Search results for: steel space frame

Authors: Ming-Wei Wu, Zih-Jie Lin

Abstract:

Liquid phase sintering (LPS) is a feasible means for decreasing the porosity of powder metallurgy (PM) Fe-based material without substantially increase the production cost. The aim of this study was to investigate the effect of 0.6 wt% boron on the densification of PM 304L stainless steel by LPS. The results indicated that the increase in the sintered density of 304L+0.6B steel is obvious after 1250 ºC sintering, and eutectic structures with borides are observed at the interfaces of the raw steel powders. Differential scanning calorimetry (DSC) results show that liquid is generated at 1244ºC during sintering. The boride in the eutectic structure is rich in boron and chromium atoms and is deficient in nickel atoms, as identified by electron probe micro-analyzer (EPMA). Furthermore, the sintered densities of 304L and 304L+0.6B steels sintered at 1300 ºC are 6.99 g/cm3 and 7.69 g/cm3, respectively, indicating that boron is a suitable alloying element for facilitating LPS of PM 304L stainless steel.

Keywords: powder metallurgy, liquid phase sintering, stainless steel, boron, microstructure

Procedia PDF Downloads 333

Authors: Alimohammad

Abstract:

Man's entry into space is one of the most important results of developments and advances made in information technology. But this human step, like many of his other actions, is not free of danger, as space pollution today has become a major problem for the global community. Paying attention to the issue of preserving the space environment is in the interest of all governments and mankind, and ignoring it can increase the possibility of conflict between countries. What many space powers still do not pay attention to is the freedom to explore and exploit space should be limited by banning pollution of the space environment. Therefore, freedom and prohibition are complementary and should not be considered conflicting concepts. The legal system created by the current space treaties for the effective preservation of the space environment has failed. Customary international law also does not have an effective provision and guarantee of sufficient executions in order to prevent damage to the environment. Considering the responsibility of each generation in the healthy transfer of the environment to the next generation and considering the sustainable development concept, the space environment must also be passed on to future generations in a healthy and undamaged manner. As a result, many environmental policies related to Earth should also be applied to the space environment..

Keywords: law, space, environment, responsibility

Procedia PDF Downloads 77

Authors: Emre Alan, Zafer Cetin

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Electrical steels are widely used as a magnetic core materials in many electrical applications such as transformers, electric motors, and generators. Core loss property of these magnetic materials refers to dissipation of electrical energy during magnetization in service conditions. Therefore, in order to minimize the magnetic core loss, certain precautions are taken from steel producers; “Steel Cleanliness” is one of the major points among them. For obtaining lower core loss values, increasing proper elements in chemical composition such as silicon is a must. Therefore, impurities of these alloys are a key value for producing a cleaner steel. In this study, effects of impurity levels of different FeSi alloying materials to the steel cleanliness will be investigated. One of the important element content in FeSi alloy materials is Calcium. A SEM investigation will be done in order to present if Ca content in FeSi alloy is enough for proper inclusion modification or an additional Ca-treatment is required.

Keywords: electrical steels, FeSi alloy, impurities, steel cleanliness

Procedia PDF Downloads 326

Authors: M. Bahgat, H. Hanafy, H. Al-Tassan

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Cluster formation is an essential phenomenon during direct reduction processes at shaft furnaces. Decreasing the reducing temperature to avoid this problem can cause a significant drop in throughput. In order to prevent sticking of pellets, a coating material basically inactive under the reducing conditions prevailing in the shaft furnace, should be applied to cover the outer layer of the pellets. In the present work, steel dust is used as coating material for iron ore pellets to explore dust coating effectiveness and determines the best coating conditions. Steel dust coating is applied for iron ore pellets in various concentrations. Dust slurry concentrations of 5.0-30% were used to have a coated steel dust amount of 1.0-5.0 kg per ton iron ore. Coated pellets with various concentrations were reduced isothermally in weight loss technique with simulated gas mixture to the composition of reducing gases at shaft furnaces. The influences of various coating conditions on the reduction behavior and the morphology were studied. The optimum reduced samples were comparatively applied for sticking index measurement. It was found that the optimized steel dust coating condition that achieve higher reducibility with lower sticking index was 30% steel dust slurry concentration with 3.0 kg steel dust/ton ore.

