Steel Support Structure Research Articles

Neutron irradiation effects on the low cycle thermal fatigue performance of first wall mock-ups

For the first wall (FW) of ITER, beryllium will be the plasma facing material and has to sustain high thermal, particle and neutron loads. In order to assess the synergistic effects of thermal and neutron loads in total ten Be-armored FW normal heat flux (NHF) mock-ups were produced consisting of two Be flat tiles each joined via hot isostatic pressing (HIP) to a CuCrZr heat sink and a steel support structure by different manufacturing routes to assess the most promising ones. Five of them were neutron irradiated, two at Centrum Výzkumu Řež in Czech Republic and three in the High Flux Reactor at NRG in the Netherlands. The remaining mock-ups were kept as reference. All flat-tile mock-ups had two Be-tiles and were exposed to cyclic steady state heat loads in the electron beam facilities JUDITH 1 and 2 up to a maximum power density of 3.75 MW/m2, in order to find the damaging threshold. A screening step using 1 MW/m2 was performed after finishing each loading step and after failure for direct comparison and detection of any deterioration caused by the cycling. Despite being still in the early development phase of Be joining, all mock-ups sustained the cycling up to at least 2.75 MW/m2 and clear differences in the performance of irradiated vs. non-irradiated mock-ups were observed.

Determination of steel arch support distance for roadways under the open-pit mine: a case study at the Mong Duong Coal Mine (Vietnam)

Purpose. Nowadays, in Quang Ninh coalfield, the mining activity in quarries is increasing. For this purpose, mine roadways are dug and supported. After the mine roadways are dug, they are mainly supported by steel arches. Statistics in fact show that about 85 % of the roadway support structure at the underground coal mines in Quang Ninh are supported by the steel arch support made of SVP profile. The purpose of the study is to calculate and determine a reasonable steel support distance for the roadways located under the open-pit mine to ensure their stability and the safety of exploitation. Methodology. In this study, the numerical simulation method was used. On the basis of Phase2 software and geological conditions of the mine, the authors established a simulation model to determine the pressure acting on the roadway and select a reasonable support distance. Findings. The study considered different steel arch support structure distance following the structure of the rock mass under the 790 open-pit area at the Mong Duong Coal Mine, the internal forces in SVP steel arch support structure distance were also studied for one-lane railway and two-lane railways roadway. From the results of internal forces in the steel support structure, a reasonable SVP-22 steel arch distance was selected, which is 0.7 m for the one-lane railway roadway, as well as SVP-27, which is 0.7 m for the two-lane railway roadway. Originality. Using Phase2 software, the authors created a simulation model of the roadways in Seam L7 located on the West side of Mong Duong Coal Mine, which allowed analyzing and describing the condition of the surrounding rock mass. This study utilized a numerical modeling approach to simulate and establish the bending moment and axial force of both single and double lane railway roadways, across a range of support distances. Based on the results of pressure calculation for the roadways, the authors have selected a reasonable support distance for each corresponding roadway. Practical value. The findings of the study serve as the foundation for the practical application of production methods at the Mong Duong Coal Mine. On the basis of calculating the pressure acting on the roadways at the Seam L7 in the West Side under the 790 open-pit area, the distance of steel arch support was determined, from which the roadway support plan has been developed. This research result will also serve as a basis for other mines with similar geological conditions in Quang Ninh coalfield to consider and apply.

