A Detailed Numerical Investigation of Insulated Glass subjected to the Standard Pendulum Test

S. Brendler (Landesgewerbeamt BW, Landesstelle für Bautechnik) Structural glazing design must reliably withhold static loads e.g. hand rails loaded by crowds, as well as dynamic loads, e. g. impacting persons or objects. Due to the ideally elastic behavior up to the brittle failure of glass, the verification of the load carrying capacity has been regularly done by experimental studies. However, it seems that trusting experimental results has more and more stopped engineers from looking into other means to safe design of glass structures, e. g advanced finite element tools that are able to simulate the dynamic response of glass designs. In relying solely on experimental investigations, one should also be aware of the fact that a safety factor against glass failure can neither be gained nor be trusted from only a limited number – in most cases only a single test is done - of experimental investigations. The latter holds even more, since scatter in material strength and even worse of the experimental setup are predominant. Contrary to the experimental result, that has to be obtained through thorough and complicated gauging of a 50ms impact test, the numerical investigation allows easy and comprehensive studying of all mechanical parameters that may or may not influence the overall results. Also, simple design changes, that would otherwise raise the question if another test should be made, can easily be accomplished when a suitable, validated numerical model is available. Finally, this will lead to safer and more economic glazing design. The present paper will focus on a sophisticated finite-element pendulum model that has been validated through pendulum tests against a rigid wall (see [1]). Furthermore it is used to simulate the impact on monolithic and isolated glass structures. The results are compared to experimental test data. It is shown that state-of-the-art numerical models are not only capable of representing the correct load carrying capacity of glass structures and the correct acceleration characteristics of the pendulum but also allow a deep insight into the complete mechanical behavior and the whole impact process of such discretized structures. In the following the results of the numerical investigation on impact loading of glass structures as described in DIN EN 12600 will be discussed. The main part of the present paper will focus on the setup, validation and calibration of the finite element model. A state-of-the-art discretization of the pendulum, the loading frame and the glass itself s presented.