Keywords: reduction, ironmaking, steel dust, coating

Procedia PDF Downloads 299

Authors: Samuel David Dunstan

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An elementary observation of a laminar cylindrical Poiseulle-Couette flow profile reveals no distinction in the parabolic streamwise profile from one without a cross-stream flow in whatever reference frame the observation is made. This is because the laminar flow is in solid-body rotation, and there is no intrinsic fluid rotation. Hence the main streamwise Poiseuille flow is unaffected. However, in turbulent (unsteady) cylindrical Poiseuille-Couette flow, the rotational reference frame must be considered, and any observation from an external inertial reference frame can give outright incorrect results. A common misconception in the study of fluid mechanics is the position of the observer does not matter. In this DNS (direct numerical simulation) study, firstly, turbulent flow in a pipe with axial rotation is established. Then in turbulent flow in the concentric pipe, with inner wall rotation, it is shown how the wall streak direction is oriented by the rotational reference frame. The Coriolis force here is not so fictitious after all!

Keywords: concentric pipe, rotational and inertial frames, frame invariance, wall streaks, flow orientation

Procedia PDF Downloads 85

Authors: Nety Trisnawaty, Mirna Febriani

Abstract:

The use of stainless steel wires in the field of dentistry is widely used, especially for orthodontic and prosthodontic treatment using stainless steel wire. The oral cavity is the ideal environment for corrosion, which can be caused by saliva. Prevention of corrosion on stainless steel wires can be done by using an organic or non-organic corrosion inhibitor. One of the organic inhibitors that can be used to prevent corrosion is black tea leaves extracts. To explain the comparison of chromium ions release for stainlees steel between artificial saliva and black tea leaves extracts. In this research we used artificial saliva, black tea leaves extracts, stainless steel wire and using Atomic Absorption Spectrophometric testing machine. The samples were soaked for 1, 3, 7 and 14 days in the artificial saliva and black tea leaves extracts. The results showed the difference of chromium ion release soaked in artificial saliva and black tea leaves extracts on days 1, 3, 7 and 14. Statistically, calculation with independent T-test with p < 0,05 showed a significant difference. The longer the duration of days, the more ion chromium were released. The conclusion of this study shows that black tea leaves extracts can inhibit the corrosion rate of stainless steel wires.

Keywords: chromium ion, stainless steel, artificial saliva, black tea leaves extracts

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Authors: Mustafa Gülen, Eylem Güzel, Soner Guler

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The concrete filled steel tube (CFST) columns are commonly used in construction applications such as high-rise buildings and bridges owing to its lots of remarkable benefits. The use of concrete filled steel tube columns provides large areas by reduction in cross-sectional area of columns. The main aim of this study is to examine the axial load capacities of circular high strength concrete filled steel tube columns according to Eurocode 4 (EC4) and Chinese Code (DL/T). The results showed that the predictions of EC4 and Chinese Code DL/T are unsafe for all specimens.

Keywords: concrete-filled steel tube column, axial load capacity, Chinese code, Australian Standard

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Authors: Abdulmagid A. Khattabi, Ahmed A. Hablous, Mofied M. Elnemry

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The carbon steel is of one of the most common mineral materials used in engineering and industrial applications in order to have access to the required mechanical properties, especially after the change of carbon ratio, but this may lead to stimulate corrosion. It has been used in models of solids with different carbon ratios such as 0.05% C, 0.2% C, 0.35% C, 0.5% C, and 0.65% C and have been studied using three testing durations which are 4 weeks, 6 weeks, and 8 weeks and among different corrosion environments such as atmosphere, fresh water, and salt water. This research is for the purpose of finding the effect of the carbon content on the corrosion resistance of steels in different corrosion medium by using the weight loss technique as a function of the corrosion resistance. The results that have been obtained through this research shows that a correlation can be made between corrosion rates and steel's carbon content, and the corrosion resistance decreases with the increase in carbon content.

