Buckling Analysis of Steel Frames Exposed to Natural Fire Scenarios

<p>According to the Eurocode 3 Part 1-2 (EN1993-1-2) (CEN 2005b), it is possible for structural engineers to consider physical based thermal actions and to do performance based design instead of using prescriptive rules based on nominal fire curves. However, some uncertainties remain in the use of such approaches. This study focus on the clarification of the use of the simplified design methods to assess the fire resistance of unbraced steel frames exposed to fire. On the other hand, a recent study (Couto et al. 2013) suggests the use of a buckling coefficient of 1.0 for all the columns except those belonging to the first storey of a pinned framed where 2.0 should be taken instead and it is unclear if the consideration of such values for the buckling lengths is adequate when using performance based designs.</p>In this study, a comparison is made between simple and advanced calculation models and it is demonstrated that the simple design methods, using the suggested buckling coefficients to calculate the fire resistance of the frames are safe sided when compared to the use of advanced calculations using the finite element method (FEM).

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Buckling analysis of braced and unbraced steel frames exposed to fire

Engineering Structures ◽

10.1016/j.engstruct.2012.11.020 ◽

2013 ◽

Vol 49 ◽

pp. 541-559 ◽

Cited By ~ 11

Author(s):

Carlos Couto ◽

Paulo Vila Real ◽

Nuno Lopes ◽

João Paulo Rodrigues

Keyword(s):

Steel Frames ◽

Buckling Analysis

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Buckling analysis of structural steel frames with inelastic effects according to codes

Journal of Constructional Steel Research ◽

10.1016/j.jcsr.2009.04.018 ◽

2009 ◽

Vol 65 (10-11) ◽

pp. 2078-2085 ◽

Cited By ~ 5

Author(s):

Behrooz Farshi ◽

Farshad Kooshesh

Keyword(s):

Structural Steel ◽

Steel Frames ◽

Buckling Analysis

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Advanced analyses of the membrane action of composite slabs under natural fire scenarios

Journal of Structural Fire Engineering ◽

10.1108/jsfe-12-2016-0020 ◽

2018 ◽

Vol 9 (1) ◽

pp. 77-90 ◽

Cited By ~ 1

Author(s):

Lorenzo Lelli ◽

Jonas Loutan

Keyword(s):

Gas Temperature ◽

Reinforced Concrete Structure ◽

Membrane Action ◽

Content Type ◽

Natural Fire ◽

Small Thickness ◽

Composite Frame ◽

Composite Slabs ◽

Fire Scenarios ◽

Definition Of

Purpose This paper aims to detail the advanced natural fire simulations that were carried out for the composite steel-reinforced concrete structure of the JTI Building in Geneva, Switzerland. The results of these analyses led to a significant reduction of in the fireproofing of the steel floor framing. Design/methodology/approach Several scenarios were studied considering different thermal behaviours of the peripheral cladding. Despite the small thickness of the resisting slabs, the analyses performed with SAFIR software showed that the typical wide storey bay (12 × 15.86 m) can resist to the design’s fire temperatures without the protection of the main and secondary beams while the spandrels remain protected. For study completeness, the composite frame-membrane model was also simulated with Hasemi-localized fire routines on SAFIR. Findings The analyses have showed that the membrane behaviour of composite slabs under fire allows a significant reduction of the fire protection, even in case of small thickness of the concrete topping. The increase of the reinforcement ratio to sustain the membrane forces is widely compensated by the savings related to the fireproofing of the steel framing. Practical/implications A natural fire approach is particularly advisable in case of fully glazed buildings. In fact when the façade collapses, the entry of a large cold air quantity limits the increase of the gas temperature inside the compartment. Originality/value The analyses were carried out with recent SAFIR routines for localized fires (Hasemi fire model) and represent one of the first applications in practice. The issue of the rebar orientation in mesh is raised out. The latest SAFIR release allows the definition of a global orientation of the rebars and amends the issue.

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Buckling Analysis of Sway Steel Frames with Semi-Rigid Connections

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.250-253.3876 ◽

2011 ◽

Vol 250-253 ◽

pp. 3876-3879

Author(s):

Wan Zhen Wang ◽

Ji Xiang Xu ◽

Fei Yi Chen

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Steel Frames ◽

Buckling Analysis ◽

Nonlinear Finite Element ◽

Effective Length ◽

Finite Element Models ◽

Rotational Stiffness ◽

Element Analysis ◽

Effective Length Factor

The modified factor formulas, which are applicable to sway steel frames, are derived by considering joint relative rotational stiffness and adopting the modified stiffness factor. The finite element models of steel frames with semi-rigid and rigid connections are established using ANSYS program. Nonlinear finite element analysis of steel frames with two web and top-seat angles steel semi-rigid connections is conducted. Through bulking analysis of sway steel frames with semi-rigid connections, the effective length factor of sway steel frames is derived, which considers nonlinear rotation of two web and top-seat angles steel semi-rigid connections.

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The Influence of Fire Scenarios on the Structural Behaviour of Composite Steel-Concrete Buildings

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.82.368 ◽

2011 ◽

Vol 82 ◽

pp. 368-373 ◽

Cited By ~ 4

Author(s):

Emidio Nigro ◽

Anna Ferraro ◽

Giuseppe Cefarelli

Keyword(s):

Fire Safety ◽

Risk Mitigation ◽

Correct Identification ◽

Structural Behaviour ◽

Natural Fire ◽

Structural Fire ◽

Concrete Buildings ◽

Design Fire ◽

Fire Scenarios ◽

Composite Steel

Fire Safety Engineering can be defined as a multi-discipline based on the application of scientific and engineering principles to the effects of fire in order to reduce the loss of life and damage to property by quantifying the risks and hazards involved and provide an optimal solution to risk mitigation. The correct identification of fire scenarios is the central stage in the process of the structural fire design. A design fire scenario is the description of the spread of a particular fire with respect to time and space. In the process of identification of design fire scenarios for the structural fire safety check, all fires must be assessed realistically, choosing those most severe for the structural response. This paper is devoted to evaluate the influence of fire scenarios on the structural behaviour of composite steel-concrete buildings. In order to that, an office building subjected to different fire scenarios was considered. In particular the fire scenarios were defined by both standard fire (prescriptive approach) and natural fire (performance approach). Finally, a comparison between the prescriptive approach and the FSE approach is presented.

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Structural behaviour of concrete filled hollow steel sections exposed to parametric fire

Challenge Journal of Structural Mechanics ◽

10.20528/cjsmec.2017.02.004 ◽

2017 ◽

Vol 3 (4) ◽

pp. 160

Author(s):

Mohammed Salah Dimia ◽

Soumia Sekkiou ◽

Mohamed Baghdadi ◽

Mohamed Guenfoud

Keyword(s):

Steel Tube ◽

Concrete Cover ◽

Critical Conditions ◽

Structural Behaviour ◽

Natural Fire ◽

Composite Columns ◽

Section Size ◽

Fire Scenarios ◽

Steel Sections ◽

Cooling Phase

This article analyzes steel-concrete composite columns subjected to natural fire scenarios in order to verify that the possibility of structural collapse during or after the cooling phase is real. The main objectives of this study are: first, to highlight the phenomenon of delayed collapse of this type of columns during or after the cooling phase of a fire, and then analyze the influence of some determinant parameters, such as section size, tube thickness, reinforcement (ratio), concrete cover and column length. The results show that critical conditions with respect to delayed failure arise for massive sections, small values of the steel tube thickness and for columns with massive section.

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