Proposal of a methodology for mass optimization of realistic steel structural systems composed of columns and galleries for support of solid bulk conveyors

Unlike most works in the literature that propose the optimization of benchmark problems or very simple real structures, with idealized loads and restrictions, this work proposes a complete methodology to optimize real support structures of belt conveyor lines, considering realistic loads and restrictions imposed by international technical codes. Thus, the present work proposes a comprehensive methodology to minimize the mass of realistic steel structural systems composed of columns and galleries to support solid bulk conveyors. The objective is to obtain the minimum mass for different interactions between gallery spans and column heights for conveyors, taking into account the optimization of size, shape, and topology of each structural subsystem (columns and galleries) and thus obtaining the mass per unit of length of the conveyor line. For this, recurrent steel support structures are identified, analyzed, and selected according to their performance and, structurally resisting the applied load inputs, they are designed to minimize the structural system mass. The Enhanced Particle Swarm Optimization (EPSO) algorithm is used considering multiple constraints involving stress, displacement, buckling, frequency, and acceleration limits according to various international codes. An example of a realistic conveyor line is presented, in which 42 different interactions among the dimensions of the subsystems are simulated and the minimum mass of the system is obtained for each one of them. Thus, the results obtained allow, from the knowledge of the geometrical characteristics of the span and height of the system, to identify the optimized linear mass for any situation within the study boundary, resulting in an important practical contribution. Additionally, the graphs presented allow the designer to choose optimized solutions in terms of cost and raw material consumption for real-field applications. It was possible to determine that appropriate choices represent up to 35% mass reduction of structural systems.

Analysis of Factors Influencing Mechanical Properties of Corrugated Steel Based on Entropy Method

In recent years, corrugated steel has been used in some domestic tunnel construction for its large section and high strength, and has become a new type of tunnel support structure. Corrugated steel mechanical properties will directly affect the stability of support structure. Therefore, the important thing is to choose the appropriate parameter to improve the mechanical performance of ripples. Parameters that affecting the mechanical properties of corrugated steel include wave height, corrugation thickness and wave distance. This massage will rely on the Qipan Mountain tunnel project, studying its fabricated corrugated steel supporting structure, and selects corrugated steel with different thicknesses, wave heights and corrugated spans for transient analysis. The largest deformation of corrugated steel under blasting shock is calculated by numerical simulation to react the corrugated steel mechanical properties, and then use the method of Entropy to determine the influence of different parameter values on mechanical performance of corrugated steel. The weight coefficient of wave thickness is 92.38%, the influence weight coefficient of wave height is 7.54%, and the influence weight coefficient of wave short is 0.07%. It is shows that the thickness has the greatest influence on the mechanical properties of the supporting structure, and the wave distance has no influence. Through the above analysis, the parameter design and stability design of corrugated steel support structure can be given some reference and help.

Investigation of the effect of pitting corrosion on the fatigue strength degradation of structural steel using a short crack model

Steel support structures of offshore wind turbines (jackets and monopiles) undergo both fatigue and corrosion damage, impacting their lifetime. This paper investigates how pitting corrosion, caused by being exposed to the marine environment, affects the fatigue strength of structural steel. A short fatigue crack model is used to estimate the minimum required applied load amplitude which causes a growing crack emanating from the bottom of a semi-elliptical pit. Pit growth rate data, reported in literature, is employed to update the pit size and its sharpness at each time step. The modelling results show the fatigue strength degradation as a function of the exposure time to the corrosive environment. As exposure time increases, it is observed that degradation happens more quickly in the early years followed by a gradually decreasing degradation rate of the fatigue strength in the following years.

Experimental and numerical simulation of the propagation law of shock waves in corrugated steel-lined tunnels

Corrugated steel support structures are widely used in engineering tunnels owing to their rapid construction and high bearing performance, allowing for the complex propagation of shock waves. To clarify the propagation law of shock waves in a corrugated steel tunnel with interior lining, a 30-m-long straight tunnel was built to explore the propagation of an explosion shock wave, and three different tunnel inner walls were designed, namely, a concrete inner wall and two types of corrugated steel linings. Based on the data on the monitored shock wave, the propagation law of shock waves in the tunnel was obtained, and the influence of corrugated steel linings on the shock waves was analyzed. A finite element model of the channel was established to verify the results of experiment and determine the model and related parameters. This model was also used to perform a numerical simulation of explosion shock wave propagation in corrugated steel-lined tunnels of various sizes. Based on the experimental and numerical simulation results, a prediction model of shock wave overpressure in corrugated steel-lined tunnels was obtained. Research showed that the shock-wave energy of wavefronts near walls was diverted, the formation and propagation of waves reflected from walls was affected by corrugated steel linings, which effectively improved the attenuation efficiency of shock waves in tunnels.

