Multicriteria Decision-Making Methods in Selecting Seismic Upgrading Strategy of High-Rise RC Wall Buildings

Reinforced concrete (RC) structural walls are widely used in high-rise structures in earthquake-prone areas. Damaged by the earthquakes in the past decades, these buildings need retrofitting in order to increase the resilience of buildings with concrete shear walls. This study aimed to investigate the retrofitting of high-rise RC wall buildings using energy dissipation devices. To this end, a total of four buildings with 15, 20, 25, and 30 stories equipped with concrete shear walls as their lateral load-resisting system were retrofitted using passive seismic control systems. The buildings were subjected to the set of the far-field and near-field records presented in the FEMA standard (P-695), and an index was defined to relate the structural responses of the building, such as drift, acceleration, velocity, displacement, and base shear, to the earthquake records. For this purpose, numerical models, which have been validated with the experimental results, have been performed. The resulting index values were considered as the criteria, and the passive systems were ranked by the efficient Multicriteria Decision Making (MCDM) method. Based on the results from the MCDM method and using the considered criteria, friction damper was ranked first among the available energy dissipation devices for high-rise RC wall buildings. © 2022 American Society of Civil Engineers

Solubility investigation of ether and ester essential oils in water using spectrometry and GC/MS

Background and objectives: Essential oils (volatiles) are aromatic oily liquids prepared from different parts of plants and demonstrate various therapeutic and cosmetic properties. The dissolution of essential oils are not desirable in water, therefore the aim of this research was evaluation and selection the best co-solvents for increasing their solubility and bio availability. Methods:The solubility of six  plants essential oils were investigated in presence of propylene glycol (PG), polyethylene glycol 300 (PEG), glycerin and ethanol as solvent and tween 80 or lecithin as co-solvent by observation and spectrophotometric assay. Chemical composition of the essential oils and supersaturated 50% ethanol (SSE) and 50% PG or PEG (SSP) solutions were analyzed by GC/MS, too. Results: Ester (Lavandula dentata, Heracleum persicum and, Elettaria cardamomum) essential oils showed the best solubility in ethanol and PG, respectively. Ether (Foeniculum vulgare, Pimpinella anisum and Petroselinum crispum) essential oils had the best solubility in ethanol and PEG, respectively. In ester class, mixture of ethanol/water was the best solvent according to solubility and total amounts of major compounds of the essential oils. In ether class, all samples had better solubility in mixtures of ethanol/water than PEG, but the amounts of total phenols or ethers in SSP of some samples were higher than SSE. Therefore selecting the best solvent for these class need more experiments. Conclusion: Selecting the solvent for essential oils changes their chemical composition; therefore the best solvent was different for various purposes

Multiple Network Hydrogels: A Study of Their Nanoindentation Hardness

Nanoindentation is employed to investigate at the nanoscale the mechanical properties of multiply-interpenetrated N,N-dimethylacrylamide hydrogels cross-linked using N,N′-methylenebis(acrylamide). The main result from these measurements is the determination of the hardness of the materials, that is, their resistance to penetration by the nanoindenter, which increases with network multiplicity, arising from the increase in network compactness with multiplicity. In addition to hardness, the nanoindentation elastic modulus and the percentage of recoverable energy are also determined, and both are found to increase with network multiplicity as well. A general conclusion from this study is that nanoindentation is a facile and fast method for the characterization of a number of mechanical properties of hydrogels, with the important advantage of small amount of sample required for the measurements