Model for deformational analysis of reinforced structural lightweight concrete flexural members

This thesis is focused on deformation behaviour of lightweight concrete (LWC) flexural members subjected to short-term loading. Several mixtures of structural LWC has been developed and applied for production of experimental beams. The inverse analysis approach has been applied for deriving the tension-stiffening model of the LWC flexural members. Based on the test data, the earlier proposed tension-stiffening model has been modified to represent the effects of lightweight aggregates. The adequacy of the proposed model is analysed using test data reported in the literature via nonlinear finite element software.

The main aim of the thesis – to propose a physical model for stress–strain analysis of reinforced lightweight concrete flexural elements subjected to short–term loading. Several tasks are set in this thesis: to perform a review of physical models of reinforced LWC, to select mix composition of LWC, to conduct experimental research of reinforced concrete elements, to obtain stress–strain diagrams for reinforced concrete in tension, to propose constitutive model of reinforced concrete in tension, to perform evaluation of the adequacy of the proposed model, to perform numerical modelling of full size reinforced LWC structures.

The thesis consists of an introduction, four main chapters summarized below, general conclusions, list of references and author‘s publications on the topic of thesis, and three annexes.

The introduction discusses the research problem, the relevance of the thesis, describes the object of the research, formulates the aim and objectives, describes the research methodology, scientific novelty of the thesis, practical value of research findings, defended statements.

The first chapter deals with the literature review. It presents a historical overview of lightweight concrete and its main features, physical material models and numerical models.

The second chapter presents the selection of lightweight concrete composition. The issue of the durability of lightweight concrete is also studied.

The third chapter describes experimental research on reinforced lightweight concrete elements.

The fourth chapter presents the theoretical derivation of the material model of LWC and evaluation of its adequacy by applying the numerical method. The results of numerical modelling of full-size structures are also presented.

There are 8 scientific publications published on the topic of this thesis, one in a journal with Impact Factor, two – in Conference Proceedings which are referenced in the Clarivate Analytics Web of Science database. The results of the research conducted in the thesis were published in 5 reports at international and national scientific conferences.

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DOI: https://doi.org/10.20334/2019-019-M