A Study on the Damping Ratio of the Viscous Fluid Dampers in the Braced Frames

The main task of a structure is to bear the lateral loads and transfer them to the foundation. Since the lateral loads imposed on a structure have a dynamic nature, they cause vibrations through the structure. In order to have resistant structures to the seismic vibrations, two viewpoints have been suggested. According to the first viewpoint, the resistance of the structure results from providing non-elastic shapeable capacity and resistance for the structural members. To achieve this purpose, different structural components such as shear walls, braced frames, moment frames, diaphragms, and trusses should be provided and combined to form a resistant system to the lateral loads. The present paper intends to study the optimal damping ratio of the viscous fluid dampers (VFD) in the braced frames. In order to reach the purposes of the present paper, the library studies, and proper software have been used to analyze data and make a conclusion

A STUDY OF MICROSTRUCTUR AND MECHANICAL PROPERTIES OF CEMENT MORTAR BY ADDING NANOPARTICLES

In this study, research has been done on the compressive and tensile strength of cement mortar containing 1, 3 and 5 percent by weight of cements Fe2O3nano-particles. The results show that the mechanical properties of samples containing 1 and 3 percent Fe2O3nano-particles is desirable then the ordinary cement mortar. SEM study about the micro structure of cement mortar containing nano particles and ordinary cement mortar showed that Fe2O3 nano-particles fills the pores completely and reduces the mixture of CaOH2 with hydrates and increases the final density of the prepared samples. The mechanical properties results showed that by increasing iron oxide nano-particles the mechanical properties enhances to 5 percent

A Study on the Damping Ratio of the Viscous Fluid Dampers in the Braced Frames

The main task of a structure is to bear the lateral loads and transfer them to the foundation. Since the lateral loads imposed on a structure have a dynamic nature, they cause vibrations through the structure. In order to have resistant structures to the seismic vibrations, two viewpoints have been suggested. According to the first viewpoint, the resistance of the structure results from providing non-elastic shapeable capacity and resistance for the structural members. To achieve this purpose, different structural components such as shear walls, braced frames, moment frames, diaphragms, and trusses should be provided and combined to form a resistant system to the lateral loads. The present paper intends to study the optimal damping ratio of the viscous fluid dampers (VFD) in the braced frames. In order to reach the purposes of the present paper, the library studies, and proper software have been used to analyze data and make a conclusion

Synthesis of Zinc Oxide Nanoparticles and Their Effect on the Compressive Strength and Setting Time of Self-Compacted Concrete Paste as Cementitious Composites

In the present study, the mechanical properties of self-compacting concrete were investigated after the addition of different amounts of ZnO nanoparticles. The zinc oxide nanoparticles, with an average particle size of about 30 nm, were synthesized and their properties studied with the help of a scanning electron microscope (SEM) and X-ray diffraction. The prepared nanoparticles were partially added to self-compacting concrete at different concentrations (0.05, 0.1, 0.2, 0.5 and 1.0%), and the mechanical (flexural and split tensile) strength of the specimens measured after 7, 14, 21 and 28 days, respectively. The present results have shown that the ZnO nanoparticles were able to improve the flexural strength of self-compacting concrete. The increased ZnO content of more than 0.2% could increase the flexural strength, and the maximum flexural and split tensile strength was observed after the addition of 0.5% nanoparticles. Finally, ZnO nanoparticles could improve the pore structure of the self-compacted concrete and shift the distributed pores to harmless and less-harmful pores, while increasing mechanical strength

Synthesis of ZnO nanoparticles and their antibacterial effects

The zinc oxide nanoparticles with the average particle size of about 30 nm were synthesized by the chemical technique and their properties were studied with the help of scanning electron microscope and X-ray diffraction. The aim of this study was to detect the antibacterial properties of 0.01, 0.5 and 1% nano-ZnO against Escherichia coli. E. coli was cultured in liquid and agar nutrient medium to evaluate the antibacterial effects of 0.01, 0.05 and 1% of ZnO via the optical density (OD) and log CFU/ml measurements. Non-significant effect was seen for 0.01% of ZnO nano-particles, while 0.05 and 1% of nanoparticles showed considerably decreased bacterial number. A 4.385 and 2.04 times decrease in the OD value was found in the presence of 1 and 0.5% nano-ZnO, respectively (P<0.001) as compared to the control. In the second study, 6.3 log CFU/ml of E. coli were present in the cultures treated with 1% nano-ZnO at 4°C in water. Control E. coli cells survived for 12 days, while complete cell death was seen when 1% nano-ZnO was applied for 24 h. In the third study, E. coli was grown in the agar medium with and without nanoparticles and suppressed growth (8.56 times; P<0.001) was seen in the presence of 1% nano-ZnO.Keywords: ZnO-nanoparticle, antibacterial, bactericidal, Escherichia col