Parametric Study on the Fire Resistance of Steel Columns with Cold-Formed Lipped Channel Sections (original) (raw)
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Fire design proposal for cold-formed steel lipped channel beam-columns
Routledge eBooks, 2021
Steel structural elements composed of cold-formed thin-walled sections are commonly applied in buildings due to their efficiency in terms of stiffness and strength. How ever, under fire conditions the thin walls of these profiles, along with the steel high thermal conductivity, induce fast increase on the steel temperature and corresponded significant loss of those referred stiffness and strength. This paper presents a numerical study on the members behaviour with cold-formed lipped channel sections at high temperatures, when subjected to bending plus compression. Comparisons between the finite element results and the analytical methodologies from EN1993-1-2 are presented, using its Annex E as well as its French National Annex, where different reduction factors for the steel constitutive law and different design formulae are recommended for cold-formed profiles. Both methodologies revealed to be safe but sometimes too conservative, which motivated the development of a new design proposal.
Numerical study on structural behaviour of cold-formed steel columns under fire conditions
Research and Applications in Structural Engineering, Mechanics and Computation, 2013
This paper presents the results of numerical studies on the behaviour of cold-formed galvanized steel columns under fire conditions, based on results of experimental tests, previously conducted by the authors. This numerical study was performed by the finite element program ANSYS. First, it is presented the details of the finite element models used in this research and compared the finite element analysis results with those obtained in the experimental tests. Moreover, it is carried out a parametric study in order to investigate the influence of the axial restraining to the thermal elongation of the column, the axial preload ratio on the columns mechanical behaviour.
Cold-formed steel members differ greatly from hot-rolled steel members in shape, as well as strength and deformation properties. The cold work process alters the properties of the steel, resulting in a higher post-forming strength of the cross section by about 20-50% depending on the type of forming and thickness of the section. Among a variety of steel sections available, hollow sections are preferred to be used as columns in residential, commercial and industrial buildings due to their architecturally pleasing shape which are also structurally efficient and economical.
Compressive Performance of Cold-Formed Thin-Walled Steel Channnel Sections in Fire
Volume 1 Number 1, 2005
This paper presents the main results of an extensive study of the compressive performance of cold-formed thin-walled steel sections under conditions of fire, recently conducted by the authors. Experimental, numerical and design calculation studies were performed. The experiments include: • Fire tests on small panels, measuring 300 x 300 mm, consisting of a solid or perforated cold-formed thin-walled steel channel section, one or two layers of 12.5 mm thick gypsum plasterboard on both sides and either with or without interior insulation, exposed to the standard BS 476 fire condition on one side; • Compression tests on short (400 mm) channel sections at various uniform elevated temperatures up to 700 o C; • Fire tests on six full-scale panels of 2.2 x 2.0 m, each consisting of three cold-formed thin-walled steel channel sections, one layer of 12.5 mm gypsum plasterboard on both sides and with interior insulation, exposed to the standard BS 476 fire condition on one side; • Fire test on one full-scale panel with the same arrangement as above, but using channel sections with perforations along the length of the web of the steel section. Numerical studies, using ABAQUS, were carried out to investigate the following aspects: • Validation of heat transfer analysis against the small panel fire test results; • Structural behaviour of the short test columns under uniform temperature; • Effect of non-uniform temperature distributions in the steel cross-section of a column on its structural behaviour; • Effect of gypsum plasterboard falling on column structural behaviour. The different current design methods were assessed by comparing the design calculation results against finite element simulation and experiment results. It has been concluded that the behaviour of this type of construction is complex, affected by a number of factors of some of which our current understanding is poor, for example, how to predict gypsum plasterboard falling at high temperatures. ABAQUS is a useful tool for studying detailed thermal and structural behaviour of cold-formed thin-walled steel structures in fire. This paper shows that provided steel temperatures are available, ENV 1993-1-2 provides a reasonable and conservative prediction of ultimate strength and failure time of the samples tested in this study.
