Types Of Structural Components Research Articles

Optical Force-Induced Nanowire Cut.

One-dimensional nanometer scale-sized materials, such as nanowires, nanotubes, etc., have gradually become new types of structural components, which can be integrated into micro/nano-opto-electromechanical systems. In this paper, optical forces were applied to cut nanowires precisely, which were broken with arbitrary length ratios. The optical force exerted by the optical tweezers proved to be the cause of the fracture of the high-aspect ratio nanowires, and the fracture mechanism of the nanowires was developed. Nanowires of different semiconductor materials were cut with optical tweezers in the experiments. The precise cut with optical tweezers can provide nanowires of appropriate lengths for the construction of nanowire-based structures, which have potential applications for micromachining and microfabrication of micro-electro-mechanical system or semiconductor devices.

Impact failure characteristics of LNG carrier cargo containment system

The most critical issue related to the maritime transportation of liquefied natural gas (LNG) is the structural safety of the cargo containment system (CCS), because LNG is stored at temperatures below –163 °C. During the unloading of LNG, several types of structural components can fall into CCSs from significant heights. Thus, the structural safety of LNG CCSs against dropped objects should be verified; however, the actual failure characteristics of the primary barrier are not well understood. In this study, the failure mechanism of the primary barrier of an LNG CCS was investigated by conducting falling-object-induced structural failure tests. To clarify the effect of the failure response of the primary barrier, impact tests were performed using various membrane types and impactor types. In addition, to ensure the wide applicability of the results, a finite element analysis-based design-aid numerical method was developed by comparison with experimental observations. Excellent numerical verification results were obtained using the Johnson–Cook material model, which can be applied to the dynamic failure problem for the corrugated plates used in LNG CCSs. Finally, guidelines that could set safety standards for the primary barrier were identified, considering the shape, weight, and height of potential falling objects.

Eco-biological interaction of Polyphenols among Acanthus ilicifolius, detritus, and Uca lactea annulipes in estuarine-ecosystem

Bio-cycling of polyphenols in estuarine ecosystem have not been documented adequately among the floraand fauna thereof. Total phenolic contents, antioxidative potential and free-radical scavenging activityhave been analysed from three types of structural components (leaves of Acanthus illicifolius, and detritusloaded estuarine soil and a benthic fauna, Uca lactea annulipes), of the estuarine mangrove ecosystem of theNorth Eastern coastal belt of India. HPLC and MALDI-TOF Mass spectrometry analysis were performed toidentify and quantify the phenolic compounds. Results reveal that all the three samples contain Polyphenols that can be related through the process and pathways of eco-biological transformation. Though quantitativelyless, the presence of deprotonated polyphenols enriches the detritus laden soil. Interestingly, very fewparent ions of phenolic acids from leaf sample show up in the crab hemolymph. It contained new metabolitesconsisting of fragmented ions. This establishes the role of the fiddler crabs as agents participating in thebio-cycling of polyphenols and also depicts the interdependence of plants, animals, and soil for the exchangeof essential life supporting ingredients as an outcome of coevolutionary process.

Surface effect on the necking of hyperelastic materials

Necking is a widely observed instability phenomenon. Surface tension often plays a significant role in the deformation of soft materials, especially at the micro scale, but its influence on the necking behavior of soft structures remains unclear. In this paper, we use the energy method to explore surface effects on the necking of soft plates and cylindrical bars under uniaxial tension. Analytical solutions are derived for the critical conditions of necking instability in the two types of structural components with a power-law constitutive relation. It is found that surface energy shows different impacts on their necking behaviors – it tends to postpone the occurrence of necking in soft plates but promote that in soft cylinders. This work not only deepens our understanding of the instability of soft materials but also helps design soft devices and robots.