Research of the Stress-Strain State for Steel Support Structures of Nuclear Power Plant Components under Seismic Loads

Seismic resistance of equipment and piping of nuclear power plant units is determined, particularly, by seismic resistance of their steel support structures. A significant number of these structures are located in the reactor building of nuclear power plants and belong to seismic resistance categories I and II. Therefore, such support structures of nuclear power plant equipment and piping, in general, shall perform their functions under seismic hazards that correspond to the safe shutdown earthquake and design-basis earthquakes, respectively.
 Steel support structures of serial equipment (piping valves, electric and pneumatic drives of piping and pump valves, expansion tanks, etc.) are often designed “on site” in the limited conditions of their actual location. Therefore, it is necessary to design steel support structures of a number of equipment taking into account the fact that it can be connected, in particular, to existing piping with their actual routing. In connection with the above, the research of operation for such support structures under seismic loads is relevant.
 The article presents the research results for the spectrum of natural oscillation frequencies of the equipment support structure, and the stress-strain state of the considered structure under seismic loads is determined. At the same time, the parameters during normal operation and maximum design basis accident at the nuclear power plant power unit are considered. The calculated combination of loads, which simultaneously includes two episodic impacts (maximum design basis accident and an earthquake) is considered.

Influence of Wind Characteristics and Other Parameters on Module Mounting Structures

As one of the most common and imperative contributing factors to clean energy aspect, solar energy takes a significant role around the whole world. Among neighbouring countries regarding the energy sources India has a relatively more potential for solar energy to decrease its energy dependence to the other countries and to increase awareness for sustainable, easily reachable, economical and continuous energy use. In the photovoltaic (PV) solar power plant projects, PV solar panel (SP) support structure is one of the main elements and limited numerical studies exist on PVSP ground mounting steel frames to be a research gap that has not be addressed adequately in the literature. In this paper, aiming to provide a contribution to this gap, a PVSP steel support structure and its key design parameters are described to obtain actual demand of environmental effect like loads wind, snow, and seismic loads.

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.

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].

Dynamics of a Y-shaped semi-submersible floating wind turbine: a comparison of concrete and steel support structures

ABSTRACT Concrete semi-submersible floating wind turbines (FWTs) have generated increasing interest in the offshore wind energy industry due to their superiority over steel structures in aspects of construction and maintenance. However, the influence of construction materials on the dynamics of FWTs was scarcely studied before. The dynamics of two FWTs, mounted on a concrete and a steel Y-shaped semi-submersible platform respectively, are investigated by means of 1:60 scale combined wind and wave model tests and coupled multi-body simulations. The results indicate that the steel structure with a lower centre of gravity exhibits advantages in platform pitch motion alleviation. The steel structure is also subjected to lower pitch-induced tower base loads and nacelle acceleration than its concrete counterpart. However, an opposite trend is found in the wave-frequency responses, leading to an insignificant difference of tower base loads and nacelle acceleration between the two structures. ABBREVIATIONS: FWTs: Floating wind turbines; CoG: Centre of gravity; CoB: Centre of buoyancy; LCP3: Lightweight prestressed concrete platform; HSP3: High-strength steel platform; WTWF: Wind tunnel and wave flume joint laboratory; ROC: Rated operational condition; JONSWAP; Joint North Sea Wave Observation Projection; RAO: Response amplitude operator; BEM: Blade element momentum theory; DOF: Degree of freedom; GDW: Generalised dynamic wake theory; PSD: Power spectral density; QTF: Quadratic transfer function

