In the present research, an attempt was made to improve the behavior of T-stub connections by providing stiffener
details for these joints and then investigating the effect of using the proposed stiffener on the joint with non-rolled tee profiles. In
this regard, five full-scale experimental samples were constructed and tested. The first sample was considered a control sample,
which was designed and manufactured based on the regulations. The next two samples were constructed with rolled tee sections
using proposed stiffeners of different thicknesses. In the next two specimens, the T-stub connection was constructed using the
non-rolled tee sections, and in one of the specimens, the proposed stiffener was used. The tests were performed under quasi
static cyclic loading, and based on their results, the seismic parameters of ultimate strength, effective stiffness, ductility, and
energy dissipation capacity were evaluated. The results of connections with rolled tee sections indicated that the proposed
stiffeners increased ultimate rotational strength by up to 13.8%, effective stiffness by 92%, energy dissipation capacity by 67%,
and ductility by 58%. Adding stiffeners to non-rolled tee sections boosted rotational strength by 12%, stiffness by 117%,
ductility by 59%, and energy dissipation by 62%, significantly improving T-stub connection behavior.
