scholarly journals Influence of geometrical imperfection on critical temperature evaluation for steel corrugated arch sheets exposed to fire

2019 ◽  
Vol 262 ◽  
pp. 09007
Author(s):  
Mariusz Maślak ◽  
Michał Pazdanowski ◽  
Maciej Suchodoła
Keyword(s):  
Critical Temperature ◽  
Steel Sheet ◽  
Local Buckling ◽  
Equilibrium Path ◽  
Buckling Mode ◽  
Initial Shape ◽  
Steel Sheets ◽  
Computational Environment ◽  
Geometrical Imperfection ◽  
Predetermined Level

The critical temperature for an arched corrugated steel sheet exposed to fully developed fire is determined in this paper. The analysis is performed on 3D numerical model developed within the ANSYS computational environment with parameters calibrated experimentally on an experiment performed for persistent design scenario. During the simulations performed the self-supporting steel sheet with an assumed initial shape imperfection is at first loaded with static load, up to a predetermined level of material effort, and subsequently evenly heated until the capability to safely resist the applied load is completely exhausted. Because of the nonlinearity of the analysis having several sources, the location of the limit point on the equilibrium path determined during calculations represents the temperature sought. Three imperfection patterns, denoted as A, B and C are considered. In the case A the imperfection has the shape and magnitude measured in situ, selected as representative for a set of 10 steel sheets of the same type. In the case B the imperfection is a substitute one with size analogous to that assumed in the case A, but with a different shape, corresponding to the first antisymmetric buckling mode identified in conventional Local Buckling Analysis (LBA). In the case C the shape of imperfection B has been kept, but the positive and negative deviation from the perfect circular shape have been increased twofold.

ELASTIC BUCKLING OF THIN-WALLED CIRCULAR TUBES CONTAINING AN ELASTIC INFILL

2006 ◽  
Vol 06 (04) ◽  
pp. 457-474 ◽  
Author(s):  
M. A. BRADFORD ◽  
A. ROUFEGARINEJAD ◽  
Z. VRCELJ
Keyword(s):  
Axial Compression ◽  
A Priori ◽  
Local Buckling ◽  
Steel Tube ◽  
Transcendental Equation ◽  
Buckling Mode ◽  
Buckling Stress ◽  
Elastic Tubes ◽  
Thin Walled ◽  
Energy Formulation

Circular thin-walled elastic tubes under concentric axial loading usually fail by shell buckling, and in practical design procedures the buckling load can be determined by modifying the local buckling stress to account empirically for the imperfection sensitive response that is typical in Donnell shell theory. While the local buckling stress of a hollow thin-walled tube under concentric axial compression has a solution in closed form, that of a thin-walled circular tube with an elastic infill, which restrains the local buckling mode, has received far less attention. This paper addresses the local buckling of a tubular member subjected to axial compression, and formulates an energy-based technique for determining the local buckling stress as a function of the stiffness of the elastic infill by recourse to a transcendental equation. This simple energy formulation, with one degree of buckling freedom, shows that the elastic local buckling stress increases from 1 to [Formula: see text] times that of a hollow tube as the stiffness of the elastic infill increases from zero to infinity; the latter case being typical of that of a concrete-filled steel tube. The energy formulation is then recast into a multi-degree of freedom matrix stiffness format, in which the function for the buckling mode is a Fourier representation satisfying, a priori, the necessary kinematic condition that the buckling deformation vanishes at the point where it enters the elastic medium. The solution is shown to converge rapidly, and demonstrates that the simple transcendental formulation provides a sufficiently accurate representation of the buckling problem.

Effect of Coating Layer on Advanced Stud Welding of 2024 Aluminum Alloy to Galvanized and Galvannealed Steel Sheet

2014 ◽  
Vol 794-796 ◽  
pp. 351-356
Author(s):  
Yohei Harada ◽  
Kozo Ishizuka ◽  
Shinji Kumai
Keyword(s):  
Aluminum Alloy ◽  
Steel Sheet ◽  
Coating Layer ◽  
Fracture Load ◽  
Tensile Fracture ◽  
2024 Aluminum Alloy ◽  
Steel Sheets ◽  
Sheet Surface ◽  
Stud Welding ◽  
Galvannealed Steel

High strength 2024 aluminum alloy studs were joined to galvanized, galvannealed and non-coated steel sheets by using an advanced stud welding method. Effect of the coating layer on the interfacial microstructure and the tensile fracture load of the joints were evaluated. A specially-designed stud having a circular projection at its bottom was pressed against a sheet surface. A discharge current was introduced from the upper part of the stud. Local heating could be achieved by a high current density at a contact point between the projection and sheet. The observation of joint area revealed the projection was severely deformed and spread along the sheet surface. The coating layer of the galvanized steel sheet was removed at the joint interface under the charging voltage of 200 V, while that of the galvannealed one locally remained on the steel surface even at 400 V. This would be strongly related to the melting or liquidus and solidus temperatures of each coating layer. Joining was not achieved at a low charging voltage in the non-coated and galvannealed steel sheets, while high tensile fracture load was obtained even at 200 V in the galvanized ones.

