A T-shaped tension member was fabricated by cutting a S355 grade (Fy=355 MPa, Fu=510 MPa) HEA260 section into two as shown below. The member is attached to gusset plates at both ends. The tension member is welded to gusset plates using 400 mm long longitudinal welds. The gusset plate is 20 mm thick and from S235 grade steel (Fy=235 MPa, Fu=360 MPa). Determine φPn by considering all possible limit states according to AISC360-16. In addition, determine the maximum preferred length of this tension member.

Gusset plate (20 mm thick, 350 mm wide) HEA260 350mm , in Gusset plate 400mm long weld