چكيده به لاتين
Conventional bracing systems have issues such as residual deformations after an earthquake, damage to primary structural members, and inelastic deformations in structural elements. Over the years, researchers in structural and earthquake engineering have introduced new structural systems known as pendulum and center-oriented systems. These structures, using various methods, restore the building to its original state after an earthquake, thereby reducing permanent deformations and residual distortions. Furthermore, earthquake-induced damage is limited as much as possible to non-structural and replaceable components, preventing harm to the main structural members.To achieve centrality, prestressed cables can be used either at the center of the bracing span or along the column axes so that, after deformations occur, the structure returns to its original upright position. Similarly, to create pendulum conditions, the bases of the columns can be designed to allow uplift under applied loads. Therefore, in this study, several typical braced structural specimens with different column base conditions and various cable restraint locations along the column axes were examined under the aforementioned conditions. To this end, three-, six-, and nine-story structures were first designed and modeled in ETABS software and then simulated in ABAQUS under the specified conditions to investigate nonlinear seismic behavior. The simulated models were subjected to cyclic and time-history analyses, and the required results were extracted.Based on the obtained results, in configurations with non-liftable (fixed) column bases, the optimal condition was achieved when the prestressed cables extended throughout all floors; in this scenario, the structure’s stiffness, energy absorption, and damping ratio increased compared to other cases. In configurations where the column base is allowed to lift, models with the fewest prestressed floors exhibited the best performance, experiencing lower displacements and shear forces. Due to maintained stiffness and reduced vulnerability, these models demonstrated more stable behavior. Furthermore, time-history analyses indicated that changes in the prestressing pattern have a direct impact on roof displacement and shear forces. Consequently, the optimal design of seismic structures requires a combined approach so that, through the controlled distribution of prestressed cables, a balance is achieved among stiffness, energy dissipation, and resistance to lateral and vertical forces.
