Steel Support Research Articles

Effects of applying external voltage on development of anaerobic dynamic membrane under high suspended solids conditions

Maintaining proper dynamic membrane (DM) thickness and structure is the key factor for effective filtration and biomass retention in DM bioreactors. This study investigated the effects of negative and positive applied voltages on the development and characteristics of anaerobic DM under high suspended solids conditions. The DM filtration experiments with anaerobic sludge were performed using submerged DM modules with stainless steel support material at applied voltages of –1.2 to +1.2 V. Negative applied voltage (i.e., cathodic DM) delayed the DM fouling, while positive applied voltage (i.e., anodic DM) accelerated the DM growth, within certain voltage ranges by the combined effect of electrostatic forces and electrochemical reactions. Too large negative or positive voltages caused electrochemical corrosion of support material and precipitation of mineral scales, resulting in serious chemical fouling. The cathodic and anodic DMs formed at different applied voltages achieved high suspended solids rejection efficiencies of 86.4–89.6%. The applied voltage had a significant effect not only on the DM growth and filtration resistance but also the surface morphology, cell viability (live/dead cell ratio), and extracellular polymeric substances distribution of DM. Cell damage by electrochemically formed reactive species was observed at high electrode potentials. The overall results suggest that applying external voltage within an appropriate range can be an effective way to control the DM development. Although much more research is needed, the findings of this study offer a new possibility to improve the feasibility of DM technology and its applicability in anaerobic DM bioreactors.

Technologies of mine roof support using cable bolters: Experience and prospects

The modern mines in Russia and in the near abroad target themselves at effective mechanization and higher production output through modernization of manufacturing capabilities. Currently mining is carried out at great depths and in wider roadways using large-size self-propelling machinery. The geological conditions complicate with growing depth of mining, which impedes operations as a rule. At the present day, mine support systems for great depths include heavy steel support, which calls for essential physical and technical resources. Thus, it is required to improve methods of mine support and to expand application ranges of rock bolting. As a case-study of Maisky Mine, the authors discuss applicability of RANK 2 AK series cable bolting using a cable bolter and with anchorage using chemical ampules and injection syringe. The two-level support design, using a cable bolt anchored using a chemical ampule, with individual supporting components such as a plate or a pickup without complete fill of a hole, is the most effective method of mine roof support. Moreover, it enables safe and efficient operations at intersections in the mine, or in wide roadways, with no blocking the ways for personnel or for rock haulage by large-size self-propelling machines.

Conceptual Design of the Transformational Challenge Reactor

The Transformational Challenge Reactor is a 3-MW(thermal) helium-cooled experimental nuclear reactor designed using an additive manufacturing–informed agile design process. This design process leverages rapid prototyping and advanced materials from emerging additive manufacturing technologies, key characteristics that enable rapid design maturation. The resulting core design incorporates a blend of advanced reactor technologies into an intermediate-spectrum microreactor, including conventionally manufactured tristructural isotropic (TRISO) fuel particles in an advanced manufactured SiC fuel element and a solid yttrium hydride moderator encapsulated in steel. Matured during the design effort, these technologies are incorporated with additively manufactured steel support and fluidic structures to form a 75-cm-outer-diameter cylindrical active core region. Below and above the active core region are axial SiC reflectors, which are housed inside the reactor pressure vessel. The reactor is controlled with an annular shroud actuated external to the pressure vessel in the gap between the pressure vessel and a steel radial reflector. A safety rod is at the center of the core to shut down the reactor when necessary. Helium pressurized at 5 MPa is forced into the pressure vessel below the core and around the core to the top plenum before it is forced down through the axial reflectors and the active core region. The primary pressurized helium loop is operated up to 500°C and includes the pressure vessel, the circulator, and the hot side of a helium-to-air heat exchanger. The secondary loop rejects all heat from the primary loop to ambient air through a heat exchanger. A vented temporary confinement building contains the entire primary loop, with penetrations for a stack, cooling, and the secondary ambient air loop. This is the first advanced nuclear microreactor designed using additive manufacturing technologies, demonstrating their applicability in an accelerated advanced design process.

