General Creep-Time Equation

Poh, K. W.

doi:10.1061/(asce)0899-1561(1998)10:2(118)

Cited by 9 publications

(4 citation statements)

References 3 publications

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“…In the analysis of steel at high temperatures, it may be important to account explicitly for creep deformations. Poh & Skarajew [20,21] conducted extensive testing of modern structural grade steels and developed mathematical relationships in the form of continuous functions [22] for thermal expansion [23], stress-related strain [24] and creep strain [25] as a function of temperature and time. Although the behaviour of steel has been extensively studied previously, these data represent new information, and the mathematical relationships developed are more easily incorporated into computer programs to enable analysis of steel members under elevated temperature conditions…”

Section: Steel Behaviourmentioning

confidence: 99%

Design of steel structures under fire conditions

Bennetts

Thomas

2002

Progress Structural Eng Maths

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Changes have occurred internationally in regulations for fire safety in buildings, and there has been significant recent progress towards rational design for fire safety in buildings. Possible design objectives for fire safety are listed and the interacting factors that influence fire safety in buildings are discussed. A factor of particular importance is fire growth and development, with recent developments in this area leading to increased recognition of non-uniform conditions occurring in many enclosures of practical significance in fire safety design. Coroner's records and fire statistics have been used to improve our understanding of the factors that lead to casualties (particularly fatalities) in fires, and these have shown that the structure is rarely a factor.Recent progress in understanding and modelling the behaviour of steel structures in fires is reviewed. Recent testing for modern structural steels has resulted in new data for thermal expansion and stress-related and creep strain, with new mathematical relationships for strain that can easily be used in computer models. Studies of the response of steel columns and composite beams are reviewed, including studies of the effect of temperature gradients and axial restraint on column performance, the development of a simplified equation for concrete-filled tubular column behaviour and lateral buckling of beams. A major area of recent research is the behaviour in fire of significant parts of a building structure (rather than individual members), particularly in response to the Cardington eight storey steel-framed building tests. Several recently published approaches to modelling overall structural behaviour are reviewed in the light of these tests.

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Section: Steel Behaviourmentioning

confidence: 99%

Design of steel structures under fire conditions

Bennetts

Thomas

2002

Progress Structural Eng Maths

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“…In Eurocode 3 [3], viscous creep deformations are taken into account implicitly, as integral part of stressstrain relationship, and are thus not considered to be time dependent. Since viscous creep deformations are not easily distinguished from plastic deformations, both experiments and numerical modelling are quite rare and demanding [4,5,6,7]. Since viscous creep deformations are not easily distinguished from plastic deformations, both experiments and numerical modelling are quite rare and demanding [4,5,6,7].…”

Section: Introductionmentioning

confidence: 99%

“…In 1988 Kirby and Preston [4] published set of results of uniaxial tensile tests where structural steel grades 43A, equivalent to European steel grade S275, and 50B, equivalent to European steel grade S355, were used. On the other hand, there are more recent viscous creep models that are limited in application [5,7]. These experimental results were used by Kodur and Dwaikat [6] for calibration of their model of viscous creep in 2009.…”

Section: Introductionmentioning

confidence: 99%

“…The tests were carried out at different stress levels and at constant heating rate of 10 °C/min. For example, some of the models can be applicable only to one type of steel, like the one proposed by Cowan and Khandelwal in 2014 [5], others demand that construction is subjected to specific mechanical load ratio and temperature regime, as proposed by Poh in 1998 [7]. Kodur's and Dwaikat's model can be widely used on different types of steel at various heating rates and at different stress levels.…”

Section: Introductionmentioning

confidence: 99%

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10.30: Mechanical response of steel structures in fire: Influence of different material and creep models

et al. 2017

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The paper deals with the influence of viscous creep of steel on the behaviour of steel structures during fire. Two stress-strain relationships for structural steel, combined with Harmathy's explicit model of viscous creep at elevated temperatures, are presented in the paper: (i) bilinear stress-strain relationship and (ii) modified Poh's stress-strain relationship. The presented models have been implemented in self-developed software Pozar for numerical analysis of mechanical response of planar steel frames in fire. Further on results are validated against experimental ones published by Rubert and Schaumann, 1985. The numerical results, obtained with stress-strain relationship according to the Eurocode 3, are added for comparison. It is shown that all tested models give satisfactory results for small load ratios. Poh's stress-strain relationship in combination with Harmathy's model of viscous creep and newly proposed coefficients give the best results among the tested models with explicitly considered viscous creep. However, none of the considered models give good agreement with the experiment at high values of load ratio. Furthermore, the comparison between the different material and creep models is conducted for three heating regimes, namely linear heating regime and fast and slow natural fire development. A prominent influence of the employed material model on the final midspan displacements is observed.

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