# Overview of FEM-Based Resistance Models for Local Buckling of Welded Steel Box Section Columns
## 6 Conclusions  
After an extensive literature review, 124 sets of experimental data on local buckling failure in square-welded box sections were collected. These test results formed the basis for a detailed verification and validation process of an advance computational model that incorporated the main factors contributing to the decrement of ultimate resistance in welded thin-walled sections. These factors include residual stress distribution patterns and geometric imperfections. Based on the comparison of the test results and the advanced numerical model, the accuracy of each residual stress and geometric imperfection models were  
Figure 15: Local buckling curve comparison based on models of [4] and [6].  
evaluated from the local buckling resistance point of view. The best performing geometric imperfection model was developed in this research and is shown by Equation (19), building upon the proposal presented by [PERSON] et al. [50]. For residual stresses pattern generated during the manufacturing process the best performing model is the model presented by [PERSON] et al. [20].  
After identifying the most accurate numerical model, a numerical parametric study was conducted to analyze the local buckling resistance of welded box section columns. The resistances were compared to different analytical design approaches, which were evaluated by the obtained results. Numerical calculations prove the following:  
* The best analytical approach closest to the calculated data points obtained by the most accurate numerical model was the buckling curve proposed by [PERSON] [6];
* The buckling curve given by Anne B of EN 1993-1-5 [4] leads to safe side resistances, especially for very slender plates;
* The Winter-type buckling curve would overestimate the buckling resistance for the welded box section columns, as proven by previous research results as well.  
Based on the current investigations, proposal can be given to designers to use the buckling curve given in the Annex B of EN 1993-1-5 [4] within the design process by calculating the local buckling resistance of slender welded box section columns. Other conclusions and design proposals is, if direct resistance check is used in the design process by calculating the local buckling resistance with numerical model, residual stresses and geometric imperfections should be selected properly; thus, they can have a significant impact on the obtained buckling resistance. The given overview can help to select the most appropriate models for the design purposes.  
The current study analyzed only welded box section columns where the failure mode was pure local buckling, eliminating any global flexural buckling failure. All the analyzed cross-sections were sensitive to local plate buckling, so they belong to class 4 cross-sections according to EN 1993-1-1 [54]. Another limitation of the current research program is that cross-section widths varied between 70 and 700 mm and plate thicknesses between 1 and 14 mm were analyzed. This was the investigation range within the current study.  
I.Q.: conceptualization, methodology, software, validation, data curation, formal analysis, writing--original draft preparation, writing--review and editing, visualization; B.S.: conceptualization, validation, writing--review and editing, supervision, project administration; B.K.: conceptualization, methodology, writing--review and editing, supervision, project administration, funding acquisition. All authors have read and agreed to the published version of the manuscript.  
The presented research program has been financially supported by the Grant MTA-BME Lendulet LP2021-06/2021 \"Theory of new generation steel bridges\" program of the Hungarian Academy of Sciences, which is gratefully acknowledged.  
Not applicable.  
Data Availability Statement: Data will be made available on request. The data are not publicly available due to privacy.  
The authors declare no conflicts of interest.