A comparative study has been done to analyze the behavior of regular steel building structures of 4, 6, 8 and 10
stories, located in seismic zone 5 and soil type S1. The structures were upgraded with different brace configurations according
to current Venezuelan codes. A total number of 24 numerical models were analyzed considering non-linear static
and incremental dynamic analysis (IDA). The buildings were initially designed as moment resisting frames, and upgraded
with six different bracing configurations: concentric braces in “X” and inverted “V”; eccentric braces inverted "V" with
horizontal links, inverted “Y” and “X” with vertical links. Short length links were used to ensure a shear failure.
The used methodology is based on obtaining the capacity, IDA curves, and bilinear approximations of these curves that
allow the determination of yield and ultimate capacity points, in order to estimate important parameters of seismic response:
overstrength and ductility; and considering these areas under the curves to estimate elastic deformation energy,
energy dissipated by hysteretic damping and equivalent damping.
According to the results, the cases with no brace enhancement showed the lowest lateral strength and lateral stiffness and
high deformation capacity. On the other hand, the concentric bracing cases, resulted with the highest stiffness and strength
and the lowest deformation capacity, therefore they have low ductility and energy dissipation capacity under seismic loading.
Structures with links showed intermediate stiffness and strengths, resulting in the best performance in terms of ductility
and energy dissipation capacity. The present study provides a better understanding of the benefits of eccentrically
braced systems.
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