Evaluation of the Performance of Box Link Beam with Reduced Section Flange under Cyclic Loading

Previous studies have demonstrated the occurrence of brittle and early stage cracks in the connection between the link beam and the column, specifically in the vicinity of the groove welds  that connect  the flanges of the link beam to the column, when subjected to seismic activity. A similar type of rupture has also been observed in the end-plate connections of the link beam to the external link beam. This research explors the consept of utilizing a box-shaped link beam with a reduced cross-section in the Abaqus finite element software to magnitude the plastic strain demand generated at the flange ends of the box link beam. The objective is to prevent rupture in this specific region. The results indicate that the maximum equivalent plastic strain at the end of the link beam flanges can be reduced by up to 38% for short link beams, up to 41% for intermediate link beams, and up to 68% for long link beams. Consequently, this approach effectively prevents premature ruptures in the area adjacent to the groove weld connecting the beam flange to the end plate. The magnitude of the equivalent plastic strain at the end of the box link beam decreases as parameters "a" and "b" decrease, and parameter "c" (geometric parameters of the reduced cross-section) increases. Parameter "c" exhibits the most significant influence on this parameter, while parameter "b" has the least significant impact. Additionally, the adoption of a reduced cross-section in the box link beam results in an increase of up to 35% in the energy dissipation of the link beam due to enhanced participation of the flanges in energy dissipation for short link beams, up to 158% for intermediate link beams, and up to 250% for long link beams.