Improvement on the Key Element of Flexible U‐Shaped Steel Support and Its Field Applications

In China, there are a significant numbers of soft rocks roadways in underground coal mines. The roofs of these roadways are generally highly fractured, and traditional bolt installation does not provide sufficient supporting capacity. Hence, U‐shaped steel support has gained popularity, and the key influential factor of steel support is the lock unit between its mechanical structures. The commonly used two‐slotted splint lock unit can experience eversion and splitting and resulted in overall instability. To overcome the limitation, a “surface snap‐in” lock unit was developed. Based on experimental results, it was found that the relationships of bearing capacity and deformation of two lock unit types were similar under same loading conditions. The ultimate bearing capacity of surface snap‐in lock unit was lower than the two slotted splint unit. Although, its overall stability and flexibility were better. On the other hand, screw bolts of both unit types exhibited increase or decrease with the compressional deformation of steel support. The maximum stress along the screw bolt of two‐slotted splint lock unit was 1.6 to 1.8 times of the surface snap‐in lock unit. Based on the findings, the combination of two lock unit types was proposed and used at Peigou coal mine. Results show that the proposed design can effectively manage the roadway deformation while preventing the steel support damage. This in turn can reduce the associated supporting cost as the steel support can be recycled.

Production of metal-supported solid oxide fuel cells by co-sintering route

The cost-effective co-sintering route has been considered for the production of Metal-Supported Solid Oxide Fuel Cells in this study. Ferritic stainless steel, composite of Ni-YSZ, and YSZ have been utilized as parent materials for the mechanical support, anode, and electrolyte respectively. The cracking of the multilayers has been avoided by optimizing the de-binding step. The issue of delamination of layers and the interdiffusion of elements have been addressed by the introduction of an ‘intermediate layer’ (composite of LDC and steel) in between the steel support and the Ni-YSZ anode layers. In general, this work presents the optimization of steps and modification of multilayer design and materials towards the successful fabrication of MS-SOFC by co-sintering.

Research on Deformation Law of Deep Foundation Pit of Station in Core Region of Saturated Soft Loess Based on Monitoring

Saturated soft loess has a large pore structure, high compressibility, low strength, fluid plastic state, and poor engineering properties. It is still one of the key problems that engineering needs to solve. In order to study the influence of deep foundation pit excavation in the saturated soft loess area on the deformation of foundation pits, the deformation laws of ground settlement, enclosure structure, and supporting axial force were clarified based on the field tests on the deformation characteristics of deep foundation pits in areas with the high‐water level in saturated soft loess, combined with geological conditions and on‐site construction procedures. The results indicate the following: water supply and construction process were found to be the main factor in changing the surface settlement curve of deep foundation pits in saturated soft loess; increasing the construction speed of the pit bottom floor, inverted braces, floor frame beams, and sidewall frame beams to close the structure, which is conducive to restraining the deformation of the continuous underground wall and foundation pits in similar areas. In the initial stage of support layout, the axial force of steel support tends to increase too fast or even exceed the standard control value. Therefore, a reasonable preadding axial force is an effective means to control the deformation of the continuous underground wall and the axial force of the steel support. The current research results may provide a reference for constructing deep foundation pits in similar areas.

Deformation Control Monitoring of Basement Excavation at Field Construction Site: A Case of Hydraulic Servo Steel Enhancement Geotechnology

This study presents two field cases of deep excavation using the hydraulic servo geotechnology as an enhancement to the lateral support. The first excavation process was preceded with numerical simulation to investigate the deformation of excavation pit with and without servo geotechnology. Optimised axial loading capacities from the numerical simulation were adopted at the actual excavation site. On the second excavation site, servo geotechnology was applied directly on the excavation process during actual construction without prior numerical simulation. The results showed that the servo steel support geotechnology restrained above 70% of lateral displacements of the excavated walls, and ground surface influence zone settlements were kept within the acceptable warning limits. Prior application of the numerical simulation before field excavation optimised axial loads and kept the deformation caused by excavation within project limits. The numerical simulation of servo geotechnology deformation control capacity for deep excavation projects is validated, and this study provides a practical and significant reference on similar projects.

Numerical Model Developed for Thermo-Mecahnical Analysis in AlCrFeMnNiHf0.05–Armox 500 Steel Welded Joint

High entropy alloys are a new category of materials that contain at least four main chemical elements. One of the main advantages over the traditional alloys is the ability to maintain their properties at low or high temperatures. Researchers have investigated the possibility of welding these alloys so that they can be used in industrial applications. Good results have been obtained by welding butt joints of thin sheets, without the use of filler materials. In this paper it is investigated the possibility of welding overlap joints, with applications in the military field, of medium-thickness plates of AlCrFeMnNiHf0.05 high entropy alloy on an Armox 500 steel support plate, using filler materials available on the market. The research focuses on the numerical simulation of three welding processes commonly used in on-site repair operations, namely manual metal arc, metal inert gas, and tungsten inert gas.

