| 1. |
- Albrektsson, Joakim, et al.
(author)
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Assessment of fire exposed concrete with full-field strain determination
- 2011
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In: 2nd International RILEM Workshop on Concrete Spalling due to Fire Exposure. ; , s. 337-344
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Conference paper (peer-reviewed)abstract
- A concrete structure exposed to fire deteriorates when the temperature increase in the structure. An experimental study has been performed in order to evaluate the degree of degradation of concrete exposed to two different fire scenarios. As the thermal diffusivity of concrete is low, high thermal gradient is induced in the cross-section. This causes inhomogeneous mechanical properties of a concrete structure. In traditionally core testing of the elastic modulus and compressive the material is assumed to be homogeneous, this is not the case when concrete has been exposed to a real fire. By using an optical full-field strain measuring device the mechanical response at different depth, from the fire exposed surface, can be studied. In this study a typical concrete mix for civil engineer applications were used. In addition a similar concrete mix with reduced aggregate size was tested. The test samples were exposed to the standard fire curve ISO 834-1 or a temperature rise of 10 °C/min. In addition, Ultrasonic Pulse Velocity measurement and PFM Microscopy were conducted in order obtain a reliable picture of the residual mechanical properties and the durability.
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| 2. |
- Jansson, Anette M, 1963, et al.
(author)
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Experimental investigation of surface crack initiation, propagation and tension stiffening in self-compacting steel–fibre-reinforced concrete
- 2012
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In: Materials and Structures. - : Springer Science and Business Media LLC. - 1359-5997 .- 1871-6873. ; 45:8, s. 1127-1143
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Journal article (peer-reviewed)abstract
- To investigate crack initiation and propagation in reinforced, self-compacting, steel–fibre-reinforced concrete (SCSFRC) members, tie elements were tested in tension. Strain and surface crack formation were monitored with an optical strain measurement system based on digital image correlation. In addition, to capture the softening behaviour (s–w) of the material, uni-axial tension testing was performed on SCSFRC cylinders. The results show that, with the optical strain measurement system, it was possible to detect different cracking modes and to follow the crack growth. It was especially of interest to recognize that high fibre amounts tend to change a sudden opening of a crack (as in non-fibrous concrete) into a more stable procedure. It was found that, for a given crack width, the SCSFRC specimens exhibited a noticeably higher tension stiffening than the specimens without fibres. Moreover, at a given load, the crack widths decreased by as much as 65% for the SCSFRC specimens with a nominal fibre content of 1%. For the uni-axial tension tests the results showed that with higher fibre content, for this type of fibre and concrete, both the peak stress and the residual tensile stress were increased. Additionally, it was noted for both specimen types that the scatter in fibre distribution decreased with increasing fibre content.
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