Triangles give strength without weight to Geometrica’s Agridome

Texans never do anything but big and bigger. Take storage domes for example. Geometrica’s new Agridome tops out at 500 feet in diameter with a capacity of 6,970,000 bushels of corn.

“We can build a 10 million bu. dome if that’s what a customer wants, and we’ve built them up to 700 feet in diameter,” said Geometrica chief executive officer Francisco Castaño in a phone interview from his head office in Cypress, Texas.

Geometrica has been supplying big wide-span domes to the global market for 25 years, but it’s only within the past few months that it has made a commitment to the farming sector by introducing the Agridome.

Related story: Brand new Agridome built in Minnesota

The company’s premise is that current outdoor temporary piling areas can be economically converted into permanent storage using strong structural triangles assembled quickly on site with mechanical slide joints covered by galvanized steel cladding. Its first agricultural customer came as a surprise.

“We had not actively pursued the agricultural market, but then out of the clear blue sky we got an order from West Central Ag Services in Beltrami, Minnesota,” Castano said, adding that the Beltrami dome is 350 feet in diameter, 80 feet high and holds 2.6 million bu.

“According to my client, it’s economically far better than putting up conventional steel grain bins. The knock-down price before installation works out to less than $1 per bushel. Knock-down price is just as it arrives in the crate on the semi. It doesn’t include concrete, electrical, infrastructure or labour.

“We’ve done a lot of fertilizer sheds for international fertilizer companies. There’s a lot of fertilizer that moves through the ports of the world, and they all need storage sheds.”

Castano said structural links of the triangles are coated steel. The joining hubs are always aluminum, but the contents of the dome must be considered before selecting the structural materials.

For example, chlorine gas given off from a swimming pool will quickly corrode steel, even galvanized steel. In these domes, Castano said, the company uses aluminum.

“When clients store fertilizer, you would think they want the aluminum network, but that’s not a good idea. There are some fertilizers that corrode aluminum faster than they corrode galvanized steel. Urea creates a very corrosive gas when it hits aluminum.

“So we put a cladding underneath the structural mesh so corrosive gases never reach the structural network. The joint is always aluminum, so we always need to protect that, either with paint or with some other barrier.

“We use a variety of materials for the cladding, depending on the situation. It’s usually galvanized and painted steel on probably about 95 percent of our projects. Then four percent of our cladding is aluminum and the rest is either plastic or stainless steel.”

He said the domes are designed to withstand 60 percent more than the maximum expected load that might occur in a 50 year period at an industrial setting. The dome can almost have an indefinite lifespan unless hit by a tornado, he added.

“Minor damage is easily and quickly repaired because the links simply slip in and out of the aluminum hub,” he said.

“If a loader or a tractor hits some tubes, you can replace them in an hour if you have spare links on hand. The other consideration is that with no pillars and an open working area, machine operators are much more efficient because they have no pillars to avoid hitting.”

Castano’s engineers are developing a series of standardized farm-oriented designs for farmers. By having a blueprint ready in advance, the design cost can be spread out over many customers. He can also design special domes for specific needs.

The smallest of his grain domes measures 250 feet in diameter and holds 690,000 bu. without the retaining wall. With a 10-foot retaining wall, it holds 1,050,000 bu.

The largest grain dome measures 500 feet in diameter and holds 5,550,000 bu. without the retaining wall.

Castano said his company has built domes for convention centres, sport fields and machine shops. It also builds churches, building the dome for the Glory Sanctuary in Nigeria, billed as the world’s largest church. It holds services for 100,000 worshippers.

The strength of a dome depends on the network of triangular links, but what happens when you install one or more big doors capable of semi traffic or even rail cars?

Castano said every big door, man door and conveyor port is re-enforced with one or two extra layers of the linked network. There are Geometrica domes with doors all the way around, he added, and the added double-density network at the bottom supports the weight of the entire structure.

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