scholarly journals Equivalent Geometric Imperfections for Local Buckling of Slender Box-section Columns

2021 ◽  
Author(s):  
Mohammad Radwan ◽  
Balázs Kövesdi
Keyword(s):  
Parametric Study ◽  
Local Buckling ◽  
Special Role ◽  
Geometric Imperfections ◽  
Geometric Imperfection ◽  
Box Section ◽  
Buckling Resistance ◽  
Pure Compression ◽  
Design Calculations ◽  
Numerical Parametric Study

Determining the plate or the local buckling resistance is highly important in designing steel buildings and bridges. The EN 1993-1-5Annex C provides a FEM-based design approach to calculate the buckling resistance based on numerical design calculations (geometrical and material nonlinear analysis - GMNIA). Within the GMNIA analysis-based stability design, the application of the imperfections has a special role. Thus, the applicability of the EN 1993-1-5 based buckling curve (Winter curve) has been questioned for pure compression, and previous investigations showed the buckling curve of EN 1993-1-5 Annex B is more appropriate for the design of slender box-section columns subjected to pure compression, the magnitude of the equivalent geometric imperfection to be applied in numerical models for local buckling is also questioned and investigated by the authors within the current paper. The aim of the current research program is to investigate the necessary equivalent geometric imperfections to be applied in FEM-based design calculations using GMNIA calculations. A numerical parametric study is executed to investigate the imperfection sensitivity of box-section columns having different local slenderness. The necessary imperfection magnitudes are determined to each analyzed geometry leading to the buckling resistance predicted by the standardized buckling curves. Based on the numerical parametric study, a proposal for the applicable equivalent geometric imperfection magnitude is developed, which conforms to the plate buckling curves of the EN 1993-1-5 and giving an improvement proposal to the local buckling imperfection magnitudes of the prEN 1993-1-14, which is currently under development.

scholarly journals Interactive Buckling of Q420 Welded Circular Tubes under Axial Compression

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Bin Huang ◽  
Zhou Che Hong
Keyword(s):  
Residual Stresses ◽  
Axial Compression ◽  
Test Data ◽  
Local Buckling ◽  
Ultimate Capacity ◽  
Geometric Imperfection ◽  
Circular Tubes ◽  
Limit Value ◽  
Buckling Resistance ◽  
Interactive Buckling

Finite element models (FE models) of high-strength steel Q420 (yield strength 420 MPa) circular tubes considering residual stresses and local and overall geometric imperfections were established and verified against existing test data. Based on parameter analysis, it was derived that the reduction of ultimate capacity resulting from residual stresses was up to 11.8%. When slenderness ratio was larger than 25, the effect of overall geometric imperfection played a major role compared with that of local geometric imperfection, which resulted in the reduction of the ultimate capacity of about 11.5%. Through tracking the failure process, it was found that, in the initial stage of loading, the deformation of columns mainly presents overall bending. When the load increased near the ultimate load, local buckling occurred and the bearing capacity decreased rapidly. The D/t limit value 27 was determined for preventing the local buckling, and the overall slenderness λl limit value 40 was proposed to distinguish whether local buckling occurs. Based on the FEM result and test data, the applicability of ASCE48-05 and AS4100 for local buckling resistance was evaluated. Continuing the result of stub columns, curve a in GB50017-2017 and in Eurocode 3 of the overall buckling factor φ was proposed to be used in EWM and DSM for estimating the interactive buckling resistance of circular tubes of Q420 under axial compression.

Parametric Study on the Effect of Geometric Imperfections on the Bending Capacity of High-Strength Linepipes

2008 ◽  
Author(s):  
Takashi Sato ◽  
Yoshiki Mikami ◽  
Masahito Mochizuki ◽  
Nobuhisa Suzuki ◽  
Masao Toyoda
Keyword(s):  
Internal Pressure ◽  
Parametric Study ◽  
High Strength ◽  
Yield Ratio ◽  
Experimental Results ◽  
Material Strength ◽  
Empirical Formulas ◽  
Geometric Imperfections ◽  
Geometric Imperfection ◽  
Bending Capacity

It is important to determine the bending capacity of linepipes for strain-based design. Several empirical formulas have been proposed in order to evaluate the bending capacity of linepipes, which are presented in terms of the D/t ratio, the internal pressure, the yield ratio and the material strength. FEAs considering these parameters have been performed, however, it has been reported that the results do not always agree with experimental results. It has already been clarified that the geometric imperfections must be considered so that two types of results agree. This paper presents the results of a parametric study examining the effect of geometric imperfections on the bending capacity of linepipes. In addition, the effect of combining two or all of three types of geometric imperfections on the bending capacity was also investigated. When a single imperfection was taken into consideration in the FE models, it was quantitatively clarified that the bending capacity of linepipes improves with a decreasing geometric imperfection. Moreover, when combined geometric imperfections were taken into consideration in the FE models, it was also clarified that the largest imperfection tends to dominate the results and the smallest imperfection does not necessarily affect the bending capacity of the linepipes.

