Document Type : Research Article
Authors
1
M.Sc. Graduate, Department of Civil Engineering, Islamic Azad University, South Tehran Branch, Tehran, Iran
2
Associate Professor, Structural Engineering Research Center, International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, IranTehran, Iran
Abstract
Generally, in the analysis and design of buildings, the foundation is assumed to be rigid and the effect that soil subsidence under the foundation and the flexibility of the foundation may have on the response of the structure is not considered. If the interaction between the structure, the foundation and its supporting soil environment significantly changes the actual behavior of the structure compared to the study of the behavior of the structure alone, and one of the most important issues in soil-structure interaction is the Diagrid Rocking motion of the structure.
Examination of the behavior of structures in past earthquakes shows that asymmetric torsion has been one of the causes of severe vulnerabilities. Considering the advantages of modern seismic design methods in which energy dissipation additives such as dampers are used to control the responses in an earthquake, it is possible to control the seismic torsion in the structure. However, recent earthquakes have shown that Steel structures are damaged by earthquakes, making them very difficult and even impossible to repair. For this reason, after relatively severe earthquakes, these buildings have been damaged and destroyed, and in order to reuse the structure, it is necessary to spend a lot of time and money due to the extent of damage to the structure, and this issue creates a new idea to limit damage specific points of the structure. In this way, buildings can be exploited more quickly by replacing damaged elements. One of the new methods to improve the seismic performance of steel buildings is the use of systems that limit damage to the structure. Among these methods, we can mention systems with rocking motion. In these systems, the main building behaves elastically so that the energy absorption and nonlinear performance occur only in certain parts of the building that have been predicted. Therefore, in this study, a new system has been introduced, using the mechanism of Rocking movement in the shear walls of the structure, transmits damage to the structural fuses and makes the steel structure safe during and after earthquake, and very repairable. The systems used in this research include Diagrid structural system considering the interaction of soil and structure on the foundation and its comparison with Diagrid structural system. To better model this new system, first design post-tensioned cables as well as the exact details of the column connections in ABAQUS software are designed considering the connection dimensions for the 12th story. Then, in SAP2000 software, structural members were designed for 12-story and 16-story diagrid structures with rocking motion. The Results show the high performance of rocking motion on the foundation in reducing the stresses distributed in the diagrid structure. Because with the post-tensioned cables, the displacement of the structure is greatly reduced, while in the diagrid structure, with the movement of the Diagrid, the displacement of the structure is increased by 20%, but due to high attenuation, it has good seismic performance. It has been shown because the number of plastic joints in the LS area has reached less than that. The use of a controlled rocking motion system significantly reduces axial force in structural members by about 30 % and retractable cables in the rocking drive system have an effect more than 70 % in reducing the deformation of the structure and then the flow damper is placed.
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