scholarly journals Damage Detection Technique for Cold-Formed Steel Beam Structure Based on NSGA-II

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Byung Kwan Oh ◽  
Se Woon Choi ◽  
Hyo Seon Park
Keyword(s):  
Damage Detection ◽  
Failure Mode ◽  
Optimization Technique ◽  
Local Buckling ◽  
Detection Technique ◽  
Steel Beam ◽  
Beam Structure ◽  
Nsga Ii ◽  
Error Functions ◽  
Cold Formed Steel

Cold-formed steel is uniform in quality, suitable for mass production, and light in weight. It is widely used for both structural and nonstructural members in buildings. When it is used in a bending structural member, damage such as local buckling is considered to be more important than general steel members in terms of failure mode. However, preceding studies on damage detection did not consider the failure characteristics of cold-formed beam members. Hence, this paper proposes a damage detection technique that considers the failure mode of local buckling for a cold-formed beam member. The differences between the dynamic characteristics from vibration-based measurements and those from finite element model are set to error functions. The error functions are minimized by the optimization technique NSGA-II. In the damage detection, the location of local damage and the severity of damage are considered variables. The proposed technique was validated through a simulation of damage detection for a cold-formed steel beam structure example.

scholarly journals Damage Detection in a Steel Beam Based on an Impact-Acoustics Approach

2018 ◽  
Vol 23 (No 3, September 2018) ◽  
pp. 327-331
Keyword(s):  
Damage Detection ◽  
Damage Identification ◽  
Impact Force ◽  
Detection System ◽  
Steel Beam ◽  
Acoustic Detection ◽  
Beam Structure ◽  
Acoustic Signatures ◽  
The Impact ◽  
Non Destructive

Vibration and acoustics travel through a structure under the action of an impact force at a position on that structure. The acoustic detection system comprises either an accelerometer or a microphone to capture the acoustic signatures of the vibrations. Both signatures can be simultaneously collected by an impact hammer test and are analysed by this non-destructive test to obtain more reliable results than those of a single signature. This work investigates the damage identification of the beam structure based on the experimental data collected from the impact hammer test using an accelerometer and a microphone. The damage detection experiment on a steel beam illustrates the reliability of the defect detection using the simultaneous measurements by two sensors.

Elimination of outlier measurements for damage detection of structures under changing environmental conditions

2021 ◽  
pp. 147592172199847
Author(s):  
William Soo Lon Wah ◽  
Yining Xia
Keyword(s):  
Damage Detection ◽  
Multiple Regression ◽  
Natural Frequencies ◽  
Detection Method ◽  
Detection Methods ◽  
Structure Model ◽  
Bridge Structure ◽  
Beam Structure ◽  
Dependent Variables ◽  
The Difference

Damage detection methods developed in the literature are affected by the presence of outlier measurements. These measurements can prevent small levels of damage to be detected. Therefore, a method to eliminate the effects of outlier measurements is proposed in this article. The method uses the difference in fits to examine how deleting an observation affects the predicted value of a model. This allows the observations that have a large influence on the model created, to be identified. These observations are the outlier measurements and they are eliminated from the database before the application of damage detection methods. Eliminating the outliers before the application of damage detection methods allows the normal procedures to detect damage, to be implemented. A multiple-regression-based damage detection method, which uses the natural frequencies as both the independent and dependent variables, is also developed in this article. A beam structure model and an experimental wooden bridge structure are analysed using the multiple-regression-based damage detection method with and without the application of the method proposed to eliminate the effects of outliers. The results obtained demonstrate that smaller levels of damage can be detected when the effects of outlier measurements are eliminated using the method proposed in this article.