APPLICATION OF DIGITAL STRUCTURE SIMULATION AS A TOOL FOR THE EXPLORATION OF WIDE SPAN STRUCTURE IDEAS

Review on structure behaviour and visual appearance of a building is needed in generating creativity in the making of an architectural design. The use of any specific structure software will facilitate this in the process. This research aims to prove the effectiveness with which designers can compose alternative forms of architectural appearance through the use of the software. One of the tools in the creative process used in the exploration of 2-dimensional frame structures is DR FRAME. The observations were carried in the Structure and Construction IV Studio at Itenas Architecture Study Program Bandung through a digital simulation using DR. FRAME software demo version. Several students are invited to explore various forms of wide-span truss structures at the level of unified integration. The results through the program execution show various diagrams which can be implemented in the design of the form and the type of structural components. DR.FRAME software enriches ideas in the wide-span structure design which provides an understanding of the relationship between structural behaviour and the appearance of architectural design. The use of other supporting software is supposed to be applied as an alternative search for various structural design ideas for architecture students

Prerequisites for developing an advanced welding technology for repair of worn elements of steam-conducting systems

The main disadvantage of standard technologies of welding steam pipelines of thermal power plants is that they can allow the presence of defective structures close to the defective ones in the metal of the seam and in the sections of the HAZ. In this regard, the question arises about the development of a new technology that will provide the appropriate structure and properties that will increase the service life of steam pipelines and get a significant economic effect. Goal. The goal is improvement of the technology of welding pipelines of thermal power plants based on the study of the features of the formation of welded joints operating in Creep conditions. Methodology. The level of wear of the elements of the Steam-conducting path was estimated taking into account the provisions of the regulatory documentation of metallographic analysis, determination of chemical composition and properties, as well as the degree of their deformation. Results. It is revealed that welded joints are characterized by initial structural heterogeneity, which is closely related to long-term strength, ductility and impact strength. For example, at different sections of a welded joint, there is a different intensity of transition of alloying elements and, accordingly, a different type of structural component can be formed. The proposed technology of welding repair of damaged elements of steam pipelines using mechanized welding in CO2+Ar provides for the production of welded joints with a higher level of uniformity of structure, chemical composition and properties. Scientific novelty and practical significance. The welding technology has been improved, which includes developing the modes for performing repair work by mechanized welding in an Ar + CO2 environment of steam pipeline samples with a depth of ≥ 20 mm and a width of ≥ 30 mm, and differs from the known ones by using linear energy welding of 1.2–1.5 MJ/m.

Dynamical characteristics and influencing factors of stator end-windings of a turbine generator analyzed via heterogeneous element fusion modeling

The power output rating of a turbine generator is affected directly by efficient cooling, especially near the stator end-windings. However, modeling the coolant flow through the stator end-windings of a high-powered generator remains challenging because of the many parts with irregular geometries and the intricacy of the cooling flow paths.In order to study the dynamical characteristics of stator end-windings, the finite element modeling of the stator end-winding with beam element, shell element and solid element has been established based on the analysis of different types of structural components. Further, a large number of modal calculations under different considerations including modulus of elasticity, boundary condition, connection area, position and temperature have been carried out.The frequency of the elliptical mode at the turbo-generator end was 81.5 Hz, and that at the exciter end was 77.2 Hz. The errors from the test average were 1.62% and 3.34%, respectively. The results showed that the FEM of the TG stator end reflects the vibration of the actual prototype precisely. The laws of natural frequencies with respect to different circumferential spacer blocks, radial pressure plate, external boundary conditions, spring-plate connection area, positions of spacers between bars and temperature including have been clarified.The structure of the stator end is complex, and researches continue into its dynamic characteristics with much work remaining. (1) Some more complex factors such as preload will be added to the model, and the influence of multiple factors on the vibration characteristics have been analyzed. (2) When using multi-point binding constraints, setting of the pinball region has a significant impact on calculation results. There is currently no fixed conclusion on how to set a reasonable PINBALL area size. (3) The mechanical properties of the end insulating material will change with the increase of temperature, but the trends cannot be predicted accurately.

