On the Use of Shell Finite Element Analysis to Assess the Local Buckling and Post-Buckling Behaviour of Cold-Formed Steel Thin-Walled Members

Author(s):  
Pedro B. Dinis ◽  
Dinar Camotim
2015 ◽  
Vol 9 (1) ◽  
pp. 724-735
Author(s):  
Bo Cheng ◽  
Zhenyu Wu

This paper presents a finite element analysis on the tensile stiffness of steel bolted connections which are fabricated from thin-walled cold-formed steel strips and their members. This type of bolted connection is usually used to assemble the diagonal bracing member in the light steel structure. Unlike the architectural steel structure, thin walled steel bolted connection cannot be simplified into a hinge joint due to the weak tensile stiffness of connection. The calculation of tensile stiffness of bolted connection is necessary to accurately evaluate the effectiveness of bracing system in the coldformed steel structure. Based on the existing test results and analysis results, finite element (FE) models with threedimensional solid elements were established to investigate the tensile stiffness of bolted connections between cold-formed steel plates under shear. The analysis with non-linear material and contact elements was carried out in order to predict the load-displacement relationships of bolted connections. Furthermore, a parametric study on single-bolted or two-bolted connections with different configurations was performed to study the relationship of connection tensile stiffness and structural parameters such as bolt diameter, plate thickness and steel yield strength. According to the stiffness results obtained from parametric study, six calculating equations for practical design of cold-formed steel bolted connection have been proposed. The calculation results of the stiffness equations are in a good correlation with those of FE analysis, and the proposed equations have been found to provide estimates of tensile stiffness of bolted connections with reasonable accuracy.


2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Yanli Guo ◽  
Xingyou Yao

The objective of this paper is to investigate the buckling behavior and to present the design method of the ultimate strength in the basic effective width method (EWM) for cold-formed steel (CFS) lipped channel stud columns with holes in the web. 28 column tests were conducted under axial compression on the CFS lipped channel stud columns with circular and rectangular holes in different dimensions of cross sections and holes. The tested stud columns included 4 members without holes, 12 members with circular holes, and 12 members with rectangular holes. The test results showed that the stud columns with holes were governed by local buckling or the interaction of local buckling and distortional buckling. Compared with the stud columns without holes, the small hole had a slight influence on the ultimate strength of the tested specimens, and the large hole had a great effect on the ultimate strength of the tested specimens. The load capacities of the specimens decreased with the increase of the dimension of holes. Then, the finite element analysis was carried out to simulate the tested stud columns. The finite element analysis results showed good agreement with the experimental results about buckling modes and ultimate strengths, which indicated that it is feasible to analyze this kind of stud columns with holes by using the finite element method (FEM). Finally, the proposed effective width method was used to predict the ultimate strengths of stud columns with holes based on the proposed buckling coefficient formulas of the plate with holes. The comparison between calculated results and test and finite element results indicated that the proposed EWM is feasible and accurate to predict the ultimate strength of the CFS lipped channel stud columns with holes in the web.


2019 ◽  
Author(s):  
Miguel Abambres ◽  
Dinar Camotim ◽  
Miguel Abambres

A 2nd order inelastic Generalised Beam Theory (GBT) formulation based on the J2 flow theory is proposed, being a promising alternative to the shell finite element method. Its application is illustrated for an I-section beam and a lipped-C column. GBT results were validated against ABAQUS, namely concerning equilibrium paths, deformed configurations, and displacement profiles. It was concluded that the GBT modal nature allows (i) precise results with only 22% of the number of dof required in ABAQUS, as well as (ii) the understanding (by means of modal participation diagrams) of the behavioral mechanics in any elastoplastic stage of member deformation .


2017 ◽  
Vol 11 (1) ◽  
pp. 244-257 ◽  
Author(s):  
Xingyou Yao

Background: Cold-formed steel structural sections used in the walls of residential buildings and agricultural facilities are commonly C-shaped sections with web holes. These holes located in the web of sections can alter the elastic stiffness and the ultimate strength of a structural member. The objective of this paper is to study the buckling mode and load-carrying capacity of cold-formed thin-walled steel column with slotted web holes. Methods: Compression tests were conducted on 26 intermediate length columns with and without holes. The tested compressive members included four different kinds of holes. For each specimen, a shell finite element Eigen-buckling analysis and nonlinear analysis were also conducted. The influence of the slotted web hole on local and distortional buckling response had also been studied. The comparison on ultimate strength between test results and calculated results using Chinese cold-formed steel specification GB50018-2002, North American cold-formed steel specification AISI S100-2016, and nonlinear Finite Element method was made. Result: Test results showed that the distortional buckling occurred for intermediate columns with slotted holes and the ultimate strength of columns with holes was less than that of columns without holes. The ultimate strength of columns decreased with the increase in transverse width of hole in the cross-section of member. The Finite element analysis results showed that the web holes could influence on the elastic buckling stress of columns. The shell finite element could be used to model the buckling modes and analysis the ultimate strength of members with slotted web holes. The calculated ultimate strength shows that results predicted with AISI S100-2016 and analyzed using finite element method are close to test results. The calculated results using Chinese code are higher than the test results because Chinese code has no provision to calculate the ultimate strength of members with slotted web holes. Conclusion: The calculated method for cold-formed thin-walled steel columns with slotted web holes are proposed based on effective width method in Chinese code. The results calculated using the proposed method show good agreement with test results and can be used in engineering design for some specific cold-formed steel columns with slotted web holes studied in this paper.


2020 ◽  
Vol 41 (1) ◽  
Author(s):  
Apai Benchaphong ◽  
Rattanasak Hongthong ◽  
Sutera Benchanukrom ◽  
Nirut Konkong

The purpose of this research was to study the behavior of cold-formed steel cantilever truss structures. A cantilever truss structure and bolt-moment connection were tested and verified by the 3D-finite element model. The verification results showed a good correlation between an experimental test and finite element analysis. An analytical method for elastic rotational stiffness of bolt-moment connection was proposed. The equation proposed in the analytical method was used to approximate the elastic rotational stiffness of the bolt group connection, and was also applied to the Richard-Abbott model for generating the nonlinear moment-rotation curve which modeled the semi-rigid connection stiffness. The 2D-finite element analysis was applied to study the behavior of the truss connection, caused by semi-rigid connection stiffness which caused a change of force to the truss elements. The results showed that the force in the structural members increased by between 13.62%-74.32% of the axial forces, and the bending moment decreased by between 33.05%-100%. These results strongly suggest that the semi-rigid connection between cold-formed steel cantilever truss structures should be considered in structural analysis to achieve optimum design, acknowledging this as the real behavior of the structure.


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