Search Results (24)

In this research project a large linear electromagnetic actuator (LLEA) was designed and manufactured. The electromagnetic performance was published in previous works, but in this paper we focus on the technological challenges related to the manufacturing in particular. This LLEA was based on the magnet-free switched-reluctance principle, having six effective energised stator “teeth” and four passive mover parts (4:6 ratio). Various aspects and challenges encountered during the manufacturing, transport, and assembly are discussed. Thermal expansion of steel contributed to the decision of the modular design, with each module having 1.3 m in length, with a 2 mm longitudinal dilatation gap. The initial prototype was tested with a 10.6 m length, with plans to extend the test track to 60 m, which was fully achievable due to the modular design and required 29 tons of electrical steel to be built. The stator laminations were cut by a bespoke progressive tool with stamping, and other parts by a CO₂ laser. Mounting was based on welding (back of the stator) and clamping plates (through insulated bolts). The linear longitudinal force was on the order of 8 kN, with the main air gap of 7.5–10 mm on either side of the mover. The lateral forces could exceed 40 kN and were supported by appropriate construction steel members bolted to the concrete floor. The overall mechanical tolerances after installation remained below 0.5 mm. The technology used for constructing this prototype demonstrated the cost-effective way for a semi-industrial manufacturing scale. Full article

This study assessed the viable and culturable microbial diversity that remained on equipment surfaces after hygiene procedures in Brazilian poultry and fish slaughterhouses. Food-contact surface samples were collected using sterile swabs in poultry (n = 50) and fish (Oreochromis niloticus, n = 50) slaughterhouses. The swab samples were used to prepare culture plates to recover viable and culturable cells. The grown plates were washed, and the total DNA of the cell suspension was extracted with a commercial kit. Sequencing of the total DNA extracted from cultures was targeted at the V3 and V4 regions of the 16S rRNA. DNA reads were analyzed by QIIME2 software, with results expressed in relative frequency (%RF). Alpha and beta diversity indexes were analyzed considering the spots of sample collection, type of industry, surfaces (smooth or modular), and materials (polypropylene, stainless steel, or polyurethane). The results showed that in the poultry slaughterhouse, the most abundant genera were Acinetobacter (27.4%), Staphylococcus (7.7%), and Pseudomonas (5.3%), while for the fish slaughterhouse, there was a higher abundance of Staphylococcus (27.7%), Acinetobacter (17.2%), and Bacillus (12.5%). Surface characteristics influenced the microbial diversity, with Acinetobacter spp. dominating modular surfaces and Staphylococcus spp. prevailing on smooth surfaces. The results obtained indicate there is an important resident microbiota that persists even after hygiene processes, and surface-specific cleaning strategies should be developed. Full article

Upright-posture motorcycle crashes against steel safety barriers (SSBs) often result in severe upper-body injuries due to the sharp upper edge of the rail. While solutions for sliding crashes on curves, called a ‘motorcyclist-friendly barrier’, are already implemented in practice, protective measures for upright-posture impacts remain underdeveloped. This study systematically reviews patents and patent applications addressing upper guardrail protection for motorcyclists. We identified and analysed a small number of existing innovations aimed at mitigating the consequences of upright crashes. The selected solutions were evaluated according to their technical design, ease of installation, potential for recycling, environmental compatibility, and expected costs. Our comparative analysis reveals that while some patents or patent applications offer promising features, such as flexible caps, bent plates, or modular attachments, none comprehensively address all safety, environmental, and economic requirements. The findings provide a basis for further development of motorcyclist-friendly SSB designs and suggest specific criteria that should be included in future guidelines and standard updates. Full article

