The use of photoelastic foils for stress and strain investigation of concrete beams

• Published in: Cement and concrete research Vol. 12; no. 4; pp. 497 - 510
• Main Authors: Kocian, Vlademir, Weiss, Vladimir
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 1982
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/0008-8846(82)90064-3

In order to explain higher bending and tensile strength and extensibility of concrete reinforced by a GRP surface coating detailed measurements were made of surface strains of these composite beams and analogous comparative beams without surface coating by means of thin birefringent photoelastic surface foils. With regard to very small deformations of concrete in tension the sensibility of foils had to be high. The production and application of large size foils were connected with a number of technical problems which were solved successfully. The results of tests performed made it possible to describe the process of development of structural cracks in concrete and to explain the mechanism of cooperation of concrete with the more ductile GRP coating. Pour expliquer les resistances en flexion ou tension et l'extensibilité elevéei du béton revĕté par plastique renforcé on a mesuré en détail les deformations superficielles des poutres revĕtés et des poutres-témoins a l'aide des couches birefringentes minces. A l'égard des deformations petites du béton tendu, la sensibilité des couches photoélastiques devait être la plus élevée. La fabrication et l'application de ces couches en grandes dimensions ont apporté plusieurs difficultées techniques qu'on a résolus. Les resultats des essais effectués ont permis de décrire le procś du developpement des microfissures en béton et d'elucider le mécanisme de cooperation du béton avec le revêment plus ductile.