Comparison and Study on Calculation Methods of Cold-Formed Thin-Walled Lipped Channel Members’ Capacity about Distortional Buckling

2012 ◽  
Vol 256-259 ◽  
pp. 581-587
Author(s):  
Ting Ting Tang ◽  
Jian Yao
Keyword(s):  
Structural Design ◽  
Ultimate Load ◽  
Design Method ◽  
Local Buckling ◽  
Test Results ◽  
Distortional Buckling ◽  
Widespread Application ◽  
Buckling Modes ◽  
Global Buckling ◽  
Comparison And Study

Distortional buckling which is one of the most important buckling modes for cold-formed lipped channel sections as well as local buckling and global buckling may change mechanical properties and decrease the ultimate load of members. This paper reviews research achievements in distortional buckling, compares the existed design methods according to five national (regional) codes and the latest research achievements. Based on the comparison between five calculating data and test results, it is shown that the design method of North American specification has widespread application and relatively high accuracy, which could supply references for structural design.

Using Controlled Global Buckling to Improve Buried Pipelines Performance Under Large Compressive Ground Displacements

2018 ◽  
Author(s):  
Ali Fathi ◽  
Onyekachi Ndubuaku ◽  
Samer Adeeb
Keyword(s):  
Boundary Conditions ◽  
Design Method ◽  
Local Buckling ◽  
Test Results ◽  
Buried Pipelines ◽  
Buckling Mode ◽  
Buried Pipes ◽  
Global Buckling ◽  
Novel Method ◽  
Simulated Field

This paper presents the basic concept and verification tests results of a novel method designed to prevent failures of buried pipelines subjected to compressive deformations which are usually caused by ground movements. In this method the boundary conditions of the buried pipes are modified by installing soft elements next to the pipe before backfilling. With the new boundary conditions, the pipe response under large compressive forces will be in form of a stable global buckling mode with a predefined deformed shape. This behavior prevents rapid increase in the compressive axial force that causes local buckling, wrinkling, and subsequent softening, and strain localization. By using this method, pipes can have an extended compressive hardening response that absorbs large compressive displacements. The evaluation of this concept and its performance level were studied through a series of lab tests on 4-1/2 inch pipe specimens under simulated field conditions. The test results confirmed the anticipated performance of this technique which can evolve into a design method.

scholarly journals Numerical Simulation of Multi-Span Greenhouse Structures

Agriculture ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 499
Author(s):  
María S. Fernández-García ◽  
Pablo Vidal-López ◽  
Desirée Rodríguez-Robles ◽  
José R. Villar-García ◽  
Rafael Agujetas
Keyword(s):  
Matrix Method ◽  
Local Buckling ◽  
External Pressure ◽  
Climatic Conditions ◽  
Wind Loads ◽  
Buckling Modes ◽  
First Order ◽  
Global Buckling ◽  
Computational Fluid Dynamics Cfd ◽  
Buckling Failure

Greenhouses had to be designed to sustain permanent maintenance and crop loads as well as the site-specific climatic conditions, with wind being the most damaging. However, both the structure and foundation are regularly empirically calculated, which could lead to structural inadequacies or cost ineffectiveness. Thus, in this paper, the structural assessment of a multi-tunnel greenhouse was carried out. Firstly, wind loads were assessed through computational fluid dynamics (CFD). Then, the buckling failure mode when either the European Standard (EN) or the CFD wind loads were contemplated was assessed by a finite element method (FEM). Conversely to the EN 13031-1, CFD wind loads generated a suction in the 0–55° region of the first tunnel and a 60% reduction of the external pressure coefficients in the third tunnel was not detected. Moreover, the first-order buckling eigenvalues were reduced (32–57%), which resulted in the need for a different calculation method (i.e., elastoplastic analysis), and global buckling modes similar to local buckling shape were detected. Finally, the foundation was studied by the FEM and a matrix method based on the Wrinkler model. The stresses and deformations arising from the proposed matrix method were conservative compared to those obtained by the FEM.