Keywords: proportion of carbon in the steel, corrosion rate, erosion, corrosion resistance in carbon-steel

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Authors: Sylwia Wiewiorowska, Zbigniew Muskalski

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The strain intensity and redundant strains, dependent in multistage TRIP wire drawing processes from values used single partial reductions, should influence on the intensity of transformation the retained austenite into martensite and thereby on mechanical properties of drawn wires. The numerical analysis of drawing processes with use of Drawing 2D programme, for steel wires made from TRIP steel with 0,29 % has been shown in the work. The change of strain intensity Ԑc and the values of redundant strain Ԑxy, has been determined for particular draws in dependence of used single partial reductions.

Keywords: steel wire, TRIP steel, drawing processes, fem modelling

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Authors: Mohammed Jibrin Ndejiko

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Modern and current models such as flow cell technology which enhances a non-destructive growth and inspection of the sessile microbial communities revealed a great understanding of biofilms. A continuous flow system was designed to evaluate possibility of biofilm formation by Escherichia coli DH5α on the stainless steel (type 304) under continuous nutrient supply. The result of the colony forming unit (CFU) count shows that bacterial attachment and subsequent biofilm formation on stainless steel coupons with average surface roughness of 1.5 ± 1.8 µm and 2.0 ± 0.09 µm were both significantly higher (p ≤ 0.05) than those of the stainless steel coupon with lower surface roughness of 0.38 ± 1.5 µm. These observations support the hypothesis that surface profile is one of the factors that influence biofilm formation on stainless steel surfaces. The SEM and FESEM micrographs of the stainless steel coupons also revealed the attached Escherichia coli DH5α biofilm and dehydrated extracellular polymeric substance on the stainless steel surfaces. Thus, the fabricated flow system represented a very useful tool to study biofilm formation under continuous nutrient supply.

Keywords: biofilm, flowcell, stainless steel, coupon

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Authors: Sadhvi Gupta, Charulatha S.

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Since the dawn of the early 1950s humans have launched numerous vehicles in space. Be it from rockets to rovers humans have done tremendous growth in the technology sector. While there is mostly upside for it for humans the only major downside which cannot be ignored now is the amount of junk produced in space due to it i.e. space debris. All this space junk amounts from objects we launch from earth which so remains in orbit until it re-enters the atmosphere. Space debris can be of various sizes mainly the big ones are of the dead satellites floating in space and small ones can consist of various things like paint flecks, screwdrivers, bolts etc. Tracking of small space debris whose size is less than 10 cm is impossible and can have vast implications. As the amount of space debris increases in space the chances of it hitting a functional satellite also increases. And it is extremely costly to repair or recover the satellite once hit by a revolving space debris. So the proposed solution is, Actively removing space debris while keeping space sustainability in mind. For this solution a total of 8 modules will be launched in LEO and in GEO and these models will be placed in their desired orbits through Hohmann transfer and for that calculating ΔV values is crucial. After which the modules will be placed in their designated positions in STK software and thorough analysis is conducted.

Keywords: space debris, Hohmann transfer, STK, delta-V

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Authors: Hyungoo Kang, Minsung Kim, Jinkoo Kim

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This study investigates the performance of a 2D and 3D steel moment frame subjected to vehicle collision at a first story column using LS-DYNA. The finite element models of vehicles provided by the National Crash Analysis Center (NCAC) are used for numerical analysis. Nonlinear dynamic time history analysis of the 2D and 3D model structures are carried out based on the arbitrary column removal scenario, and the vertical displacement of the damaged structures are compared with that obtained from collision analysis. The analysis results show that the model structure remains stable when the speed of the vehicle is 40km/h. However, at the speed of 80 and 120km/h both the 2D and 3D structures collapse by progressive collapse. The vertical displacement of the damaged joint obtained from collision analysis is significantly larger than the displacement computed based on the arbitrary column removal scenario.

