Naeem, Maida, Koichi, Javidan 2023
This study proposes a seismic resilient device known as self-centering disc slit damper (SC-DSD) which comprises hollow boxed-shaped steel sections with sets of prestressed disc springs placed inside. The damage avoidance design (DAD) with the proposed device was developed as an alternative to conventional ductile design in structures to minimize damage due to earthquakes. Different assessments were carried out on the device including loading experiments and numerical prediction of its energy dissipation capacity, self-centering ability, and force-displacement relationship. Further analysis was then done by comparing its performance with existing conventional steel slit dampers. With minimal residual damage, the test results indicated that the introduced device has greater seismic bearing force as well as provides a cost-effective replaceable solution for buildings.
System Concept
The configuration of the proposed system includes two box-shaped steel sections designed in a telescopic arrangement. Four dampers are created by cutting out slits from each face of the outer steel section. The inner and outer steel section boxes are held together, by plug weld connections, causing the dampers to yield when the sections move relative to each other. This makes up the energy-dissipating component of the SC-DSD. The self-centering component of the system is made up of two sets of Belleville disc springs, one in the outer box and the other in the inner steel box, and a threaded rod running through the axis. The high-strength nut and washer, attached to the end of the springs, are tightened to apply a preloading force for self-centering. This spring set configuration, however, can be altered by using different layouts, spring sizes, and arrangements to achieve different results. When an external load is applied, the internal forces in the slit dampers increase as the sections slide until it surpasses the preloaded compression force of the disc springs. This activates the device and provides a self-centering ability in both tension and compression stages.
Experimental Study, Results and Discussion
To evaluate the seismic resilience of the proposed system, a displacement-controlled quasi-static cyclic loading test was conducted on the specimens. The performance of the SC-DSD such as hysteretic response, energy dissipation capacity, and residual displacement was investigated. The test set-up included a 5000 k N hydraulic actuator attached to a loading arm, the proposed prototype connected to a load cell and strain gauges on the split steel sections to monitor yield strain. The test results proved the validity of the new device such that the prototype demonstrated stable and large energy dissipation capacity with minor residual deformation and generated a flag-shaped hysteresis loop. No buckling was observed in the plates or the plug welds, and the springs were elastic till the end of the investigation. These characteristics proved that the novel slit damper device is a promising alternative to conventional steel slit damper with the convenience of only requiring the outer box to be replaced after an earthquake.
Reference
Naeem, A., Maida, Y., Koichi, K., & Javidan, M. M. (2023). Development and experimental verification of self-centering disc slit damper for buildings. Journal of Constructional Steel Research, 201, 107759. https://doi.org/10.1016/j.jcsr.2022.107759