Post-breakage Behaviour Research Articles

Influence of Temperature on Post-Breakage Behaviour of Laminated Glass Beams : Experimental Approach

The assessment of the post-breakage performances of laminated glass elements used in construction need to take into account the sensitivity to the temperature of the mechanical behaviour and properties of the product, in particular of the interlayer material. A general problem statement and an overview of different experimental approaches are firstly presented. Then results of specific orientation tests on pre-cracked laminated glass beams with a stiff interlayer of DuPont carried at three different temperatures (23, 45 and 60°C) are presented and commented. A comparison of the mechanical behaviour at the different temperatures is done, aiming to give a comprehensive order of magnitude of the sensitivity to temperature of the post-breakage behaviour observed during the tests.

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.

Postbreakage Behavior of Heat Strengthened Laminated Glass under Wind Effects

Results of a full‐scale experimental investigation into the postbreakage behavior of heat‐strengthened laminated glass subjected to windstorm effects are presented. Two different interlayer constructions and two different glazing configurations are examined. The two interlayer constructions are a PVB polymer and a PVB/PET/PBV composite polymer. The two glazing configurations are a conventional dry glazed system and an unconventional system with a silicone anchor bead. Two test criteria are established that relate to effects of a severe windstorm. The first criterion addresses impact with windborne debris; the second defines a wind‐load spectrum that represents a severe windstorm of a 4‐hr duration. Three principal findings are presented. First, the ability of heat strengthened laminated glass to reject small missile impacts with small probabilities of breaking the inner glass ply is established. Second, heat‐strengthened laminated glass with the silicone anchor bead performed significantly better than similar glass in a dry‐glazed system. Finally, the heat‐strengthened laminated glass with the PVB/PET/PVB composite interlayer performs significantly better than similar glass with PVB interlayer.

Post-breakage behavior of architectural glazing in Windstorms

The selection of architectural glazing products for use in tall buildings has evolved into a complex process in a relatively short period of time. Many new factors have to be considered in the design procedure, and the array of new available products has created unlimited design choices. Among the new design considerations are missile impacts and the behavior of glass after breakage in a windstorm. Post-breakage behavior is described, principally, in terms of resistance to small missile impact, glass particle fallout and the propensity of glass panels to remain in the frame. These behavioral characteristics are directly related to hazards to people and a desire to protect the building and its interior furnishings and equipment from the effects of windstorms.