Stairs and elevator shafts are the means of vertical transportation in multistory buildings. These structures not only allow vertical movement of occupants from floor to floor but their cores often serve as the main lateral stability system for these structures. Typically centrally located in buildings, they have become an integral part of building design and architecture. The code requires that occupants be able to exit during catastrophic events and be protected from fire. Due to the magnitude of loads often applied to these cores, they are stout and consume valuable space, which has prompted construction teams to make them more than just an anchor for the tower.
All of these challenges and more were present in the project in this case study. The building is a 12-story-plus-basement dormitory in Ann Arbor, Mich. The precast concrete components include an elevator core, two stair cores, and a freestanding shear wall. The core height exceeds 160 ft (48.7 m). One of the stair cores has a reduced footprint above the fourth floor, which creates an irregularity requiring transfer of significant forces at the wall discontinuity. This paper presents the process of development and implementation of the cores from a design concept to completed construction. It focuses primarily on the cores because of the unique logistic challenges that are presented in the following sections. Another paper presents the hierarchy of the decision-making process for wall panelization and discusses in depth the weighing of various considerations.