Resumen

Lateral distortional buckling (LDB) of I-beams is characterized by simultaneous lateral deflection, twist and cross section change due to web distortion. The present study investigates the effect of web distortion in LDB resistance of doubly-symmetric welded I-beams. Elastic stability and physical and geometrical nonlinear analyses are performed, using GBTul and ABAQUS softwares, respectively. The numerical model is calibrated considering experimental tests. The beams are simply supported, with fork supports at the ends, and subject to neutral and destabilizing effects of loading. The beams are subject to uniform bending, mid-span concentrated load and uniformly distributed loads. The parametric study is performed by varying the geometric cross section parameters. The results are compared with international standards and analytical procedures. It is concluded that the occurrence of LDB is responsible for the resistance reduction, especially for the slender web sections. With the elastic stability analysis, it is possible to estimate the critical moment for the calculation of the ultimate moment considering the LDB. It is found that there is no need to propose a new solution for the determination of LDB resistance, since some procedures allow the use of the elastic stability analysis response for the calculation of the ultimate moment, such as EC3. However, some adjustments can be made to the ANSI/AISC 360–16 and AS 4100: 1998 standards, since the results compared to these procedures are not conservative.

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Resumo

Lateral distortional buckling (LDB) of I-beams is characterized by simultaneous lateral deflection, twist and cross section change due to web distortion. The present study investigates the effect of web distortion in LDB resistance of doubly-symmetric welded I-beams. Elastic stability and physical and geometrical nonlinear analyses are performed, using GBTul and ABAQUS softwares, respectively. The numerical model is calibrated considering experimental tests. The beams are simply supported, with fork supports at the ends, and subject to neutral and destabilizing effects of loading. The beams are subject to uniform bending, mid-span concentrated load and uniformly distributed loads. The parametric study is performed by varying the geometric cross section parameters. The results are compared with international standards and analytical procedures. It is concluded that the occurrence of LDB is responsible for the resistance reduction, especially for the slender web sections. With the elastic stability analysis, it is possible to estimate the critical moment for the calculation of the ultimate moment considering the LDB. It is found that there is no need to propose a new solution for the determination of LDB resistance, since some procedures allow the use of the elastic stability analysis response for the calculation of the ultimate moment, such as EC3. However, some adjustments can be made to the ANSI/AISC 360–16 and AS 4100: 1998 standards, since the results compared to these procedures are not conservative.

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