1- Faculty of Civil Engineering, Semnan University, Semnan, Iran
2- Assistant Professor , rvahdani@semnan.ac.ir
3- Associate Professor
Abstract: (495 Views)
Although conventional earthquake-resistant systems such as moment frames and braced frames meet the requirements for the safety of a structure when an earthquake occurs, these systems have not guaranteed the prevention of damage to the structure after an earthquake occurs. So that sometimes the repair of some structures seems uneconomic due to these serious damages. Repairing the damage caused by the earthquake was expensive and caused business interruption. A highly effective solution in the new generation of seismic resistance is self-centering systems that eliminate and limit residual drift. The self-centering system's key features affected how the system behaves during earthquakes. The first crucial feature is the amount of post-tensioning (PT) force, which is often used for the standing position after the earthquake. Another one that is played the important role in the behavior of the self-centering system is the energy dissipater element. Employing the damper as a replaceable and cost-effective tool and fuse in self-centering frames to improve energy absorption and damping of structural systems under earthquakes has been considered. A system that can restore the structure to its original state after applying earthquake loads is necessary to minimize damage. Self-centering systems are elements that have the ability to minimize the residual drifts while enduring earthquakes of great intensity.
In this study, flexural damper as an energy dissipator system is employed in the self-centering steel moment frame connections to improve energy absorption, post yielding stiffness, and is easily replaceable after the earthquake. Moreover, providing the sufficient stiffness, strength, and ductility, while reducing permanent deformations in the self-centering steel moment frames subjected to seismic loading have been deliberated. In this paper, after validating the results from the FE model with the prior experimental PT connection, the behavior of the self-centering connection with the flexural damper has been analyzed. In the FE modeling, the geometric and material nonlinearities and preloading strands are contemplated in the modeling. Gap opening and closing action beside contact and sliding phenomena are involved in the models. To achieve this goal, a large-scale experimental test program of analyzed and designed models using the finite element method has been planned. Changing the height of the beam has a great effect on the performance of the moment capacity of self-centering connection. This issue has been tested much less in the experiments and researches carried out until today, but the numerical studies have confirmed this issue. In this research, the change in beam height has been evaluated as one of the main factors in the experiments. According to the test results, the beam and column remained in the elastic range. Also the damage is accumulated in the damper. Flexural dampers can enhance the post-yield stiffness and energy absorption of SF-MRF frames, while maintaining minimal permanent deformation at particular damper thicknesses. The obtained results show that in addition to reducing the residual drift to less than 0.5%, the effective energy the dissipation ratio, β, is also improved to 0.25%. Also, this improvement in the seismic performance of self-centering connection with the flexural damper has been achieved with an acceptable ratio of the moment capacity to the beam plastic moment capacity.
Article Type:
Original Research |
Subject:
Earthquake Received: 2023/09/1 | Accepted: 2024/02/28 | Published: 2024/08/31