In-Plane Drift Capacity of Contemporary Point Fixed Glass Facade Systems

Abstract

The point fixed glass facade system (PFGFS), also known as a spider glass system, is popular because it is the most transparent facade system available for buildings. The glass facade system is fixed to the support structure at minimal points using bolts and spider arms. Generally, the racking performance of these systems is not considered at the design stage. The facade system will be vulnerable to racking actions mainly during severe earthquakes and wind actions if the system does not have sufficient in-plane drift capacity. A unique real-scale in-plane racking laboratory test on a typical PFGFS was conducted to assess the in-plane racking performance. A maximum drift of 2.1% was measured, which was much larger than initially anticipated because of the rigid-body articulation of the system and higher than typical maximum allowable interstory drift for buildings in regions of lower seismicity. A sophisticated nonlinear finite-element (FE) model was developed and conservatively benchmarked against the experimental results with excellent correlation. The FE analyses showed that a significant amount of the drift capacity was attributed to the rigid-body translation at the built-in oversize holes for construction tolerances provided in the facade system connections. In this paper, the laboratory test setup and experimental results are discussed together with the confirmatory FE analysis results.