LOCAL BUCKLING BEHAVIOR OF DOUBLE-COPED STEEL BEAMS

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Cheng Fang ◽  
Michael Yam ◽  
V. P. Iu ◽  
K. F. Chung
Keyword(s):  
Failure Modes ◽  
Pushover Analysis ◽  
Local Buckling ◽  
Design Approach ◽  
Steel Beams ◽  
Buckling Mode ◽  
Buckling Behavior ◽  
Buckling Resistance ◽  
Web Buckling ◽  
Irregular Bridges

Local web buckling is one of the most common failure modes for coped steel beams. While several studies have been undertaken focusing on the behavior of top-flange/single-coped beams, double-coped beams have received little attention. To fill this knowledge gap, this paper presents experimental and numerical studies on local web buckling behavior of double-coped steel beams. Five full-scale tests were conducted, and the main test parameters were cope length and cope depth. Local web buckling was observed as the main failure mode for all of the five specimens, and the buckling resistance was found to decrease with increasing cope length and cope depth. A FE study was subsequently conducted, where the response of the FE models agreed well with the test results, especially in terms of buckling mode and buckling resistance. The test and FE results were compared with those predicted by an existing design approach. The design results were found to be quite conservative, and hence further investigation may be required to achieve a more accurate design approach. procedure and faster computational efficiency than the Modal Pushover Analysis (MPA) procedure for irregular bridges.

Interactive shear resistance of corrugated web in steel beam exposed to fire

2016 ◽  
Vol 7 (1) ◽  
pp. 69-78
Author(s):  
Mariusz Marcin Maslak ◽  
Marcin Lukacz
Keyword(s):  
Failure Modes ◽  
Steel Beams ◽  
Steel Beam ◽  
Safety Level ◽  
Design Algorithm ◽  
Content Type ◽  
Corrugated Webs ◽  
Buckling Resistance ◽  
Corrugated Web ◽  
Shear Buckling

Purpose The purpose of this paper is to present and discuss in detail the design approach to shear buckling resistance evaluation for corrugated web being a part of a steel beam exposed to fire. Design/methodology/approach It is based on the interaction between the local and global elastic instability failure modes as well as on the possible yielding of the whole web cross-section during fire. Findings New formulae, adequate for specification of the suitable shear buckling coefficients, depend not only on the web slenderness but also on the temperature of structural steel. Originality/value The methodology proposed by the authors can be added to the current European standard recommendations given in EN 1993-1-2 as a well-justified design algorithm helpful in reliable evaluation of a safety level for steel beams with slender corrugated webs subject to fire exposure. It seems to be highly desirable because, at present, there are no detailed instructions in this field.

scholarly journals Behavior of partially encased composite members under various load conditions: Experimental and analytical models

2018 ◽  
Vol 22 (1) ◽  
pp. 94-111 ◽  
Author(s):  
Mehdi Ebadi Jamkhaneh ◽  
Mohammad Ali Kafi ◽  
Ali Kheyroddin
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Numerical Models ◽  
Local Buckling ◽  
Marginal Effect ◽  
Composite Column ◽  
Buckling Behavior ◽  
Bending Load ◽  
Torsional Behavior ◽  
Load Conditions

This study addresses the experimental behavior of octagonal partially encased composite column under axial and bending load conditions. The complementary study on axial and combined axial–torsional behavior is done through finite element analysis. The main parameters for the experiment part are reinforcement details and failure modes. The six parameters of this analytical analysis include width-to-thickness ratio of flange, transverse links spacing and diameter, welding line arrangements, and different types of retrofit of cross-shaped steel (concrete encasement, use of stiffener plates and transverse links). To verify accuracy of the proposed three-dimensional finite element model, the axial behavior of the numerical models was compared with test specimens. Experimental results of the axial study show that concrete crushing phenomena and local buckling behavior occurred for all specimens under ultimate stage of loading. It should be noted that local buckling behavior occurred after crushing phenomena. The analysis of bending assessment demonstrated that the use of stirrups has no remarkable effect on increasing the effective bending moment strength of octagonal partially encased composite columns. Meanwhile, an equation was developed based on comprehensive parametric study of octagonal partially encased composite column using detailed finite element analyses. Under axial–torsional load conditions, one could conclude that steel shear plates should be placed at the end zones of column to heighten torsional resistance of member. Meanwhile, transverse links were found to exert marginal effect on torsional behavior of octagonal partially encased composite column.