Optical Measuring Technique for the Investigation of Built-Up Cold-Formed Steel Structural Members

2011 ◽  
Vol 473 ◽  
pp. 343-351 ◽  
Author(s):  
Iveta Georgieva ◽  
Luc Schueremans ◽  
Guido De Roeck ◽  
Lincy Pyl
Keyword(s):  
Local Buckling ◽  
Structural Members ◽  
Distortional Buckling ◽  
Residential Housing ◽  
3D Motion Analysis ◽  
Vertical Displacements ◽  
Global Buckling ◽  
Cold Formed Steel ◽  
Thin Walled ◽  
Displacement Transducers

The construction industry uses cold-formed steel (CFS) sheets in the form of galvanised thin-walled profiles and corrugated sheets. In the past decade, CFS profiles have been competing with their hot-rolled counterparts as primary structural members of industrial halls, office buildings and residential housing of up to 3-4 storeys. The spans and column heights achieved with CFS profiles are ever larger. Due to the large slenderness of these members, adequate strength and stability are necessary, as well as reliability in design. Thin-walled members go through buckling during all stages of their working life. Local buckling appears at loads sometimes much lower than the design load. Distortional buckling seriously reduces the member resistance. It interacts with warping and lateral-torsional buckling, being significant for these asymmetric open sections. To restrict these effects, builders employ double sections - usually two standard cold-formed shapes bolted together to form a built-up section. These sections have the advantages of symmetry, higher stability and strength. The design of built-up members involves many uncertainties - although the European standard includes guidelines on the prediction of local, distortional and global buckling, the partial integrity and interaction between the parts of the composed members is still not studied. To study the actual behaviour, built-up members are tested in bending. An optical device for 3D motion analysis measures the displacement of points of interest on the specimen. Two interacting cameras use parallax to obtain the position of an arbitrary number of reflective markers glued to the specimen. The device tracks the movement of the markers in a 3D coordinate system without any contact with the specimen. Standard displacement transducers measure vertical displacements to validate the results. The paper gives an appraisal of the applicability of the method, a summary of the difficulties faced and the outcome of the test campaign.

Designing Hierarchical IsoTruss Column Based on Controlling Multi-Buckling Behaviors

2021 ◽  
Author(s):  
Changliang Lai ◽  
Qianqian Sui ◽  
Hualin Fan
Keyword(s):  
Finite Element ◽  
Parametric Design ◽  
Local Buckling ◽  
Fe Model ◽  
The Finite Element Method ◽  
Buckling Modes ◽  
Buckling Behavior ◽  
Global Buckling ◽  
Buckling Failure ◽  
Theoretical Analyses

To develop large-span but ultralight lattice truss columns, a hierarchical IsoTruss column (HITC) was proposed. The multi-buckling behavior of the axially compressed HITC was analyzed by the finite element method (FEM) using a parametric approach in the framework of ANSYS parametric design language (APDL). It was demonstrated that the program enables efficient generation of the finite element (FE) model, while facilitating the parametric design of the HITC. Using this program, the effects of helical angles and brace angles on the buckling behavior of the HITC were investigated. Depending on the helical angles and brace angles, the HITCs mainly have three buckling modes: the global buckling, the first-order local buckling and the second-order local buckling. Theoretical multi-buckling models were established to predict the critical buckling loads. Buckling failure maps based on the theoretical analyses were also developed, which can be useful in preliminary design of such structures.

scholarly journals Experimental Study and Proposal to Improve the EWM Design of Cold-Formed Steel Lipped Channel Columns with Circular Holes under Axial Compression

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Xingyou Yao
Keyword(s):  
Circular Hole ◽  
Axial Compression ◽  
Design Method ◽  
Local Buckling ◽  
Effective Width ◽  
Distortional Buckling ◽  
Channel Section ◽  
Circular Holes ◽  
Failure Loads ◽  
Cold Formed Steel

