Semi-analytical buckling analysis of reinforced concrete columns exposed to fire

Bajc, Urška; Saje, Miran; Planinc, Igor; Bratina, Sebastjan

doi:10.1016/j.firesaf.2014.11.018

Cited by 12 publications

(7 citation statements)

References 29 publications

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“…Furthermore, the steel reinforcement ratio marginally increased critical buckling temperature. This result was also obtained by Bajc et al (2015) who proposed a semianalytical model for the inelastic buckling analysis of concrete columns subjected to fire loading. Exposure time and slenderness were deduced as the critical factors behind fire resistance time.…”

Section: Jsfe 111supporting

confidence: 67%

“…The critical axial force for a pinned or fixed-ended shallow arch in uniform compression is the same for an equivalent length column, which can be derived by stability analyses typically consisting of generalisations of those applied to straight members. As with arches, elevated temperature fields may cause instability in columns (Huang et al, 2007;Sadaoui and Khennane, 2009;Han et al, 2014;Bajc et al, 2015). Although commonly governed by material strength, reinforced concrete columns are not exempt from the problem of instability when subjected to combined mechanical and thermal loading due to severe reductions in stiffness caused by high temperatures.…”

Section: Jsfe 111mentioning

confidence: 99%

“…Few studies explicitly analyse the effect of fire loading on the stability of loaded concrete columns when considering TTS. Examples include the work by Franssen and Dotreppe (2003), Bratina et al (2005), Huang et al (2007) and Bajc et al (2015). Huang et al (2007) conducted an inelastic buckling analysis of reinforced concrete columns subjected to fire loading using Shanley's inelastic buckling theory and finite element (FE) analysis.…”

Section: Jsfe 111mentioning

confidence: 99%

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In-plane stability of shallow concrete arches under fire

Bouras

Vrcelj

2020

JSFE

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Purpose Concrete arch structures are commonly constructed for various civil engineering applications. Despite their frequent use, there is a lack of research on the response and performance of concrete arches when subjected to fire loading. Hence, this paper aims to investigate the response and in-plane failure modes of shallow circular concrete arches subjected to mechanical and fire loading. Design/methodology/approach This study is conducted through the development of a three-dimensional finite element (FE) model in ANSYS. The FE model is verified by comparison to a non-discretisation numerical model derived herein and the reduced modulus buckling theory, both used for the non-linear inelastic analysis of shallow concrete arches subjected to uniformly distributed radial loading and uniform temperature field. Both anti-symmetric and symmetric buckling modes are examined, with analysis of the former requiring geometric imperfection obtained by an eigenvalue buckling analysis. Findings The FE results show that anti-symmetric bifurcation buckling is the dominant failure mode in shallow concrete arches under mechanical and fire loading. Additionally, parametric studies are presented which illustrate the influence of various parameters on fire resistance time. Originality/value Fire response of concrete arches has not been reported in the open literature. The authors have previously investigated the stability of shallow concrete arches subjected to mechanical and uniform thermal loading. It was found that temperature greatly reduced the buckling loads of concrete arches. However, this study was limited to the simplifying assumptions made which include elastic material behaviour and uniform temperature loading. The present study provides a realistic insight into the fire response and stability of shallow concrete arches. The findings herein may be adopted in the fire design of shallow concrete arches.

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Section: Jsfe 111supporting

confidence: 67%

Section: Jsfe 111mentioning

confidence: 99%

Section: Jsfe 111mentioning

confidence: 99%

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In-plane stability of shallow concrete arches under fire

Bouras

Vrcelj

2020

JSFE

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“…The time of fire analysis is divided into small time intervals [t i-1 , t i ] and the stress-strain state at each time t i is then determined iteratively. For in-deep description of mechanical analysis, see the work of Bajc et al (2014).…”

Section: Mechanical Analysismentioning

confidence: 99%

BUCKLING LOAD OF RC COLUMNS EXPOSED TO ISO FIRE LOAD, The influence of the cross-sectional dimensions

Bajc¹,

Saje²,

Hozjan³

et al. 2016

ASFE

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The influence of the cross-sectional dimensions on the buckling load capacity of reinforced concrete column exposed to ISO fire load is presented. The fire analysis is divided in two separate phases. In the first phase, the calculation of the temperatures over the cross-section of the concrete column is performed. Here more advanced hygro-thermal analysis is executed to take into account the influence of moisture on the distribution of the temperatures. In the second step of the fire analysis, the mechanical analysis is performed. The mechanical and thermal properties of concrete and reinforcement at elevated temperatures are used in accordance with EN 1992-1-2 (2004). For two different cross-sections, the parametric study has been performed. The critical buckling time and critical buckling capacity as a function of a load and slenderness of reinforced concrete column have been determined.

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“…Almost all of previous analytical studies have been carried out on isolated RC columns with both ends pinned (Lie and Irwin, 1993; Kodur et al , 2004; Bajc et al , 2015) or fixed (Raut and Kodur, 2011) when subjected to elevated temperatures. These studies, in general, focused on tracing the axial column deformation, whereas the lateral deflection was disregarded or ill-defined.…”

Section: Introductionmentioning

confidence: 99%

Lateral deformation behavior of eccentrically loaded slender RC columns with different levels of rotational end restraint at elevated temperatures

Mahmoud

2020

JSFE

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Purpose In literature, previous studies have focused on analyzing rienforced concrete (RC) columns with idealized end conditions when subjected to fire. In nature, full fixity or free rotation at column ends is not attained. Such ends may be considered partially restrained in rotation. This paper aims to shed a new light on the effect of different degrees of rotational restraint on the lateral deformation behavior of slender heated RC columns subjected to non-linear strain distributions produced by a time-dependent temperature history. Design/methodology/approach To find the strain distribution on the cross section, an iterative technique is adopted using Newton–Raphson method. By introducing a reliable calculation procedure, the lateral deformational behavior is expressed using numerical and searching techniques. A methodology is presented to calculate the effective length factor for RC columns at elevated temperature. Findings The results of the proposed model showed good agreement with available experimental test results. It was also found that the variation of rotational end restraint level has a considerable effect on the lateral deformation behavior of heated slender RC columns. In addition, the effectiveness and the validity of an analytical model should be verified by simultaneously validating the axial and lateral deformations. Moreover, the effective length factor for heated column is higher than that for the corresponding column at ambient temperature. Originality/value This paper shows the impact of different boundary conditions on the behavior of heated slender RC columns. It suggests powerful techniques to determine the lateral deflection and the effective length factor at high temperatures.

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Semi-analytical buckling analysis of reinforced concrete columns exposed to fire

Cited by 12 publications

References 29 publications

In-plane stability of shallow concrete arches under fire

In-plane stability of shallow concrete arches under fire

BUCKLING LOAD OF RC COLUMNS EXPOSED TO ISO FIRE LOAD, The influence of the cross-sectional dimensions

Lateral deformation behavior of eccentrically loaded slender RC columns with different levels of rotational end restraint at elevated temperatures

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