Failure Analysis of a Reinforced Concrete Silo

Silos are most often constructed of steel panels or reinforced concrete; and are typically used to store bulk solids such as food, fuel, and feed for livestock. Because the stored bulk material is flowable, silos are subjected to complex load scenarios requiring unique design considerations. In the spring of 2013, a recently constructed reinforced concrete silo storing solid biomass material suffered a catastrophic failure resulting in displacement of the stored material and complete loss of the structure’s use until it was repaired. Additionally, multiple neighboring silos, which were of comparable construction and design, manifested similar distress patterns to those observed at the subject silo just prior to its failure. The objective of this paper is to explain the investigative methodology and conclusions drawn regarding the failure mode of the subject silo. The investigation revealed that the failure initiated at a concrete keyway cast into the silo wall at the silo’s elevated concrete floor; and that the failure was caused by construction defects.