The cold-formed steel (CFS) lipped channel section with circular holes has been widely used in low-rise and multistory building structures as the column. However, the circular hole in the web makes the lipped channel column become susceptible to buckle. A total of 54 CFS lipped channel axial compression columns with and without circular holes were used to study the buckling behavior and the effective width design method. The interaction of the local buckling and the distortional buckling were observed for the short and intermediate columns, while the slender columns were controlled by the interaction of the local buckling, distortional buckling, and flexural buckling or flexural-torsional buckling. The experimental failure loads were gradually decreased with the increase in the diameter of the circular hole for the specimens with the same section. The failure loads of the specimens with two holes were lower than those of the specimens with one hole with same section and same diameter of holes. Then, the experimental results were used to validate a nonlinear finite element model (FEM) previously developed by the authors. The validated FEM was subsequently used to obtain additional 36 numerical failure results concerning the effects of the length, the section, and the diameter and the number of the circular holes. Furthermore, the proposal to calculate the distortional buckling coefficient of the CFS lipped channel section with circular holes were put forward based on numerical analysis considering the reduction of effect of holes. Finally, a proposal to improve the effective width method (EWM) design approach for CFS lipped channel sections with circular holes under axial compression was presented. The comparisons between experimental and numerical capacities and their calculations provided by the proposed EWM design method illustrate a great application of the proposed approach.

scholarly journals Enhancing Stability of Thin-Walled Short Steel Channel Using CFRP under Eccentric Compression

2016 ◽  
Vol 2016 ◽  
pp. 1-11
Author(s):  
Hongyuan Tang ◽  
Canjun Wang ◽  
Ruijiao Wang
Keyword(s):  
Analytical Study ◽  
Ultimate Load ◽  
Load Capacity ◽  
Local Buckling ◽  
Fiber Reinforced Polymer ◽  
Actual Behavior ◽  
Thin Wall ◽  
Ultimate Load Capacity ◽  
Reinforced Polymer ◽  
Global Buckling

This paper presents the experimental and analytical results of eccentrically loaded short cold-formed thin-wall steel channels strengthened with transversely oriented carbon fiber reinforced polymer (CFRP) strips around their web and flange. Seven specimens, each 750 mm long, were fabricated; the main parameters were the number of CFRP plies (one or two) and the space between the CFRP strips (50, 100, or 150 mm). The application of the CFRP strips results in increases in ultimate load capacity and, with the exception of the most heavily reinforced (2 plies at 50 and 100 mm), local buckling was observed prior to global buckling. To extend and better understand the experimental work, a companion analytical study was conducted. Comparisons between experimental observations and computed results show that the analyses provided good correlation to actual behavior. In addition, the numerical results explained the observed phenomenon that flange local buckling was constrained to regions between the CFRP strips.

scholarly journals Experimental study and finite element analysis of energy dissipating outriggers

2016 ◽  
Vol 20 (8) ◽  
pp. 1196-1209 ◽  
Author(s):  
Qingshun Yang ◽  
Xinzheng Lu ◽  
Cheng Yu ◽  
Donglian Gu
Keyword(s):  
Finite Element ◽  
Energy Dissipation ◽  
Local Buckling ◽  
Tall Buildings ◽  
Initial Imperfection ◽  
High Strength ◽  
Test Results ◽  
Element Analysis ◽  
Global Buckling ◽  
Energy Dissipation Capacity

The outriggers are widely adopted in tall and super-tall buildings. Their energy dissipation capacity can significantly influence the nonlinear seismic responses of the entire building structure. Based on an actual tall building project, the structural responses and energy dissipation capacities of three different outriggers were studied through experiments and finite element analyses. The test results of conventional outrigger specimen showed a steep deterioration after peak strength and an unfavorable energy dissipation capacity due to the global buckling of the braces and the local buckling of the chords after flexural yielding. Using buckling-restrained braces and reduced beam sections in a new design of the outriggers, the energy dissipation capacity and the ductility of the outriggers were significantly improved. The yield and peak strengths were further improved with the use of high-strength steel in chords on a third specimen. The finite element simulation of the three specimens indicated that the initial imperfection of the specimens shall be considered, and the developed finite element models yielded good agreements with the test results. The outcome of this work can provide additional references for the application of the outriggers in tall buildings.

scholarly journals Numerical Modeling of Square Steel Members Wrapped by CFRP Composites

