Experimental behavior of buckling restrained braces by adding diferent admixtures concrete and using the steel core under cyclic loads

The fibers in the concrete cause soft rupture, and the compressive and tensile samples are not ruptured after failure, this is one of the benefits of Steel fibers, especially the sinusoidal and hooked fibers during an earthquake which allows residents to escape. In addition to the positive effect on mechanical properties, steel fibers improve the matrix of concrete, provide ductility and response to impact load, and control crack width and propagation. This study, given that the use of fly ash and micro-silica in addition to improving the durability and performance of concrete is also effective in protecting the environment by replacing cement instead. In the following, preparing samples of the compressive and tensile strength of non-fibrous concrete, and concrete containing steel fibers with 6 different percentages (0.4, 0.6, 0.8, 1, 1.2, 1.5) and composition of Steel fiber and polypropylene in three different compositions (0.3PP + 0.8SF and 0.4PP + 0.4SF and 0.15PP + 1.5SF) were investigated and after achieving the optimal percentage (the percentage with the highest compressive and tensile strength given economic considerations), under the loading protocol SAC/BD 97.02, while extracting seismic parameters and studying curves of hysteresis, energy absorption, the lateral displacement, the effects of the use of these fibers were investigated. In the last step of the research, considering the major properties of pozzolanic materials, adding fly ash and micro-silica to concrete containing steel fibers with the optimum percentage of Steel fibers, by comparing it with concrete containing Steel fibers and non-fiber concrete and determining the appropriate percentage of cement replacement, the effect of the use of fly ash and micro-silica in preventing the buckling of buckling restrained braces was investigated.