Behaviour of steel frames under fire conditions

1999 ◽  
Vol 26 (2) ◽  
pp. 156-167 ◽  
Author(s):  
D I Nwosu ◽  
VKR Kodur

A state-of-the-art review of the behaviour of steel frame structures in fire is presented. Results from different studies indicate that the behaviour of a complete structure is different from that of a single structural member under fire conditions from the point of view of fire resistance. Earlier studies also show that analysis and design of steel structures against fire based on their overall behaviour could lead to a reduction or the elimination of applied fire protection to certain structural members. The effects of continuity, restraint conditions, and load ratio on the fire resistance of frame structures are discussed. The beneficial aspects derived from considering overall structural rather than single-member behaviour in fire are illustrated through the analysis on two one-bay, one-storey, unprotected steel portal frames, a column, and a beam. Also comparison is made between the performance of a beam with different end restraints in fire. Results from the analyses indicate that the fire resistance of a member is increased when it is considered as part of a structure compared with when it is considered as a single member.Key words: steel, frames, fire resistance, buckling, loads, overall structural behaviour.

Author(s):  
Davor Skejić ◽  
Ivan Ćurković ◽  
Marija Jelčić Rukavina

The interest in the application of aluminium as a structural material has been greatly increased in recent years. However, behaviour of aluminium structures when exposed to fire is still relatively unresearched. Due to low melting temperature of the alloy, aluminium structures have low fire resistance, but aluminium is reflective and has surface emissivity which is more than two times lower compared to carbon steel. The Eurocode facing this issue (EN 1999-1-2) is based mainly on the Eurocode for structural fire design of steel structures (EN 1993-1-2) and therefore is not fully suitable for the application on aluminium structures. Here, an overview of the structural behaviour of aluminium structures exposed to fire is given through the comparison with steel structures. As a conclusion, priorities for a future research are highlighted, which should provide a base for the next generation of modern codes for structural fire design of aluminium structures.


2012 ◽  
Vol 446-449 ◽  
pp. 793-796
Author(s):  
Hui Zhu ◽  
Yu Ching Wu

In this paper, co-rotational total Lagrangian finite element formulation is derived, and the corresponding numerical model is developed to study creeping behavior of plane steel frames in fire. Geometrical nonlinearity, material nonlinearity, high temperature creeping, and temperature rising rate are taken into account. To verify accuracy and efficiency of the numerical model, four prototypical numerical examples are analyzed using this model. Results are in a great agreement with solutions in literatures. Then the numerical model is used to analyze creeping behavior of the plane steel frames when temperature is lowering. The numerical results have significant contribution to resistance and protection for steel structures against disastrous fires.


2012 ◽  
Vol 594-597 ◽  
pp. 849-859
Author(s):  
Man Li Ou ◽  
Wei Jun Cao ◽  
Long Min Jiang ◽  
Hui Cao

As the result of great changes occurring to mechanical properties under high temperature (fire) conditions, steel structures will soon lose the strength and stiffness and lead to structural damage. Through analysis of the steel structure fire resistance design methods under the conditions of high temperature (fire), this article explores the most used fire protection methods in steel structures—brushing or painting fire-resistant coatings, studies the fire-resistance theory of steel structure under fire conditions; in addition, the author proposes the reasonable thickness of the steel structure fire retardant coating of fire-resistant design through design examples.


2005 ◽  
Vol 8 (3) ◽  
pp. 231-245 ◽  
Author(s):  
K. F. Chung

This paper presents a number of experimental and theoretical investigations into the structural behaviour of cold-formed steel structures with bolted connections. Firstly, the basic deformation characteristics of bolted fastenings between cold-formed steel strips in lap shear tests is described, and advanced finite element modelling with solid elements as well as contact elements is carried out for comparison. Secondly, the structural behaviour of lapped Z sections with bolted moment connections is reported, and both analytical and numerical predictions on strength and stiffness of lapped Z sections are presented. Finally, the structural performance of double span lapped Z purlins is investigated numerically where the effects of lapped Z sections over internal supports on the internal force distributions along the purlin members are examined. The description is intended to provide both analysis and design methods as well as understandings to structural engineers, enabling them to design and build cold-formed steel structures rationally with improved structural performance.


