Experimental and numerical research on the critical temperature of laterally unrestrained steel I beams

Mesquita, L.M.R.; Piloto, P.A.G.; Vaz, Mário; Real, Paulo Vila

doi:10.1016/j.jcsr.2005.04.003

Cited by 43 publications

(18 citation statements)

References 7 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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“…g 0 is the utilization factor for room temperature design. Substituting Equation (5) into Equation (4) yields Equation (6) from which the critical temperature can be determined. Generally, a trial and error procedure is needed to determine the critical temperature.…”

Section: Derivation Of Modified Critical Temperature Modelmentioning

confidence: 99%

“…[6,16], including both laterally unrestrained and restrained steel beams. The details of the test beams are shown in Table 1.…”

Section: Model Validationsmentioning

confidence: 99%

“…Currently, the heat sink effect of composite or concrete slab has been incorporated into Eurocode 3 by considering an adaptation factor [1]. Some researchers have also studied the effects of restrained thermal elongation on the critical temperatures of steel members [4][5][6][7][8]. It was stated that neglecting the effect of thermal restraint may overestimate the critical temperatures thus lead to an overestimated fire resistance of steel members.…”

Section: Introductionmentioning

confidence: 99%

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Modified Critical Temperatures for Steel Design Based on Simple Calculation Models in Eurocode 3

2015

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Critical temperature is defined as the temperature at which failure is expected to occur in a structural steel member given a uniform temperature distribution and load level. Determination of the critical temperature is a simple but efficient way for structural fire design. This paper proposed a new model which incorporated the buckling, load levels and non-dimensional slenderness to calculate the critical temperature of steel member under fire based on the simple calculation models in Eurocode 3. To advance the application of this new model, design charts for determining the critical temperatures were developed. The design charts showed that the critical temperature decreases with increasing load level, and increases as the buckling curve varies from ''a 0 '' to ''d''. It is also recommended to use higher grade steel in both normal and fire situations. The accuracy of this model was ascertained by comparing with the test results in available literature. The new model gave an average prediction-to-test ratio of 0.980 with a standard deviation of 0.077, indicating conservative and less scattered predictions. The percentage of over-prediction (i.e., prediction-to-test ratio >1.0) was less than 5.8% when the nominal yield strength of steel rather than its test strength was used for predictions. In general, reasonable agreements were obtained between the test results and the predictions.

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“…Mesquita et al [1] studied the critical temperatures of lateral unrestrained steel beams under high temperatures. Huang and Tan [2] used the Rankine approach to analyse the high temperature resistance of steel columns, and the accuracy and feasibility of this approach were verified by experiments.…”

Section: Introductionmentioning

confidence: 99%

Modal Analysis of a Simply Supported Steel Beam with Cracks under Temperature Load

Yan¹,

Chen²,

Yang³

2017

Shock and Vibration

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Based on the transfer matrix method, an analytical method is proposed to conduct the modal analysis of the simply supported steel beam with multiple transverse open cracks under different temperatures. The open cracks are replaced with torsion springs without mass, and local flexibility caused by each crack can be derived; the temperature module is introduced by the mechanical properties variation of the structural material, and the temperature load is caused by the temperature variation, which can be transformed to the axial force on the cross-section. The transfer matrix of the whole beam with the temperature and geometric parameters of cracks can be obtained. According to boundary conditions of the simply supported beam, natural frequencies of the beam can be calculated, which are compared with the finite element results. Results indicate that the analytical method proposed has a high accuracy; the natural frequencies of the simply supported steel beam are mostly affected by the temperature load, which cannot be ignored.

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Experimental and numerical research on the critical temperature of laterally unrestrained steel I beams

Cited by 43 publications

References 7 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

Modified Critical Temperatures for Steel Design Based on Simple Calculation Models in Eurocode 3

Modal Analysis of a Simply Supported Steel Beam with Cracks under Temperature Load

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