Fiber reinforced concretes due to their acceptable performance on structural members have been evaluated in many research. Planty of materials have been used in combination with the concrete and caused researcher focused on the concrete compressive strength. In this experimental regard, effects of three types of fibers such as Glass, Carbon and double hook steel on tensile strength, compressive strength and slump of standard concrete samples have been investigated. Four various weight ratios for any of these fibers are used (0.5, 1.0, 1.5 and 2% of cement weight). Analysis is done on the 7 and 28 days of concrete age and a simple concrete sample is existing to compare with fiber concrete samples. Results showed that in all dosage of Glass and Steel, compressive strength is increased but in samples with carbon fibers in 1.5 and 2% is decreased. Tensile strength in all used dosage of fibers is increased. Slump values of all fiber samples are decreased and maximum decrease experienced in glass fiber samples. Manuscript profile

The current study set to investigate the seismic performance of the steel moment-resisting frames equipped with multi-level pipe dampers considering the connection flexibility in the model. Initially, the behavior model of the damper, connections, and steel columns are presented and calibrated based on the experimental results. Then, three steel moment-resisting frames having 4, 8, and 12 stories with poor lateral strength were modeled in the OpenSees software, while the flexibility of the beam-column connection was taken into account. The structural models were then subjected to the one-direction lateral load and evaluated using the nonlinear static analysis. The results revealed that the rehabilitation of steel moment-resisting frames using the multi-level pipe dampers significantly led to enhanced load bearing capacity of frames compared to the corresponding control frame. The maximum load bearing capacity increase was 57%, 56%, and 60% in the 4-, 8-, and 12-story frames, respectively. The ultimate deformation capacity increased as well, while the yield displacement of frames decreased. The maximum increase on the ultimate ductility of strengthened frames was 43%, 34%, and 33% in the 4-, 8-, and 12-story frames, respectively. The findings can be considered as a criterion to compare the performance of this type of damper with the conventional control structures. Manuscript profile

Base isolation is an appropriate approach to mitigate the seismic hazards. A common type of elastomeric rubber bearing is included rubber pads, intermediate steel plates and steel end plates (anchor plates). The hysteresis behavior of elastomeric rubber bearings is affected by vertical pressure and shape factor. In this study cyclic loading is applied and hysteresis behavior in the first and second cycles is evaluated. Finite element method with ABAQUS software is used and validation analysis was done. The results show that second cycle of force-displacement in the elastomeric rubber bearings is more stable than the first cycle and vertical pressure and shape factor influenced damping and hysteresis behavior. Also, elastomeric rubber bearings with lower shape factor have higher damping in comparison with larger shape factor and increase in vertical load led to increase in the damping. The innovation of this paper is adopted various hysteresis parameters in finite element analysis to achieve closest results in comparison with experimental work. Manuscript profile