Post-fire flexural behaviour and performance of unrestrained cold-formed steel built-up section beams: Experimental and numerical investigation

Kumar, Gowtham; Kiran, Tattukolla; Anand, N.; Anbarasu, M.; Lublóy, Éva

doi:10.1016/j.cscm.2023.e01978

Cited by 3 publications

(7 citation statements)

References 27 publications

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“…Notably, the ITF specimen exhibited approximately a 10-15% higher carrying capacity compared to the ETF condition. Similar trends were observed in the previous studies [1,2,23]. At elevated temperatures, the CFS WH and WCH specimens displayed a reduction in web-load-carrying capacities, measuring 13.82 kN, 8.14 kN, 6.58 kN, 4.86 kN and 8.5 kN, 5.8 kN, 3.27 kN, 1.56 kN, for 30, 60, 90, and 120 min, respectively.…”

Section: Load-deflection Behaviour At Itf Conditionsupporting

confidence: 89%

“…quently, the steel beams experience a loss of rigidity, degradation of stiffness, and strength properties [2].…”

Section: Load-deflection Behaviour At Etf Conditionmentioning

confidence: 99%

“…When the web perforation ratio increases, the web-crippling capacity of section decreases and fails quickly under higher durations of heating. Consequently, the steel beams experience a loss of rigidity, degradation of stiffness, and strength properties [2].…”

Section: Load-deflection Behaviour At Etf Conditionmentioning

confidence: 99%

“…This is primarily due to the several advantages offered by highperformance CFS, including the use of light-gauge sections, innovative profiles of preferable size, high strength-to-weight ratio, requirement of less manpower, and ease of transportation and assembly [1]. Moreover, in various countries, the design standards and guidelines for CFS elements have been well established, thereby increasing the demand for CFS members in construction practices and for other applications [2].…”

Section: Introductionmentioning

confidence: 99%

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Web-Crippling Capacity of High Performance Cold-Formed Lipped Steel Sections Subjected to Elevated Temperature

Jayakumar,

Kiran,

Nammalvar

et al. 2023

Buildings

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High-performance steel has emerged as an advanced structural material in the construction practice of industrial buildings, due to its excellent properties. However, fire poses a significant threat to cold-formed steel structures, as they are prone to deform and buckle under the exposure, potentially leading to building collapse. This study aimed to evaluate the post-fire web-crippling behaviour of high performance CFS sections for End Two Flange (ETF) and Interior Two Flange (ITF) load cases. Two types of specimens were used: CFS webs without holes and CFS webs with circular holes. All test specimens were heated according to the ISO 834 standard fire curve and were subsequently cooled by air or water. A total of 52 specimens (ambient and post-fire) were tested under ETF and ITF load conditions. The load-deflection behaviour and failure modes were evaluated through experimental and numerical analysis. Finite element modelling was used to compare the load-deflection behaviour and failure modes of CFS members with experimental results. The experimental results indicate that the web load-carrying capacity of the high-performance steel member decreases drastically as the heating duration increases. Furthermore, the ITF load case specimens exhibited a lower strength loss than the ETF load case specimens at elevated temperatures. There was an excellent agreement between the experimental and FEM results in terms of the load-carrying capacity and failure modes of high performance CFS.

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Section: Load-deflection Behaviour At Itf Conditionsupporting

confidence: 89%

“…quently, the steel beams experience a loss of rigidity, degradation of stiffness, and strength properties [2].…”

Section: Load-deflection Behaviour At Etf Conditionmentioning

confidence: 99%

Section: Load-deflection Behaviour At Etf Conditionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Web-Crippling Capacity of High Performance Cold-Formed Lipped Steel Sections Subjected to Elevated Temperature

Jayakumar,

Kiran,

Nammalvar

et al. 2023

Buildings

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“…Furthermore, unrestrained CFS built-up beams exhibit a significant drop in their loadbearing capability with increasing temperature exposure and heating times, as revealed by testing findings. Under chilling conditions, specimens chilled by air demonstrate a residual strength capacity approximately 10-15% greater than specimens cooled by water [75]. Subsequently, as the temperature escalates from 20 to 700 • C, the average axial capacity of the cold-formed steel (CFS) face-to-face (FTF) built-up unlipped channel members drop by 88.9%, while the lipped channel sections experience a drop of 90.2% [76].…”

