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Secrets to Structurally Engineering the World’s Largest Timber Frame Structure 2 by 2

Make yourself an ark of gopher wood. Make rooms in the ark and cover it inside and out with pitch. This is how you are to make it: the length of the ark 300 cubits, its breadth 50 cubits, and its height 30 cubits. Make a roof for the ark, and finish it to a cubit above, and set the door of the ark in its side. Make it with lower, second, and third decks. (Genesis 6:14–16 ESV)

Other than the mention above, we know remarkably little of Noah’s Ark from The Bible. It took 100 years for Noah and his family to complete the massive undertaking following the scant God-given instructions above. But build it they did. What a marvel of engineering it must have been in its time. The Ark Encounter is an exact full-scale replica of Noah’s Ark built according to the dimensions outlined in Genesis. The Ark Encounter, the world’s largest timber-frame structure, is seven stories tall and 1.5 football fields in length – 510’ long, 85’ wide, and 54’ high (based upon the Egyptian cubit of 20.4”).

The Genesis of a Project

If ever there was a project custom-made for a structural engineering firm it’s The Ark Encounter. In 2014, Tamarack Grove Engineering (TGE) was in a state of flux and founding principles Bonnie and Brian Sielaff were contemplating the future of the firm. While the Sielaffs literally sat in the shadow of their backyard studio considering next steps, they received a phone call that would define the next steps for their firm.

The caller was The Ark Encounter’s architect Leroy Troyer of The Troyer Group. Troyer had been given a short list of structural engineering firms capable of undertaking design for the timber frame engineering challenge. Tamarack Grove Engineering was at the top of the list and had the necessary timber expertise to handle the project. Several meetings later and TGE was engaged (February 2014) as the design and detail engineer of record for the bow and stern portions of the ark. TGE also worked collaboratively on the middle section of the structure completing detail connections for The Troyer Group.

Build it and They Will Come

When you’re tasked with engineering the bow and stern of the largest timber-frame structure in the world — and one of the most iconic and recognizable structures from The Bible — you have a lot to live up to. Replicating The Ark, is…daunting at best.

After the land for the project was secured, the challenge of clearing over 1.7 cubic yards of dirt and rock to ready the site began. The client was committed to using techniques only available to crafters of the original Ark. So, 100 Amish craftsmen from around the country were employed. The Amish crews used ancient timber framing techniques, such as manually bending the wood for the rudder rather than steaming it to make it more pliable, and whole timbers (averaging over 42 inches in diameter) as the main internal supports for the structure, more than 3.3M feet of board timber, and over 1.5M nails. Due to current building codes, wooden pegs (which would have been used on the original Ark) were replaced with steel fasteners.

While building methods reflected those of the original vessel, The Ark Encounter was designed to 2013 Kentucky building code regulation. All life/safety code-related items were addressed including fire protection, egress, and ADA compliance. A key difference in the current structure and the original is that the Ark was designed as a building rather than a boat (it does not float). “I am often asked if The Ark Encounter would float. I always answer with a firm “of course not” — we designed it as a building, not a boat. The final architectural planning and aesthetics came together to give The Ark Encounter a feeling of what it might have felt and looked like in those times, but underneath the finishes is a code-compliant building structure that meets all life/safety, structural integrity, energy, and fire requirements,” said Sielaff. The structural integrity was created using sawn wood, real trees, engineered lumber, glued laminated beams (GLB), concrete, concrete masonry units (CMU), steel beams, custom steel plates, bolts, screws, and nails. The structure is attached to three CMU towers with a center tower housing the restrooms, elevators, and stairwells while the two end towers house a set of emergency exit stair towers.

The double curvature of the bow and stern presented another significant challenge to the project. TGE used 3D BIM modeling to visualize each section in addition to structural analysis. Due to the unique nature of timber — it is living and continues to expand and contract dependent on moisture content — continual evaluation of each connection was performed throughout the project. The bents and heavy timber logs were assembled at grade and lifted into place. In June 2015 the first bent was set.

The replica project took just over two years to complete (much faster than Noah’s 100+ year project). The Ark Encounter officially opened on July 7, 2016. This date was picked to coincide with Genesis 7:7, which states:

And Noah and his sons and his wife and his sons’ wives entered the ark to escape the waters of the flood. (Genesis 7:7 NIV)

Today, even with pandemic considerations, The Ark Encounter boasts 9,000 visitors per day. “Being part of this design team has been so rewarding. This project is important to Bonnie and me personally, as well as the history of TGE. For us, it’s a privilege to help recreate a structure so important in Biblical history. This project certainly fulfills our need to serve and preserve,” says Sielaff.

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