![]() ![]() The steel used to construct these bins is covered with a thin coating of zinc. While this may not cause a bin failure, it can have a detrimental effect on the filling and unloading equipment. With some of the very large diameter and tall bins, even 12 inches has been allowed but not preferred. The top of a bin leaning out 6 inches to 8 inches over the base is probably not going to be an issue, but a check with the bin manufacturer would be very prudent. However, if the settlement is not uniform, the bin can lean toward the low side. If the settlement is uniform, there is no problem. It is not uncommon to see settlement in the foundation when the bin is filled with grain. The other issue with foundations is whether they are level. High spots at stiffener locations can also cause significant stresses higher up in the bin which may show up as buckling stiffeners or body sheet recorrugation. A stiffener starting to bulge, or signs of bulging or recorrugation in the body sheets with inside stiffeners, is a warning that a failure has started. While there is always a factor of safety in any design, such an increased load can cause stiffener failure. ![]() This forces the stiffeners on each side to carry more than their designed load. When the concrete is not level, there is the possibility that one of the stiffeners may not be carrying its design load if not properly shimmed. This, of course, depends on the diameter of the bin and the height, but suffice it to say that the greatest part of the load is in the stiffeners. Research at the University of Kentucky many years ago showed that as much as 80% of the grain load could be in the sidewalls. The greatest part of the load is through the stiffeners. The load from the grain is transferred to the foundation by the stiffeners and sheets. The foundation is probably the most important part of any grain bin. Before unloading the bin, be sure to contact the manufacturer or an expert in the business to ensure that the bin is unloaded in a way that will not cause additional failure. If the stiffeners are on the inside of the bin, the only thing that will show up is the recorrugation of the body sheets. The first signs of this are bulging of the stiffeners and subsequently recorrugation of the body sheets. When this occurs, the entire ring will simply recorrugate. While there have been a few cases where the body sheets or stiffeners were placed in the wrong location, it is very rare. The biggest contributor to failures in improper construction is related to the foundation and bin anchoring. On some bins this can occur when only a few hundred bushels are removed. The bin will start to buckle in on this side, and if allowed to go long enough, a catastrophic failure can occur. When this occurs, the pressure on the side of the bin being unloaded by the intermediate well no longer exists. You may also hear the term "side draw" used when someone unloads from an intermediate well before the grain funnel has reached the floor from unloading through the center well (sump). Each time the side draw is used without the proper refilling, the egg shaping can continue to get worse. If the grain is not center-cored after unloading from a side draw unit before refilling the bin, the same egg shaping can occur. The same situation can occur when side-draw baffles are used. ![]() You may also see some flattening of the sidewalls. The roof will overhang the sidewall further on the sides where the bin wall is pulled in while barely covering the sidewall that has been pushed out. The most obvious location to see this is at the roof. The uneven pressures caused by grain flowing in at an angle causes the bin to egg shape and force two sides out while pulling two sides in. It is fairly easy to tell if a bin is being loaded improperly. This allows the grain to flow to the outside uniformly, creating even pressures. Off-center loading or unloading creates non-uniform pressures on the bin walls that can result in bin damage or even catastrophic failure.ĭuring loading it is imperative that the grain drop straight down from the center at the top of the bin. ![]() They rely on uniform pressures around the bin to maintain their structural integrity. What can you do to make sure you do not have a failure with your bins? Steel bins are thin-shelled structures. The vast majority of failures fall into three main categories: improper construction improper loading and unloading and loss of structural integrity due to rust and wear and tear. While some will say there are design flaws with these bins, the fact that there are hundreds of thousands in use today dispels their claims. While steel bin failures rarely occur, those that do fail could have been prevented in most, if not all, cases. ![]()
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