Sharif Digital Repository

This paper presents the results of an experimental work in order to evaluate the performance of a novel proposed retrofitting technique on a typical dome-roof adobe building by shaking table tests. For this purpose, two specimens, scaled 2:3, were subjected to a total of nine shaking table tests. The unretrofitted specimen, constructed by common practice, is designed to evaluate seismic performance and vulnerability of dome-roof adobe houses. The retrofitted specimen, exactly duplicating the first specimen, is retrofitted based on the results obtained from unretrofitted specimen tests, and the improvement in seismic behavior of the structure is investigated. Zarand earthquake (2005) Chatrood... 

Recently it was shown that the differential form of Eringen’s nonlocal elastic theory is unable to model, predict and track the mechanical behaviors of many nano-structures due to their boundary conditions. Therefore, having an accurate model for formulating such structures became an important issue. With respect to this concern, in this study, the influence of having an axially varying elastic environment on vibrational behavior of nanobeams is investigated for the first time. Size-dependent effects are modeled using Eringen’s two-phase local/nonlocal integral model which is well-posed with higher accuracy. The elastic environment is modeled using the Pasternak-Winkler method which could... 

The seismic behaviour of a 4-story building is investigated under horizontal excitation of simulated earthquakes. The model has been constructed with a 3D sandwich panel system without any conventional frame system in four storeys on a shaking table. The building has been modelled before construction. Due to the table limit, the scale factor of the model is chosen as 1: 2.35 of a prototype. The shaking table test of the scaled model of the building is carried out under several ground motions to verify the safety of the system. The simulated motions were applied to the model in two-perpendicular directions, simultaneously. The failure mechanism and dynamic behaviour of the model, as a... 

Keggin-type polyoxometalate (POM) nanoparticles based on [PW12O40]3- and [SiW12O40]4- with Ag+ and (ZrO)2+ cations were prepared under ultrasound irradiation. The results of SEM and XRD revealed the average size of particles in the range of 24–95 nm. The moles of crystallization water per mole of nanocatalysts were in the range of 3–9. EDX spectra confirmed the successful replacement of protons of H3PW12O40 and H4SiW12O40 with Ag+ and (ZrO)2+ cations. These nanoparticles were used as heterogeneous catalysts for the synthesis of a poly (amido-ester) at room temperature. All polymers were fully characterized. Although employing the nanocatalyst resulted in at least 22% improvement in the... 

Seismic isolators are used to decrease the energy and forces of earthquakes. The weight of conventional steel-reinforced elastomeric isolators (SREIs) is high, mostly due to the use of multiple steel shim plates. On the contrary, the damping ratio of SREIs is relatively low. Accordingly, this research utilizes a new approach in which the steel shim plates are replaced by carbon and polyamide fibers. This study attempts to obtain the dynamic and mechanical properties of such carbon fiber- and polyamide fiber-reinforced elastomeric isolators, in comparison with SREIs. In this work, a number of specimens were initially designed and manufactured. Afterwards, compression and cyclic shear tests... 

The article presents a 2-port multiple-input multiple-output (MIMO) antenna array designed for millimeter-wave band operation, specifically optimized for Vehicle-to-Everything (V2X) applications. To enhance performance, a novel approach employing two types of metasurfaces on a single plate is utilized. The first metasurface, based on a loop structure, aims to improve the frequency bandwidth, while the second metasurface, utilizing a composite right/left-handed (CRLH) design, focuses on reducing mutual coupling. These two steps result in an improved frequency bandwidth exceeding 45% and a decreased structure width of about 50% compared to other designs. Notably, the compact nature of these... 

In order to evaluate the seismic behavior of confined masonry buildings, based on Iranian seismic code design, a single storey full-scale unreinforced confined brick masonry building has been constructed on the shaking table facility at the Earthquake Engineering Research Center (EERC) of Sharif University of Technology. The 4 by 4 meter model consists of four brick masonry walls confined with reinforced mortar tie-columns and steel bond beams, with a traditional jack-arch roof system. Three of the wall panels contained openings of different sizes and geometries. The model was subjected to the scaled earthquake records of Bam, Tabas and El Centro, as well as a harmonic acceleration with... 

Thin film composites (TFCs) as forward osmosis (FO) membranes for seawater desalination application were prepared. For this purpose, polyacrylonitrile (PAN) as a moderately hydrophilic polymer was used to fabricate support membranes via nonsolvent-induced phase inversion. A selective thin polyamide (PA) film was then formed on the top of PAN membranes via interfacial polymerization reaction of m-phenylenediamine and trimesoyl chloride (TMC). The effects of PAN solution concentration, solvent mixture, and coagulation bath temperature on the morphology, water permeability, and FO performance of the membranes and composites were studied. Support membranes based on low PAN concentrations (7 wt... 

This paper studies a two-echelon reverse supply chain (RSC) involving a remanufacturer and a collector, in which the collector receives the used products by paying a reward to consumers. The reward amount given to customers is crucial for encouraging them to exchange used products. An exchanged item is accepted if it meets the minimum acceptable quality level (AQL). Both the remanufacturing capacity and the quality of exchanged products present uncertainties. Under the buyback contract, the remanufacturer purchases used products at a higher price than in the decentralized and centralized cases from the collector. In return, the collector undertakes to repurchase a certain number of used... 

