Structural Analysis of the Museum of the City of New York (MCNY) Staircase

Abstract

The purpose of this thesis is to analyze the structural behavior of a spiral cantilevered staircase in the Museum of the City of New York (MCNY) and use this analysis as the case study to determine the feasibility of using finite-element analysis (FEA) for the modeling of these complex structures. This is especially important as the flow of forces within cantilever staircases are not well understood, and previous distinct-element models have showed that our current mathematical models greatly underestimate some variables for cantilevered stairs. The MCNY staircase was modeled using Abaqus, in which various models such as a single tread model and full staircase model were considered. FEA in these more complex structures can provide a general foundation for other modeling methods. Principal stresses and displacements on locations along the staircase were calculated. Strain data was post-processed from the Abaqus model and compared with previous on-site sensor data measurements to determine the adequacy of the model. The results of this thesis show that the free end varies in compressive magnitude depending on the amount of pressure applied to the top of the tread. Along the tread, tensile stresses from the top of the tread move from the free end and are transferred into the fixed wall. Conversely, compressive stresses are transferred from the fixed wall to the bottom of the fixed end of the tread. FEA provides qualitative agreement with the on-site sensor data, but further refining of the material properties and contact interactions may be needed to simulate the physical strain results more accurately. However, this research demonstrates that FEA can serve as an effective introductory model for complex staircase structures as seen from the MCNY case study.