scholarly journals Graphical tool for assessing the critical temperatures of steel beams and columns in fire

Fire Research ◽  
2018 ◽  
Author(s):  
Valdir Pignatta Silva ◽  
Arthur Ribeiro Melão ◽  
Igor Pierin
Keyword(s):  
Critical Temperature ◽  
Design Method ◽  
Limit State ◽  
Local Buckling ◽  
Steel Beams ◽  
Ultimate Limit State ◽  
Structural Element ◽  
Critical Temperatures ◽  
Graphical Tool ◽  
In Fire

In a fire situation, the temperature in which the ultimate limit state of the structural element is reached is called critical temperature. It is very laborious to determine it. The aim of this work was to create a graphical tool to allow quick determination of the critical temperature of I shaped columns and beams without local buckling. The method used was based on the Brazilian standard and using AcoInc software developed by the authors. The result was a tool whose similarity was not found in the literature. The use of the tool developed in this study simplifies the use of the standardized design method. One conclusion to be highlighted is one in which constants values of the critical temperature, generally accepted in practice, may be unsafe.

Considering Catenary Action in Designing End-Restrained Steel Beams in Fire

2005 ◽  
Vol 8 (3) ◽  
pp. 309-324 ◽  
Author(s):  
H. X. Yu ◽  
J. Y. Richard Liew
Keyword(s):  
Design Method ◽  
Load Capacity ◽  
Limit State ◽  
Beam Deflection ◽  
Steel Beams ◽  
Ultimate Limit State ◽  
Ultimate Load Capacity ◽  
Element Analysis ◽  
Catenary Action ◽  
In Fire

When a building compartment is subjected to fire attack, there are complex interactions between the fire affected members with the surrounding members. The behaviour of the steel frame members in fire can be drastically different from that of its member in isolation. This paper studies the behaviour of steel beams with the increase of temperature from beam action phase to catenary action phase and until failure. The load bearing mechanism in the catenary action phase is discussed and the failure criterion is defined. A new ultimate limit state based on 15% maximum strain of steel material at elevated temperature is proposed to determine the ultimate load capacity of beams failed in the catenary action phase. Wide ranges of beam parameters including various beam sizes and span lengths with different degrees of end restraints are studied. Comparison of results with those obtained from nonlinear finite element analysis shows that the proposed design method could enhance the critical temperature of steel beams by over 200 °C if proper attention is given to the integrity of connections to resist the catenary force. In this respect, methods to estimate the catenary force and beam deflection are provided.

Combined flexure and torsion of I-shaped steel beams

1989 ◽  
Vol 16 (2) ◽  
pp. 124-139 ◽  
Author(s):  
Robert G. Driver ◽  
D. J. Laurie Kennedy
Keyword(s):  
Limit State ◽  
Bending Moment ◽  
Phase Behaviour ◽  
Inelastic Interaction ◽  
Steel Beams ◽  
Ultimate Limit State ◽  
Second Phase ◽  
Design Standards ◽  
Limit States ◽  
Interaction Diagram

Design standards provide little information for the design of I-shaped steel beams not loaded through the shear centre and therefore subjected to combined flexure and torsion. In particular, methods for determining the ultimate capacity, as is required in limit states design standards, are not presented. The literature on elastic analysis is extensive, but only limited experimental and analytical work has been conducted in the inelastic region. No comprehensive design procedures, applicable to limit states design standards, have been developed.From four tests conducted on cantilever beams, with varying moment–torque ratios, it is established that the torsional behaviour has two distinct phases, with the second dominated by second-order geometric effects. This second phase is nonutilizable because the added torsional restraint developed is path dependent and, if deflections had been restricted, would not have been significant. Based on the first-phase behaviour, a normal and shearing stress distribution on the cross section is proposed. From this, a moment–torque ultimate strength interaction diagram is developed, applicable to a number of different end and loading conditions. This ultimate limit state interaction diagram and serviceability limit states, based on first yield and on distortion limitations, provide a comprehensive design approach for these members. Key words: beams, bending moment, flexure, inelastic, interaction diagram, I-shaped, limit states, serviceability, steel, torsion, torque, ultimate.

scholarly journals Platform for dynamic tests: preliminary studies, design and construction

2013 ◽  
Vol 6 (1) ◽  
pp. 55-74 ◽  
Author(s):  
J. E. Campuzano ◽  
R. de Castro ◽  
S. Ávila ◽  
G. Doz
Keyword(s):  
Natural Frequencies ◽  
Limit State ◽  
Physical Space ◽  
Dynamic Responses ◽  
Steel Beams ◽  
Ultimate Limit State ◽  
Dynamic Tests ◽  
Short Columns ◽  
Brazilian Standard ◽  
Design And Construction