Buckling Mode Interaction in Composite Plate Assemblies

1995 ◽  
Vol 48 (11S) ◽  
pp. S52-S60 ◽  
Author(s):  
Ioannis G. Raftoyiannis ◽  
Luis A. Godoy ◽  
Ever J. Barbero
Keyword(s):  
Linear Elasticity ◽  
Composite Plate ◽  
Mode Interaction ◽  
Equilibrium Path ◽  
Buckling Mode ◽  
Fiber Reinforced Composite ◽  
Composite Columns ◽  
Reinforced Composite ◽  
Coupled Solution ◽  
Coordinate Basis

The analysis of buckling mode interaction of fiber-reinforced composite columns, modeled as plate assemblies, is presented. The main assumptions are linear elasticity; a linear fundamental equilibrium path; the existence of critical states that are coincident or near coincident; and a coupled path rising from a quadratic combination of modal displacements due to interaction. The formulation adopted is known as the W-formulation, in which the energy is written in terms of a sliding set of incremental coordinates, measured with respect to the fundamental path. The energy is then expressed with respect to a reduced modal coordinate basis, and the coupled solution arising from interaction is computed. An example of a pultruded composite I-column subjected to axial compression illustrates the procedure.

Dynamic Analysis of Response of Cofferdam with Steel Sheet Piles Induced by Earthquake Excitation

2011 ◽  
Vol 117-119 ◽  
pp. 695-698
Author(s):  
Chun Yi Cui ◽  
Zhong Tao Wang ◽  
Jian Huang
Keyword(s):  
Geometric Nonlinearity ◽  
Steel Sheet ◽  
Natural Frequencies ◽  
Response Spectrum ◽  
Seismic Excitation ◽  
Earthquake Excitation ◽  
Positive Direction ◽  
Steel Sheets ◽  
Port Engineering ◽  
Horizontal Displacements

For its construction convenience and structure integrity, cofferdams are widely employed in port engineering. Past experience has shown that cofferdam are subjected to damage due to earthquake excitations. Numerical analyses with both response spectrum and step-by-step integration methods are conducted by using Lanczos eigenvalue extraction technique to obtain natural frequencies and modes, and solving dynamic equations with Newmark implicit method to consider geometric nonlinearity. The computational results show that the natural frequency of cofferdam system is low and the horizontal translation stiffness of cofferdam in positive direction is higher than that in negative direction. Under seismic excitation, the displacement response of inner steel sheet is much more obvious than that of outer one. And the distribution of horizontal displacements in steel sheets presents the characteristics that the corresponding values increase with their heights in the cofferdam system. On the contrary, the deviatonic stresses of cofferdam decrease with the augments of height.

scholarly journals The Micro-Geometry Evaluation on Steel Sheets after Chemical Surface Treatment

2013 ◽  
Vol 10 (2) ◽  
pp. 22-25
Author(s):  
Dagmar Draganovská ◽  
Miroslav Tomáš ◽  
Peter Ižol
Keyword(s):  
Surface Treatment ◽  
Steel Sheet ◽  
Unit Length ◽  
Mean Deviation ◽  
Maximum Height ◽  
Chemical Surface ◽  
Steel Sheets ◽  
Mean Width ◽  
The Mean ◽  
Metal Materials

Abstract The protection of metal materials by coatings is one of the most important way to protect the surface against corrosion. Galvanisation of metal surfaces by an electric current is one of the most frequent way of surface treatment due to its wide application. The paper is oriented to the evaluation of the surface quality in terms of micro-geometry. The basic surface of the steel sheet S235JRG2 has been evaluted and compared to the degreased one, galvanized one and surface after galvanizing, chromatizing and phosphating. The microgeometry parameters such as the arithmetical mean deviation Ra, the maximum height of profile Rz, the total height of profile Rt as well as the the mean width of the profile elements RSm and the number of peaks per unit length RPc has been compared.

Experimental Investigations on Spot Welded Built-Up Cold-Formed Steel Beams

2018 ◽  
Vol 1146 ◽  
pp. 142-151
Author(s):  
Viorel Ungureanu ◽  
Ioan Both ◽  
Mircea Burca ◽  
Ştefan Benzar ◽  
Thai Hoang Nguyen ◽  
...  
Keyword(s):  
Spot Welding ◽  
Steel Sheet ◽  
Experimental Program ◽  
Experimental Investigations ◽  
Steel Beams ◽  
Technological Solution ◽  
Research Project ◽  
Steel Sheets ◽  
Cold Formed Steel ◽  
Thin Walled

Within the WELLFORMED research project, ongoing at the CEMSIG Research Center of the Politehnica University of Timisoara, a new technological solution was proposed for built-up beams made of corrugated steel sheets for the web and thin-walled cold-formed steel profiles for the flanges, connected by spot welding. The research project integrates an extensive experimental program on such beams, using full scale specimens, to demonstrate the feasibility of the proposed solutions and to assess their performance, followed by numerical simulations to characterize and optimize the connecting details. The present paper presents the results of a large experimental program, on small specimens subjected to shear, consisting of two or three layers of steel sheet connected by spot welding.