The pier-type repair equipment for bridges is a crucial branch of bridge emergency repair. However, the existing bridge pier repair equipment predominantly utilizes rod systems, which require substantial assembly work, hindering the rapid restoration of damaged bridges. Modular steel structure buildings, as a highly integrated form of prefabricated construction, can play a significant role in emergency rescue operations. Based on the modular architectural design concept, this paper proposes a new type of modular steel structure emergency repair pier joint that facilitates rapid assembly and connection between modular units. Using ABAQUS 2022 software to establish a finite element model of the joint, the bending performance under lateral displacement loads perpendicular to the joint opening direction (X-direction in the model coordinate system) and parallel to the joint opening direction (Z-direction in the model coordinate system) is analyzed. The influence of the width-to-thickness ratio of the upper corner piece base plate D/t₁ (where D is the width of the upper corner piece base plate and t₁ is the thickness of the upper corner plate), the height-to-thickness ratio of the lower corner piece top plate h/t₂ (where h is the height of the protrusion of the lower corner piece and t₂ is the thickness of the lower corner piece top plate), the height of the protrusion of the lower corner piece (h), and the bolt diameter (d) on the bending performance of the joint is investigated. Recommendations for the design values of the joint are provided. Then, the flexural behavior of the joint under 0.1, 0.2, and 0.3 axial compression ratios is studied, respectively. The results show that with the increase of axial compression ratio, the yield rotation angle and ultimate rotation angle of the joint decrease, and the bearing capacity decreases faster after the joint reaches the ultimate bearing capacity. When the joint is subjected to the X-direction horizontal lateral displacement load, the initial flexural stiffness and flexural capacity of the joint increase with an increase in the axial compression ratio. When subjected to the horizontal lateral displacement load in the Z-direction, the initial bending stiffness of the joint increases with an increase in the axial compression ratio, and the bending capacity does not change much. In addition, the joint is classified; from the perspective of load-bearing capacity, it is a partially resistant joint, and from the perspective of stiffness, it is a semi-rigid joint. Finally, a simplified calculation model for the joint is proposed based on the component method. Full article

This paper introduces a new self-locking-unlockable modular building with an inter-module connection, and its seismic performance is investigated. The new connection can realize fast connection and unlocking during construction through exceptional design. In this paper, taking the Tianjin Binhai Apartment project as the background, for the actual force situation of the new connection, considering the influence of corrugated steel plate stiffness, a simplified model of the connection is constructed by using multi-fold elastic connection, and the corrugated steel plate stiffness is simulated with equivalent support. In the MIDAS Gen 2021 software, the five-story and six-story structural models using traditional rigid connections and new connections were established, respectively, and reaction spectrum analysis was carried out. Meanwhile, seismic waves that comply with codes were selected for dynamic time course analysis. The results show that the stress ratios of all components of the new connection model and the traditional rigid model are less than 1. Among them, the maximum stress ratios of both floor beams are 0.745 and 0.725, respectively; the maximum stress ratios of the modular columns are 0.655 and 0.494, respectively; the stress ratios of the ceiling beams are all less than 0.5; and the two models show good strength and stiffness reserves, following the design principle of strong columns and weak beams and verifying the reliability of the new connection model. Meanwhile, it is found that the inter-story displacement angle of the six-story structure with the new connections is less than the normative value under the action of rare earthquakes, and the difference in top displacement is about 18% compared with that of the rigid structure, so it is suggested that the new connections can be applied within the height of six stories. Full article

Existing support systems for thermal pipeline trenches often fail to meet the specific needs of narrow strips, tight timelines, and short construction periods in urban environments. This study introduces a novel recyclable, non-embedded support system composed of corrugated steel plates, retractable horizontal braces, angle steel, and high-strength bolts designed to address these challenges. The system’s effectiveness was validated through prototype testing and optimized using Abaqus finite element simulations. The research hypothesizes that this new support structure will enhance construction efficiency, reduce installation costs, and provide adaptable and sustainable solutions in urban trench applications. Prototype tests demonstrated that the proposed support had maintained safety and stability in trenches of 2 m and 3 m depth under a 58 kPa load and rainfall, as well as the 4 m deep trenches under asymmetric loading of 80 kPa. Optimization of the proposed system included installing two screw jacks on each horizontal brace and adjusting the corrugated plates, resulting in reduced weight, improved node strength, and enhanced screw jack adjustability. Numerical simulations confirmed the optimized system’s reliability in trenches up to 3 m deep, with caution required for deeper applications to avoid structural failure. The proposed support system offers notable advantages over traditional methods by improving construction efficiency, flexibility, and adaptability while also reducing costs, ensuring safety, and promoting environmental sustainability. Its modular design allows for rapid installation and disassembly, making it suitable for projects with strict deadlines and diverse construction conditions. The findings uphold the initial hypotheses and demonstrate the system’s practicality in urban trench projects. Full article