Keywords: vehicle collision, progressive collapse, FEM, LS-DYNA

Procedia PDF Downloads 331

Authors: E. K. K. Agyeman, P. Mousseau, A. Sarda, D. Edelin

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During the cooling of hot metals by the circulation of water in canals formed by boring holes in the metal, the rapid phase change of the water due to the high initial temperature of the metal leads to a non homogenous distribution of the phases within the canals. The liquid phase dominates towards the entrance of the canal while the gaseous phase dominates towards the exit. As a result of the different thermal properties of both phases, the metal is not uniformly cooled. This poses a problem during the cooling of moulds, where a uniform temperature distribution is needed in order to ensure the integrity of the part being formed. In this study, the simultaneous use of multiple water jets and an airflow for the uniform and controlled cooling of a steel block is investigated. A circular hole is bored at the centre of the steel block along its length and a perforated steel pipe is inserted along the central axis of the hole. Water jets that impact the internal surface of the steel block are generated from the perforations in the steel pipe when the water within it is put under pressure. These jets are oriented in the opposite direction to that of gravity. An intermittent airflow is imposed in the annular space between the steel pipe and the surface of hole bored in the steel block. The evolution of the temperature with respect to time of the external surface of the block is measured with the help of thermocouples and an infrared camera. Due to the high initial temperature of the steel block (350 °C), the water changes phase when it impacts the internal surface of the block. This leads to high heat fluxes. The strategy used to control the cooling speed of the block is the intermittent impingement of its internal surface by the jets. The intervals of impingement and of non impingement are varied in order to achieve the desired result. An airflow is used during the non impingement periods as an additional regulator of the cooling speed and to improve the temperature homogeneity of the impinged surface. After testing different jet positions, jet speeds and impingement intervals, it’s observed that the external surface of the steel block has a uniform temperature distribution along its length. However, the temperature distribution along its width isn’t uniform with the maximum temperature difference being between the centre of the block and its edge. Changing the positions of the jets has no significant effect on the temperature distribution on the external surface of the steel block. It’s also observed that reducing the jet impingement interval and increasing the non impingement interval slows down the cooling of the block and improves upon the temperature homogeneity of its external surface while increasing the duration of jet impingement speeds up the cooling process.

Keywords: cooling speed, homogenous cooling, jet impingement, phase change

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Authors: Mandlenkosi G. R. Mahlobo, Peter A. Olubambi

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Cathodic protection (CP) has been widely considered as a suitable technique for mitigating corrosion of steel structures buried in soil. Plenty of efforts have been made in developing techniques, in particular non-destructive techniques, for monitoring and quantifying the effectiveness of CP to ensure the sustainability and performance of buried steel structures. This study was aimed at using a specifically modified voltammetry approach as a non-destructive tool to monitor and quantify the effectiveness of CP of steel in simulated soil. Carbon steel was subjected to electrochemical tests with NS4 solution used as simulated soil conditions for four days before applying CP for further 11 days. A specifically modified voltammetry technique was applied at various time intervals of the experiment to monitor the corrosion behaviour and therefore reflect CP effectiveness. The voltammetry results revealed that the application of CP reduced the corrosion rate from the highest value of 410 µm/yr to 8 µm/yr between days 5 and 14 of the experiments. The microstructural analysis of the steel surface performed using x-ray diffraction identified calcareous deposit as the dominant phase protecting the surface from corrosion. It was deduced that the formation of calcareous deposits was linked with the effectiveness of CP of steel.

Keywords: carbon steel, cathodic protection, NS4 solution, voltammetry, XRD

Procedia PDF Downloads 64

Authors: Alfredo Reyes-Salazar, Mario D. Llanes-Tizoc, Eden Bojorquez, Federico Valenzuela-Beltran, Juan Bojorquez, Jose R. Gaxiola-Camacho, Achintya Haldar

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Seismic analysis of steel buildings is usually based on the use of the concentrated mass (ML) matrix and the Rayleigh damping matrix (C). Similarly, the initial stiffness matrix (KO) and the first two modes associated with lateral vibrations are commonly used to develop matrix C. The evaluation of the accuracy of these practices for the particular case of steel buildings with moment-resisting steel frames constitutes the main objective of this research. For this, the non-linear seismic responses of three models of steel frames, representing low-, medium- and high-rise steel buildings, are considered. Results indicate that if the ML matrix is used, shears and bending moments in columns are underestimated by up to 30% and 65%, respectively when compared to the corresponding results obtained with the consistent mass matrix (MC). It is also shown that if KO is used in C instead of the tangent stiffness matrix (Kt), axial loads in columns are underestimated by up to 80%. It is concluded that the consistent mass matrix should be used in the structural modelling of moment-resisting steel frames and that the tangent stiffness matrix should be used to develop the Rayleigh damping matrix.

