Скачать или смотреть Arunita Das | Numerical investigations on the influence of concrete cover on bond behaviour of...

reinforcement in concrete after fire

Abstract: The development of proper bond between steel and concrete in a reinforced concrete structure is essential for a safe and effective transfer of stresses between them. In case of realistic concrete covers, failure of bond between reinforcement and concrete can be limited by the premature splitting of concrete cover prior to bond pull-out failure. Moreover, bond in reinforced concrete structures or structural elements are vulnerable to fire. Under ambient temperature, bond behaviour has been extensively investigated so far and guidelines for assessing the bond strength are well-established (EC2, fib MC2010). However, relatively fewer investigations are carried out for estimating post fire bond strength.
In this study, degradation of bond behaviour after fire (residual state) has been studied using beam-end specimens, which simulates the boundary conditions more closely to reality than conventional pull-out specimen. ISO 834-1 fire scenario is considered for the heating of the specimens. First, the numerical investigations are carried out employing 3D finite element analysis for the specimens at ambient temperature to validate the modelling approach. Then the numerical models are utilized to investigate the influence of different concrete covers on post-fire bond behaviour considering different fire exposure durations. The obtained results clearly demonstrate that with realistic concrete cover, failure of concrete is almost always governed by splitting of concrete prior to bond pull-out leading to a limitation in usable bond strength and also a rather strong degradation of bond strength with fire exposure duration takes place, particularly for short exposure durations. The results also show that considering the degradation in bond strength only as a function of temperature for assessing residual bond capacity may be rather un-conservative. The results of the numerical analysis have been verified against a few experiments.

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Join us for the 13th edition of the fib International PhD Symposium in Civil Engineering. Since its conception in 1996, this PhD Symposium has evolved into a highly respected scientific meeting, connecting young researchers and high-profile scientists alike.

This event provides an excellent opportunity for PhD students to share scientific thoughts and findings with the international research community from all over the world in the following fields: innovation in materials and structures, construction technology, structural analysis and design, durability and life assessment, sustainability and life cycle assessment and monitoring and structural assessment.

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The fib, Fédération internationale du béton, is a not-for-profit association formed by 42 national member groups and approximately 1000 corporate and individual members. The fib’s mission is to develop at an international level the study of scientific and practical matters capable of advancing the technical, economic, aesthetic and environmental performance of concrete construction.

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The fib was formed in 1998 by the merger of the Euro-International Committee for Concrete (the CEB) and the International Federation for Pre-stressing (the FIP). These predecessor organizations existed independently since 1953 and 1952, respectively.