This paper is about the design and construction of a platform for dynamic tests especially with people jumping, walking, etc. Initially it was tried to find out projects already implemented in platforms and dynamic tests and to study the loads produced by movement of people on slabs and the structural response to these loads. The limits established by different standards have been also studied for these dynamic responses, taking into account the ultimate limit state, as well as the structure in service, since the human body is very sensitive to structural vibrations. Parametric studies were performed considering various configurations of slabs (different spans, thicknesses and conditions of support) have been done, looking for a configuration that could have natural frequency close to the frequencies of the human loads. The slab should have dimensions compatible with the available physical space, fundamental frequency below 5 Hz and maximum immediate deflection compatible with the indications of the Brazilian standard NBR6118: 2007. Based on these criteria was chosen a rectangular structure consists of a solid reinforced concrete rectangular slab studded in two opposite edges of steel beams with shear connectors type U. The other two edges are free. The steel beams supporting the slab, in turn, are supported on eight metal profiles (two in each corner of the slab) that are supported on two to two short columns of steel profile H. Profiles U in steel are welded to four columns, forming a horizontal frame. Numerical analysis of the dynamic test platform have been performed for free and forced vibration, for obtaining the natural frequencies and corresponding vibration modes, considering the self-weight of the structure and the load that simulates people's weight. After obtaining a structural configuration that fulfilled the stipulated requirements, the design of the slab taking into account the recommendations of the Brazilian standard NBR6118: 2007. The platform was built and has been done a preliminary experimental study to obtain the first natural frequencies.

scholarly journals A RATIONALIZED SEISMIC DESIGN METHOD FOR BUILDINGS IN EARTHQUAKE-PRONE DEVELOPING COUNTRIES

2021 ◽  
Vol 11 (4) ◽  
pp. 266-279
Author(s):  
Tint Lwin ◽  
Takeshi Koike ◽  
Ji Dang
Keyword(s):  
Developing Countries ◽  
Seismic Design ◽  
Design Method ◽  
Limit State ◽  
Design Procedure ◽  
Ultimate Limit State ◽  
Design Guideline ◽  
Seismic Safety ◽  
Seismic Design Method ◽  
Ultimate Limit

In general, the US codes such as the UBC-97 and ASCE-7 are widely used in developing countries including Myanmar, Syria, Philippines and so on. When the current seismic design guideline based on the UBC-97 and ACI 318-99 in Myanmar is assessed, several problems can be found in the following items: firstly, the fundamental period is not checked in modeling; secondly, reduction factor R is introduced a priori for the base shear estimation. And finally, a limit state assessment is done only for Design Basic Earthquake (DBE) but not for other design earthquakes. As a result, adequate yield strength is not checked for Maximum Operational Earthquake (MOE). Then there is no way to assess the seismic safety of the ultimate limit state for Maximum Considered Earthquake (MCE). In order to solve these problems, a rationalized seismic design method for earthquake prone developing countries is proposed. A new seismic design method is developed for MOE and MCE with adequate yield acceleration and typical period of the building estimated by using pushover analysis. A simplified procedure to estimate the inelastic response for a given design spectrum is also proposed. Finally, this design procedure can provide a rational method to assess the seismic safety for the ultimate limit of the building.

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.

DESIGN OF BOLTED CONNECTIONS SUBJECT TO TORSION AND SHEAR IN THE ULTIMATE LIMIT STRESS STATE

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mohamed S. Abu-Yosef ◽  
Ezzeldin Y. Sayed-Ahmed ◽  
Emam A. Soliman
Keyword(s):  
Failure Modes ◽  
Focal Point ◽  
Design Method ◽  
Limit State ◽  
Bending Moment ◽  
Steel Structures ◽  
Ultimate Limit State ◽  
Shear Forces ◽  
Limit States ◽  
Ultimate Limit

Steel connections transferring axial and shear forces in addition to bending moment and/or torsional moment are widely used in steel structures. Thus, design of such eccentric connections has become the focal point of any researches. Nonetheless, behavior of eccentric connections subjected to shear forces and torsion in the ultimate limit state is still ambiguous. Most design codes of practice still conservatively use the common elastic analysis for design of the said connections even in the ultimate limit states. Yet, there are some exceptions such as the design method proposed by CAN/CSA-S16-14 which gives tabulated design aid for the ultimate limit state design of these connections based on an empirical equation that is derived for ¾ inch diameter A325 bearing type bolts and A36 steel plates. It was argued that results can also be used with a margin of error for other grade bolts of different sizes and steel of other grades. As such, in this paper, the performance of bolted connection subject to shear and torsion is experimentally investigated. The behavior, failure modes and factors affecting both are scrutinized. Twelve connections subject to shear and torsion with different bolts configurations and diameters are experimentally tested to failure. The accuracy of the currently available design equations proposed is compared to the outcomes of these tests.

