چكيده لاتين
Yielding metal dampers are one of the most common types of passive control devices. These dampers dissipate energy by entering to the plastic area. Several researchers have proposed different types of yielding dampers. In this research, a type of yielding damper has been introduced under the title of tubular yielding damper with torsional behavior. This damper can be used in Chevron bracing frame. Due to the presence of pure torsion in the steel shaft as a yielding member, the energy dissipation capacity of the damper is significant. This issue makes optimal use of the capacity of the shafts. At first, an experimental specimen was made to investigate the behavior of the proposed damper and has been tested using cyclic loading according to FEMA-461 regulations. The maximum displacement considered in this loading protocol is seven cm, corresponding to the non-linear drift of the floor in a typical building frame. The test results showed a stable behavior, adequate energy absorption capacity and remarkable ductility. Due to the fact that steel has the property of cyclic hardening, the capacity of the damper increased in each cycle compared to its previous cycle. The yield force of this damper was 809.78 kg and the maximum force recorded in the hysteresis curve of the first test was 1321.954 kg. The equivalent viscous damping ratio in the last loop of the force-displacement curve obtained from the experimental results was 35.63%. According to the presence of the equivalent viscous damping ratio from the initial cycles in the force-displacement curve of the damper, the action of energy consumption from the initial vibrations of the earthquake is performed by the damper. Then, with the help of tension test, the stress-strain curve and the elastic modulus of the used shaft were obtained. After modeling a numerical model in the finite element software, and verifying it using experimental outcomes, various parameters affecting the behavior of the damper were analyzed with the help of 15 software models. The results showed that the number of shafts, the free distance between two welds in the shaft, the diameter of the shaft, the type of steel used in the shaft and the length of the lever have an effect on the behavior of the damper. In order to increase the efficiency of the damper and using the steel optimally, the yield stress of the shaft and the diameter of the shaft should be increased, and the length of the shaft and the length of the force transmitting lever from the frame to the shaft should be reduced. Also, due to the parallel function of the shafts as a ductile members, if different capacities are needed in the damper, the number of shafts can be used according to the required capacity.
