Residual mechanical capacity of small-scale partially fractured annealed laminated glass elements subjected to a quasi-static cyclic protocol

Ensuring appropriate levels of post-fracture security and structural safety for laminated glass (LG) elements in constructions are a primary need. Besides, these features are rather challenging to assess, due to a multitude of influencing parameters and uncertainties. As such, roughly simplified strategies are taken into account in the design of LG, to ensure suitable residual stiffness and resistance in case of possible partial damage. For safety purposes, any mechanical contribution from a cracked glass layer is fully disregarded in the analysis of the residual LG section. In this study, small-scale 2-ply LG specimens (50 mm wide × 100 mm in length) composed of annealed (AN) glass and bonded by EVA or SG interlayers are investigated. The specimens (60 in total) are subjected to randomly imposed partial fracture for one of the constituent glass layers, and tested in a three-point-bending setup in the so-called STAGE 2 (57 tests). A cyclic quasi-static protocol is imposed to the specimens, to quantify their mechanical response and partially fractured bending stiffness. The experimental results are also exploited to derive the equivalent modulus of elasticity for the cracked glass layer. In general, the experimental analysis shows a relatively stable performance of mechanical features for the given number of cycles, which suggests the availability of a minimum post-fracture capacity. However, the effect of some important influencing parameters is also highlighted.