Kajian Parametrik Balok Beton Memadat Mandiri Menggunakan Analisis Nonlinier Elemen Hingga

Self-compacting concrete has self-flowing, viscous and compact properties that minimize mechanical compaction. This concrete is suitable for solving the concrete pouring in the narrow and congested reinforcement. Beams made of both self-compacting concrete and normal high-strength concrete are analyzed by MSC Marc / Mentat software. Steel is modeled by being embedded in concrete. The failure criterion of Linear Mohr-Coulomb is used for concrete and Von Mises for reinforcing steel, respectively. Concrete and the plate support are modelled by 3D solid elements. For the steel, the truss element is used. The contact analysis is implemented between beam and both steel plate and steel supports. The load-deflection curve for both concrete are almost the same as the results of the experimental curve. The results of the contact analysis also showed that there were contact and separation in the contact area. The shear retention factor value close to one meaning will restrain greater loads. The results of the study on the reinforcement ratio also showed a reduction of 70% and an increase of 70% when using minimum and maximum reinforcement, respectively. The larger concrete cover also reduces the load that the beams can restrain.

The Self Healing Effect on Bacteria Enriched Steel Fiber Reinforced SCC

Steel fiber reinforced self-compacting concrete is well accepted for better resistance for segregation, and effective use in congested reinforcements. It will have improved ductile property and crack propagation is minimum. As the need for sustainable materials is increasing all over the world, innovative technique for making the concrete more durable have significant importance. As the concrete is prone to cracking, the cracks make the concrete vulnerable to the fact that it debases the concrete and erodes the steel support. Bacterial concrete is a progression of current concrete innovation. The limestone hastening microscopic organisms are brought into the concrete during casting and when the crack happens within the sight of dampness, microorganisms accelerate and mend the breaks. So the presentation of a blend of Self-healing attributes and qualities of Steel fiber fortified self-compacting concrete is headway to the solid business. In this paper Micro silica is utilized to supplant OPC up to 30%. Steel fiber is utilized around 1.5% of all out the volume in Self-compacting concrete. An ideal sum for the Micro silica substitution is 20% of OPC. The exhibition of Self-compacting concrete under specific burdens and the impact of healing are contemplated. The quality of recovered concrete is likewise examined. All together increment in elasticity and durability than typical self-compacting concrete is seen.

Analysis of Ultimate Bearing Capacity and Parameters of Steel Support Cutting Pipe Roofing Structure

A new pipe-roof construction method, the steel support cutting pipe method (SSCP), was proposed to improve the construction security and accuracy of pipe jacking as well as underground space usage. The pipe-roof method is one of the underground excavation methods which push multiple steel pipes into the soil, then connect the steel pipes horizontally to form a whole. The proposed structure’s failure mode and force characteristics were determined through theoretical analysis, and then its ultimate bearing capacity and influencing parameters were analyzed through laboratory experiments and numerical simulation. The research results show that the structure’s bearing capacity depends on the steel pipe’s buckling load; the structure’s failure mode is a result of the steel pipe’s buckling. The ultimate bearing capacity of the pipe-roof structure first increases and then decreases with the increase of the steel pipe chord height ratio. The ultimate bearing capacity reaches the maximum when the ratio is 0.33. In addition, the structure’s ultimate bearing capacity is positively related to the steel pipe wall thickness and the pipe section’s length. This can be obtained from the relationship curve showing that the steel pipe wall thickness should be selected according to the engineering requirements and that the pipe section’s length is preferably 2.3 times the diameter of the steel pipe in the construction design.

Nondestructive evaluation of FRP-reinforced structures bonded joints using acousto-ultrasonic: Towards diagnostic of damage state

In civil engineering, structural adhesive bonding is increasingly used for the reinforcement or rehabilitation of degraded structures using adhesively bonded composite materials. However, the presence of defects within the bonded joint may affect the effectiveness of the assembly, and their detection is still an issue. The purpose of our study is to evaluate the acousto-ultrasonic (AU) method to detect and identify most common types of defects encountered in adhesively bonded joint and more specifically in FRP reinforced structures. Two types of assembly (made of carbon fibre reinforced polymer pultruded plates bonded on steel or concrete support) were investigated considering three types of defect (voids, kissing-bond defects simulated using a layer of grease at the composite-adhesive interfaces, and weakly polymerized zones implemented through a softer adhesive). The objective of this work is to investigate the ability of acousto-ultrasonic method to detect all those types of defects in the bonded joint with a data-driven methodology. It is expected that the extracted features from the received signals represent the damage state in the joint. For the methodology, a data-driven modelling by means of a Principal Component analysis is performed. Additionally, a Random Forest (RF) is trained using extracted parameters.