A new design method for calculating critical temperatures of restrained steel column in fire

2010 ◽  
Vol 45 (6-8) ◽  
pp. 349-360 ◽  
Author(s):  
Peijun Wang ◽  
Yong-Chang Wang ◽  
Guo-Qiang Li
Keyword(s):  
Design Method ◽  
Critical Temperatures ◽  
Steel Column ◽  
In Fire

Application of Reliability-Based Design Method of Pipeline Material Selection

2014 ◽  
Author(s):  
Zhenyong Zhang ◽  
Wen Wei Zhang ◽  
Jinyuan Zhang ◽  
Yuqing Liu
Keyword(s):  
Failure Probability ◽  
Material Selection ◽  
Design Method ◽  
Limit State ◽  
Third Party ◽  
Ultimate Limit State ◽  
Permafrost Region ◽  
Pipe Material ◽  
Pipe Failure ◽  
Reliability Design

A certain inland pipeline is located in a cold area and traverses the alpine-cold and permafrost region. For design and selection of steel grade pipeline in such an area, the resistance of X52 and X60 pipes is calculated and analyzed using the reliability design method for the first time based on a comparison of conventional economy and technical schemes, combined with the analysis on pipe failure, reason, and type as well as the ultimate limit state. According to calculation and analysis, the overall resistance of X52 9.5mm pipe is higher than that of X60 8.7mm pipe, except for the equal resistance against excavation and puncture by a third party. This is especially true in regard to the ultimate tensile strain and compression strain, increasing by 17% and 31% respectively. By adopting the Monte Carlo method using certain parameters about pipe material, construction and operational maintenance, the failure probability of X52 and X60 pipes under corrosion as well as excavation and puncture by a third party is calculated and analyzed quantitatively. The result shows that the failure probability of X52, 9.5mm pipe is 2.61 ×10−4 times per kilometer per year which is much less than that of X60 8.7mm pipe (5.50 ×10−4 times per kilometer per year). Considering the safe reliability of pipeline, the X52 9.5mm pipe scheme is far superior to X60 8.7mm pipe scheme. Therefore the former scheme is recommended for design which only increases the cost by 1.5%.

Applicability of Mandrel Elbow to High Pressure Gas Pipeline

2014 ◽  
Author(s):  
Hiroyuki Horikawa ◽  
Hideo Toma ◽  
Yasuo Yabe ◽  
Mitsunori Tsukidate ◽  
Nobuhisa Suzuki
Keyword(s):  
High Pressure ◽  
Ground Deformation ◽  
Design Method ◽  
Limit State ◽  
Local Buckling ◽  
Lateral Spreading ◽  
Bending Test ◽  
Design Code ◽  
Seismic Design Code ◽  
Permanent Ground Deformation

Applicability of mandrel elbows to high pressure gas pipelines is discussed in this paper taking into account the seismic integrity to withstand liquefaction-induced permanent ground deformation. Bending test and FE analysis of X65, 45 deg. mandrel elbow with diameter of 24-in were conducted in order to evaluate the seismic integrity for lateral spreading due to liquefaction. Local buckling behaviors of the closing-mode test was simulated by FEA and calculation of existing seismic design code for high pressure pipelines can estimate maximum bending angle as limit state of the mandrel elbow conservatively. The results clarify that mandrel elbows can be applied to high pressure pipelines using conventional design method including the design code and FEA. In addition, buckling behaviors of the mandrel elbow were similar to those of high-frequency induction bends which have been used for high pressure pipelines in Japan.

Numerical Simulation of Fire Resistance Performance for Planar Frame with Concrete Filled Steel Tubular Columns and Steel Beams

2011 ◽  
Vol 94-96 ◽  
pp. 755-758
Author(s):  
Yan Yin ◽  
Tang Li
Keyword(s):  
Fire Resistance ◽  
Limit State ◽  
Plastic Hinge ◽  
Local Buckling ◽  
Horizontal Displacement ◽  
Steel Beams ◽  
Bottom Flange ◽  
Tubular Columns ◽  
Fire Endurance ◽  
Resistance Performance

In this paper, the fire resistance performance of the unprotected two-layer and two-cross planar frame, which is composed of concrete filled steel tubular columns and steel beams, was analyzed under local fire by ANSYS. After analyzing the structure with the method of hot - structural coupling using standard heating curve ISO-834, some consequence were obtained such as the regularity of temperature field distribution of beams and columns and the fire endurance and critical temperature of the structure. It turned out that the bottom flange at the end of the beams appeared local buckling when the structure reached the limit state by fire, and the first plastic hinge appeared at the end of beams. Furthermore, because the horizontal displacement of column is small, the overall collapse of structure can be avoided effectively.

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