Abstract

In this research, an effort was made to evaluate the structural behavior of high-rise buildings constructed in fields near to seismic sources that have sustained severe fire damage on some floors against the upcoming near-field earthquakes. Then, the seismic rehabilitation of these buildings was conducted using the proposed hybrid friction-elastic damper (with ''SMA'' super-elastic wires) to prepare them to resist future earthquakes. Therefore, high-rise special steel moment-resisting frames were designed for the life-safety performance level versus design-basis earthquake (''DBE''). These frames were then subjected to three fire scenarios in either of the lower, middle, or upper two stories until to collapse outset. Then, a rehabilitation approach, using a hybrid friction-elastic damper, was proposed to improve the seismic performance against future earthquakes as well as to reuse these structures. Moreover, a set of 10 near-field records including directivity effects were applied to these rehabilitated frames at both ''DBE'' and ''MCE'' hazard levels. The nonlinear dynamic analysis was then conducted. The results indicated that the proposed diagonal brace equipped with this simply-conformed damper is able to increase the energy dissipation capacity in the fire story during the possible forthcoming ground motions. It also provides a large hysteretic response with a minimal structural mechanism of damaged beams in that story. The application of this rehabilitation approach, in addition to a significant increase in ductility-stiffness and lateral load resistance, provides a proper elastic capacity in the frames. Accordingly, the global maximum relative displacement of the structure is reduced considerably, and the local interaction points of the critical columns in the fire-exposed frames fall inside the failure envelope. It also leads to a significant reduction in the average bending moment and axial force by 16-70% and 29-57%, respectively, applied to the fire-exposed columns.

Abstract