Drift Performance of Point Fixed Glass Façade Systems

Glass façade systems in buildings are subject to racking actions caused by inter storey drifts from earthquakes and wind action. The performance of façade systems is dependent on the amount of imposed drift and the interaction of the glass panels with the façade structural support frames. There are two major concerns related to the glass façade system performance during and immediately after a seismic event; hazards to people from falling glass and the cost associated with building down time and repair. It was observed that earthquake damage to glass façade systems resulting from in-plane racking actions is increasingly common and yet there has been limited research published in this field. The research completed to date has mainly focused on traditional framed glass façade systems; however, the racking performance of point fixed glass façade system (PFGFS) is likely to be quite different. Therefore, the aim of the research presented in this paper is to assess the in-plane racking performance of PFGFS which is a façade system gaining popularity worldwide. Two unique full scale in-plane racking laboratory tests on typical PFGFS with different types of connections were conducted and specific racking mechanisms were identified. Sophisticated non-linear finite element models (FE models) were developed and benchmarked against experimental results with excellent correlation. Further detailed FE analyses were conducted to evaluate the individual drift contributions of each racking mechanism such as rigid body translation of the glass panels at the oversize holes for construction tolerance, spider arm rotation and spider arm deformation. It was found that most of the drift capacity is attributed to the rigid body translation at the oversize holes. In this paper, the laboratory test setup and the experimental results are discussed together with the confirmatory FE analysis results to assess the in-plane racking performance of the PFGFS.