Semi-automated generation of parametric BIM for steel structures based on terrestrial laser scanning data

As-built building information models (BIMs) are increasingly needed for construction project handover and facility management. To create as-built BIMs, laser scanning technology has gained popularity in the recent decades due to its high measurement accuracy and high measurement speed. However, most existing methods for creating as-built BIMs from laser scanning data involve plenty of manual work, thus becoming labor intensive and time consuming. To address the problems, this study presents a semi-automated approach that can obtain required parameters to create as-built BIMs for steel structures with complex connections from terrestrial laser scanning data. An algorithm based on principal component analysis (PCA) and cross-section fitting techniques is developed to retrieve the position and direction of each circular structural component from scanning data. An image-assisted edge point extraction algorithm is developed to effectively extract the boundaries of planar structural components. Normal-based region growing algorithm and random sample consensus (RANSAC) algorithm are adopted to model the connections between structural components. The proposed approach was validated on a bridge-like steel structure with four different types of structural components. The extracted as-built geometry was compared with the as-designed geometry to validate the accuracy of the proposed approach. The results showed that the proposed approach could efficiently and accurately extract the geometry information and generate parametric BIMs of steel structures.

Virtual hybrid simulation of beams with web openings in fire

Purpose Perforated composite beams are an increasingly popular choice in the construction of buildings because they can provide a structurally and materially efficient design solution while also facilitating the passage of services. The purpose of this paper is to examine the behaviour of restrained perforated beams, which act compositely with a profiled slab and are exposed to fire. The effect of surrounding structure on the composite perforated beam is incorporated in this study using a virtual hybrid simulation framework. The developed framework could also be used to analyse other structural components in fire. Design/methodology/approach A finite element model is developed using OpenSees and OpenFresco using a virtual hybrid simulation technique, and the accuracy of the model is validated using available fire test data. The validated model is used to investigate some of the most salient parameters such as the degree of axial and rotational restraint, arrangement of the openings and different types of fire on the overall fire behaviour of composite perforated beams. Findings It is shown that both axial and rotational restraint have a considerable effect on time-displacement behaviour and the fire performance of the composite perforated beam. It is observed that the rate of heating and the consequent development of elevated temperature in the section have a significant effect on the fire behaviour of composite perforated beams. Originality/value The paper will improve the knowledge of readers about modelling the whole system behaviour in structural fire engineering and the presented approach could also be used for analysing different types of structural components in fire conditions.

Structural Optimization and Reliability Analysis of Automotive Composite Bumper Against Low-Velocity Longitudinal and Corner Pendulum Impacts

To improve the safety performance and maintain light weight of composite automotive bumper beams subjected to low-velocity impacts, a structural optimization and a novel reliability analysis procedure for multi-objectives are established in this paper. Both longitudinal and corner pendulum impacts are considered, and the optimized bumper beam has significant improvements. Compared with the original composite bumper beam, the section force of the crash box in the corner pendulum impact and the mass of the optimal bumper beam are decreased by 9.6% and 20.3%, respectively. The novel reliability analysis results show that the knee point may be less reliable whereas the design with inferior knee point is of higher reliability. Therefore, a design on an inferior knee point may be more attractive in engineering design practices. Our numerical results have demonstrated that the optimization procedure established in this paper to improve the performance of composite bumper beams and our proposed reliability analysis method considering multi-objectives are effective and useful in the engineering design of bumper beams. These techniques are also useful for the design of other types of structural components where weight and safety are of importance.

