چكيده به لاتين
In today's world, designing and implementing structures with less vulnerability and damage and easier repair after a severe earthquake is very important and debatable, because severe earthquakes are still the main source of building failures, accidents and human casualties. is considered Unfortunately, despite significant advances in the modern era of research, even now, many existing structures are unable to withstand strong earthquakes. In addition, damage to building structures against severe earthquakes causes permanent changes in them. One of the cost reduction methods is the use of self-centering systems, which In addition to the capability of energy consumption and damage reduction, it imposes less lasting deformations on the structure. These systems create a flag-shaped curve, which is one of the main advantages of using them compared to conventional systems. In general, most self-centering systems include pre-tensioned cables with self-centering properties and also use dampers that cause energy consumption in the system. On the other hand, one of the methods of protecting structures against dynamic loads is to use structures control. In this method, many mechanical tools and equipments are used in order to consume energy. In this research, the self-centering steel bracing frame with the number of 12, 18 and 24 stories, designed using the modified modal superposition method in Rafei et al.'s paper [1], is modeled in the OpenSeespy software. These models are then subjected to gravity, pushover, and time-history analyses with far-field, near-fault without pulse, and near-fault with pulse accelerograms. According to the concept of structural control, the impact of different prestressing levels of the cables on various responses of these models is investigated. Overall, the results indicate that increasing the level of pre-tensioning boosts the capacity of the models by up to 280%, which on average results in a 24% increase in story shear, a 21% increase in story moment, and a 72% increase in story acceleration across all models and ground motions. Additionally, increasing the pre-tensioning level enhances the self-centering ratio and increases the peak stress in the cables, leading to a reduction in the β factor (energy dissipation ratio) to the point where the structure exhibits completely self-centering behavior. Furthermore, the relative residual drifts of the stories and the changes in inter-story drifts are negligible. Since the pre-tensioning of these cables can be adjusted using jacks in these structures, the results of this research can be useful for achieving desirable responses.
