A canopy covering a gas station in Arizona collapsed in early December exactly one week after a similar incident in New York that was reportedly the result of rust and corrosion issues, according to WSYR-TV Syracuse and Southwest-area news stations.
The cause of what was deemed to be a partial collapse in Arizona on Dec. 10 was not yet determined as of the following day, according to ABC-15 Arizona. Heavy rain and hail had been reported in the area at the time of the collapse, Fox 10 Phoenix reported. The two incidents occurred in Glendale, Arizona and Cicero, New York. No injuries were reported as a result in either, although multiple vehicles were damaged by the falling debris.
New York Sunoco station collapse
An investigation of the Cicero collapse found that the base of the gas station's canopy was significantly rusted at the time it occurred, although the extent of the corrosion was not visible to the naked eye. The town's code enforcement director told WSYR-TV that after seeing the damage, he predicted that heavy snow or rain could also have caused a collapse, "considering the amount of rust."
Syracuse.com reported that winds at the time were "light" at about 5 mph. A subsequent article from the outlet reported that the Cicero town code enforcement office determined the official cause to be the combination of wet snow on the roof and corroded steel support columns.
"It was not something someone would see unless they got into it and took it apart," the town supervisor explained.
The gas station's owner was one of the two individuals whose vehicles were damaged by the collapse. According to the code enforcement director, gas stations and structures are inspected every three years, although only for their fire and safety aspects rather than structural integrity. Instead, gas station owners are responsible for the upkeep of canopies and other structures. To rebuild the structure, the owner will now have to apply for a building permit and submit construction plans for town approval, officials said.
Collapses caused by support column corrosion
Gas station canopy collapses as a result of corrosion are not a new issue facing owners and communities in the U.S. and have occurred with some regularity in recent years. According to a University of Puerto Rico study, several corrosion-related gas station canopy collapses that occurred in 2005 during Hurricane Katrina and Rita were found to have involved the exact same issue that caused the most recent New York one: corroded support column bases.
For an example, an analysis of a Chevron station canopy collapse in Texas concluded that the cause was the result of poor maintenance of the bases of the columns holding up the structure (determined to be its weakest points). It further concluded that the bases were most likely never inspected in the first place for corrosion because they were covered with metal boxes. The boxes were installed to protect the columns from being hit by vehicles entering and exiting the station throughout any given day. The report explained that the corroded bases couldn't take "moments of tensile stress" to provide equilibrium under wind pressure – the canopy itself had detached from the foundation and was thrown 20 meters away, landing in an inverted position.
Another collapse in Louisiana also involved column corrosion hidden by metal box coverings. It was found that rainwater had accumulated on the roof of that structure instead of being diverted to the columns as intended – a "major cause" for the corrosion. On the subject of preventing collapses, one lesson experts stated that they learned from the study was that "maintenance is crucial to maintain the integrity of the canopy, especially in relation to corrosion of the columns at the base. This is a weak point and at the same time it is vulnerable to water and moisture action."