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Analysis of steel storage rack columns.

Analysis of steel storage rack columns.

Storage rack systems are structures composed of cold-formed steel structural members that are used as columns, beams and bracing. The rack columns present peculiar features in their design because they have perforations to facilitate assemblage of the system, which makes them more difficult to analyze by cold-formed steel structures design codes. There are several design codes proposed by the manufacturers associations, as the specifications of Rack Manufacturers Institute (RMI), applied in the USA along with the specification of the American Iron and Steel Institute (AISI). These codes propose experimental stub columns tests for the determination of their resistance. In this work, the commercial software, ANSYS, is used for material and geometric non- linear analysis of these columns, and the results are compared with experimental data obtained by stub column tests, for a typical section of racks manufactured in Brazil.
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Application of geometrically exact beam finite elements in the advanced analysis of steel and steel-concrete beam-columns

Application of geometrically exact beam finite elements in the advanced analysis of steel and steel-concrete beam-columns

Many of the recent research efforts concerning the improvement of design rules for steel beam- columns rely on non-linear analyses using shell element models (e.g., Taras 2016). However, for compact cross-sections, which are unaffected by local and distortional buckling, it should be preferable to use beam (one-dimensional) finite elements, as they provide sufficiently accurate results with a much lower computational cost and, moreover, deal directly with cross-section stress resultants, which are of interest for designers. Unfortunately, many of the available structural analysis programs do not have, in their finite element library, beam elements capable of handling large displacements and finite rotations (although small strains can be generally assumed), namely involving moderate torsion. This aspect is particularly relevant given the fact that modern codes, such as Eurocodes 3 (CEN 2005) and 4 (CEN 2004b), already allow the use of advanced analysis methods, including geometrically and/or materially non-linearities, and even geometric imperfections. It is worth mentioning that the Eurocodes are currently under revision and an emphasis on advanced methods will be given in the forthcoming versions.
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Finite element implementation for the analysis of 3D steel and composite frames subjected to fire.

Finite element implementation for the analysis of 3D steel and composite frames subjected to fire.

This paper presents a finite element formulation for the numerical analysis of three-dimensional framed steel, reinforced concrete or composite steel and concrete structures subjected to fire. Several specialized and commercial programs may be used for the analysis of structures in fire condition. Within this context, the purpose of this work is to present the steps taken to extend a previously developed static analysis procedure with beam elements in order to cope with the thermal and structural analysis of structures under fire action. Physical nonlinearity and material property degradation considering the temperature distribution are taken into account at the cross section level, which is divided into quad- rilateral or triangular finite elements. Thermal strains are consid- ered through the effective strain concept, and the resulting nonlin- ear system of equations is solved by the Newton-Raphson scheme. The accuracy and capability of the formulation to simulate the behavior of framed structures under fire action are assessed through comparison with various numerical and experimental results.
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Thermal analysis of steel-concrete composite cross sections via CS-ASAFA

Thermal analysis of steel-concrete composite cross sections via CS-ASAFA

When exposed to high temperatures, such as in a fire situation, the physical and resistance characteristics of the materials employed in the structure deteriorate as the temperature increases. This fact promotes a considerable loss in the bearing capacity and stiffness of the structural system. The verification of a structure exposed to fire depends primarily and principally on the thermal analysis of the cross section of the structural element. This analysis permits determination of the temperature variation or temperature range in the element from the boundary conditions provided by the fire model adopted. As such, this study had the objective of performing a thermal analysis in a transient regime by means of a finite element method on steel-concrete composite cross sections that are employed in civil construction through use of the Computational Sys- tem for Advanced Structural Analysis/Fire Analysis (CS-ASA/FA). Two cross sections are analyzed and the results obtained were satisfactory. In addition, different iterative solution processes were adopted in the analysis. Parametric studies were also performed related to the mesh variation of the finite elements and time increase. From the results, it was possible to conclude that CS-ASA/FA can supply the necessary information when a thermo-structural analysis is performed for the evaluation of strength and stiffness losses of the structural material when exposed to fire.
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Load-deflection analysis of flat and corrugated stainless steel diaphragms

