engleski

Modelling of fracture of concrete at high loading rates

It is well known that the loading rate has a significant influence on the structural response. The response depends on the loading rate through the influence of three different effects: (i) through the creep of the bulk material between the cracks, (ii) through the rate dependency of the growing micro-cracks and (iii) through the influence of the structural inertia forces. Depending on the material and the loading rate, it dominates the first, the second or the third effect. For quasi-brittle materials, such as concrete, which exhibit cracking and damage phenomena, the second and the third effects dominate for very high loading rates (impact loading). However, for lower loading rates the first effect is more important. In the present study the model, which is based on the rate process theory of bond rupture is used for modeling of rate effect. The model is applicable over a many orders of magnitude of the loading rate. It was coupled with the microplane model for concrete, implemented into a 3D finite element code and calibrated based on the available experimental data. The FE code was then used in: (i) fracture studies of plain concrete beams of different sizes and (ii) penetration analysis of anchor into a concrete block.

concrete; rate effect; microplane; fracture; contact; finite elements

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