Critical temperatures of steel columns exposed to fire

Rubert, Achim; Schaumann, Peter

doi:10.1016/0379-7112(88)90031-8

Cited by 13 publications

(8 citation statements)

References 2 publications

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“…Numerous isothermal tests on isolated long columns [7][8][9], stub columns [10] and beams [11,12] have been conducted to investigate the effect of high temperature on the structural response of members failing by local buckling or overall buckling without the added complexity of the effects of heating rate. Tests on isolated members [13,14] subjected to standardized fire curves [15], which allow a more realistic representation of the structural response of members in fire, have also been performed and are utilized to obtain critical temperatures as a function of parameters such as the load level and the member slenderness [16].…”

Section: Introductionmentioning

confidence: 99%

The continuous strength method for steel cross-section design at elevated temperatures

Theofanous

Propsert

Knobloch³

et al. 2016

Thin-Walled Structures

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When subjected to elevated temperatures, steel displays a reduction in both strength and stiffness, its yield plateau vanishes and its response becomes increasingly nonlinear with pronounced strain hardening. For steel sections subjected to compressive stresses, the extent to which strain hardening can be exploited (i.e. the strain at which failure occurs) depends on the susceptibility to local buckling. This is reflected in the European guidance for structural fire design EN1993-1-2 [1], which specifies different effective yield strengths for different cross-section classes. Given the continuous rounded nature of the stress-strain curve of structural steel at elevated temperatures, this approach seems overly simplistic and improved accuracy can be obtained if strain-based approaches are employed [2]. Similar observations have been previously made for structural stainless steel design at ambient temperatures and the continuous strength method (CSM) was developed as a rational means to exploit strain hardening at room temperature. This paper extends the CSM to the structural fire design of steel cross-sections. The accuracy of the method is verified by comparing the ultimate capacity predictions with test results extracted from the literature. It is shown that the CSM offers more accurate ultimate capacity predictions than current design methods throughout the full temperature range that steel structures are likely to be exposed to during a fire. Theofanous, M., Prospert, T., Knobloch, M. and Gardner, L. (2016). The continuous strength method for steel cross-section design at elevated temperatures. Thin-Walled Structures. 98, 94-102. 2Moreover due to its strain-based nature, the proposed methodology can readily account for the effect of restrained thermal expansion on the structural response at cross-sectional level.

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Section: Introductionmentioning

confidence: 99%

The continuous strength method for steel cross-section design at elevated temperatures

Theofanous

Propsert

Knobloch³

et al. 2016

Thin-Walled Structures

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“…Rubert and FIGURE 3. Comparison of computed and Schaumann [6] note that the utilisation ratio experimental utilisation ratio P, I P,,, .…”

Section: Resultsmentioning

confidence: 97%

“…Vandamme and Janss [4] and Janss and Mime [S] developed a similar procedure with ECCS (European Convention for Constructional Steelwork) expressions and compared the method with a large number of experimental results. Rubert and Schaumann [6] used finite element analysis results to develop a method for estimating column temperature at collapse. Olawale and Plank [7] and Burgess et al [S] present a finite strip method for analysing the behaviour of pin-ended columns at elevated temperatures.…”

Section: Introductionmentioning

confidence: 99%

Analysis Of Time Of Collapse Of Steel Columns Exposed To Fire

Chandrasekaran¹,

Mulcahy²

1997

Fire Safety Science - Proceedings of the 5th International Symp

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Unprotected steel columns exhibit a rapid deterioration in strength with increasing temperature. A method for the analysis of unprotected steel columns in fire conditions is presented. Beam finite elements are used to model the columns that are concentrically loaded with initial out-of-straightness and temperature-dependent elasto-plastic material properties. The accuracy of the model was determined by comparing it with available experimental results for column strength at elevated temperature and for time of collapse with time-varying temperatures. A study of the time to collapse of unprotected steel columns was undertaken for a range of load levels, slenderness ratios and column section sizes.

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“…The fire situation is classified as an accidental situation in EN 1990 [6]. The design effect of actions for the fire situation, , , , can be obtained using the combination of actions for accidental situation given by expressions (1) and (2).…”

Section: Load Combinations and Reduction Factor For The Case Of Firementioning

confidence: 99%

“…However, if no safety check is performed, EN 1993-1-2 suggests the use of 350 °C as the critical temperature for class 4 members irrespective of loading conditions and degree of utilization, which has been proven to have a considerable influence on the behaviour of members subjected to elevated temperatures [2].…”

Section: Introductionmentioning

confidence: 99%

10.09: Critical temperatures of members with class 4 cross‐section

et al. 2017

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This paper describes a numerical investigation on the critical temperatures of members with Class 4 cross-sections according to Eurocode 3 design. For such sections, the norm suggests the use of a default critical temperature of 350 °C irrespective of the load level conditions if no other calculation is made. On that regard, the authors have previously demonstrated that this temperature might be too conservative for certain conditions, especially if different degrees of utilization are taken into account. As a consequence, the authors recommended and validated new default critical temperatures for Class 4 cross-sections subjected to compression and bending about the major axis, for different reduction factors for the design load level under fire conditions.Building up on said studies regarding slender cross-sections, the present work aims at extending and establishing the groundwork for future studies on the critical temperature of members subjected to fire with the ultimate goal of achieving and validating a wide-reaching proposal of more appropriate default critical temperatures for steel members and cross-sections subjected to fire.From this study it was observed that the critical temperatures for laterally restrained members (in-plane) are in agreement with those proposed in previous research by the authors. The out-of-plane simulations, however, displayed similar patterns to those of their in-plane counterparts up until a certain slenderness threshold, after which a noticeable loss of resistance seems to occur, likely due to the higher influence of second-order effects in the out-of-plane direction.

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Critical temperatures of steel columns exposed to fire

Cited by 13 publications

References 2 publications

The continuous strength method for steel cross-section design at elevated temperatures

The continuous strength method for steel cross-section design at elevated temperatures

Analysis Of Time Of Collapse Of Steel Columns Exposed To Fire

10.09: Critical temperatures of members with class 4 cross‐section

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