The Methodist University Hospital (MUH) Shorb Tower is a nine-story, 450,000 SF hospital addition to the existing two-story Emergency Department near midtown Memphis, Tennessee. As the structural and civil engineering consultant, Allen & Hoshall provided creative design solutions for the tower which was constructed over Eastmoreland Avenue and on top of the existing Emergency Department. Unique considerations included the design of a Risk Category IV facility in a major seismic zone and the continued operation of the Emergency Department throughout construction.
The gravity structural system consists of structural steel columns, composite beams, and girders with camber. The lateral load resisting system consists of Special Reinforced Concrete Shear Walls (SRCSW) at the elevator cores, utilizing both the existing walls and new walls in combination with existing Steel Special Concentrically Braced Frames (SSCBF) for the existing first two stories of the Emergency Department. The lateral load resisting system was designed using dynamic modal analysis and a seismic site-specific study, utilizing a Refraction Microtremor (ReMi) survey to obtain a measurement of the site’s shear-wave velocity characteristics. The seismic study resulted in a reduction from Site Class “D” to Site Class “C” and the modal analysis additionally reduced the seismic design forces by 15%.
The north portion of the addition has a seven-story new structural steel tower on top of the functioning existing two-story Emergency; with an adjacent nine-story new portion of the tower to the south, across Eastmoreland Avenue. Both the south and north portions of the hospital are connected by (7) 76-ft long by 10-ft deep, steel-plate transfer girders; just below Floor-3. Each girder supports two column lines of seven-stories of structure over Eastmoreland Avenue. Having a long-span transfer girder system in a high seismic design was a serious design challenge requiring a creative structural engineering design.