Post Breakage Strength Testing for Overhead Laminated Glass

Abstract

Design and structural performance of laminated glass in over-head glazing applications like canopies, skylights is very critical as it has an impact on the safety of occupants of a building and its maintenance workers. For such applications post breakage strength of laminated glass construction is of utmost importance. Pre breakage strength can be predicted with reasonable accuracy by FEM technique based software packages, which allow the user to input mechanical properties of viscoelastic interlayers along with glass. This helps in interlayer based differentiation of pre breakage structural strength and design optimization. However, post breakage strength of glass is still an unknown area as analytical models for this are inconclusive so far and thus destructive testing is the only reliable solution. Impact testing, simulating the accidental fall of a maintenance worker was done to assess the “fall through” resistance of point fixed laminated glass constructions having varying interlayers viz, PVB, Ionoplast Interlayer, Stiff PVB, and EVA. In addition, medium  duration (30 mins or more ) post breakage strength tests driven by the new requirements set in place by German Standard pr DIN 18008-6 were conducted at subzero (-20°C), room temperature (+21°C) and at elevated temperatures of +50° Celsius.