Properties of dune sand concrete containing coffee waste

In the last years, an increase of coffee beverages consumption has been observed all over the world; and its consumption increases the waste coffee grounds which will become an environmental problems. Recycling of this waste to produce new materials like sand concrete appears as one of the best solutions for reduces the problem of pollution. This work aims to study the possibility of recycling waste coffee grounds (Spent Coffee Grounds (SCG)) as a fine aggregate by replacing the sand in the manufacturing of dune sand concrete. For this; sand concrete mixes were prepared with substitution of sand with the spent coffee grounds waste at different percentage (0%, 5%, 10%, 15% and 20% by volume of the sand) in order to study the influence of this wastes on physical (Workability, bulk density and porosity), mechanical (compressive and flexural strength) and Thermal (Thermal conductivity and thermal diffusivity) properties of dune sand concrete. The results showed that the use of spent coffee grounds waste as partial replacement of natural sand contributes to reduce workability, bulk density and mechanical strength of sand concrete mixes with an increase on its porosity. However, the thermal characteristics are improved and especially for a level of 15% and 20% of substitution. So, it is possible to obtain an insulating material which can be used in the various types of structural components. This study ensures that reusing of waste coffee grounds in dune sand concrete gives a positive approach to reduce the cost of materials and solve some environmental problems.

The effects of manipulating microhabitat size and variability on tropical seawall biodiversity: field and flume experiments

Previous studies have shown that concrete tiles on seawalls that incorporate microhabitat size variability (i.e. complexity) can increase species richness compared to unmodified seawalls. In a recent study, we showed that manipulating complexity at the 4–28mm scale can have an effect on seawall community composition and that the type of structural component (microhabitats such as pits and grooves) can influence assemblage diversity independently of their complexity. It is not known, however, whether these effects will be exhibited at a larger scale; in other words, will the positive relationship be present if the size range of components on concrete tiles is enlarged (8–56mm). Therefore, in the present study, we examine: (1) the effects of changing the scale of structural manipulation on species richness and, (2) the hydrodynamic properties (i.e. velocity of flow over the whole tile) of different designs. We doubled the size of all x, y and z dimensions to create 400×400×64mm concrete tiles (up from 200×200×32 mm in the previous study) with two different basic designs: ‘Pits’ and ‘Grooves’. These were deployed for one year at two island sites off Singapore’s mainland along with ‘Granite control’ tiles so that we could assess what the existing seawall would host within the same timeframe. Results showed that the ‘complex’ tiles supported greater richness (S) than ‘simple’ ones, suggesting that the size range tested here (8–56mm) is relevant to tropical intertidal communities. Flume experiments revealed similar wave amplitude values over the surfaces of all tile types, including the granite controls, suggesting that intertidal organisms are unlikely to colonise the tiles differentially as a result of cm-scale hydrodynamic differences, i.e. the dominant mechanism underlying this ‘complexity-diversity’ relationship is unlikely to be due to differences in flow velocities over a 400×400 mm tile surface but, rather, is related to resource (e.g. refuge) availability. These results help identify the “scale of effect” of topographic complexity which can be directly integrated into ecological engineering designs to increase biodiversity on tropical seawalls.

Immunohistochemical Analysis of Debris Captured by Filter-Type Distal Embolic Protection Devices for Carotid Artery Stenting

Little is known about the micro-debris captured in filter-type distal embolic protection devices (EPD) used for carotid stenting (CAS). This study aimed to determine the histological and immunohistochemical characteristics of such debris by using a new liquid-based cytology (LBC) technique. Fifteen patients who underwent CAS using a filter-type distal EPD (FilterWire EZ; Boston Scientific, Marlborough, MA, USA) were included in the study. After gross inspection of each recovered filter device, micro-debris were collected using a new LBC technique (SurePath; TriPath Imaging, Inc., Burlington, NC). Histological and immunohistochemical analysis of the recovered debris was performed. The pre- and postoperative brain magnetic resonance imaging and neurological status of each patient were also reviewed. No patient developed ipsilateral symptomatic stroke due to a thromboembolic event. All 15 patients (100%) had microscopically identifiable debris in the filters, whereas gross inspection detected visible debris only in 5 patients (33.3%). Histological analysis revealed various types of structural components in an advanced atheromatous plaque, including fragments of fibrous cap, calcified plaque, smooth muscle cells, and necrotic tissue fragment infiltrated with monocytes and macrophages. Filter-type EPDs may contribute to reducing the risk of CAS-related embolic events by capturing micro-debris even when gross inspection of the recovered filter shows no visible debris in the device.