Serpent neutronics model of Wendelstein 7-X for 14.1 MeV neutrons

In this work, a Serpent 2 neutronics model of the Wendelstein 7-X (W7-X) stellarator is prepared, and an response function for the Scintillating-Fibre neutron detector (SciFi) is calculated using the model. The neutronics model includes the simplified geometry for the key components of the stellarator itself as well as the torus hall. The objective of the model is to assess the 14.1 MeV neutron flux from deuteron-triton fusions in W7-X, where the neutrons are modelled only until they have slowed down to 1 MeV energy. The key messages of this article are: demonstration of unstructured mesh geometry usage for stellarators, W7-X in particular; technical documentation of the model and first insights in fast neutron behaviour in W7-X, especially related to the SciFi: the model indicates that the superconducting coils are the strongest scatterers and block neutrons from large parts of the plasma. The back-scattering from e.g. massive steel support structures is found to be small. The SciFi will detect neutrons from an extended plasma volume in contrast to having an effective line-of-sight.

Status of the ITER Divertor IVT procurement

The Ansaldo Nucleare (ANN) Prototype manufacturing is under completion. The stainless steel support structure was manufactured by Walter Tosto (Italy) and the Plasma Facing Units (PFUs) were manufactured by ENEA (Italy) by diffusion bonding between the CuCrZr pipe and the W monoblocks equipped with a pure Cu compliance layer (Hot Radial Pressing, HRP).This paper presents some of the learnings of the Inner Vertical Target (IVT) Prototype manufacturing and provides the main results of the dimensional control tests. The outcomes of the PFUs High Heat Flux (HHF) testing performed in the ITER Divertor Test Facility (IDTF) in Efremov institute, Saint Petersburg (Russia) are presented as well.

Regarding Requirements to Load Combinations in Case of Evaluation of SSC Seismic Resistance by Indirect Methods

Extension of the list of load combinations that should be analyzed during the nuclear power plant (NPP) components seismic resistance justification is one of the important new regulatory requirements.
 The paper deals with the thermomechanical equipment for which seismic resistance assessment is performed using operating experience method, in particular the methodology of indirect assessment using the GIP (Generic Implementation Procedure) for the WWER reactors (GIP-WWER procedure).
 Review of GIP-WWER procedure has been performed. The paper presents the analysis of seismic screening evaluation work sheet based on the example of motor-operated valve. The disadvantages of the GIP-WWER procedure in terms of ensuring compliance with current regulatory requirements for combinations of operating and seismic loads have been identified and the ways of eliminating the revealed disadvantages have been offered.
 The supporting structures of the equipment in most cases are the metal structures. Impact of different NPP operating modes to the steel supporting structures of the equipment has been considered and the provisions of building codes governing the calculation of steel support structures have been analyzed. A minimum listing of operating and seismic loads combinations has been established, which should be considered in the justification of the seismic strength of steel support structures referred to the first and second seismic categories.
 The paper is a part of a series of publications devoted to consideration of regulatory requirements to combinations of operational and seismic loads in assessing the seismic resistance of NPP components.

Nete Bridge in Lier – Long‐term experience with galvanized bridge components

AbstractIn Europe, hot‐dip galvanizing has hitherto had no appreciable application in bridge construction, which, despite decades of positive practical experience in building construction, is partly due to a lack of knowledge and regulations regarding the influence of galvanizing on the fatigue behaviour. By contrast, diverse examples from non‐European countries already confirm the technical and economic significance of galvanized bridge structures. Based on recent research and a guideline, the basics for wider application have been laid in the recent past. Nete Bridge in the Belgian city of Lier is one of the few road bridges with a fully galvanized steel support structure. The current state of the bridge, after more than 20 years in use, is described below – and a positive interim conclusion is drawn. Nete Bridge is in a good technical condition in terms of corrosion protection; no significant maintenance or repair measures have been required in this regard and are not expected in the future either. The example presented illustrates the feasibility of galvanizing bridge components as an alternative to the organic coating systems previously established. This also offers the bridge management authorities responsible economic benefits due to the very high durability and the associated very low maintenance costs.