Effects of the Initial Geometric Imperfections on the Buckling Behavior of High-Strength UOE Manufactured Steel Pipes

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Muntaseer Kainat ◽  
Meng Lin ◽  
J. J. Roger Cheng ◽  
Michael Martens ◽  
Samer Adeeb
Keyword(s):  
High Strength ◽  
Sensitivity Study ◽  
Element Analysis ◽  
Geometric Imperfections ◽  
Geometric Imperfection ◽  
Steel Pipes ◽  
Buckling Behavior ◽  
Measurement Results ◽  
Buckling Resistance ◽  
Initial Geometric Imperfections

The effects of the initial geometric imperfections on the buckling response of grade X-100 UOE manufactured pipes are studied through finite element analysis (FEA). The initial geometric imperfections had been previously measured and quantified in terms of deviations in outside radius (OR) and wall thickness. The measurement results are used to develop imperfection models to be incorporated into buckling analysis. The OR deviation is seen to have insignificant effects on the buckling behavior, while the effects of thickness deviation are seen to be profound for both unpressurized and pressurized pipes. The geometric imperfection models are further investigated through a sensitivity study to isolate the most influential imperfection aspects on the buckling resistance of UOE pipes. A parametric study is carried out using these models and shows that excluding geometric imperfections will always result in overprediction of buckling capacity irrespective of D/t ratios.

scholarly journals Influence of Geometric Imperfections on Buckling Resistance of Reinforcing Bars during Inelastic Deformation

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3473
Author(s):  
Jacek Korentz
Keyword(s):  
Inelastic Deformation ◽  
Initial Deformation ◽  
Radius Of Curvature ◽  
Reinforcing Bars ◽  
Shear Forces ◽  
Geometric Imperfections ◽  
Geometric Imperfection ◽  
Buckling Resistance ◽  
Main Factors ◽  
Very High

This paper presents the results of numerical simulations on three main factors and their influence on the buckling resistance of reinforcing bars and on their behaviour in the range of postcritical deformations. These three factors are the shape of initial deformation, the amplitude of geometric imperfection and the slenderness of bars. The analysis was made of bars fixed on both sides for three initial shapes of deformation between adjacent stirrups, four amplitudes of geometric imperfections and eight bar slendernesses. The results of the numerical analyses carried out showed that the factors analysed have a very high influence on the inelastic buckling of the bars. The initial deformation shape, the radius of curvature and the slenderness of the bars have a significant influence on the buckling resistance of these bars and their longitudinal and transverse deformations. The research demonstrates that bars which are bent or compressed initially have a smaller resistance to buckling compared to straight bars, as the amplitude of geometric imperfections increases and the slenderness of the members increases. However, for the deformation shape of the bars, which is accompanied by shear forces, the drop in the buckling resistance of the members is small, and resistance to buckling for items with a small slenderness was higher than that of straight bars.

Elastic Averaging in Flexure Mechanisms: A Muliti-Beam Parallelogram Flexure Case-Study

2006 ◽  
Author(s):  
Shorya Awtar ◽  
Edip Sevincer
Keyword(s):  
Mechanism Design ◽  
Parametric Model ◽  
Nonlinear Load ◽  
Geometric Imperfections ◽  
Geometric Imperfection ◽  
Flexure Mechanism ◽  
Important Concern ◽  
Proposed Model ◽  
Geometric Arrangements

Over-constraint is an important concern in mechanism design because it can lead to a loss in desired mobility. In distributed-compliance flexure mechanisms, this problem is alleviated due to the phenomenon of elastic averaging, thus enabling performance-enhancing geometric arrangements that are otherwise unrealizable. The principle of elastic averaging is illustrated in this paper by means of a multi-beam parallelogram flexure mechanism. In a lumped-compliance configuration, this mechanism is prone to over-constraint in the presence of nominal manufacturing and assembly errors. However, with an increasing degree of distributed-compliance, the mechanism is shown to become more tolerant to such geometric imperfections. The nonlinear load-stiffening and elasto-kinematic effects in the constituent beams have an important role to play in the over-constraint and elastic averaging characteristics of this mechanism. Therefore, a parametric model that incorporates these nonlinearities is utilized in predicting the influence of a representative geometric imperfection on the primary motion stiffness of the mechanism. The proposed model utilizes a beam generalization so that varying degrees of distributed compliance are captured using a single geometric parameter.

Local buckling behaviour of high strength steel welded box-section columns under axial compression

2022 ◽  
Vol 171 ◽  
pp. 108677
Author(s):  
Bing Li ◽  
Chao Cheng ◽  
Zhimin Song ◽  
Xianlei Cao ◽  
Zhengyi Kong
Keyword(s):  
Axial Compression ◽  
High Strength Steel ◽  
Local Buckling ◽  
High Strength ◽  
Box Section

Remaining Local Buckling Resistance of Corroded Pipelines

2010 ◽  
Author(s):  
Qishi Chen ◽  
Heng Aik Khoo ◽  
Roger Cheng ◽  
Joe Zhou
Keyword(s):  
Finite Element ◽  
Wall Thickness ◽  
Phase 1 ◽  
Compressive Strain ◽  
Research Work ◽  
Local Buckling ◽  
Model Verification ◽  
Metal Loss ◽  
General Corrosion ◽  
Buckling Resistance

This paper describes a multi-year PRCI research program that investigated the local buckling (or wrinkling) of onshore pipelines with metal-loss corrosion. The dependence of local buckling resistance on wall thickness suggests that metal-loss defects will considerably reduce such resistance. Due to the lack of experimental data, overly conservative assumptions such as a uniform wall thickness reduction over the entire pipe circumference based on the defect depth have been used in practice. The objective of this research work was to develop local buckling criteria for pipelines with corrosion defects. The work related to local buckling was carried out in three phases by C-FER and the University of Alberta. The first phase included a comprehensive finite element analysis to evaluate the influence of various corrosion defect features and to rank key parameters. Based on the outcome of Phase 1 work, a test matrix was developed and ten full-scale tests were carried out in Phase 2 to collect data for model verification. In Phase 3, over 150 parametric cases were analyzed using finite element models to develop assessment criteria for maximum moment and compressive strain limit. Each criterion includes a set of partial safety factors that were calibrated to meet target reliabilities selected based on recent research related to pipeline code development. The proposed criteria were applied to in-service pipeline examples with general corrosion features to estimate the remaining load-carrying capacity and to assess the conservatism of current practice.

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