Limit State of Steel Frames under Fire Conditions

1996 ◽  
pp. 281-286
Author(s):  
Li Guoqiang ◽  
Jiang Shouchao ◽  
B.S. Choo
Keyword(s):  
Limit State ◽  
Steel Frames ◽  
Fire Conditions

Comparison of steel frames with RWS and WFP beam-to-column connections through seismic fragility analysis

2020 ◽  
pp. 136943322097728
Author(s):  
Haoran Yu ◽  
Weibin Li
Keyword(s):  
Limit State ◽  
Pushover Analysis ◽  
Steel Frames ◽  
Fragility Analysis ◽  
Structural Safety ◽  
Seismic Fragility ◽  
Fe Modelling ◽  
Collapse Resistance ◽  
Seismic Collapse ◽  
Probabilistic Seismic Demand

Reduced web section (RWS) connections and welded flange plate (WFP) connections can both effectively improve the seismic performance of a structure by moving plastic hinges to a predetermined location away from the column face. In this paper, two kinds of steel frames—with RWS connections and WFP connections—as well as different frames with welded unreinforced flange connections were studied through seismic fragility analysis. The numerical simulation was conducted by using multiscale FE modelling. Based on the incremental dynamic analysis and pushover analysis methods, probabilistic seismic demand analysis and seismic capability analysis were carried out, respectively. Finally, combined with the above analysis results, probabilistic seismic fragility analysis was conducted on the frame models. The results showed that the RWS connection and WFP connection (without double plates) have little influence on reducing the maximum inter-storey drift ratio under earthquake action. RWS connections slightly reduce the seismic capability in non-collapse stages and improve the seismic collapse resistance of a structure, which exhibits good structural ductility. WFP connections can comprehensively improve the seismic capability of a structure, but the seismic collapse resistance is worse than that of RWS connections when the structure has a large number of storeys. The frame with WFP connections has a lower failure probability at every seismic limit state, while the frame with RWS connections sacrifices some of its structural safety in non-collapse stages to reduce the collapse probability.

Behaviour of steel frames under fire conditions

1999 ◽  
Vol 26 (2) ◽  
pp. 156-167 ◽  
Author(s):  
D I Nwosu ◽  
VKR Kodur
Keyword(s):  
Fire Resistance ◽  
Steel Frames ◽  
Load Ratio ◽  
Steel Structures ◽  
Point Of View ◽  
Frame Structures ◽  
Structural Behaviour ◽  
Analysis And Design ◽  
In Fire ◽  
Fire Conditions

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.

scholarly journals Some considerations on shear and torsion in R/C structural members in fire

2018 ◽  
Vol 9 (2) ◽  
pp. 94-107 ◽  
Author(s):  
Patrick Bamonte ◽  
Pietro G. Gambarova ◽  
Nataša Kalaba ◽  
Sergio Tattoni
Keyword(s):  
Limit State ◽  
Ultimate Limit State ◽  
Structural Members ◽  
Zone Method ◽  
Concrete Core ◽  
Content Type ◽  
Dowel Action ◽  
In Fire ◽  
Ultimate Limit ◽  
Fire Conditions

Purpose This study aims to provide a factual justification of the extension to fire conditions of the well-known design models for the calculations of R/C members at the ultimate limit state in shear and torsion. Both solid and thin-walled sections are considered. In the latter case, the little-known topic of shear-transfer mechanisms at high temperature is introduced and discussed. Design/methodology/approach Both the effective-section method and the zone method are treated, as well as the strut-and-tie models required by the analysis of the so-called D zones (discontinuity zones), where heat-enhanced cracking further bears out the phenomenological basis of the models. Findings The increasing role played by the stirrups in shear and by the rather cold concrete core in torsion stand out clearly in fire, while high temperatures rapidly reduce the contributions of such resisting mechanisms as concrete-teeth bending, aggregate interlock and dowel action. Originality/value On the whole, beside quantifying the side contributions of web mechanisms and section core in fire conditions, this study indicates a possible approach to extend to fire the available models on the coupling of shear and bending, and shear and torsion in R/C members.

Research of Fire Resistance of Elements of Steel Frames of Industrial Buildings

2021 ◽  
Vol 1038 ◽  
pp. 506-513
Author(s):  
Viktor Hvozd ◽  
Eugene Tishchenko ◽  
Andriy Berezovskyi ◽  
Stanislav Sidnei
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mathematical Models ◽  
Bearing Capacity ◽  
Fire Resistance ◽  
Limit State ◽  
Steel Frames ◽  
Steel Structures ◽  
Computational Experiments ◽  
Industrial Buildings

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.

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