Buckling analyses of double-shell octagonal lattice truss composite structures

2017 ◽  
Vol 52 (9) ◽  
pp. 1227-1237 ◽  
Author(s):  
Qianqian Sui ◽  
Changliang Lai ◽  
Hualin Fan
Keyword(s):  
Failure Mode ◽  
Composite Structures ◽  
Failure Modes ◽  
Local Buckling ◽  
Buckling Mode ◽  
One Dimensional ◽  
Load Carrying ◽  
Global Buckling ◽  
Buckling Failure ◽  
Equivalent Continuum

To reveal the compression failure modes of one-dimensional hierarchical double-shell octagonal lattice truss composite structures (DLTCSs), finite element modeling and equivalent continuum models were developed. DLTCS has three typical failure modes: (a) fracture of the strut, (b) global buckling, and (c) local buckling. Failure mode maps were constructed. It is found that column of long enough length will collapse at global buckling. When the column length decreases, the failure mode will turn to local buckling and strut fracture successively. Bay length greatly influences the buckling mode. Longer bay length could change the buckling mode from global buckling to local buckling. Compared with single-shell lattice truss composite structure, DLTCS has advantage in load carrying when the column fails at strut fracture or global buckling, while local buckling tolerance of DLTCS is smaller.

scholarly journals Structural fire performance of restrained composite columns made of concrete-filled square and circular hollow sections

Fire Research ◽  
2016 ◽  
Author(s):  
João Paulo C. Rodrigues ◽  
Luís Laím ◽  
Helder D. Craveiro
Keyword(s):  
Fire Resistance ◽  
Failure Modes ◽  
Local Buckling ◽  
Critical Time ◽  
Load Level ◽  
Steel Frame ◽  
Hollow Section ◽  
Standard Fire ◽  
Buckling Behavior ◽  
Rotational Restraint

Most of the previous studies on concretefilled steel hollow section columns at high temperatures addressed the effect of depth-tothickness ratio, column slenderness, initial applied load level, load eccentricity, and local buckling of concrete-filled steel tubes on the fire resistance of these columns. For this reason, it important and required to study the influence of the axial and rotational restraint on the buckling behavior of these types of columns subjected to fire. The results of a series of fire resistance tests on these types of columns inserted in a steel frame are presented and discussed in this paper. The primary test parameters taken into account were column slenderness, type of section geometry, and axial and rotational restraint level imposed by a surrounding steel frame to the columns. The specimens were then uniformly exposed to the ISO 834 standard fire curve, and the critical time (fire resistance), failure temperature distribution and respective failure modes were assessed. Finally, the results of this research study showed most of all that the fire resistance of identical semi-rigid ended columns may be not significantly affected by the stiffness of the surrounding structure but, on the contrary, their post-buckling behavior may be affected.

scholarly journals Buckling Behavior of Non-Retrofitted and FRP-Retrofitted Steel CHS T-Joints

2021 ◽  
Vol 11 (7) ◽  
pp. 3098
Author(s):  
Amin Yazdi ◽  
Maria Rashidi ◽  
Mohammad Alembagheri ◽  
Bijan Samali
Keyword(s):  
Compressive Loading ◽  
Local Buckling ◽  
Buckling Mode ◽  
T Joints ◽  
Hollow Section ◽  
Frp Composite ◽  
Buckling Behavior ◽  
Global Buckling ◽  
Post Buckling ◽  
Circular Hollow Section

This paper aims to investigate the buckling behavior of circular hollow section (CHS) T-joints in retrofitted and non-retrofitted states under axial brace compressive loading. For this purpose, two types of analysis are carried out. The first one is evaluating the critical buckling load in various tubular joints, and the other one is investigating the post-buckling behavior after each buckling mode. More than 180 CHS T-joints with various normalized geometric properties were numerically modeled in non-retrofitted state to compute their governing buckling mode, i.e., chord ovalization, brace local, or global buckling. Then three joints with different buckling modes were selected to be retrofitted by fiber-reinforced polymer (FRP) patches to illustrate the improving effect of the FRP wrapping on the post-buckling performance of the retrofitted joints. In addition, FRP composite failures were investigated. The results indicate that the FRP retrofitting is able to prevent the brace local buckling, and that matrix failure is the most common composite failure in the retrofitted joints.

Behaviour of partly stiffened cold-formed steel built-up beams: Experimental investigation and numerical validation

2018 ◽  
Vol 22 (1) ◽  
pp. 172-186 ◽  
Author(s):  
M Adil Dar ◽  
N Subramanian ◽  
A R Dar ◽  
M Anbarasu ◽  
James BP Lim ◽  
...  
Keyword(s):  
Failure Modes ◽  
Numerical Study ◽  
Local Buckling ◽  
Steel Structures ◽  
Vital Role ◽  
Steel Beams ◽  
Design Strength ◽  
Finite Element Software ◽  
Cold Formed Steel ◽  
Reserve Strength

