By Blair Fannin
With severe weather systems becoming more constant across the country, a team of multistate agricultural researchers found in a new study that grain bins need to be carefully scrutinized for structural safety, soundness and engineering integrity.
The study was prompted by a string of severe weather outbreaks in the Midwest that began in 2020, as well as severe weather that has occurred throughout Texas.
“We’ve had some strong storms across Texas this spring and summer,” said Rebekka Dudensing, Ph.D., Texas A&M AgriLife Extension Service economist, professor and associate vice president for the Economic Development and Community Impact unit in the Texas A&M Division of Academic and Strategic Collaborations.
The novelty of studying grain bins in Texas as well as the overall safety of structures brought the research team together.
The study’s lead investigator is Christine Wittich, University of Nebraska-Lincoln research engineer. Joining Dudensing on the research team are AgriLife Extension economists Dean McCorkle, Ph.D., senior program specialist, and Steven Klose, Ph.D., associate department head, all in the Department of Agricultural Economics of Texas A&M’s College of Agriculture and Life Sciences based in Bryan-College Station. Maria Watson, business and disaster recovery specialist, University of Florida, rounds out the team.
Severe weather outbreak
“Recovery after a windstorm, like the 2020 Derecho, is a multiyear process for many farmers,” Wittich said. “Based on early responses to the survey we are conducting, common concerns from farmers included the availability of building materials and labor to begin reconstruction for their farm structures. This seems to be a major barrier towards farm recovery.”
When asked what advice they would give to other farmers in similar situations, most respondents discussed insurance.
“Primarily, this involved recommendations to know your insurance policy well and to follow up with your agent regularly,” Wittich said.
Dudensing said the research team wants to help minimize damage. “It’s a good idea to check structures for loose panels and to make sure doors and hatches are secured prior to storms,” she said.
They also want agricultural businesses to recover quickly and cost-effectively.
“This study will provide information about best practices in construction and in the preparation of structures for storms,” she said. “We see more grain bins and machine sheds at the edge of fields rather than on farmsteads. Often there are no windbreaks or other buildings to slow windspeeds, so these structures can be more susceptible to damage.”
Grain bin safety
“When I visit with producers and discuss their purchase of grain bins, they are expecting these systems to last a lifetime,” said Bryan Davis, AgriLife Extension Disaster Assessment and Recovery team lead, headquartered in District 10, in Seguin.
“It’s a metal structure, engineered so a commodity flows in from the top and through the center. It’s designed that way so grain can evenly distribute into the bin and there is no uneven pressure on one side of the wall. One of the biggest problems we see is when the bins don’t distribute the weight evenly.”
Davis said it’s critical to pay attention to these structures and conduct annual inspections to ensure the structure’s integrity.
“During these inspections, we recommend that producers work in teams with a safety harness and proper PPE,” Davis said. “Inspections should include cleaning, inspecting the walls and linings, and reviewing every aspect of the structure.”
Producers should also be mindful that the bottom metal rings of the grain bin can rust over time, Davis said. The false floor must also be inspected closely for any defects or sign of wear.
“Most of our grain bins are designed with manholes on the top and bottom,” Davis said. “Always inspect those areas, and never perform any modifications without consulting an engineer.”
Davis also recommends checking the footing of the grain bin on a concrete slab.
“Inspect for cracks or any separation or movement,” he said.
This is especially important for those individuals who are using grain bins as part of entertainment venues.
“We advise consulting with an engineer and evaluating the integrity of the structures, ensuring they are structurally stable to withstand a wind event, if and when it occurs,” Davis said.
Study findings
Preliminary findings were compiled as assessments were made of hundreds of steel grain bins following the 2020 August windstorms in Iowa.
- Steel grain bins are vulnerable to high wind loads when not full. Very tall bins or bins that are highly exposed are particularly vulnerable to wind, especially on hilltops.
- Steel grain bins that are full may still fail and sustain roof damage or tear off, and/or suffer from non-structural damage such as stair damage.
- Steel grain bins with vertical stiffeners tend to perform significantly better during windstorms than those without.
Another finding was that, after a windstorm, most farmers indicated their insurance adjusters agreed with their assessments of the level of damage for agricultural buildings, center pivot irrigation systems and steel grain bins.
“Many farmers indicated they intended for their farm structures to be replaced with enhanced construction that would be more wind resistant,” Wittich said. “However, our observations of the replacement structures did not always align with this intent.”
She said many farmers want to increase their wind resistance, but their replacement structures may not actually be a significant improvement.
“For example, our structural studies indicate that vertical stiffeners typically provide the most enhancement for wind resistance of a steel grain bin,” Wittich said
Future study plans include surveying additional communities impacted by windstorms to generalize findings. Currently, the team is following up with Nebraskan communities after storms last spring and summer.
“From the engineering standpoint, a lot of our work so far has focused on steel grain bins,” Watson said. “These are very common structures that had widespread damage in our first study community following the 2020 Derecho. We are now expanding our focus to other farm structures, including center pivot irrigation systems and ag buildings — both metal and wood-framed. We plan to assess what are the key variables that predict wind resistance.”
More research is needed
Watson said there has not been extensive research on farm recovery following disasters.
“We are conducting surveys to better understand what that process looks like after windstorms and to help create that type of guidance for agricultural businesses: What challenges farmers and ranchers face during recovery, what resources are most helpful, and how to better prepare for future events,” she said.
Watson said the surveys are especially helpful in understanding the overall recovery of a farm.
“What impact does grain bin damage have on the long-term capacity and profitability of the farm, and what strategies might be used by farmers to reduce any secondary losses?”
Farmer response rates and overall reception to the study was positive, according to the researchers, who are evaluating a follow up study.
Source : tamu.edu