Cracking and stiffness analysis of steel fiber reinforced concrete members

Darius Ulbinas

Doctoral dissertation

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In last decades, fibre reinforcement is widely used in many countries as additive for concrete and cement mortar mixture for production of structures. Fibre reinforcement applications in Lithuania are often restricted to production of concrete floor for different purposes. Whereas, in other countries (USA, Japan, Germany and other) application area of fibre reinforcement is much wider, for example: bridge deck, thin-walled structures for special constructions (tunnels, reservoirs, etc), covering of roadway, airport landing strip, pipelines, pile foundation. Application of fibre reinforcement is considered as one of the most important development area of structural construction in the world.

Fibre reinforcement significantly improves service properties of concrete. Fibre reinforcement does not have considerable influence on concrete compressive strength, however it significantly changes fracture characteristics of tensile concrete. Fracture of non-reinforced tensile concrete is brittle, whereas with fibre reinforcement–plastic. This is due to restraining of tensile deformations by distributed fibres. Fibre reinforcement influence on concrete member is more effective than bar reinforcement, as tensile deformations are restrained in the whole volume of tensile zone. Whereas, tensile deformations in a RC member are restrained in the specific interaction area of reinforcement and concrete. Main advantages of fibre reinforcement are slow crack propagation, greater tensile and bending strengths, greater impact and fatigue resistance, and plasticity.

The stress-strain state and cracking of steel fiber reinforced concrete subjected to short-term static loading has been investigated in this dissertation work. Experimental research on deformation and cracking of RC elements reinforced with fiber and bar reinforcement was performed.

In this dissertation a new method for residual stress determination of steel fiber reinforced tensile concrete has been proposed. The proposed methodology allows to determine stress-strain diagrams of tensile concrete and to evaluate residual stresses from experimental data of SFRC elements. The average stress-strain diagrams of tensile concrete has been the first time obtained from experimental moment-curvature relationship of bending reinforced concrete beams reinforced with steel fiber and bar reinforcement, using proposed methodology. These models can be directly applied to finite element programs.

In this work was determined that the residual stresses have a significant influence on the calculation of crack widths. The proposed method of determining crack widths, evaluates residual stresses of the cracked steel fiber reinforced tensile concrete. The comparative analysis was carried out on the calculated and experimentally obtained crack widths.

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DOI: https://doi.org/10.20334/2092-M

Book details

Data sheet

Year:
2012
ISBN:
978-609-457-389-7
Imprint No:
2092-M
Dimensions:
145×205 mm
Pages:
124 p.
Cover:
Softcover
Language:
Lithuanian
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