Experimental observations suggests that concrete specimens subjected to uniaxial tension may have different responses depending on the imposed kinematic ‘‘constrains”. A simple model is proposed here to explain the experimental findings. Concrete specimens are schematized as a system composed of three trusses. This model can thus consider the non-homogeneity of the material, and the eccentricity between the head of the testing machine and the specimen. Two kinds of tests are considered: imposed uniform displacement (fixed platens) and freely rotating platens. The results of the model show that the tests based on fixed platens provide higher peak loads. Only for a perfect specimen and testing conditions (homogeneous material and absence of geometric eccentricity) the results of a fixed platens test and of a rotating platens test coincide. Furthermore, the same results are obtained by energy balance.

A simple model to explain the effect of different boundary conditions in direct tensile tests

CATTANEO, SARA;ROSATI, GIANPAOLO;
2009

Abstract

Experimental observations suggests that concrete specimens subjected to uniaxial tension may have different responses depending on the imposed kinematic ‘‘constrains”. A simple model is proposed here to explain the experimental findings. Concrete specimens are schematized as a system composed of three trusses. This model can thus consider the non-homogeneity of the material, and the eccentricity between the head of the testing machine and the specimen. Two kinds of tests are considered: imposed uniform displacement (fixed platens) and freely rotating platens. The results of the model show that the tests based on fixed platens provide higher peak loads. Only for a perfect specimen and testing conditions (homogeneous material and absence of geometric eccentricity) the results of a fixed platens test and of a rotating platens test coincide. Furthermore, the same results are obtained by energy balance.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11311/544463
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