Fire resistance of steel columns with restrained thermal elongation
Fire Safety Journal, 2012
The behavior of steel columns subjected to fire depends on their interaction with the surrounding building structure. To improve knowledge of the phenomenon a great many fire resistance tests have been carried out on steel columns with restrained thermal elongation. A new experimental system was designed and constructed to carry out the tests.
Experimental investigation on box-up cold-formed steel columns in fire
International Journal of Geomate, 2018
Cold-formed steel is a popular material with various advantages. Its easy production and assembly give engineer an option to speed the construction process. However, thinness relates to the major issue of buckling, especially when dealing with high temperature. The unprotected cold-formed steel behaviour under fire is expected to have a little strength as compared to hot-rolled steel. Information on such behaviour is still limited. Fire resistance testing on built-up box CFS column was presented in this paper. Two fire resistance tests were carried out under compression load. The Standard ISO 834 Fire Resistance Test under 50% and 70% degree of utilisation measured the temperatures at several points of the steel column surface by using a surface thermocouple and axial column deformation. For reference purpose, one same static test at ambient temperature was carried out to assess the load bearing capacity. Results found that the failure temperature of built-up CFS could reach up to 5...
Numerical Analysis of Steel Columns Considering the Walls on Fire Condition
Steel columns are structural elements widely used in multi-storey buildings, industrial, commercial warehouse, among others. However, the reduction of stiffness and strength of steel in response to a temperature raise imposes the need to predict the critical time of exposure of the structure in fire, looking for safety and economic design structures. The presence of walls introduces change in gradient temperature at the steel cross section. In those circumstances, this paper aims to present a numerical study of steel columns with open section of type I, whereas the compartment of the environment in fire. The buckling of the compressed element will be marked by a reduction factor obtained using the relationship between the buckling load in a fire situation, characterized by asymptotic displacement, and buckling load identified at room temperature.
Temperature Rise of Cold-Formed Steel Built-Up Back-To-Back Column Under Standard Fire
Jurnal Teknologi, 2016
Cold-formed steel (CFS) structure is one of the most popular construction materials due to its various advantages. Its most popular use is as a structural framing for residential and light loading buildings. Constructions of lightweight building components such as the CFS have been used to build or renovate existing single-and two-families' private homes [1]. The applications of built-up shapes such as in a composing member truss have attracted many designers of light-steel framing to widen the applications of CFS to larger scale structures. In addition, the CFS built-up has several advantages in its production, handling, and mechanical strength. Therefore, it is suitable to be used for fast constructions of low rise ups to double storey buildings as well as emergency houses. However, the fire resistance of this material is a critical issue as it is susceptible to have a low level of stiffness when exposed to fire compared to other materials like hotrolled steel member. Many researchers had conducted the studies of CFS under high temperature. Most of these researches were mainly focused on the elevated temperature test and the finite element simulation of CFS at elevated temperatures [2, 3, 4, 5, 6, 7, 8]. However, there is still a limited amount of research data on individual tests of CFS exposed directly to the fire. A research conducted by Kankanamge [9] found that in the case of fire, the CFS beam always experienced the local buckling failure mode similar
Metals
An investigation into fire resistance subjected to the ISO fire standard was conducted on a cold-formed steel (CFS) column. The variables involved were the CFS sections with various cross-section types and service loadings known as the degree of utilization. Three types of cross-section, known as channel, back-to-back (BTB), and box-up (BU) sections, were studied. All supports for the column are in constant condition. To simulate the real fire situation, the column was preloaded at 30%, 50%, and 70% of its ultimate strength. After the load was static, the column was exposed to the ISO fire standard. The column was loaded at the centroid of the section. The temperature at the column surface and the time was recorded until the column became unstable. The results show that the shape did not have any significant effects on the critical temperature of the CFS columns. The higher the applied load—or as used in this study, the higher the degree of utilization of the CFS columns—the greater...