Two-directional cyclic racking of corner curtain wall glazing

Abstract

In an earthquake, curtain wall glazing systems may be a hazard to both building occupants and nearby pedestrians. This is the third phase of a BRANZ research programme to study earthquake behaviour of glazing systems used for multi-storey buildings. 

Earlier work looked at in-plane behaviour, this report looks at two-way loading (in-plane and out-of-plane), as would be experienced by glazing near building corners. Three (full-sized) generic wall types are tested: a conventional dry-glazed gasketed curtain wall; a unitised structural silicone system; and a combination unitised system comprising structural silicone on two sides of each glass panel with conventional gaskets on the other two sides.  Sinusoidal loading was applied simultaneously in two directions to what was effectively a three storey glazing wall, comprising four panels at each level, arranged in an “L” shape (ie, corner configuration). Glass failure was low, even under severe imposed seismic deformations. The imposed curtain wall deflections resulted in distinctly different deformation mechanisms in each instance. 

It was concluded (with some restrictions) that in-plane loading can be used to test curtain glazing walls and a recommended test procedure is provided.