Evaluation of the bending behaviour of laminated glass beams via electronic speckle pattern interferometry

The paper is devoted to the experimental analysis of the kinematical and mechanical behaviour of laminated glass beam structures. In particular, the utilized laminated glass specimens are composed of two glass layers bonded by a polymer layer constituted by Ethylene-vinyl acetate whose thickness has been nominally considered as constant for all the specimens. The experimental behaviour of the analyzed specimens is deduced by applying Electronic Speckle- Pattern Interferometry technique; actually, among optical methods this technique (handled by phase-stepping technique) is very effective to obtain a full-field displacement map and to numerically achieve the longitudinal strain. In particular, this technique has been used to analyse the pure bending behaviour of two-layers specimens characterized by different thicknesses of glass layers. The longitudinal strain, numerically obtained, is the basis for the subsequent analysis of the stress acting on the specimen. The longitudinal stress shows the role of the stacking sequence in the structural behaviour of the analysed specimens opening new approaches to the optimization of such elements. The principal aim of the present paper is the evaluation of the reliability of the methods suggested by the international standards by means of the comparison of the obtained experimental results with those arising from the effective monolithic thickness approach reported in international standards. The effected analyses allow to observe that the numerical results obtainable by using the methods provided by international standards are not very effective especially for thin layers.