Load-deflection analysis of flat and corrugated stainless steel diaphragms

Abstract- In this study analytical model for flat and corrugated stainless steel (SS-304, ASTM A240) diaphragm has been proposed. The load-deflection analyses of flat and corrugated stainless steel diaphragms are performed to compare the sensitivity of the flat and corrugated diaphragm. The application of corrugated diaphragms offers the possibility to control the sensitivity of thin diaphragms by geometrical parameters. Depth of corrugations, thickness of diaphragms, and number of corrugations plays an important role to increase the mechanical sensitivity of the corrugated diaphragm. Verification of results for load-deflection obtained by analytical formulae compared with finite element analysis and experimental results.
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Mechanical analysis of a portal steel frame when subjected to a post-earthquake fire

Mechanical analysis of a portal steel frame when subjected to a post-earthquake fire

In this study, finite element models were used to predict the behavior of steel portal frames in PEF condition. The results presented in this study show that the hori- zontal displacements given by the PEF analysis are significant different when com- pared to the fire analysis of an undamaged structure, unlike the vertical displacements. For the PEF loading, it is important to con- sider the maximum displacement values which depend on the damage level. The later is induced in the structural system due to the residual displacement field after an earthquake, producing results with a differ- ence between 3.3% and 21.9% in fire resist- ance situation for different performance levels.
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Analysis of heat balance in a light steel frame residence with different insulating thickness

Analysis of heat balance in a light steel frame residence with different insulating thickness

Sustainability and efficiency in buildings are concepts that have been recently growing and developing. Its application in several buildings has become mandatory in many countries around the world. One of the major challenges faced by sustainable buildings is the achievement of satisfactory levels in efficiency terms, without negatively impacting the economics. The residential construction sector has great potential for energy savings and is also where building strategies need to be carefully planned, as they seek to meet the needs of residents not only in the present, but also over time. Residential design must be done thoroughly and must include the analysis of all climate variables involved. In order to verify a residential building envelope behaviour regarding energy and thermal efficiency, this paper intended to evaluate through software Design Builder®, walls and roofs with a rock wool layer, placed in a Light Steel Frame (LSF) house.
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The analysis of solidification process of ferritic-austenitic cast steel

The analysis of solidification process of ferritic-austenitic cast steel

The object of examination has been the ferritic-austenitic cast steel GX2CrNiMoN25-6-3 and GX2CrNiMoCuN25-6-3-3. Both grades have been taken from industrial heats performed in the medium frequency induction furnace of about 150 kg capacity. A series of test castings has been produced of both cast steel grades in order to assess their technological and working properties. The used specimens have served as a charge for cast steel melting in order to perform derivative differential thermal analysis (DDTA). Melting of small quantities of cast steel (about 400 g) have been done at Cz Ċstochowa University of Technology. Small ceramic crucibles placed inside the induction coil powered with the medium frequency current have been used. The process have been held under argon atmosphere. The constant temperature of pouring metal into the DDTA probe has been provided by measuring the temperature of the molten cast steel with PtRh10-Pt thermocouple.
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Fire resistance of composite slabs with steel deck: experimental analysis and numerical simulation

Fire resistance of composite slabs with steel deck: experimental analysis and numerical simulation

The PDE toolbox from Matlab was used for the analysis of this thermal model, using the finite element method [13]. The maximum size of the finite element mesh is 0.01m, see Figure 2. The thermal properties (specific heat, density and conductivity) of the materials (concrete and steel) are temperature dependent. The exposed side is submitted to a heat flux by convection and radiation, using different view factors and a bulk temperature following the standard fire. The unexposed side is submitted to a convective heat flux (including the radiation heat flux), using a constant bulk temperature of 20ºC. The model considers 1.2 mm for the thickness of the steel deck, the geometric ratio L1/L2 is equal to 105/60 and the concrete depth above the deck measures h1=40 mm. The mesh uses triangular finite elements with 3 nodes and one degree of freedom per node (temperature). The interpolating functions are linear. The time increment is smaller than 1 s. The convergence criterion is based on the heat flow calculation, for an absolute tolerance of 10-6, a relative tolerance of 10-3, a residual tolerance of 10-4, using a maximum number for iterations equal to 25.
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Mechanical analysis of a portal steel frame when subjected to a post-earthquake fire

