FAILURE MECHANICS OF CONCRETE SUBJECTED TO HIGH STRAIN LOADING RATE

Abstract

A meso-scale concrete model is created and used in the research work to examine the failure mechanics of concrete subjected to quasi-static and dynamic loading. Analysing the stress distribution in concrete at the failure and identifying the crucial areas that contribute to the failure are the main goals of the study. Three distinct proportional loading scenarios - which are typically seen in the field in concrete structures - have the failure mechanics examined. These loading scenarios can be classified as uniaxial, three distinct biaxial, and finally a real triaxial loading path. In dynamic loading situations, all of the above-mentioned loading paths are analysed and stress distribution is examined. An aggregate particle is initially created based on its geometrical characteristics, such as its elongation index, flakiness index, and sieve size, in order to create the concrete meso-model. Aggregate points are produced in a spherical coordinate system using MATLAB, which incorporates all of these geometrical features. To create the aggregate particle, these are later moved to cartesian coordinates. In Ansys APDL, where the aggregate particles are built, a solid is created using the randomly generated points. After that, the Hypermesh programme receives these aggregate particles for additional processing. The geometrical model meshing is done with the Hypermesh software. Every aggregate particle in the meshing process has its constituent elements given to the aggregate part, and the remining is handled like mortar. To create a more accurate meso-model of concrete, the interfacial transition zone is also developed in the final one. The interfacial transition zone, aggregate, and mortar make up the three phases of the concrete meso-model. When the meso-model featuring spherical aggregates is compared to the irregular aggregate particles created in Chapter 2, no discernible difference is found. Concrete failure mechanics are further studied biaxially and triaxially using the meso-model with spherical aggregates. A four phased meso-model of concrete is created by further modifying the three-phase model. The interfacial transition zone, aggregate, mortar, and macropores are the four phases of the concrete meso-model. When examining the stress distribution in concrete under a real triaxial loading path, the four phased meso-model is employed. The distribution and crushing of stress in the actual triaxial loading path are largely dependent on the pores. Furthermore, an investigation is conducted on the impact of the aggregate spatial distribution. The distribution of stress in concrete is also influenced by the aggregate's spatial distribution.