Local buckling capacity of C-shaped cold-formed steel sections with punched webs

1984 ◽  
Vol 11 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Robert Loov
Keyword(s):  
Local Buckling ◽  
Effective Width ◽  
Test Results ◽  
Average Yield ◽  
Steel Sections ◽  
Load Tests ◽  
Cold Formed Steel ◽  
Stub Column ◽  
Best Fit ◽  
The Web

Load tests were carried out on 36 stub column samples of cold-formed steel studs having 38.1 mm wide × 44.5 mm long holes punched through their webs, steel thicknesses of 1.21–2.01 mm, and overall section depths of 63–204 mm. Based on these tests a best-fit equation for the effective width of the unstiffened portion of the web beside the holes has been developed. Suggested design equations have been proposed. The test results support the present equation for the average yield stress [Formula: see text] in Canadian Standards Association Standard S136-1974 but the present code equations for unstiffened plates are unduly conservative when applied to the design of the web adjacent to openings of the size considered.

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.

Experimental Study on Mechanical Behavior of Cold-Formed Steel Three Limbs Built-up Section Members

2010 ◽  
Vol 163-167 ◽  
pp. 651-654
Author(s):  
Tian Hua Zhou ◽  
Shao Feng Nie ◽  
Xiang Bin Liu ◽  
Guang Yi Li
Keyword(s):  
Experimental Study ◽  
Mechanical Behavior ◽  
Axial Compression ◽  
Local Buckling ◽  
Distortional Buckling ◽  
Torsional Buckling ◽  
Failure Characteristics ◽  
Compression Load ◽  
Cold Formed Steel ◽  
Flexural Torsional Buckling

18 specimens of cold-formed steel three limbs built-up section members are tested under axial compression load in this paper. The section forms are divided into two categories: A and B. Load-displacement (P-Δ) curves and failure characteristics of specimens are obtained. The results show that: As to section A members, the failure characteristics of LC, MC and SC series of specimens are flexural-torsional buckling, torsional buckling and distortional buckling, local buckling and distortional buckling. As to section B members, the failure characteristics of LC, MC series of specimens are flexural buckling, while local buckling and distortional buckling for members of SC series.

scholarly journals Comparação entre a eficiência estrutural de perfis soldados de aço e perfis de aço formados a frio

2016 ◽  
Vol 12 (3) ◽  
Author(s):  
Uiatan Aguiar Nogueira ◽  
Matilde Batista Melo ◽  
Daniel De Lima Araujo
Keyword(s):  
Bending Strength ◽  
Steel Beams ◽  
Steel Beam ◽  
Structural Elements ◽  
Structural System ◽  
Welded Steel ◽  
Bending Tests ◽  
Structural Efficiency ◽  
Cold Formed Steel

RESUMO: A Análise de elementos estruturais, realizadas durante as etapas de projeto de uma estrutura, é parte fundamental para garantia de bom desempenho e estabilidade do sistema estrutural. Na execução de algumas estruturas, como as coberturas em edificações, é usual o emprego de perfis leves de aço formados a frio devido ao seu baixo peso. Esta pesquisa tem por objetivo avaliar a eficiência estrutural desses perfis quando comparados, por exemplo, aos perfis soldados compactos. Para tanto, foram realizados ensaios de flexão em quatro vigas biapoiadas submetidas a duas forças concentradas, de forma a se obter flexão pura no meio do vão das vigas. Estas foram instrumentadas para a determinação da sua rigidez e da sua resistência à flexão. A principal contribuição deste trabalho é demonstrar a eficiência estrutural de perfis formados a frio em seção caixa submetidos à flexão em comparação com perfis de seção tipo “H” soldados. ABSTRACT: The analysis of structural elements, in a structure’s design, is an essential step to ensure good performance and stability of the structural system. In any types of structures, such as roofing in buildings, it’s usual using cold-formed steel beams due to their small weight. This research seeks to evaluate the structural efficiency of cold-formed steel beams when compared, for example, to compact welded steel beams. Thus, bending tests were performed in four simply supported beams submitted to two concentrated loads, in order to obtain pure flexure at the mid-span of the beams. These beams were instrumented for the determination of their rigidity and bending strength. The results showed that the cold-formed steel beam, box-shaped, presented structural efficiency similar to the welded steel beam “H” shaped.

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