Mechanical analysis of a portal steel frame when subjected to a post-earthquake fire

Fire or earthquake pose a significant threat to the human life, and cause an enormous damage to the structures, moreover the dual effect of a Post-Earthquake Fire (PEF) is a major hassle to designers and rescuers alike. Designers, when considering Algerian seismic rule (RPA99v2003) [1], ignore the possibility of a post-earthquake fire, whose effect can lead to the dramatic collapse of the structures. This paper presents the evaluation of the fire resistance for a two-story steel portal frame, damaged by an earthquake simulated through spectrum response of Chlef scaled three in the Algerian Seismic Code [1], see figure 1 and 2. First the design of the steel structure considers seismic actions by a static nonlinear analysis. Second it is followed by a fire analysis using an ISO834 standard fire model, considering that the structure is partially damaged. The finite element simulation and numerical analysis of the structure in post-earthquake fire condition yield the bilinear capacity curve at ambient temperature [2] and the variation of local and global displacement at high temperature [3]. A final comparison of the damaged (PEF) and undamaged (FIRE) frames subjected to the different fire scenarios is done.
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Structural reliability analysis of steel plane frames with semi-rigid connections.

Structural reliability analysis of steel plane frames with semi-rigid connections.

The design codes for structural design traditionally establish the adoption of par- tial safety factors to deal with uncertainties. These standards do not allow one to know the real probabilities of failure of a structure. What is needed, from a practical and sci- entific point of view, is a more consistent approach, based on reliability theory. This ar- ticle addresses an initial attempt at determining the safety levels of structures based on advanced analysis and design with structural reliability theory. In this context, the au- thors consider the effects of the geometric nonlinearity and flexibility of connections in the reliability analysis, which aims at setting a certain displacement as the service limit state. For this purpose, a computer program was written called Structural Reliability Module. This program uses a First Order Reliability Method to analyse reliability. To carry out the structural analysis of steel structures, this study uses the program Compu- tational System for Advanced Structural Analysis. Validating the Structural Reliability Module involved comparing the results from other authors with those generated by the program. Results for the structures under study indicate the efficiency of the imple- mented measures. Results suggest that, when a certain displacement is set as a service limit state, the reliability of the structures under analysis are only slightly influenced by geometric nonlinearity but considerably so by semi-rigid connections.
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Mechanical analysis of a portal steel frame when subjected to a post-earthquake fire

Mechanical analysis of a portal steel frame when subjected to a post-earthquake fire

Designers, when considering Algerian seismic rule (RPA99v2003) [8], ignore the possibility of a post-earthquake fire, whose effect can lead to the dramatic collapse of the structures [9]. This paper presents the evaluation of the fire resistance for a two-story steel portal frame, damaged by an earthquake simulated through spectrum response of Chlef scaled three in the Algerian Seismic Code [8]. First the design of the steel structure considers seismic actions by a static nonlinear analysis. Second a fire analysis using an ISO834 standard fire model is followed, considering that the structure is partially damaged. The finite element simulation and numerical analysis of the structure in post-earthquake fire condition yield the bilinear capacity curve at ambient temperature and the variation of local and global displacement at high temperature. A final comparison of the damaged (PEF) and undamaged (FIRE) frames subjected to the different fire scenarios is presented.
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FINITE ELEMENT ANALYSIS OF STEEL BEAMS WITH WEB APERTURES UNDER FIRE CONDITION

