New Parameters to Describe High-Temperature Deformation of Prestressing Steel Determined Using Digital Image Correlation

Gales, John; Bisby, Luke; Stratford, Tim

doi:10.2749/101686612x13363929517730

Cited by 23 publications

(30 citation statements)

References 1 publication

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“…Measurement scatter with this length was shown to be less than 0.005% strain [39]. Gauge lengths above 1000 pixels were appropriate for reducing the influence of the inherent bias error of the DIC technique (see [43]).…”

Section: Verification Of Dic Technique For Deformation Approximationmentioning

confidence: 98%

“…At high temperature, DIC has been shown to accurately describe the deformation behaviour of various structural materials and assemblies (see [39,44,45]). …”

Section: Deformation Measurementmentioning

confidence: 99%

“…Efforts were made to reduce the levels of measurement error by considering the best practices listed in aforementioned literature [39,41,43]. However, with the unique nature of high temperature testing of concrete and the risks associated with instrumentation breakage while testing, a rigorous endeavour to quantify error at high temperature may benefit future studies that use the DIC technology.…”

Section: Fire Technology 2015mentioning

confidence: 99%

“…These paint mixtures were chosen to be similar to those that had been utilised in other high temperature tests [39].…”

Section: Deformation Measurementmentioning

confidence: 99%

“…Gauge lengths above 1000 pixels were appropriate for reducing the influence of the inherent bias error of the DIC technique (see [43]). The gauge length size represented the validated high end for uniaxial at-elevated temperature testing of materials [39]. A pixel subset of 64 9 64 pixels was followed as was defined as appropriate for concrete within Ref.…”

Section: Verification Of Dic Technique For Deformation Approximationmentioning

confidence: 99%

See 4 more Smart Citations

Fire Performance of Sustainable Recycled Concrete Aggregates: Mechanical Properties at Elevated Temperatures and Current Research Needs

et al. 2015

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The materials used for the construction of buildings are changing. There are now many sustainability drivers for developing novel green construction materials. An emerging material used for building construction is concrete with conventional coarse aggregates substituted as recycled concrete aggregates (RCA). This is a form of sustainable concrete. A finite number of buildings (>10) with this material have been constructed in North America, Europe and Asia. However; to help facilitate wide spread use and development of sustainable concrete with RCA, there is purpose in considering this material's at-elevated temperature (in-fire) mechanical properties. To date, this topic has seen limited research attention as it is difficult to study. The study herein considered the mechanical properties of conventional and sustainable concrete with RCA. The only difference between the conventional and the sustainable concrete mixes was the mass proportion of a conventional natural coarse aggregate, Limestone, which had been substituted with coarse RCA (at replacement proportions of 0%, 30% and 100%). Both the ambient and elevated temperature mechanical properties were considered with compressive mechanical tests using an innovative optical technology for strain measurement. Based on the analysis performed, a proportional decrease in retained strength and elasticity of concrete at-elevated temperature with increasing RCA content was observed. For example both mechanical properties showed a 0.2% decrease in retained value for every 1% RCA increase at 500°C. In addition the modelling parameter of Poisson ratio appeared to be influenced by the heat imposed and the aggregate type contained within the concrete. For example at 500°C, this parameter showed an 73% increase for concrete samples with only Limestone aggregate and a 15% decrease for samples with only RCA (of mixed origin primarily Siliceous). This paper concludes with highlighting current knowledge gaps and research needs that when addressed could help improve the facilitation of using sustainable concrete's with RCA in construction of buildings.

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Section: Verification Of Dic Technique For Deformation Approximationmentioning

confidence: 98%

“…At high temperature, DIC has been shown to accurately describe the deformation behaviour of various structural materials and assemblies (see [39,44,45]). …”

Section: Deformation Measurementmentioning

confidence: 99%

Section: Fire Technology 2015mentioning

confidence: 99%

“…These paint mixtures were chosen to be similar to those that had been utilised in other high temperature tests [39].…”

Section: Deformation Measurementmentioning

confidence: 99%

Section: Verification Of Dic Technique For Deformation Approximationmentioning

confidence: 99%

See 3 more Smart Citations

Fire Performance of Sustainable Recycled Concrete Aggregates: Mechanical Properties at Elevated Temperatures and Current Research Needs

et al. 2015

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Creep of prestressing steels in fire

Gales

Robertson

Bisby³

2016

Fire and Materials

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SUMMARYWhen prestressing steel (PS) is applied as continuous unbonded tendons within concrete, as in the case of post-tensioned (PT) construction, localized damage to the tendons may affect the integrity of the entire structure. When fire exposed, unbonded PT concrete structures are prone to tendon rupture because of a complex relaxation and strength reduction relationship influenced by high temperature PS creep. Explicit consideration of creep is necessary for the fire safe design of such buildings. High temperature PS creep has received limited research: few models can be used within the expected service stress range; none reliably model tertiary creep; and no studies are available investigating the influences of metallurgy on high temperature PS creep. A BS 5896 PS creep model is developed and validated. This model is used to provide PS failure insights at high temperatures. This understanding can be used to build validated models of structural fire experiments on PT concrete structural elements and to develop defensible, validated structural models that are essential towards performance based structural fire design of such systems. Finally, the high temperature creep performance of equivalent PS from different mills is compared, demonstrating strong influence of manufacturing and alloying techniques used. Future research is discussed.

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Application of narrow‐spectrum illumination and image processing to measure surface char formation in lateral ignition and flame spread tests

et al. 2019

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SUMMARY The Lateral Ignition and Flame Spread Test (LIFT) is used to characterize fire ignition and flame spread on solid materials. This test requires the operator to visually monitor the flame spread over a combustible material and manually record the position of the flame during an experiment. Visual inspection limits the quantity of data obtained from a test and introduces uncertainty in the measurement. In this study, we use narrow-spectrum light with a peak wavelength of 450 nm and a digital camera with frequency-matched optical filters to capture images of surface charring, which underlies the flaming combustion, in a LIFT apparatus. The imaging technique reduced unwanted energy emissions from the flame in the visible light spectrum, allowing the test operator to directly view the charring of the material; which is otherwise hidden behind the flames. We describe data processing routines to analyze the sequences of high-resolution images. The method improves temporal and spatial resolution of the surface charring compared to visual observations.

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New Parameters to Describe High-Temperature Deformation of Prestressing Steel Determined Using Digital Image Correlation

Cited by 23 publications

References 1 publication

Fire Performance of Sustainable Recycled Concrete Aggregates: Mechanical Properties at Elevated Temperatures and Current Research Needs

Fire Performance of Sustainable Recycled Concrete Aggregates: Mechanical Properties at Elevated Temperatures and Current Research Needs

Creep of prestressing steels in fire

Application of narrow‐spectrum illumination and image processing to measure surface char formation in lateral ignition and flame spread tests

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