Keywords: moment-resisting steel frames, consistent and concentrated mass matrices, non-linear seismic response, Rayleigh damping

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Authors: Ben Chater, Jingbang Pan, Mark Evernden, Jie Wang

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Traditional structural steel manufacturing routes normally produce prismatic members with flat plate elements. In these members, plate instability in the lowest buckling mode often dominates failure. It is proposed in the current study to use a new technology of metal 3D printing to print steel-plated elements with predefined imperfection patterns that can lead to higher modes of failure with increased buckling resistances. To this end, a numerical modeling program is carried out to explore various combinations of predefined buckling waves with different amplitudes in stainless steel square hollow section stub columns. Their stiffness, strength, and material consumption against the traditional structural steel members with the same nominal dimensions are assessed. It is found that depending on the slenderness of the plate elements; it is possible for an ‘imperfect’ steel member to achieve up to a 30% increase in strength with just a 3% increase in the material consumption. The obtained results shed some light on the significant potential of the new metal 3D printing technology in achieving unprecedented material efficiency and economical design in the future steel construction industry.

Keywords: 3D printing, additive manufacturing, buckling resistance, steel plate buckling, structural optimisation

Procedia PDF Downloads 139

Authors: Zhao Cai-qi, Ma Jun

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Twin steel plates-concrete composite shear walls are composed of a pair of steel plate layers and a concrete layer sandwiched between them, which have the characteristics of both reinforced concrete shear walls and steel plate shear walls. Twin steel plates-composite shear walls contain very high ultimate bearing capacity and ductility, which have great potential to be applied in the super high-rise buildings and special structures. In this paper, we analyzed the basic characteristics and stress mechanism of the twin steel plates-composite shear walls. Specifically, we analyzed the effects of the steel plate thickness, wall thickness and concrete strength on the bearing capacity of the twin steel plates-composite shear walls. The analysis results indicate that：（1）the initial shear stiffness and ultimate shear-carrying capacity is not significantly affected by the thickness of concrete wall but by the class of concrete,（2）both factors significantly impact the shear distribution of the shear walls in ultimate shear-carrying capacity. The technique of twin steel plates-composite shear walls has been successfully applied in the construction of a 88-meter Huge Statue of Buddha located in Hunan Province, China. The analysis results and engineering experiences showed that the twin steel plates-composite shear walls have great potential for future research and applications.

Keywords: twin steel plates-concrete composite shear wall, huge statue of Buddha, shear capacity, initial lateral stiffness, overturning moment bearing

Procedia PDF Downloads 397

Authors: V. Sadeghi Balkanlou, M. Reza Bagerzadeh Karimi, A. Hasanbakloo, B. Bagheri Azar

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In this paper, the behavior of different types of DST columns has been studied under bending load. Briefly, composite columns consist of an internal carbon steel tube and an external stainless steel wall that the between the walls are filled with concrete. Composite columns are expected to combine the advantages of all three materials and have the advantage of high flexural stiffness of CFDST columns. In this research, ABAQUS software is used for finite element analysis then the results of ultimate strength of the composite sections are illustrated.

Keywords: DST, stainless steel, carbon steel, ABAQUS, straigh columns, tapered columns

