rural farming operation near Craig, Iowa is claimed to have sustained damage during a wind storm.  Lerch Bates was asked to evaluate the condition of installed and uninstalled portions of the grain silo structure and to offer an engineering opinion as to the cause of any damage sustained.

Based on a review of the available information and Lerch Bates observations, a determination based on a reasonable degree of engineering certainty showed that the lack of an appropriately designed and installed temporary bracing system to provide stability of the structure during the erection process was causal to the grain silo failure.  Although the loading condition created by the wind storm event initiated the collapse of the silo, it was determined that the documented wind speed of 109 kilometers per hour would not be sufficient to cause the damage observed, if the structure had been properly braced.