TENSILE AND FRACTURE BEHAVIOUR OF VERY THIN 304 STAINLESS STEEL SHEET

2016 ◽  
Vol 78 (6-9) ◽  
Author(s):  
Ammar Adil Al-Bakri ◽  
Zainuddin Sajuri ◽  
Ahmad Kamal Ariffin ◽  
Mohammed Abdul Razzaq ◽  
Mohd Salehudin Fafmin
Keyword(s):  
Stainless Steel ◽  
Cross Section ◽  
Steel Sheet ◽  
Rectangular Cross Section ◽  
Fracture Morphology ◽  
304 Stainless Steel ◽  
Stainless Steel Sheet ◽  
Steel Sheets ◽  
Ductile Mode ◽  
Mode Formation

Specimen with rectangular cross-section usually used to measure the tensile properties of materials. However, the specimen size and thickness may affect the results. In this study, tensile and fracture behaviours of very thin 304 stainless steel sheet were investigated. The thickness of the stainless steel sheets investigated were 100 and 300 µm. Tensile samples were cut into dumbbell-shaped of rectangular cross-section with same width for both thickness according to ASTM E8. The results showed that 100 µm thin steel sheet exhibited higher tensile strength with no clear evidence of yielding as compared to 300 µm sheet. The fracture morphology images observed by scanning electron microscopy revealed that both specimens fracture in ductile mode. Formation of dimples on the fracture surface could be recognized easily in 300 µm sample at higher magnification as compared to 100 µm sample.

The Influence of Major Defects on the Properties of Continuous Galvanized Steel Sheet

2012 ◽  
Vol 445 ◽  
pp. 661-666 ◽  
Author(s):  
A. Azimi ◽  
F. Shahriari ◽  
F. Ashrafizadeh ◽  
M.R. Toroghinezhad ◽  
J. Jamshidi
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Tensile Test ◽  
Steel Sheet ◽  
Corrosion Behaviour ◽  
Salt Spray ◽  
Galvanized Steel ◽  
Tafel Polarization ◽  
Steel Sheets ◽  
Bare Spot

Production of defect-free galvanized steel sheet is considered a major concern for automotive and other critical applications; nevertheless, the occurrence of some defects in the coated sheets is unavoidable. In order to alleviate the problem, we need to know the extent to which the properties of a galvanized sheet are influenced by the presence of a given defect. In this investigation, specimens including any of the two major defects of continuously galvanized steel sheets were selected from a large number of coated samples. The defects, including furnace roll pimples and bare spots, were microstructurally characterized and their influence on corrosion behaviour and mechanical properties of the steel sheet was evaluated. Corrosion resistance was examined via standard salt spray test and Tafel polarization. Tensile test was employed as a measure of mechanical properties of the defective galvanized sheets. The results indicated that the presence of defects had little influence on the tensile properties of the samples, but considerably reduced their corrosion resistance. Based on the results of salt spray tests, pimples reduced corrosion resistance of galvanized sheets 23 % (50 hours) on average and bare spot defects caused reduction in corrosion resistance up to 39%.

Study Status of Steel-Bamboo Composite Slabs

2014 ◽  
Vol 501-504 ◽  
pp. 727-730
Author(s):  
Jing Tang ◽  
Jun Guo ◽  
Gui Fen Hu ◽  
Yu Wen ◽  
Yu Shun Li
Keyword(s):  
Carrying Capacity ◽  
Steel Sheet ◽  
Light Weight ◽  
Building Structures ◽  
Steel Sheets ◽  
The Core ◽  
Composite Slabs ◽  
Steel Composite ◽  
Interface Slip ◽  
Core Part

At present, the development and application of new building structures are paid widely attention. In order to promote light-weight building slabs, different sections of steel-bamboo composite slabs are presented in this paper. Sandwiching thin-walled C-shaped steel or profiled steel sheet between two bamboo woods and bonding them with adhesive, a variety of different forms of steel-bamboo composite slabs are designed. For the C-shaped steel composite slabs, the reinforcement of self-tapping screws can effectively constraint interface slip between steel and bamboo plywood. It can also overcome the shortcoming of buckling which easily happen on C-shaped steel, ultimately, making the slabs have high stiffness and bearing capacity. The composite slabs with profiled steel sheets as the core part are strengthened by self-tapping screws and edge panels. And the global stability, deflection capacity and ductility performance of composite floors are significantly improved. Experimental results show that the reasonably combined composite slabs which have good combined effects, large carrying capacity and stiffness, can be used as architectural floors.

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