2021 ◽  
Vol 1038 ◽  
pp. 506-513
Author(s):  
Viktor Hvozd ◽  
Eugene Tishchenko ◽  
Andriy Berezovskyi ◽  
Stanislav Sidnei

The article considers and analyses the methods by which it is possible to carry out research to determine the fire resistance of elements of steel frames of industrial buildings. It is determined that it is expedient to use the means of computational fluid dynamics, which has no limitations due to the high cost, complexity, environmental friendliness and complexity in comparison with real experiments. In order to conduct the most reliable computational experiments, mathematical models of temperature and mechanical reaction to the thermal effect of fire were created, taking into account the equations of thermal conductivity, systems of differential equations of stress-strain state of solids in their numerical implementation based on the finite element method. The solution of mathematical models was carried out using computational fluid dynamics, which describes the process of heat and mass transfer in test fire furnaces during the determination of fire resistance of steel structures. According to the results of computational experiments it is shown that the limiting state of loss of bearing capacity of vertical and horizontal structures occurs due to the formation of a zone of plastic deformations taking into account the associative theory of plasticity. According to the results of computational experiments, the dependence of the limit of fire resistance on the level of applied load to structures, which is close to linear, was revealed. Based on the obtained dependences and the corresponding graphs, a technique is developed based on the use of maximum deformations of the elements with the corresponding fixation of the limit state on the loss of fire resistance in terms of bearing capacity by bending this curve.


2010 ◽  
Vol 10 (02) ◽  
pp. 253-271 ◽  
Author(s):  
MIN YU ◽  
XIAOXIONG ZHA ◽  
JIANQIAO YE ◽  
YI Li

This paper presents the results of dynamic responses and fire resistance of concrete-filled steel tubular (CFST) frame structures in fire conditions by using the nonlinear finite element method. Both strength and stability criteria are considered in the collapse analysis. The frame structures are constructed with circular CFST columns and steel beams of I-sections. In order to validate the finite element solutions, the numerical results are compared with those from a fire resistance test on CFST columns. The finite element model is then adopted to simulate the behavior of frame structures in fire. The structural responses of the frames, including the critical temperature and fire-resisting limit time, are obtained for the ISO-834 standard fire. Parametric studies are carried out to show their influence on the load capacity of the frame structures in fire. Suggestions and recommendations are presented for possible adoption in future construction and design of similar structures.


2011 ◽  
Vol 255-260 ◽  
pp. 519-523 ◽  
Author(s):  
Xin Meng Yu ◽  
Xiao Xiong Zha ◽  
Zhao Hui Huang

A great many of experiments has shown that reinforced concrete (RC) structures suffered from spalling in fire. However, at present there are still no convincing spalling predicting models available due to the inhomogeneous nature and complicated thermo-hydro-mechanical interactions in concrete at elevated temperatures. In order to evaluate the fire resistance of RC structures which are subjected to concrete spalling, a thermal analysis procedure is developed which considers the effects of spalling on the growth of temperature in RC members. The predicted temperatures are then used to model the structural behaviour. The spalled portion of concrete is modelled as "void", which has no thermal and mechanical properties. A series of parametric studies carried out on RC structural members with different boundary conditions shows that the influence of spalling on fire resistance is very significant apart from the RC slabs subject to higher laterally restraint.


2012 ◽  
Vol 446-449 ◽  
pp. 1298-1306
Author(s):  
Hyung Jun Kim ◽  
Heung Youl Kim ◽  
In Hwan Yeo

The temperature of the steel tube of a CFT column rises rapidly upon a fire causing the deterioration of its strength, while the concrete inside of the tube having large heat capacity provides fire-resistance performance. In order to employ CFT columns as fire-resistant structure, it is necessary to conduct studies on the factors exerting influence on structural capacities and the influence associated with each condition. Concrete’s compressive strength, cross-sectional size, axial load ratio and boundary condition are the major factors which are influential in fire-resistance performance. In particular, boundary condition between columns and beams is one of the major factors which decide fire-resistance performance because it exerts influence on load carrying capacity. The result of the test conducted in this study showed that fire-resistance time of 106 minutes was secured in the specimens with clamped ends and that of 89 minutes in those with pinned ends when cross-sectional size was 360 by 360. In the specimens with cross-sectional size of 280 x 280, fire-resistance time of 113 minutes was secured under the condition of clamped ends and that of 78 minutes was secured under the condition of pinned ends.


2017 ◽  
Vol 26 (3) ◽  
pp. 109-119
Author(s):  
Paweł Roszkowski ◽  
Bartłomiej Sędłak ◽  
Paweł Sulik

Abstract In the paper, fire resistance of linear joints seal made of elastomer spacers under standard fire conditions, and thermal degradation range of EPDM elastomeric spacers are investigated. The geometry of elastomer spacer joints is important not only for their load capacity under normal conditions - thickness, width, and cavity depth can also influence fire resistance performance. Linear joints of different thicknesses and widths have been tested. The fire insulation and fire integrity were verified for various arrangements. Relatively low thermal degradation rates have been measured, given that EPDM is a combustible material.


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