Section: Thermal Performance Assessment Of Cold-formed Steel Structuresmentioning

confidence: 99%

Investigating the Factors Influencing the Strength of Cold-Formed Steel (CFS) Sections

Hussein,

Hussein

2024

Buildings

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The utilization of cold-formed steel (CFS) sections in construction has become widespread due to their favorable attributes, including their lightweight properties, high strength, recyclability, and ease of assembly. To ensure their continued safe and efficient utilization, this review provides a comprehensive investigation into the factors influencing the strength of CFS members. This analysis encompasses design codes, prediction methodologies, material properties, and various structural configurations. This review uncovers discrepancies among existing design codes, particularly noting conservative predictions in AISI and AS/NZS standards for composite and built-up sections. Additionally, the effectiveness of prediction methods such as the direct strength method and effective width method varies based on specific structural configurations and loading conditions. Furthermore, this review delves into recent advancements aimed at enhancing fire resistance, connection design, and the composite behavior of CFS structures. The influence of factors such as eccentricity, sheathing materials, and bolt spacing on structural performance is also examined. This study underscores the crucial role of accurate prediction methods and robust design standards in ensuring the structural integrity and safety of CFS constructions. Through a comparative analysis, it is revealed that AISI and AS/NZS standards exhibit conservatism in predicting nominal buckling loads compared to experimental data. Conversely, a non-linear finite element analysis demonstrates a strong correlation with laboratory tests, offering a more accurate prediction of nominal buckling capacity. Overall, this review offers comprehensive insights aimed at optimizing CFS structural design practices. By identifying key areas for future research and development, this work contributes to the ongoing advancement of safe and efficient CFS construction applications.

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Influence of elevated temperature on buckling capacity of mild steel-based cold-formed steel column sections– experimental investigation and finite element modelling

Sabu Sam,

Adarsh,

Lyngdoh

et al. 2023

JSFE

Self Cite

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PurposeThe capability of steel columns to support their design loads is highly affected by the time of exposure and temperature magnitude, which causes deterioration of mechanical properties of steel under fire conditions. It is known that structural steel loses strength and stiffness as temperature increases, particularly above 400 °C. The duration of time in which steel is exposed to high temperatures also has an impact on how much strength it loses. The time-dependent response of steel is critical when estimating load carrying capacity of steel columns exposed to fire. Thus, investigating the structural response of cold-formed steel (CFS) columns is gaining more interest due to the nature of such structural elements.Design/methodology/approachIn this study, experiments were conducted on two CFS configurations: back-to-back (B-B) channel and toe-to-toe (T-T) channel sections. All CFS column specimens were exposed to different temperatures following the standard fire curve and cooled by air or water. A total of 14 tests were conducted to evaluate the capacity of the CFS sections. The axial resistance and yield deformation were noted for both section types at elevated temperatures. The CFS column sections were modelled to simulate the section's behaviour under various temperature exposures using the general-purpose finite element (FE) program ABAQUS. The results from FE modelling agreed well with the experimental results. Ultimate load of experiment and finite element model (FEM) are compared with each other. The difference in percentage and ratio between both are presented.FindingsThe results showed that B-B configuration showed better performance for all the investigated parameters than T-T sections. A noticeable loss in the ultimate strength of 34.5 and 65.6% was observed at 90 min (986℃) for B-B specimens cooled using air and water, respectively. However, the reduction was 29.9 and 46% in the T-T configuration, respectively.Originality/valueThis research paper focusses on assessing the buckling strength of heated CFS sections to analyse the mode of failure of CFS sections with B-B and T-T design configurations under the effect of elevated temperature.

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Post-fire flexural behaviour and performance of unrestrained cold-formed steel built-up section beams: Experimental and numerical investigation

Cited by 3 publications

References 27 publications

Web-Crippling Capacity of High Performance Cold-Formed Lipped Steel Sections Subjected to Elevated Temperature

Web-Crippling Capacity of High Performance Cold-Formed Lipped Steel Sections Subjected to Elevated Temperature

Investigating the Factors Influencing the Strength of Cold-Formed Steel (CFS) Sections

Influence of elevated temperature on buckling capacity of mild steel-based cold-formed steel column sections– experimental investigation and finite element modelling

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