To address the various instability problems in cold-formed steel members, many researchers have mainly focused on developing innovative sectional profiles wherein geometry of the section plays a vital role in enhancing the inherent resistance of such sections against premature buckling. However, the process of forming such innovative shapes is not only complex and time-consuming but sometimes such sections fail to mobilize their complete reserve strength. Hence, a stiffening arrangement of weaker zones for mobilizing the untapped reserve strength is suggested. The contribution of this simple, effective and partly stiffening arrangements, aimed at eliminating/delaying the premature local buckling, is studied both experimentally and numerically and also compared with existing codes. Experimental study was carried out on different simply supported cold-formed steel beams with judiciously proposed stiffening arrangements under four-point loading. An equivalent hot-rolled steel beam was also tested to compare the efficiency of the cold-formed steel beams. The cold-formed steel beams investigated had different width-to-thickness ratio, different geometries and different stiffening arrangements. The test strengths, failure modes, deformed shapes, load versus mid-span displacements and geometric imperfections were measured and reported. The test strengths of the beam models are also compared with the design strength predicted by North American Standards and Eurocode for cold-formed steel structures. To validate the test results further, a numerical study was carried out on such stiffened cold-formed steel beams using finite element software ABAQUS. All these results show that the proposed strengthening system is efficient and economical and allow cold-formed steel beams to reach greater load carrying capacity.

Study on shear performance of the connection with external stiffening ring between square steel tubular column and unequal-depth steel beams

2020 ◽  
pp. 136943322098166
Author(s):  
Shuhao Yin ◽  
Bin Rong ◽  
Lei Wang ◽  
Yiliang Sun ◽  
Wuchen Zhang ◽  
...  
Keyword(s):  
Failure Modes ◽  
Plastic Hinge ◽  
Steel Tube ◽  
Nonlinear Finite Element ◽  
Steel Beams ◽  
Finite Element Models ◽  
Test Results ◽  
Panel Zone ◽  
Load Paths ◽  
Shear Performance

This paper studies the shear performance of the connection with the external stiffening ring between the square steel tubular column and unequal-depth steel beams. Two specimens of interior column connections were tested under low cyclic loading. The deformation characteristics and failure modes exhibited by the test phenomena can be summarized as: (1) two specimens all exhibited shear deformation in steel tube web of the panel zone and (2) weld fracture in the panel zone and plastic hinge failure at beam end were observed. Besides, load-displacement behaviors and strain distributions have been also discussed. The nonlinear finite element models were developed to verify the test results. Comparative analyses of the bearing capacity, failure mode, and load-paths between the equal-depth and unequal-depth beam models have been carried out.

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.

Study on the Local Buckling Behavior of Steel Equal Angle Members under Axial Compression with the Steel Strength Variation

2011 ◽  
Vol 374-377 ◽  
pp. 2430-2436
Author(s):  
Gang Shi ◽  
Zhao Liu ◽  
Yong Zhang ◽  
Yong Jiu Shi ◽  
Yuan Qing Wang
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
High Strength Steel ◽  
Local Buckling ◽  
Steel Structures ◽  
High Strength ◽  
Element Analysis ◽  
Equal Angle ◽  
Buckling Behavior ◽  
Steel Strength

High strength steel sections have been increasingly used in buildings and bridges, and steel angles have also been widely used in many steel structures, especially in transmission towers and long span trusses. However, high strength steel exhibits mechanical properties that are quite different from ordinary strength steel, and hence, the local buckling behavior of steel equal angle members under axial compression varies with the steel strength. However, there is a lack of research on the relationship of the local buckling behavior of steel equal angle members under axial compression with the steel strength. A finite element model is developed in this paper to analyze the local buckling behavior of steel equal angle members under axial compression, and study its relationship with the steel strength and the width-to-thickness ratio of the angle leg. The finite element analysis (FEA) results are compared with the corresponding design method in the American code AISC 360-05, which provides a reference for the related design.

scholarly journals Compression Test on Cold-Formed Steel Built-Up Back-to-Back Channels Stub Columns

2011 ◽  
Vol 201-203 ◽  
pp. 2900-2903 ◽  
Author(s):  
Chui Huon Tina Ting ◽  
Hieng Ho Lau
Keyword(s):  
Compression Test ◽  
Failure Modes ◽  
Local Buckling ◽  
Effective Width ◽  
Test Results ◽  
Direct Strength Method ◽  
Cold Formed Steel ◽  
Stub Column ◽  
Hot Rolled ◽  
Stub Columns

Built-up sections are used to resist load induced in a structure when a single section is not sufficient to carry the design load for example roof trusses. In current North American Specification, the provision has been substantially taken from research in hot-rolled built-up members connected with bolts or welds [1]. The aim of this paper is to investigate on built-up back-to-back channels stub columns experimentally and theoretically using Effective Width Method and Direct Strength Method. Compression test was performed on 5 lipped channel and 5 back-to-back channels stub columns fabricated from cold-formed steel sheets of 1.2mm thicknesses. The test results indicated that local buckling is the dominant failure modes of stub columns. Therefore, Effective Width Method predicts the capacity of stub columns compared to Direct Strength Method. When compared to the average test results, results based on EWM are 5% higher while results based on DSM are 12% higher for stub column.

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