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Ryan LawberArch 404

SUMMARYThe catenary curve follows the path of an object in space, and is one of the strongest shapes in compres-sion. This proposed recreation center for the campus utilizes catenary forms to minimize the amount of concrete used in the structure. The primary envelope is a tensile fabric stretched between thin concrete shell catenary arches. The hollowness of the form in turn creates a void that can be used as a solar chimney in the ventilation of the building. Ventilation of some interior spaces will be done through typical forced air. Conditioning the spaces is done through slab heating and cooling. The skin of the building varies from two ply to three ply in different spaces. The pool area has three layers to minimize condensation on the fabric and better insulate the space. The other sections maintain a two ply fabric structure because the need to reduce condensation is not necessary and solar radiation will condition the space partially through louvers sand-wiched between the tensile material and engineered to increase solar gain in the winter and minimize in the summer.

Section showing solar chimney effect and fresh air brought in at the base

Exploded section of catenary arch and three laters of tensile fabric

South elevation of IIT Recreation Center

VENTILATION:The rooms are usually occupied only with 2-4 people at a time, but humidity produced in the spaces by the rapid movement of the users requires for adequate ventilation. Light used in the rooms are fl uorescent tube lights. There is no access to solar gain. Required out-door air based on room CF with a complete AC every 3 minutes:

CFM = 41’-8” x 22’-10” x 20’-0” = 18040 = 6000 CFM 3 3

CONDITIONINGSince this is an enclosed interior space inside the building envelope, heating and cooling losses are not a primary concern. But, for the sake of the class, the en-trance wall is an impact resistant single pane glass wall system with an r-value of 0.9. The walls of the rooms are metal stud with 3/4” gyp on each side. This has an R-value of only approximately 2.5 since there is no insulation between rooms. The fl oor is poured concrete slab with water fed radiant tubing through the slab top-ping under the wood plank fl oor.

supply air

exhaust air

radiant heating/cooling

room to room vent

=246 in²

DUCT SIZING:CFM=6000Velocity 98 FPM at the clear sectionof the opening

6000 CFM * 144 in²/ft² 3500 FPM

A duct with the following dimensions will work:16” x 16”14” x 18”12” x 21”10” x 25”8” x 32” (at the extreme of the L/4 rule of thumb)