Influence of Boundary Conditions on Building Behavior

When architectural engineering students graduate and enter the workforce they will be faced with analyzing and designing a variety of structural systems. Great care is often taken in accurately modeling the structure until it comes to the boundary conditions at the base of the building. Most students are exposed to fixed boundary conditions, pinned boundary conditions and roller boundary conditions in their undergraduate courses. These idealized boundary conditions simplify the analysis, however, choosing which condition is appropriate for connections in an actual building is not always clear. In addition, boundary conditions can have a large influence on the predicted building performance and associated design. Engineers are challenged with accurately modeling buildings including the boundary conditions, and therefore, facing this challenge in their undergraduate studies is important for students so that they can make informed decisions as engineers. Integrating experiments into courses uniquely exposes students to the challenges they will face as practicing engineers. In a senior level design and analysis course students were assigned the task of determining the appropriate boundary conditions for a two-story steel moment frame with columns bolted to a concrete floor. The students predicted the steel frame response by computational models and hand calculations. They completed the hand calculations first to provide a baseline for the computational models. After predicting the steel frame response the students conducted dynamic experiments to measure the response of the frame to serve as a comparison for their predictions. This laboratory experience gave students a healthy skepticism for analysis results that are not validated by hand calculations and encouraged students to consider how design details affect the boundary conditions and overall structure behavior.