Sub-macroscopic Model of Confined Concrete According to Limit Analysis: Part 2: Estimation of Strength of Actively Confined Concrete Structures

Lise Kjær Andersen*, Lars German Hagsten

*Corresponding author for this work

    Research output: Contribution to book/anthology/report/proceedingArticle in proceedingsResearchpeer-review

    Abstract

    The presentation of the sub-macroscopic model of confined concrete according to limit analysis is divided into two consecutive papers - Part 1: Principal Concrete Failure Mechanisms and Part 2: Estimation of Strength of Actively Confined Concrete Structures. The proposed model is based on the upper bound theorem of limit analysis, determining the capacity of confined concrete based on proposed failure mechanisms. In contrast to classic limit analysis where concrete is modelled as a homogeneous material, the sub-macroscopic composite structure of the concrete material is taken into account when determining the path of yield line. A concrete yield line is consequently assumed composed by linear parts through hardened cement paste, which are displaced along the interface of coarse aggregates and unhydrated cement grains. Based on geometries of the proposed failure mechanisms of the foregoing paper (Part 1), the present paper (Part 2) focuses on estimation of the strength of actively confined concrete structures. Setting up the work equation, equalling the internal dissipation of the yield line and the external work, the confined concrete strength is subsequently found by optimisation and thus determining the most critical path of yield line. The only contribution to the internal dissipation of the concrete structure is assumed to be the parts through the cement paste matrix, while the contribution from yield line parts along the aggregate interfaces is assumed negligible. Estimated strengths of concrete for varying levels of confinement and uniaxial compressive strengths are compared with experimental results of actively confined concrete specimens, where convincing agreement has been found. One main conclusion is that the confined concrete strength is strongly influenced by the volume fraction of aggregates capable of resisting failure. The forthcoming objective of the research is to expand the model to become applicable to passively confined concrete members.

    Original languageEnglish
    Title of host publicationHigh Tech Concrete : Where Technology and Engineering Meet - Proceedings of the 2017 fib Symposium
    EditorsD.A. Hordijk, M. Lukovic
    Number of pages10
    PublisherSpringer
    Publication date2017
    Pages543-552
    ISBN (Print)978-3-319-59470-5
    ISBN (Electronic)978-3-319-59471-2
    DOIs
    Publication statusPublished - 2017
    EventHigh Tech Concrete: Where Technology and Engineering Meet: 2017 fib Symposium - Maastricht, Netherlands
    Duration: 12 Jun 201714 Jun 2017

    Conference

    ConferenceHigh Tech Concrete: Where Technology and Engineering Meet
    Country/TerritoryNetherlands
    CityMaastricht
    Period12/06/201714/06/2017

    Keywords

    • Aggregates
    • Cement paste
    • Concrete
    • Confinement
    • Limit analysis

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