Procedia PDF Downloads 383

Authors: Saiada Fuadi Fancy, Fahim Ahmed, Shofiq Ahmed, Raquib Ahsan

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The worldwide use of reinforced concrete construction stems from the wide availability of reinforcing steel as well as concrete ingredients. However, concrete construction requires a certain level of technology, expertise, and workmanship, particularly, in the field during construction. As a supporting technology for a concrete column or wall construction, kicker is cast as part of the slab or foundation to provide a convenient starting point for a wall or column ensuring integrity at this important junction. For that reason, a comprehensive study was carried out here to investigate the behavior of reinforced concrete frame with different kicker parameters. To achieve this objective, six half-scale specimens of portal reinforced concrete frame with kickers and one portal frame without kicker were constructed according to common practice in the industry and subjected to cyclic incremental horizontal loading with sustained gravity load. In this study, the experimental data, obtained in four deflections controlled cycle, were used to evaluate the behavior of kickers. Load-displacement characteristics were obtained; maximum loads and deflections were measured and assessed. Finally, the test results of frames constructed with three different types of kicker thickness were compared with the kickerless frame. Similar crack patterns were observed for all the specimens. From this investigation, specimens with kicker thickness 3″ were shown better results than specimens with kicker thickness 1.5″, which was specified by maximum load, stiffness, initiation of first crack and residual displacement. Despite of better performance, it could not be firmly concluded that 4.5″ kicker thickness is the most appropriate one. Because, during the test of that specimen, separation of dial gauge was needed. Finally, comparing with kickerless specimen, it was observed that performance of kickerless specimen was relatively better than kicker specimens.

Keywords: crack, cyclic, kicker, load-displacement

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Authors: Zhan Haiyang, Zhang Lei, Ning Juan

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This paper presents a configuration software solution in Linux, which is used for the control of space environment simulator. After introducing the structure and basic principle, it is said that the developing of QT software frame and the dynamic data exchanging between PLC and computer. The OPC driver in Linux is also developed. This driver realizes many-to-many communication between hardware devices and SCADA software. Moreover, an algorithm named “Scan PRI” is put forward. This algorithm is much more optimizable and efficient compared with "Scan in sequence" in Windows. This software has been used in practical project. It has a good control effect and can achieve the expected goal.

Keywords: Linux OS, configuration software, OPC Server driver, MYSQL database

Procedia PDF Downloads 282

Authors: M. Dekmouche, M. Hadjada, Z. Rahmani, M. Saidi

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The effect of iodide ions on the corrosion inhibition of mild steel in 20% sulfuric acid in the presence of 3-méthylthio-5-p-méthoxyphényl-1,2-dithiolylium against anion (I-) A1 synthesized in our laboratory,was studied by different electrochemical techniques such as electrochemical impedance spectroscopy, potentiodynamic polarization. The obtained results showed that A1 effectively reduces the corrosion rate of steel. The adsorption of 3-méthylthio-5-p-méthoxyphényl-1,2-dithiolylium against anion (I-) followed Langmuir and temkin adsorption isotherm.

Keywords: steel XC52, corrosion, inhibition, 3-méthylthio-5-p-méthoxyphényl-1, 2-dithiolylium against anion (I-) , sulfuric acid

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Authors: Vinay Patil, Swapnil Kekade, Ashish Supare, Vinayak Pawar, Shital Jadhav, Rajkumar Singh

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In recent days, bainitic steel is used in automobile and non-automobile sectors due to its high strength. Bainitic steel is difficult to machine because of its high hardness, hence in this paper machinability of bainitic steel is studied by using Taguchi design of experiments (DOE) approach. Convectional turning experiments were done by using L16 orthogonal array for three input parameters viz. cutting speed, depth of cut and feed. The Taguchi method is applied to study the performance characteristics of machining parameters with surface roughness (Ra), cutting force and tool wear rate. By using Taguchi analysis, optimized process parameters for best surface finish and minimum cutting forces were analyzed.

Keywords: conventional turning, Taguchi method, S/N ratio, bainitic steel machining

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Authors: Prasenjit Singha, Ajay Kumar Shukla

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To produce high-quality steel in larger volumes, dynamic control of composition and temperature throughout the process is essential. In this paper, we developed a mass transfer model based on thermodynamics to simulate the ladle metallurgy steel-making process using FactSage and its macro facility. The overall heat and mass transfer processes consist of one equilibrium chamber, two non-equilibrium chambers, and one adiabatic reactor. The flow of material, as well as heat transfer, occurs across four interconnected unit chambers and a reactor. We used the macro programming facility of FactSage™ software to understand the thermochemical model of the secondary steel making process. In our model, we varied the oxygen content during the process and studied their effect on the composition of the final hot metal and slag. The model has been validated with respect to the plant data for the steel composition, which is similar to the ladle metallurgy steel-making process in the industry. The resulting composition profile serves as a guiding tool to optimize the process of ladle metallurgy in steel-making industries.