Modeling and Control of the CSCEC Multi-Function Testing System

In order to promote the research and development on evaluating the seismic performance of structures, China State Construction Engineering Corporation (CSCEC) planned to construct a large-scale loading testing facility, the Multi-Function Testing System (MFTS). This facility can perform full-scale, real-time, 6-degree-of-freedom static and dynamic testing of rubber bearings and many types of structural components including long columns, shear walls and cross shape joints. The basic performances of the MFTS are a clearance of 9.1 m × 6.6 m × 10 m for specimen installation, maximum x-directional displacement 1500 mm, maximum y-directional velocity 1570 mm/s and maximum z-directional compressive load 108 MN. The system configuration and performance specifications of the MFTS are presented in this paper. The inverse kinematics model and the nonlinear model of the hydraulic servosystem of the MFTS are built. A modified feedback forward kinematics algorithm is developed for real-time control of the MFTS. Internal force characteristics of the loading system are analyzed. The internal force control method based on real-time solution of basis of internal force space is proposed for the system with large motion ranges. The motion controller combining position control loop and internal force control loop is developed. To meet the requirement of simultaneously imposing vertical compressive load and horizontal displacement, a mixed load and displacement controller is designed, where a direct force control loop is used to improve the response speed of the force control and reduce spatial dynamic coupling effects. Finally, a dynamic bearing testing is performed. The test results demonstrate that the system using the proposed controller has good abilities on position tracking, force balance, and load following.

Structural complexity and component type increase intertidal biodiversity independently of area.

Complexity is well accepted as one of the primary drivers of biodiversity, however, empirical support for such positive associations is often confounded with surface area and undermined by other potential explanatory factors, especially the type of structural component (e.g., pits, crevices, overhangs, etc.). In the present study, sample units (artificial substrates) of equal surface area (± 0.2%) were used to simultaneously examine the independent effects of complexity and different structural component types on species richness (S), abundance (N), and community composition. We created simple and complex concrete substrates of four different geometric designs using novel software. The substrates (n = 8) were mounted onto granite seawalls (at two tidal heights) on two islands south of Singapore Island. After 13 months of colonization, all 384 tiles were collected and their assemblages compared. A total of 53 744 individuals of 70 species/morphospecies were collected and identified. Our results show that greater complexity can support greater species richness and different communities that are independent of surface area. Furthermore, the type of structure (e.g., "pits," "grooves," "towers") can have an effect on richness and community composition that is independent of complexity.

Remaining service life estimation of reinforced concrete buildings based on fuzzy approach

The remaining service life (RSL) of buildings has been an important issue in the field of building and facility management, and its development is also one of the essential factors for achieving sustainable infrastructure. Since the estimation of RSL of buildings is heavily affected by the subjectivity of individual inspector or engineer, much effort has been placed in the development of a rational method that can estimate the RSL of existing buildings more quantitatively using objective measurement indices. Various uncertain factors contribute to the deterioration of the structural performance of buildings, and most of the common building structures are constructed not with a single structural member but with various types of structural components (e.g., beams, slabs, and columns) in multistory floors. Most existing RSL estimation methods, however, consider only an individual factor. In this study, an estimation method for RSL of concrete buildings is presented by utilizing a fuzzy theory to consider the effects of multiple influencing factors on the deterioration of durability (e.g., concrete carbonation, chloride attack, sulfate attack), as well as the current structural condition (or damage level) of buildings.