Modal analysis of support structure of cylindrical container

The paper deals with dynamic analysis of a container. The analyzed structure consists of a steel support structure and a cylindrical container. The container is used for storage of road salt and other spreading materials during winter road maintenance. Three variants of support system of a structure have been analyzed. These have been introduced into the model as different boundary conditions. The modal analysis was performed, whose results are eigenfrequencies and eigenshapes of the structure. In the final part, the results obtained from the seismic analysis of the structure (displacements and internal forces) have been presented.

Spectral analysis of the support structure of the cylindrical container

The paper deals with dynamic analysis of a container. The analyzed structure consists of a steel support structure and a cylindrical container. The container is used for storage of road salt and other spreading materials during winter road maintenance. Three variants of support system of a structure have been analyzed. These have been introduced into the model as different boundary conditions. The spectral analysis was performed in which the response spectra taken from the Eurocode were used. In the final part, the results obtained from the seismic analysis of the structure (displacements and internal forces) have been presented.

Upgrades of the RFX-mod reversed field pinch and expected scenario improvements

RFX-mod is a Reversed Field Pinch device that allowed performing experiments in regimes with a plasma current up to 2 MA, thanks to its MHD active control system. Experiments have shown that improved plasma performances are obtained when in the resonant part of the m = 1 spectrum one dominant tearing mode is much higher than the other secondary ones (quasi single helicity states). Tearing modes play a crucial role in determining energy and particle transport. Based on the present understanding of the interplay between passive conductive boundaries and tearing modes in an RFP, an upgrade of RFX-mod machine assembly has been designed, dubbed RFX-mod2, and it is now being implemented. The highly resistive Inconel vessel will be removed, graphite tiles will be attached to the copper stabilizing shell and the stainless steel support structure will be modified in order to be vacuum tight. In RFX-mod2, the shell-plasma proximity decreases from b/a = 1.11 to b/a = 1.04 and copper, instead of Inconel, will be the continuous conducting structure nearest to the plasma. MHD non-linear simulations show that secondary tearing modes amplitude and the edge bulging due to their phase locking will decrease; moreover the plasma current threshold for tearing modes wall locking will also significantly increase.

Fabrication route of the ANSALDO-ENEA ITER inner vertical target divertor full scale prototype

Fabrication and qualification of a representative full-scale prototype of the International Thermonuclear Experimental Reactor (ITER) divertor inner vertical target is the subject of the contract assigned to Ansaldo Nucleare S.p.A (ANN) by Fusion for Energy, the EU-Domestic Agency. ENEA, as major partner of this contract activities, was in charge of the plasma facing units (PFU) fabrication by means of Hot Radial Pressing.In parallel the other main fabrication steps were completed by ANN and its industrial partners based on the F4E technical requirements. Finally, the feasibility of the prototype assembly by integrating the PFUs onto the steel support structure has been demonstrated and the technical capability to reach the tight geometrical tolerances required for the plasma surface was checked.High heat flux thermal fatigue testing on the 8 full-W PFUs installed on the testing frame will take place at the ITER Divertor Test Facility at Efremov Institute in Saint-Petersburg to finally demonstrating the PFUs thermal removal capability.The reliability level reached by the HRP joining process and the industrial consolidation of the fabrication route, paves the way with confidence to a forthcoming series production of the ITER full-W divertor. The paper reports the full scale prototype main production achievements.

Monk Parakeets Provide Nesting Opportunities for the Threatened Southeastern American Kestrel

We report on the nesting of Southeastern American Kestrels (Falco sparverius paulus) in nonnative Monk Parakeet (Myiopsitta monachus) nests in Florida, USA. Two kestrel pairs nested within parakeet stick nests located on top of steel support structures at electric utility substations in Pasco County, Florida. Kestrels fledged young at both sites. The Monk Parakeet's ability to exploit anthropogenic habitats may facilitate the use of these areas by nest-site-limited species such as the Southeastern American Kestrel.