Monday, November 22, 2010

Chautauqua Auditorium

By Cray Shallenbarger

The following is a summary of a paper I wrote for an architectural history class. It is a good example of a culturally rich piece of architecture that has been preserved over a surprising period of time.

In the small town of Shelbyville, Illinois, examples of unique or even “good” architecture are slim. If one is so lucky to stumble across a unique structure in the said area he should definitely inquire about it. In this obscure Central Illinois town I did just that. The Chautauqua building is located in the center of the town’s park, Forest Park. It’s not an excessively large building by any means. It is merely one hundred and fifty feet in diameter. From the outside the building looks seemingly unimportant. It is a round building with several doors and windows tracing its circumference. When viewing it from the outside it is apparent to one that the purpose of this building is to house entertainment. The building was the center of the Chautauqua festival that consisted of music and prominent speakers of the time.


Throughout time the building has seen good times and bad times. In the early nineteen seventies, the building was in ill repair. There was talk of tearing it down and building a new, more up to date building. This struggle went on for several years. In nineteen seventy seven the building teetered on being destroyed and being remodeled. It was then that a large snowfall caused the roof and part of the wall to collapse. This forced the people of the community to make a decision. Thankfully they made the decision to repair the building and restore it. Since that time, there have been few problems with the building. One electrical fire threatened the then one hundred and one year old structure but the flame was extinguished by the local fire department.

Aside from being a culturally rich building, the Chautauqua auditorium is an excellent piece of architecture. The auditorium was constructed for entertainment purposes. The designer of the building, H. B. Trout, utilized a recent invention to achieve what was required for the building to be functional. The building was to be one hundred and fifty in diameter. Also, they wanted to use little or no middle roof supports. This may have been possible to achieve with the use of arches but the builders of this building went another route. In 1902, just a few years before the auditorium was constructed, a man by the name of Morrison H. Vail of Chicago had designed a ceiling construction method that would do just that. In review of Vail’s patent information, one can see that this invention was well deserving of use. In the specifications for his patent (1902), Vail described his invention and its purpose. It was developed to provide a cheap, safe and durable solution to special obstructions caused by columns normally needed to support a ceiling. He stated that his invention would withstand any strain of wind and snow.

This new method was actually a pretty good one. The patent explained how the load of the ceiling was dealt without using columns for support. It uses tension to keep the roof from collapsing. The roof is not flat. In fact, it raises several feet from the outside edge to the center. On the inside it is obvious that tension is in use. The trusses are fastened down to vertical posts which go all the way into the ground. These are anchored in concrete and have a wrought-iron core. These two are attached by metal straps. The straps’ shape allows for secure vertical down-pull on the truss ends without cutting into the wall plates. The cast iron foot plate is shaped as to bind the members of the trusses and keep it from spreading apart under the strains. The cast iron pin plates are formed as to bind the ends of the struts, being held up in place by the bolts. The position of the ears spreads the outer pair of the tie rods giving added lateral stiffness to the trusses. The wrought iron strap is formed as to bind the pin, the strut, and the truss rafter in their proper position and assist the rafter with the strains on the pin. The straps bind the struts to the truss rafter in their proper positions. The steel tie rods are held immovably in place on the pins and by the pin plates, ears, and nuts on the ends of the said pins.

Two long, steel tie plates are employed at ninety degrees to one another. They are exactly the same width as the rafters. They extend the full length of the core all the way to the opposite truss. These are bound to the rafters by the wrought iron straps which are tightened by bolts. The plates are also lag screwed to the truss-rafter to prevent twisting of the structure. The center, circular core is built up of several layers of planks. Each layer is composed of planks lying parallel to and abutting each other. The several layers are positioned so that the individual planks of one layer will cross the underlying later at an angle. The core pieces are shaped to fit the head plates. Each is drilled as to accept to receive the nuts on the ends of the rods by which the head plates are clamped onto the ends of the rafters. All of the planks are arranged so that when finished, they form a solid body of circular outline. The thickness of this affords a bearing that makes the apex of the roof nearly solid. “Each truss-rafter is built up of several thicknesses of planks, which break joints and are securely bound together by lag-screws, spikes, and bolts.” The center tie plates are two circular steel plates drilled around the circumference. These holes allow a place for the tie rods to connect in the center of the structure. Shims are placed between the two plates to allow space for the tie rods. These plates are bolted together to stop any shifting. The plates hang several feet below the top of the structure. It is crucial that these maintain the same location in relationship to one another. To achieve this, there are steel rods run from the top portion of the roof to the bottom plates which are well above the ground. This center construction is necessary to make the entire truss-work rigid. It eliminates any twisting from uneven loads on the roof. All of the steel rods are adjustable by turnbuckles placed on them. This allows for future adjustments needed because of settling or repair needs.


As one can see the roof of this structure was constructed in one of the most advanced ways possible for that time period. Shelbyville, Illinois does not have much architecture. This building is a symbol of the town and thankfully a great piece of architecture. Not many in the town understand what a great structure it really is. Before coming to school and studying architecture I never really looked twice at it either. It just goes to show that good, sustainable architecture is everywhere. One just has to be willing to look at it with an open and critical eye.

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