Keywords: desulphurization, degassing, factsage, reactor

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Authors: Mai M. Khalaf, Hany M. Abd El-Lateef

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A new good application for the sol gel method is to improve the corrosion inhibition properties of carbon steel by the dip coating method of Nano TiO2 films and its modification with Poly Ethylene Glycol (PEG). The prepared coating samples were investigated by different techniques, X-ray diffraction, Scanning Electron Microscopy (SEM), transmission electron microscopy and Energy Dispersive X-ray Spectroscopy (EDAX). The corrosion inhibition performance of the blank carbon steel and prepared coatings samples were evaluated in 0.5 M H2SO4 by using Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization measurements. The results showed that corrosion resistance of carbon steel increases with increasing the number of coated layers of both nano–TiO2 films and its modification of PEG. SEM-EDAX analyses confirmed that the percentage atomic content of iron for the carbon steel in 0.5 M H2SO4 is 83% and after the deposition of the steel in nano TiO2 sol and that with PEG are 94.3% and 93.7% respectively.

Keywords: dip-coatings, corrosion protection, sol gel, TiO2 films, PEG

Procedia PDF Downloads 421

Authors: Hamed Abshari, M. Reza Emami Azadi, Madjid Sadegh Azar

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For studying the overall instability of members of steel structures, there are several methods in which overall buckling and geometrical imperfection effects are considered in analysis. In first section, these methods are compared and ability of software to apply these methods is studied. Buckling loads determined from theoretical methods and software is compared for 2D one bay, one and two stories steel frames. To consider actual condition, buckling loads of three steel frames that have various dimensions are calculated and compared. Also, uncertainties that exist in loading and modeling of structures such as geometrical imperfection, yield stress, and modulus of elasticity in buckling load of 2D framed steel structures have been studied. By performing these uncertainties to each reliability analysis procedures (first-order, second-order, and simulation methods of reliability), one index of reliability from each procedure is determined. These values are studied and compared.

Keywords: buckling, second-order theory, reliability index, steel columns

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Authors: Nasruddin Junus

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CFTR column is one of the improvements CFT columns by inserting reinforcing steel bars into infill concrete. The presence of inserting reinforcing steel bars is increasing the excellent structural performance of the CFT column, especially on the fire-resisting performance. Investigation on the mechanical behavior of CFTR column connection is summarized in the three parts; column to column joint, column to beam connection, and column base. Experiment that reported in this paper is concerned on the mechanical behavior of CFTR column joint under pull out testing, especially on its stress transfer mechanism. A number series of the pull out test on the CFT with inserting reinforcing steel bar are conducted. Ten test specimens are designed, constructed, and tested to examine experimentally the effect of the size of square steel tube, size of the bearing plate, length of embedment steel bars, kind of steel bars, and the numbers of rib plate.