FINITE ELEMENT ANALYSIS OF STEEL BEAMS WITH WEB APERTURES UNDER FIRE CONDITION

This work is intended to analyse the behaviour steel beams with apertures under high temperatures rise due to fire using finite elements simulations with ANSYS software. It includes a structural fire analysis and a comparative study of cellular and castellated steel beams which takes into account transient temperature effect, material and geometric non- linear behaviour. FE models which estimate limiting time, mid-span deflection and failure temperature are presented for hexagonal and circular types of web opening shapes under several uniform load levels. The study shows that for any beam with closely spaced openings failure in fire will in most cases be caused by failure of the steel web. The numbers of web-openings and cells as well as their shapes are critical for the behaviour of castellated sections and cellular beams under fire condition.
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Structural reliability analysis of steel plane frames with semi-rigid connections

Structural reliability analysis of steel plane frames with semi-rigid connections

The design codes for structural design traditionally establish the adoption of par- tial safety factors to deal with uncertainties. These standards do not allow one to know the real probabilities of failure of a structure. What is needed, from a practical and sci- entific point of view, is a more consistent approach, based on reliability theory. This ar- ticle addresses an initial attempt at determining the safety levels of structures based on advanced analysis and design with structural reliability theory. In this context, the au- thors consider the effects of the geometric nonlinearity and flexibility of connections in the reliability analysis, which aims at setting a certain displacement as the service limit state. For this purpose, a computer program was written called Structural Reliability Module. This program uses a First Order Reliability Method to analyse reliability. To carry out the structural analysis of steel structures, this study uses the program Compu- tational System for Advanced Structural Analysis. Validating the Structural Reliability Module involved comparing the results from other authors with those generated by the program. Results for the structures under study indicate the efficiency of the imple- mented measures. Results suggest that, when a certain displacement is set as a service limit state, the reliability of the structures under analysis are only slightly influenced by geometric nonlinearity but considerably so by semi-rigid connections.
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Dynamic Analysis and Fatigue Assessment of an Existing Railway Steel Bridge

Dynamic Analysis and Fatigue Assessment of an Existing Railway Steel Bridge

Metallurgical analysis of the corrosion product on the “fast fracture” face of hanger 1 (at the northwest) indicated that there was a high probability that it had fractured 5 to 7 years prior to January 14, 2003. This hanger rod would have fallen, but after the drop by about 75 mm, it was held by the beam next to the bridge deck. The threaded part of hanger 1 showed signs of abrasion and wear caused by rubbing against the steel sleeve (up and down motion), as traffic crossed the bridge. Prior to final fracture, a portion of the hanger rod would have been cracked as a result of bending fatigue stresses. Once hanger 1 had failed, the load was transferred to the neighboring hangers and to the abutment by the steel stringers, floor beams and concrete deck system. Continued loading resulted in fatigue cracks developing in hangers 2 and 3 and in the floor beam to stringer connection plate. Hanger 2 failed 1 to 3 years prior to the accident and, consequently, hanger 3 and adjacent hangers were forced to carry the entire additional load from failed hangers 1 and 2. However, hanger 3 was incapable of carrying this additional load and failed. This led to the partial collapse of the deck on January 14, 2003 (Bagnariol, 2003).
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Analysis of multistoried braced steel space frame subjected to gravity and seismic loading.

Analysis of multistoried braced steel space frame subjected to gravity and seismic loading.

In recent years, in the Indian subcontinent analysis of multistory buildings for earthquake forces has become important due to high seismic activity or potential seismic activity. Due to the exorbitant price of land, multistoried buildings are the only economically feasible construction. Hence, designers are warranted to design important structures against earthquakes for safety and to prevent loss of property. Steel structures are generally more flexible than other types of structure and lower in weight. As earthquake forces are associated with inertia, they are related to the mass of the structure and so reducing the mass inevitably leads to lower seismic design forces. This reduction of design forces significantly reduces the cost of both the superstructure and foundations of a building. As compared to reinforced concrete structures, steel has got some important properties like high strength and ductility. We know that steel is ductile so it gives warning before failures. All these properties of steel will play very important role in case of seismic design. In this study a number of structures with different heights and widths with and without braces have been analyzed. However, partially braced frames also have been studied and optimum locations of braces have been found. Fully braced frames with soft storey as well as
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Analysis of Quenching Parameters in AISI 4340 Steel by Using Design of Experiments