A Case Study on the Deformation of Metro Foundation Pit in Silt Stratum in North China

Geological conditions of urban subway foundation pits are controllable factors in determining the deformation of pits. In this paper, the monitoring data and statistical data of a subway deep foundation pit in North China are presented and compared with those of Tianjin subway. The deformation characteristics of the proposed pit, open excavated with triple-layer steel supports, are introduced in detail. Based on the aforementioned information, the energy conservation equation of the mobilized strength design (MSD) method in which the compression deformation energy of internal support is considered is applied to predict the maximum lateral movement. The maximum lateral movement turns out to be 22.2 mm according to the improved MSD method, which is very close to the measured value.

Structural Fire Protection of Steel Structures in Arctic Conditions

Most structures in the Arctic and Antarctic for oil and gas production are offshore stations, tankers, modules, steel supporting, and enclosing structures, which need to be protected against both cryogenic spills and fire exposure. Oil and gas industry facilities have products of high flammability and explosiveness, which in the case of ignition make it possible to develop a fire along the hydrocarbon curve, accompanied by a sharp jump in temperature and the formation of excessive pressure. This article discusses possible structural fire protection for metal structures in the Arctic region. Three different structural fireproofing materials are presented using super-thin basalt fiber (STBF) as an example. Tests of steel structures with fire protection are demonstrated, as a result of which the time from the beginning of cryogenic exposure to the limit state of samples is determined, and after the time from the beginning of thermal exposure to the limit state of samples under the hydrocarbon temperature regime is determined. An assessment of various flame retardants with values up to 120 min, which can be used in arctic climate conditions, was carried out. It was found that the most effective coatings are materials prepared on the basis of STBF.

Fatigue Evaluation of Offshore Steel Structures Considering Stress Concentration Factor

The installation of offshore structures and facilities in the marine environment, usually for the production and transmission of oil, gas exploration, electricity, and other natural resources is referred to as offshore construction. Since offshore structures are subjected to changing threats to the environment year-round. Fatigue behavior prediction noticed on these structures should be considered during the design stage. Fatigue is one of the failure mechanisms of offshore steel structures, and it must be investigated properly during system design. The fatigue analysis of offshore structures under drag wave force, total wave force, total moment about the sea bed, and other variables are reviewed thoroughly. The structure's dynamic response becomes a critical aspect in the whole design process. The fatigue analysis was carried out using MATLAB software, material properties of the offshore structure, and wave spectrum characteristics in this study. This study shows the JONSWAP spectrum and stress concentration analysis prediction. The offshore support structure that is predicted during the design phase will help to keep the stress concentration factor below the fatigue threshold and anticipate safe life design, according to the results of the fatigue study. The fatigue performances of tripod and jacket steel support structures in intermediate waters depth are compared in this project (20-50 m). The North Atlantic Ocean is used as a reference site, with a sea depth of 45 meters. The tripod and jacket support structures will be designed by using current industry standards. Keywords: [Fatigue evaluation, North Atlantic Ocean and Failure].

Method and Parameter Reliability of In-situ Direct Shear Test on Vibroflotation Gravel Piles

Vibroflotation gravel piles can improve the antisliding stability of soft soil foundations. However, in-situ direct shear tests have rarely been conducted on vibroflotation gravel piles, and the understanding of the test methods and the reliability of the derived parameters varies. Three groups of in-situ direct shear tests on vibroflotation gravel piles for a reservoir bank treatment project are conducted. The design diameter of the piles is 100 cm, and the pile filler is artificial sandstone gravel with a maximum particle size of 15 cm. The specimens are formed by applying a steel square frame to encase the top section of the piles. For the specimens of groups S1 and S2, only the section above the shear plane is encased with the frame. The shear surface of S1 contains a small amount of soft soil while that of S2 contains no soft soil. For group S3, two pile sections above and below the shear plane are encased with the frame, and a steel support is set upon the lower frame in the opposite direction of the shear force. The shear failure of the piles is a type of plastic shear contraction failure mode with more than 4.5% shear strain and no peak shear stress. The internal friction angles and cohesion values are 20.8° and 20 kPa for S1, 30.5° and 21 kPa for S2, and 35.0° and 30 kPa for S3. Test results show that the restraint of the steel frame enhances the bite force between the gravel particles in the shear process. Moreover, the rigid shear displacement constraint set upon the lower frame makes the test pile cut along the control shear surface, thereby increasing the shear strength. Therefore, the test parameters are higher than those under working conditions. To ensure consistency between the test conditions and the working conditions of the piles, this work proposes the following suggestions for improving test measures: 1) the pile section should not be encased below the shear plane and should be kept buried in soil; 2) some soil should be retained around the pile in the steel frame above the shear plane.