Keywords: CFTR column, pull out, stress, transfer mechanism

Procedia PDF Downloads 286

Authors: Qian Chen, Lin Xu, Ping Ju, Zhuoran Li, Yiping Yu, Yuqing Jin

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The operation of power grid is becoming more and more complex and difficult due to its rapid development towards high voltage, long distance, and large capacity. For instance, many large-scale wind farms have connected to power grid, where their fluctuation and randomness is very likely to affect the stability and safety of the grid. Fortunately, many new-type equipments based on power electronics have been applied to power grid, such as UPFC (Unified Power Flow Controller), TCSC (Thyristor Controlled Series Compensation), STATCOM (Static Synchronous Compensator) and so on, which can help to deal with the problem above. Compared with traditional equipment such as generator, new-type controllable devices, represented by the FACTS (Flexible AC Transmission System), have more accurate control ability and respond faster. But they are too expensive to use widely. Therefore, on the basis of the comparison and analysis of the controlling characteristics between traditional control equipment and new-type controllable equipment in both time and space scale, a coordinated optimizing control method within mutil-time-space frame is proposed in this paper to bring both kinds of advantages into play, which can better both control ability and economical efficiency. Firstly, the coordination of different space sizes of grid is studied focused on the fluctuation caused by large-scale wind farms connected to power grid. With generator, FSC (Fixed Series Compensation) and TCSC, the coordination method on two-layer regional power grid vs. its sub grid is studied in detail. The coordination control model is built, the corresponding scheme is promoted, and the conclusion is verified by simulation. By analysis, interface power flow can be controlled by generator and the specific line power flow between two-layer regions can be adjusted by FSC and TCSC. The smaller the interface power flow adjusted by generator, the bigger the control margin of TCSC, instead, the total consumption of generator is much higher. Secondly, the coordination of different time sizes is studied to further the amount of the total consumption of generator and the control margin of TCSC, where the minimum control cost can be acquired. The coordination method on two-layer ultra short-term correction vs. AGC (Automatic Generation Control) is studied with generator, FSC and TCSC. The optimal control model is founded, genetic algorithm is selected to solve the problem, and the conclusion is verified by simulation. Finally, the aforementioned method within multi-time-space scale is analyzed with practical cases, and simulated on PSASP (Power System Analysis Software Package) platform. The correctness and effectiveness are verified by the simulation result. Moreover, this coordinated optimizing control method can contribute to the decrease of control cost and will provide reference to the following studies in this field.

Keywords: FACTS, multi-space-time frame, optimal control, TCSC

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Authors: Kok-Chong Yong

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Poly(butadiene-co-acrylonitrile)-polyaniline Dodecylbenzenesulfonate [NBR-PAni.DBSA] blends with useful electrical conductivity (up to 0.1 S/cm) were prepared and their corrosion inhibiting behaviours for carbon steel were successfully assessed for the first time. The level of compatibility between NBR and PAni.DBSA was enhanced through the introduction of 1.0 wt % hydroquinone. As found from both total immersion and electrochemical corrosion tests, NBR-PAni.DBSA blends with 10.0-30.0 wt% of PAni.DBSA content exhibited the best corrosion inhibiting behaviour for carbon steel, either in acid or artificial brine environment. On the other hand, blends consisting of very low and very high PAni.DBSA contents (i.e. ≤ 5.0 wt % and ≥ 40.0 wt %) showed significantly poorer corrosion inhibiting behaviour for carbon steel.

Keywords: conductive rubber, nitrile rubber, polyaniline, carbon steel, corrosion inhibition

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Authors: Abdul Hakim Chikho

Abstract:

A simple method of calculating satisfactory of the effect of instability on the distribution of in-plane bending moments in unbraced semi-rigidly multistory steel framed structures is presented in this paper. This method, which is a modified form of the current amplified sway method of BS5950: part1:2000, uses an approximate load factor at elastic instability in each storey of a frame which in turn dependent up on the axial loads acting in the columns. The calculated factors are then used to represent the geometrical deformations due to the presence of axial loads, acting in that storey. Only a first order elastic analysis is required to accomplish the calculation. Comparison of the prediction of the proposed method and the current BS5950 amplified sway method with an accurate second order elastic computation shows that the proposed method leads to predictions which are markedly more accurate than the current approach of BS5950.

Keywords: improved amplified sway method, steel frames, semi-rigid connections, secondary effects

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Authors: Waheed Ahmad Safi, Shunichi Nakamura, Abdul Habib Ghaforzai

Abstract:

Steel and concrete composite bridge with concrete filled steel I-girder (CFIG) was proposed and FEM and laboratory tests were conducted to analysis bending and shear behavior. The proposed form of structural steel I-section is mainly used at the intermediate support zone by placing infilled concrete into the top and bottom flanges of steel I-section to resist negative bending moment. The bending and shear tests were carried out to find out the significance of CFIG section. The result for test showing that the bending and shear capacity of proposed CFIG is at least 3 times and 2 times greater than conventional steel I-section (IG) respectively. Finite element study was also carried out to ensure the result for laboratory tests due to bending and shear behavior and load transfer behavior of proposed structural form. Finite element result result agreed the test result. A design example was carried out for a four-span continuous highway bridge and design method was established.

Keywords: bending strength, concrete filled steel I-girder, steel I-girder, FEM, limit states design and shear strength

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