چكيده به لاتين
Traditional Steel Moment Frame systems are one of the most common seismic resisting systems. One of the most common problems in these systems is soft story mechanism.
This research investigates seismic performance of rehabilitated with self centering rocking walls.Rocking systems are a method for decreasing lateral displacement and seisemic forces.This systems are usually implemented as concrete shear walls not connected in base that helps it to rock in base.
Researches show that use of this rocking walls reduces story drifts, causes uniformity of story drifts and prevents soft story mechanism. In this research, an attempt has been made to study the linear and nonlinear behavior of rocking walls with a precise modeling. Also, the post- tensioned cables connected to the wall and its effect on the residual displacement are examined.
In these models, concrete rocking walls with different stiffnesses and heights are connected to 3-story, 6-story and 9-story buildings with a steel moment frame system whose pinned in base.
After IDA analysis of these structures under 14 records and preparing fragility curves, the probability of failure of these structures was compared with the probability of failure of the steel bending frame fixed and pinned in base without rocking wall. Also, the residual displacement of the roof and the internal forces of the rocking wall sections were compared. Eenentually, the results obtained in this study are as follows:
1- The results of comparing fragility curves show that the use of rocking walls to rehabilitate the pinned base moment frame structures Significantly reduces the failure probability of these structures, especially in Extensive and Complete failure level.
2-The higher the stiffness of the walls and the higher their height, the more the shape of the fragility curves becomes dormant.
3-In 6 and 9 storey buildings, in order to control the residual displacement, the secondary stiffness of the rocking walls should be at least more than 5% of the initial stiffness.
4-The internal forces of the rocking walls show that as the stiffness of the walls increases, the internal forces of the rocking sections also increase.
5-In 6- and 9-story buildings, the higher height of the walls, the better results in terms of the probability of failure, However, an examination of the internal forces of the walls shows that the higher the height of the walls, the higher the effect of the higher modes, and the greater the internal forces of the walls. Also, increasing the height of the rocking walls increases the implementation difficulty of these walls. Therefore, in structures where we do not expect a very low probability of failure, rocking walls can be cut on the lower floors and not continue till roof of the building.
