'To accommodate its growing collection of technical journals, texts, and rare science and engineering books, the Linda Hall Library needed to expand its stack area. The new three-level stack addition has a footprint of only 10,000 gross square feet, but will accommodate over 16 miles of high-density shelving. With the space being closed to the public, the Library’s primary goals were to maximize the density of shelving, provide excellent temperature and humidity control, and match the existing Georgian architecture.

The existing 1978 stack annex was designed for conventional shelving requiring a 150-psf floor live loading and had a low 9’-8” floor-to-floor height. The structural system consisted of a 12”–thick mild reinforced concrete flat plate with an approximate 20’ by 20’ column spacing.

Working with the architect, shelving consultant and mechanical engineer, Walter P Moore selected a structural bay size of 18’ by 24’ and a floor-to-floor height of 11’-6” for the new stack expansion. The framing system would need to accommodate a 250-psf live load, 2’’ concrete topping, and a 10-psf MEP load.

A structural floor framing study, and pricing exercise, between a conventionally reinforced 12’ concrete flat plate and an 8’ flat slab with 6’ drop panels determined the latter to be the more economical. Preliminary design was performed using the direct design method per ACI 318 section 13.6 with the final design being confirmed using ADAPT software. As with all flat slab and flat plate structures, punching shear needed to be carefully checked for all the various loading conditions including 100% alternate bay loading of the high-density shelving...'