Analysis of Quenching Parameters in AISI 4340 Steel by Using Design of Experiments

This paper aims to investigate the effects of quenching parameters (temperature and time of austenitizing and cooling rate) on the microstructure, hardness and distortion of AISI 4340 steel by Design of Experiments (DoE). The factorial design was used to determine the influence of the factors on the response variable. After quench samples were characterized by optical and scanning electron microscopy, hardness test and dimensional analysis. Navy C-rings samples are used to determine the distortions after quenching due to development of residual stresses caused by non-uniform cooling. Results show that the cooling rate has a significant effect on the steel after quenching, however, the suitability of all factors is important to achieve the desired properties.
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Non-linear Dynamic Analysis of Steel Hollow I-core Sandwich Panel under Air Blast Loading

Non-linear Dynamic Analysis of Steel Hollow I-core Sandwich Panel under Air Blast Loading

response under blast loading are not well understood. Energy dissipation in blast loaded structures is one of the most important parameters in analysis and design. Considering this fact, the current work seeks to numerically study the validity of soft core hypothesis, using a hollow I- core that allows more substantial plastic deformation and subsequently less back plate deflection. For this purpose, a series of holes were considered in the core elements of conventional I-core steel sandwich panels and potential influences of such configuration was assessed in detail. In this paper, the response of this novel steel I-core sandwich panel under blast loading was numerically investigated. The main aim of this study was to determine the dynamic response of the steel sandwich panel with hollow I-core, considering the effect of the core's elements number, charge weight and strain rate on dynamic response of the panels. Since the details can affect the dynamic response of these panels, several parameters such as boundary conditions, strain rate and asymmetrical blast loading were considered in this study. Special emphasis was placed on the evaluation of midpoint displacements and energy dissipation of models.
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REPOSITORIO INSTITUCIONAL DA UFOP: Reliability analysis of typical cold-formed steel beams sections.

REPOSITORIO INSTITUCIONAL DA UFOP: Reliability analysis of typical cold-formed steel beams sections.

Abstract.This paper presents a reliability analysis of cold-formed steel beams, based on the FORM and MC simulation and using data obtained from experimental tests performed at the Johns Hopkins University, Baltimore (Schafer, 2003; 2006). This paper approached two sets of flexural tests, one referring to the failure by local buckling, and another for distortional buckling. A failure function is assembled to obtain, by taking into account the statistical parameters of the material (M), fabrication (F), and professional factors (P). The material and fabrication factors were taken from AISI standard. The professional factor was determined by comparing the tested failure loads and the predicted ultimate loads calculated from the selected design provisions. The goal of the paper is the assessment of reliability index for two nominal live-to-dead load ratios, as well as to compare the value found considering the load combinations for ultimate limit states.
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THERMAL ANALYSIS OF WOOD-STEEL HYBRID CONSTRUCTION

THERMAL ANALYSIS OF WOOD-STEEL HYBRID CONSTRUCTION

The main objective of this work is to provide the thermal analysis in wood-steel hybrid elements for building constructions under fire conditions. A transient thermal analysis with nonlinear material behaviour will be solved with ANSYS program. The use of wood-steel hybrid models has major advantages as increased fire resistance, and improved high strength. Wood is a lightweight material, easy to assemble, great architectural features, thermal and acoustic characteristics. However, the high vulnerability of wooden elements under fire action, involves evaluating their behaviour accurately. Its physical behaviour is conditioned by the charring layer formation, which may allow the insulation into the structural section. The steel is a current use material allowing high structural strength. However, steel is a non- combustible material, and when compared with wood is a very good conductor of heat. Consequently, the unprotected sections of steel under fire quickly heats, and the fire resistance decreases considerably. The numerical modelling of the hybrid models considers the analysis at high temperatures and the nonlinear material properties. Using a computer model, it will become possible to calculate the fire resistance of these hybrid elements, an important parameter for safety and design rules.
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