2019 ◽  
Vol 8 (10) ◽  
pp. 3082-3087 ◽  
Keyword(s):  
Failure Modes ◽  
Ultimate Load ◽  
Local Buckling ◽  
Axial Loading ◽  
Test Results ◽  
Structural Members ◽  
Cfrp Sheets ◽  
Tubular Columns ◽  
Steel Members ◽  
Strain Behaviour

HSS (Hollow Structural Steel) tubular members used in buildings and bridges for structural application is rapidly developing technique in the recent era. Since, they have many advantages over RC structural members. This paper presents the application of CFRP on HSS tubular members under axial compression. Typical failure occurred during axial loading was local buckling, and this could be reduced by wrapping CFRP sheets around the HSS tubular columns were investigated experimentally. Eight steel samples are used in this test. Among eight specimens, two are unwrapped and the remaining six columns are externally wrapped by CFRP. CFRP sheets are used as strips, and the width of the sheets are constant. The spacing between the CFRP sheets is also constant. All columns are tested in column tester till the maximum to understand their failure modes, Ultimate load, load Vs. Displacement, Stress- Strain behaviour and Ductility index. Finally, results obtained from the experimental investigation could be validated with ANSYS software. The ultimate load and displacements from ANSYS validation are closely match with test results.

scholarly journals Distortional buckling behavior and design method of cold-formed steel lipped channel with rectangular holes under axial compression

2021 ◽  
Vol 18 (5) ◽  
pp. 6239-6261
Author(s):  
Yanli Guo ◽  
◽  
Xingyou Yao ◽  
Keyword(s):  
Parametric Study ◽  
Design Method ◽  
Fe Model ◽  
Building Structures ◽  
Test Results ◽  
Distortional Buckling ◽  
Comparison Results ◽  
Study Results ◽  
Load Carrying ◽  
Cold Formed Steel

<abstract> <p>The use of cold-formed steel (CFS) channel sections with rectangular holes in the web is becoming gradually popular in building structures. However, such holes can result in sections becoming more susceptible to be distortional buckling and display lower load-carrying capacities. This paper presents a total of 44 axially-compressed tests of CFS lipped channel columns with and without rectangular web holes including different hole sizes and cross-sections. The test results show that the specimens were controlled by distortional buckling or interaction of local buckling and distortional buckling. The load-carrying capacities of specimens with rectangular holes were lower than that of specimens without hole. The load-carrying capacities of specimens were gradually decreased with the increasing of dimensions of holes. Then a nonlinear elasto-plastic finite element model (FEM) was developed and the analysis results showed good agreement with the test results. The validated FE model was used to conduct a parametric study involving 16 FEM to investigate the effects of the section, the dimension of the hole, and the number of holes on the ultimate strength of such channels. Furthermore, the formulas to predict the distortional buckling coefficient were developed for the section with holes by using the verified FEM. Finally, the tests and parametric study results were compared against the distortional buckling design strengths calculated in accordance with the developed method. The comparison results show that the proposed design method closely predict the load carrying capacity of CFS channel sections with rectangular web holes.</p> </abstract>

The In-Plane Ultimate Load of I-section Beam-Columns with Slender Web

1997 ◽  
Vol 1 (1) ◽  
pp. 11-22 ◽  
Author(s):  
Qian Gu ◽  
Shaofan Chen
Keyword(s):  
Residual Stresses ◽  
Analytical Method ◽  
Ultimate Load ◽  
Local Buckling ◽  
Test Results ◽  
Buckling Strength ◽  
Beam Columns ◽  
Plate Girders ◽  
Design Formula ◽  
Relationship Of

Similar to plate girders with slender web, a welded I-section beam-column does not fail when its web buckles. To take advantage of this post-local-buckling strength, this paper at first presents a method for calculating the M-P-φ relationship of I-sections with buckled web and residual stresses. The in-plane ultimate load of beam-columns with slender web can then be calculated by using this M-P-φ relationship. Nine eccentrically loaded specimens were tested to failure. The agreement between the calculated and test results confirms the validity of the analytical method. Furthermore, a simplified design formula is presented for predicting the in-plane capacity of beam-columns with slender web.

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