Safety of Laminated Glass Structures after Initial Failure

The load carrying capacity (LCC) as well as the remaining structural capacity (RSC) have to be verified in glass structures, which take structural functions. The glass laminates have to be composed of an interlayer Poly-Vinyl-Butyral (PVB) foil such that after the first crack in the glass the interlayer holds the pieces together and the whole structure resists the load. This paper defines failure modes with their characteristic values. The ultimate force as well as the external work are the tools which are used to specify the RSC according to the failure mode. The different modes are shown in four point bending tests combined with impact tests. The executed tests also investigate different thicknesses of the glass layers. Unequal thicknesses of the glass layers increase the LCC as well as the RSC. To observe in tests the post breakage behaviour yield line mechanisms are necessary for broken laminated safety glass panes. Different types of yield lines can evolve from initial cracks. Therefore the influence of the direction of the yield lines for the RSC is discussed.