Compatible modeling of cracking, deformation and bond in reinforced concrete members

Ronaldas Jakubovskis

Doctoral dissertation

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Reinforced concrete (RC) is a composite material comprising concrete and reinforcement. The interaction of these materials, often referred as bond, has a crucial effect on performance of RC structures, both in the serviceability and the ultimate limit states.

In general practice, design of RC structures is based on the assumption of perfect bond between concrete and reinforcement, i.e. no physical slip is allowed. This simplification might be reasonable in load bearing capacity analysis, however it becomes unacceptable when serviceability of RC structures is considered. In this case, neglecting bond-slip leads to empirical relationships, which are often cumbersome and controversial. It is also important that in empirical approaches separation between deformation and cracking analysis should be done. Previous studies have shown that deflection predictions by different code techniques varied up to 100%, whereas variability of crack width predictions was found of much higher order.

In contrast to empirical nature of models used in the design codes, the stress transfer (also called force transfer, or partial interaction) approach is capable realistically reflect nature of RC: bond-slip action, development of cracks, tension stiffening and tension softening. Being mechanically based, such approach can be universally applied to any type of reinforcement (steel, fibre reinforced polymer) and concrete (fibre reinforced concrete, high performance concretes). Stress transfer algorithms allow predicting formation of cracks and determining stress and strain distribution of reinforcement and concrete along the cracked element. The major drawback of the stress transfer approach is the need of knowledge of complex local parameters (bond-slip relationships), which principally governs the obtained results. Improper choice of the bond-slip relationship for particular problem may result inadequacy in deformation and cracking analysis.

Present thesis presents a new strategy for modeling bond, cracking and deformation behaviour of RC members. The proposed modeling technique is not restricted by the geometrical dimensions of the analyzed member and may be applied for various loading conditions. Tensile as well as bending RC members may be analyzed using the proposed technique. Adequacy of the modeling strategy was evaluated by the developed numerical discrete crack algorythm, which allows modeling deformation and cracking behaviour of a tensile RC members. Comparison of experimental and numerical results proved the applicability of the proposed modeling strategy.

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DOI: https://doi.org/10.20334/2327-M

Book details

Data sheet

Year:
2015
ISBN:
978-609-457-817-5
Imprint No:
2327-M
Dimensions:
145×205 mm
Pages:
158 p.
Cover:
Softcover
Language:
Lithuanian
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