Strength prediction of annealed glass plates – A new model

• The model predicts strength probability of glass panes; normal distribution better fits predicted results.
• The model predicts the fracture origin location; it differs from the point of maximum bending moment.
• Small samples may provide an estimate of the average strength.
• A large sample is needed to get the exact strength distribution.
• The model well predicts test results and provides insight on glass plate behavior.

A new model for assessing the strength of structural members made of annealed glass plates is presented. The model refers to a glass plate that is supported at its ends and loaded by a given loading system. To fully determine the mechanical behavior of the glass plate, a flaws distribution function is presented, from which the critical stress distribution is calculated. These critical stresses determine the local ultimate resistance of the plate. The model determines the flaws distribution over the area of a large basic plate, from which plates of different sizes are cut out. Each cut out plate is characterized by a different map of flaws that is distributed over its surface and it behaves differently as a result. The flaws shape, size and location determine the critical tensile stresses that are required for crack opening. These critical stresses are compared with the growing stresses during loading, to determine at which point and at what loading level fracture is initiated. The model is capable of predicting the tensile strength distribution of a large group of glass plates of a given geometry and boundary conditions. The model provides much information concerning the probabilistic distribution of the tensile strengths and the location of the fracture origin.For an examined case the model yields an almost symmetrical tensile strengths distribution, and although it is somewhat different than existing statistical functions, it is similar to the normal distribution.It is shown that the entire analysis of determination of the critical tensile strength is independent on the plate’s thickness, although the latter is important to determine the magnitude of the bending moment at failure and the magnitude of the applied load that causes that failure. The model is found to be in close agreement with test data; it may explain the inspected and measured results and provide insight to glass plate behavior.