The demands for carrying data traffic in long distances have been increasing rapidly and Service providers encounter the challenging issue of the best approach for handling the high volumes of Ethernet traffic generated by the proliferation of network access applications. The next generation SONET/SDH solutions offer integration of several functionalities into a single network element, thus reducing the power and space requirements as well as facilitating the configuration and management of the network. They are expected to continuously support TDM services, while enabling carriers to offer new Ethernet-based data services. Therefore Ethernet over SDH standard that enables legacy SDH/SONET... 

The authors consider the problem of finding a minimum cost multicast sub-graph based on network coding, where delay values associated with each link, limited buffer-size of the intermediate nodes and link capacity variations over time are taken into account. The authors consider static multicast (where membership of the multicast group remains constant for the duration of the connection) in lossless wireline networks. For such networks, first the continuous-time (asynchronous packet transmissions) model is formulated. Subsequently, the discrete-time model for the synchronous packet transmissions scenario is derived. Then, by using an auxiliary time-expanded network, a decentralised algorithm... 

In the current global landscape where sustainability is increasingly critical, this study offers a significant contribution by redefining supply chain models through the lens of circular economy principles. It introduces a novel two-stage stochastic model tailored to designing sustainable closed-loop supply chains, adept at navigating uncertainties in location, allocation, and routing decisions. A notable feature of the model is its integration of a speed-variant fuel-efficient green vehicle routing system, which enables simultaneous pick-up and delivery, underscoring a commitment to environmental sustainability and circular economy principles. This model is distinct in its holistic... 

There are many parameters utilized to obtain a more reasonable performance for structures under earthquake excitations in seismic provisions. General considered parameters in seismic provisions are: PGA, importance factor (I) and typical inherent overstrength and global ductility capacity (R). It is well recognized that the main characteristic of the design of structures under seismic excitation is probabilistic rather than deterministic; therefore, it should be determined if whether the probability of structural damage decreases when such parameters change in the design of structures. In this paper, fragility curves are developed in order to evaluate these parameters. Fragility curves are... 

Investigation of the dynamic characteristics of an existing structure system based on field tests is of practical significance, since it can be employed in the field of examining construction quality, validating or improving analytical finite element structural models, or conducting damage assessment. The main purpose of this study is to investigate the dynamic characteristics of dams using the seismic response data. Whereas, in the process of frequency domain identification of dam properties, frequency response function (FRF) plays the most important role, evaluating the corresponding parameters with better accuracy has always been desirable. Therefore, a comparison was made between some... 

In this study, eggshell (ES) particles as an available and low-cost waste material were used for preparing hydrogel composites as dye biosorbents. For this purpose, hydrogel composites were prepared through free-radical graft copolymerization of wheat starch and sodium methacrylate (NaMA) in the presence of different contents of ES particles with various size ranges. FTIR spectroscopy confirmed graft copolymerization of NaMA moieties onto starch backbone besides the combination of ES particles with the starch-g-PNaMA matrix. The gel content values were high (>99%), which showed proper graft efficiency for hydrogel composites. Incorporation of ES particles into hydrogel matrix resulted in... 

The objective of this study is to develop analytical fragility curves for an ensemble of existing 3-to 6-story residential steel buildings with concentrically braced frames in 2 directions, designed during 2010 to 2015 in Qazvin, Iran. The buildings were modeled three-dimensionally in OpenSees considering braces buckling behavior. Maximum Inter-story Drift Ratio (.MIDR) and spectral acceleration at. fundamental period of the structure with 5% viscous damping (Sa(7,5%)) were considered as Damage Index (DI) and Intensity Measure (/M), respectively. Limit states were specified as discussed in FEMA 356. Ground motion record selection and uncertainties assessment were carried out based on FEMA... 

The objective of this study is to develop analytical fragility curves for an ensemble of existing 3-to 6-story residential steel buildings with concentrically braced frames in 2 directions, designed during 2010 to 2015 in Qazvin, Iran. The buildings were modeled three-dimensionally in OpenSees considering braces buckling behavior. Maximum Inter-story Drift Ratio (.MIDR) and spectral acceleration at. fundamental period of the structure with 5% viscous damping (Sa(7,5%)) were considered as Damage Index (DI) and Intensity Measure (/M), respectively. Limit states were specified as discussed in FEMA 356. Ground motion record selection and uncertainties assessment were carried out based on FEMA... 

In many countries, there are traditional houses made of stone, adobe and brick, which perform relatively weakly in earthquakes. To mitigate casualties in future earthquakes, it is necessary to evaluate the current status of these buildings and propose effective methods to retrofit them. One method of evaluating the performance of buildings in earthquakes is through the use of fragility curves. These diagrams show the probability of exceeding a specific state of damage versus seismic intensity parameters, such as PGA, MMI, la, CAV etc. Fragility curves will provide an important basis for analytical methods, based on probabilistic approaches. Much work has been done on bridges, concrete and...