As part of a campus-wide initiative to bring all "assembly occupancy" areas into compliance with the National Fire Protection Agency's Life-Safety Code, the UT Fire Marshal's office identified level 4 of the Fine Arts Library as needing attention. Because level 4 is a mezzanine-type floor with a balcony that overlooks level 3 (the entrance level of the library and the location of much of the public art, audio-visual materials, and computers) only one of the building's 3-hour rated fire stairs (in the north-east corner) was accessible. The Fire Marshal called for the construction of a bridge from the balcony edge to the fire stair in the south-west corner that, as originally designed and constructed in the 1970s, served levels 3 and 5, with the fire exit on level 2. The fire egress route across the new bridge that links the south end of level 4 with the south-west fire stair not only is a striking piece of artistic engineering and essential should there be an emergency but also is available for normal passage.
Several alternatives were considered before the final plan was agreed during the summer of 2010. Even such non-traditional solutions as slides and chutes were discussed. An early plan that would have involved installing a thick steel column on level 3 to support a bridge was dismissed. With encouragement from Fred Heath, Vice Provost for University of Texas Libraries, the idea of maintaining as much natural light as possible led to the incorporation of glass. The construction period was only 3 weeks, with most of the work taking place between Christmas and the first day of classes of the Spring Semester (Jan. 18).
Architectural Engineers Collaborative (Austin, TX) elegantly utilized the efficient form of a steel tube and the equally efficient principle of the cantilever to support graceful plate steel fins that mimic the rhythm of the original structural mullions of the windows while supporting a refractive structural glass floor. The obscure bottom layer of the tempered, laminated triple-plate glass also, unexpectedly, reflects the activity of the life below the bridge. The 5-ton structure appears to float through the space though it is securely welded at both ends to plates bolted to the poured-in-place original concrete structure. A finite element analysis program was used to determine bolt placement following the identification of rebar by ground penetrating radar. Side rails and top rails are bolted to the substructure using acorn nuts. The steel is painted white to match surrounding elements and the milky whiteness of the luminous glass.
Though initiated as a functional solution for a fire protection requirement, the bridge has not only fulfilled that need but created a unique, beautiful and possibly inspiring complement to the library space dedicated to supporting fine arts higher education.
by Laura Schwartz