Weak rock mass characterization for determination of support system of the DK99-DK100 Jakarta – Bandung speed railway tunnel, Indonesia

Rock mass characterization is a crucial factor in determining a safe design of a tunnel support system. This research is carried out in constructing tunnel DK 99 – DK 100 high-speed railway Jakarta-Bandung, Indonesia. The research includes determining surface and subsurface quality of rock masses based on rock mass classifications of Geological Strength Index (GSI) and the Basic Quality (BQ-System). Both rock mass classifications were then correlated to the Rock Mass Rating (RMR) for the tunnel support system determination. Another support system determination based on the Japanese Society of Civil Engineers (JSCE, 2007) method was also compared. The result showed that the rock masses at the tunnel elevation had very poor to poor quality according to GSI, RMR, and BQ. The rock masses were classified as category class E and DII according to the JSCE competence factor. The recommended tunnel support system based on the RMR are shotcrete, rockbolt, steel set, while those based on the JSCE are shotcrete, rockbolt, steel support, and lining. This paper is expected to provide a better understanding of tunnel construction in weak rock masses, particularly in Indonesia.

Extremely thin reflective metasurface for low-frequency underwater acoustic waves: Sharp focusing, self-bending, and carpet cloaking

An extremely thin metasurface is proposed for manipulating underwater reflected waves. Each metasurface unit is only 1/61.7 of the target wavelength in thickness and comprises an air cavity capped with a thin vibration plate held in place by rubber spacers on steel supports. The unit-cell design is thin, simple, and can be adjusted to obtain a full 2π phase shift in water waves that are reflected from the metasurface. It also provides this phase shift for a broad frequency range of 20–800 Hz for incident waves. The effectiveness of the design and the resolution of the expected effect is demonstrated for sharp focusing, self-bending, and directional carpet cloaking, which are applications with great potential in energy harvesting, underwater communication, and submarine stealth and antidetection.

Novel pipe-roof method for a super shallow buried and large-span metro underground station

To address the inadequacies of traditional pipe-roof methods, the steel support cutting pipe method (SSCP)—a novel pipe-roof method that improves construction security and underground space usage—is proposed. To further explore the applications of SSCP, its design scheme ought to be optimized. The failure mode and mechanical behaviors of the SSCP were investigated through laboratory experiments. Subsequently, a series of finite element models (FEMs) was established to study the deformation characteristics. Further, the parameters of the steel support of the proposed structure were optimized using fuzzy mathematics. The results indicated the ultimate bearing capacity to be 366.8 kN, and the specimen began to yield when the external load reached 70% of the ultimate value. The longitudinal spacing of the steel supports, transverse steel support size, and vertical steel support size had significant effect on the vertical deformation of the steel support and the ground settlement. Finally, the optimal combination of steel supports for the SSCP structure was obtained.

Cycling Characteristics of Tubular Liquid Antimony Anode Direct Carbon Fuel Cells Prepared by Atmospheric Plasma Spray

Liquid antimony anode direct carbon fuel cell (LAA-DCFC) is a promising technology for efficient conversion of solid carbon fuels. However, the operating process and the regeneration method of the fuel cells with LAAs are different from those with solid anodes and still need to be researched. In the present research, the tubular LAA-DCFC units were fabricated based on stainless steel support by atmospheric plasma spray (APS) technology. The LAA-DCFCs were cycled by furnace control method and “hot plug” method to simulate the normal start-stop and the anode regeneration processes, respectively. No degradation was observed after five temperature cycles of furnace control test, which showed that the phase change process of the LAA has no influence on the sprayed electrolyte and cathode. During the “hot plug” test, the tubular cell was measured in Ar atmosphere and was removed from and put back into the LAA at a speed of 20 mm min-1 and 50℃ min-1. The cell performance recovered once the cell was put back and a degradation of 0.1% cycle-1 was observed. Considering the low frequency of anode regeneration, the degradation rate is relatively acceptable. The environmental air leakage and the floating ash retarded the recovery rate, but have no influence on the degradation degree. The cycling characteristics in the present research proved the long-term operating feasibility of DCFC with LAA.