A highway overpass is supported by a two-bay rigid frame adjacent to another frame. The point of fixity for the columns is well below the ground surface. Our team has designed the frame to provide...

A highway overpass is supported by a two-bay rigid frame adjacent to another frame. The point of fixity for the columns is well below the ground surface. Our team has designed the frame to provide sufficient strength; however, we still need to confirm that the frame will not sway into the other frame during the design seismic event. There is a 1-inch gap between the frames. Our task is to predict the maximum inelastic response drift of the two-bay frame. If the maximum inelastic drift of this overpass stays below half the gap, the design is adequate. Another team member is finding the drift of the adjacent frame. To find the maximum inelastic response drift, we multiply the static equivalent drift by an amplification factor. For this frame, the amplification factor is 4.5. To make a preliminary determination of whether drift will be an issue, the team leader recommends we use the Stiff Beam Method. We can use a more elaborate model if the drift might be an issue.