Incremental-iterative model for time-variant analysis of SFRC subjected to flexural fatigue

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• 作者：Peter Heek ; Mark Alexander Ahrens ; Peter Mark
• 刊名：Materials and Structures
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：50
• 期：1
• 全文大小：1,252 KB
• 刊物类别：Engineering
• 刊物主题：Structural Mechanics
  Theoretical and Applied Mechanics
  Mechanical Engineering
  Operating Procedures and Materials Treatment
  Civil Engineering
  Building Materials
  
• 出版者：Springer Netherlands
• ISSN：1871-6873
• 卷排序：50

文摘

Fatigue behaviour of plain (PC) and steel fibre reinforced concrete (SFRC) is of growing interest in concrete engineering since structural reliability often depends on the concrete’s damage state. The current paper deals with its investigation. Starting from a new and universal SN-approach for PC and SFRC based on stress- and material-dependent ductility and a cycle-dependent strain evolution under centric pulsating loads an isotropic and time-dependent material damage parameter is derived. In the framework of the elasto-plastic damage theory, wherein PC and SFRC are idealized homogeneously on macroscopic level, this damage parameter in conjunction with the established envelope concept enables to compute time-dependent stiffness and strength degradations as well as increasing plastic strains. Additionally, an assessment of the total number of cycles to failure of specimens subjected to multi-staged cyclic loading is permitted by a specific damage accumulation procedure. Decisive parameters like fibre type, length, orientation, dosages and bond on the axial static and cyclic material response are covered. To compute numbers of cycles to failure, deflections and stress redistributions of members exposed to flexural fatigue, the findings are integrated into a plastic hinge model. This accounts for localization of damage after cracking in a discontinuity region typical for both, PC and SFRC. Cycle- and crack-width-dependent deflections are obtained for valid states of equilibriums between external loads and internal stress resultants. To assess macroscopic cracking a strain criterion serves. In the numerical simulation, time-increments are performed according to Lemaitre’s jump-in-cycles procedure. For verification test results from literature are recalculated. Theoretical and experimental data are in good accordance on average proving a comparable fatigue behaviour of PC and SFRC in principle. However, fibre’s impact on fatigue life and deformation capacities of concrete is ambivalent, depending on specific material and load characteristics.KeywordsFatigueWöhler-curvesDuctility indexSteel fibre reinforced concreteIncremental-iterative modelDamage parameter