Structural glazing joints in glass structures are subject to dynamic seismic loads in certain regions. However, to date, there is no accepted proposal for the design of such situations. The seismic design of glass structures is either neglected or performed with equivalent values for the whole building. Not considering the behavior of the bonded joints under dynamic loading might be insufficient, especially in the presence of heavy glass elements. A more thorough investigation of the structural performance of silicone or polyurethane within bonded glass structures under different loading scenarios is urgently required and an appropriate material model is essential. The calibration of such a model is crucial to better understand the performance under dynamic loading. However, structural glazing joints are subjected to different combinations of stress states, especially under dynamic seismic loading, which are difficult to model using only uniaxial tests. For this purpose, air-supported bulge tests are performed on two different silicones and a polyurethane to analyze the material behavior under biaxial stress conditions. The tests are performed using air pressure instead of a liquid that causes the material to bulge until failure. Digital image correlation is used to measure deformation and, together with the internal pressure, to calculate the resulting stresses and strains across the surface. A circular opening in the testing machine, into which the test specimens are clamped and inflated, results in an almost perfect section of a spherical surface. Using Barlow’s formula together with the recorded deformation and the measured internal pressure, the biaxial stress can then be calculated. These experiments are therefore critical to the calibration of an appropriate material model.