Economic assessment of climate adaptation strategies for existing reinforced concrete structures subjected to chloride-induced corrosion

Reinforced concrete (RC) structures placed in chloride-contaminated environments are subjected to deterioration processes that affect their performance, serviceability and safety. Chloride ingress leads to corrosion initiation and its interaction with service loading could reduce its operational life. Chloride ingress and corrosion propagation are highly influenced by weather conditions in the surrounding environment including climate change. Therefore, both structural design and maintenance should be adapted to these new environmental conditions. This study focuses on the assessment of the costs and benefits of climate adaptation strategies for existing RC structures subjected to chloride ingress and climate change. We studied RC structures built at different periods under different construction standards in France. The cost-effectiveness of adaptation measures was measured in terms of the benefit-to-cost ratio (BCR) and the probability that BCR exceeds unity – i.e. Pr(BCR>1). The results of the paper could provide practical advice to policy-makers to improve the management of existing RC structures under a changing climate by discussing the influence of the following factors on the mean BCR and Pr(BCR>1): specific exposure conditions, climate change scenarios, risk reduction due to the implementation of adaptation strategies, type of structural component, years of construction and adaptation, discount rates and damage costs.

Damage risks and economic assessment of climate adaptation strategies for design of new concrete structures subject to chloride-induced corrosion

Reinforced concrete (RC) structures are subject to environmental actions affecting their performance, serviceability and safety. Among these actions, chloride ingress leads to corrosion initiation and its interaction with service loading could reduce its operational life. Experimental evidence indicates that chloride ingress is highly influenced by weather conditions in the surrounding environment and therefore by climate change. Consequently, both structural design and maintenance should be adapted to these new environmental conditions. This work focuses on the assessment of the costs and benefits of two climate adaptation strategies for new RC structures placed in chloride-contaminated environments under various climate change scenarios. Their cost-effectiveness is measured in terms of the benefit-to-cost ratio (BCR) and the probability that BCR exceeds unity – i.e., Pr(BCR>1). It was found that increasing concrete strength grade is more cost-effective than increasing design cover. The results also indicate that the cost-effectiveness of a given adaptation strategy depends mainly on the type of structural component, exposure conditions and climate change scenarios.

Crack Growth Features in Hydrogenating High-Strength Steel AISI 4340 under Cycling

There are various types of structural components, which are subjected to hydrogen aggressive environment and cycling. Their unexpected failure occurs suddenly and may entail serious consequences such as emergency stop of equipment, failure of the structure etc. The special engineering models are developed to predict the crack kinetics in structure components, which are subjected both to hydrogen environment and to cycling simultaneously. These models enable estimation of structure component life. The paper considers some features of such empirically specified special model giving emphasis to the one of them, namely to the prevailing fracture mechanism transition from fatigue to hydrogen embrittlement and back in crack kinetics process.

A Model of Repetitive-DNA-Organized Chromatin Network of Interphase Chromosomes

During interphase, chromosomes are relatively de-condensed in the nuclear space. Interphase chromosomes are known to occupy nuclear space in a non-random manner (chromosome territory); however, their internal structures are poorly defined. In particular, little is understood about the molecular mechanisms that govern the internal organization of interphase chromosomes. The author recently proposed that pairing (or interaction) of repetitive DNA-containing chromatin regions is a critical driving force that specifies the higher-order organization of eukaryotic chromosomes. Guided by this theoretical framework and published experimental data on the structure of interphase chromosomes and the spatial distribution of repetitive DNA in interphase nuclei, I postulate here a molecular structure of chromatin organization in interphase chromosomes. According to this model, an interphase chromosome is a chromatin mesh (or lattice) that is formed by repeat pairing (RP). The mesh consists of two types of structural components: chromosome nodes and loose chromatin fibers. Chromosome nodes are DNA repeat assemblies (RAs) that are formed via RP, while loose fibers include chromatin loops that radiate from the nodes. Different loops crosslink by RPs and form a large integrated chromatin network. I suggest that the organization of the chromatin network of a given interphase chromosome is intrinsically specified by the distribution of repetitive DNA elements on the linear chromatin. The stability of the organization is governed by the collection of RA-formed nodes, and the dynamics of the organization is driven by the assembling and disassembling of the nodes.