Seismic excitation can cause significant energy to be released within structures. By using special devices, this energy can be consumed and dissipated without deforming structural members significantly. Due to this, structural damage is minimized, casualties are prevented during earthquakes, and structures are extended in their useful life. Over the past five decades, it has been widely acknowledged that steel yielding dampers are among the best energy dissipation devices. It has been stated that the hysteretic behavior of steel yielding dampers could vary slightly depending on their geometry. From a practical point of view, they are suitable for the improvement of seismic safety in new and existing structures. The purpose of this paper is to present a review related to steel yielding dampers, their development, various types, and applications, in order to help understand the role of these dampers in improving the seismic performance of structures. In terms of their shape, steel yielding dampers can be categorized as steel plate dampers, pipe dampers, curved dampers, and slit dampers. The most common use of steel plate, such as ADAS and TADAS, and pipe dampers is within braced frames, whereas U-shaped, Jshaped, and S-shaped dampers are mostly seen in frames with chevron bracing. Steel curved dampers with a 60° angle in a steel-braced frame, on the other hand, provide the best energy dissipation and frame strength. In this direction, until today, steel slit dampers have been found to be the most commonly used steel yielding dampers.
Over the past two decades the effects of different admixtures have been investigated on mechanical properties and durability of engineered cementitious composites (ECC). Despite this, materials such as silica fume and zeolite have not been thoroughly investigated. The present study was designed and implemented to evaluate the effects of silica fume, zeolite, and blast furnace slag (BFS) on engineered cementitious composites and to compare the mechanical properties and durability of the polyvinyl alcohol-ECC (PVA-ECC) and polypropylene-ECC (PP-ECC) specimens. For this purpose, specimens were subjected to adverse conditions in a 5% magnesium sulfate solution and lab conditions as the reference treatment to measure the post-treatment variations in their compressive strength, flexural strength, and mid-span deflection (MSD). Results demonstrated that PP-ECC was not only easier to manufacture but outperformed PVA-ECC in some respects as well. It was also observed that MSD increased in the PVA-ECC specimens but declined in the PP-ECC ones under identical increments in their BFS contents. Finally, all the specimens maintained under the lab conditions displayed the best performance in terms of strength and durability when 3% silica fume was added to their mixtures while the same addition led to the worst performance in the sulfate medium.
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