Seismic Performance of Nonstructural Cold-Formed Steel Framed Exterior Walls with Drift-Compatible Details in a 10-Story Mass Timber Building
Loading...
Authors
Roser, William
Issue Date
2025
Type
Dissertation
Language
en_US
Keywords
cold-formed steel , drift clips , expansion joints , nonstructural components , slip tracks
Alternative Title
Abstract
Interstory drift is a primary cause of seismic damage to building elements that span vertically between floor levels, such as nonstructural, cold-formed steel-framed exterior walls. Prior research has indicated that sliding horizontal joints can lessen seismic damage in interior partition walls, but experiments considering exterior walls with similar “drift compatible” components are lacking. To study this issue, three exterior wall subassemblies were incorporated into the recent shake table test of the full-scale NHERI TallWood 10-story mass timber building at UC San Diego. The subassemblies were built with details intended to improve seismic resilience by permitting horizontal slip and preventing damage at intersecting walls. This dissertation describes the design, development, and experimental performance of the subassemblies. Overall, only minimal wall damage occurred. Slotted slip tracks and drift clips caused wall drifts to be significantly less than building drifts, but only minimal slip occurred in nested slip tracks. However, both slotted slip tracks and drift clips demonstrated significant resistance to slip. As a result, drift clip pullout occurred. Placing vertical expansion joints at wall intersections completely prevented corner damage. In addition, a simplified model of the bypass-framed subassembly was developed in OpenSees. The model was calibrated to match observed test behavior, then the model was used to examine the effects of varying slip joint friction on wall drifts and forces. Recommendations were made for accounting for slip joint friction in wall design.