In recent years, prefabricated components have been widely used in the construction of substation superstructures, while cast-in-place foundations remain the primary method for substation foundations. This paper presents and evaluates a novel prefabricated foundation design aimed at enhancing construction efficiency and load-bearing performance. The foundation features a modular design, with each module weighing only half that of a cast-in-place foundation of the same size, significantly improving construction convenience and transportation efficiency. The load-bearing performance of the foundation was validated through static load tests and finite element modeling. The results indicate that the foundation demonstrates excellent ductility, with flexural failure as the primary mode, characterized by multiple cracks across the mid-span and complete yielding of longitudinal reinforcing steels. Further parametric analysis shows that increasing the plate thickness ratio (λ) improves the ultimate bearing capacity of the foundation significantly. Additionally, enlarging the cross-sectional size of the shear key or increasing the strength of the wet joint material enhances overall structural synergy, reduces local deformation, and improves load distribution efficiency. Overall, the sensitivity order of factors influencing the bearing capacity of the new prefabricated foundation is plate thickness ratio (λ) > wet joint strength > shear key cross-sectional size. Full article

Stainless steel core plates (SSCPs) show great potential for modular construction due to their superiority of excellent mechanical properties, light weight, and low cost over traditional concrete and honeycomb structures. During the brazing process of SSCP joints which connect the skin panel and core tubes, it is difficult to keep an even heat flow of inert gas in the vast furnace, which can lead to partially missing solder defects in brazing joints. Pulsed eddy current imaging (PECI) has demonstrated feasibility for detecting missing solder defects, but various factors including lift-off variation and image blurring can deteriorate the quality of C-scan images, resulting in inaccurate evaluation of the actual state of the brazed joints. In this study, a differential pulsed eddy current testing (PECT) probe is designed to reduce the lift-off noise of PECT signals, and a mask-based image segmentation and thinning method is proposed to eliminate the blurring effect of C-scan images. The structure of the designed probe was optimized based on finite element simulation and the positive peak of the PECT signal was selected as the signal feature. Experiments with the aid of a scanning device are then carried out to image the interrogated regions of the SSCP specimen. The peak values of the signals were collected in a matrix to generate images of the scanned brazing joints. Results show that lift-off noise is significantly reduced by using the differential probe. Image blurring caused by the convolution effect of the probe’s point spread function with the imaging object was eliminated using a mask-based image segmentation and thinning method. The restored C-scan images enhance the sharpness of the profiles of the brazing joints and the opening in the images accurately reflect the missing solder of the brazed joints. Full article

Nuclear power plants, where steel-plate concrete (SC) structures are commonly adopted, require large-scale components to withstand significant loads, such as those caused by sudden explosions. As a result, SC modular members used in nuclear power plants must have thicker walls filled with concrete compared to standard-sized ones. These large walls also require additional components, such as tie bars and H-shaped steel sections, to reinforce adhesion and resist shear stresses. This study focuses on tie bars placed adjacent to studs and evaluates their influence on the tensile strength of wall structures. To investigate this, we conducted experimental tests using full-scale specimens, including various combinations ranging from single stud to combined stud-tie configurations. Based on the results of these performance tests, we propose a design recommendation for estimating the tensile capacity of SC structures, considering the influence of tie bars. Full article

The article discusses a solution to the relevant task of analyzing and designing modular buildings made of blocks to be used in industrial and civil engineering. A block that represents a container is a combination of plate and beam systems. The criteria for its failure include both the strength of the individual elements and the loss of stability in a corrugated web. Methods of engineering analysis are hardly applicable to this system. Numerical analysis based on the finite element method is time-consuming, and this fact limits the number of design options for modular buildings made of blocks. Adjustable machine learning models are proposed as a solution to these problems. Decision trees are made and clustered into a single ensemble depending on the values of the design parameters. Key parameters determining the structures of decision trees include design steel resistance values, types of loads and the number of loadings, and ranges of rolled sheet thickness values. An ensemble of such models is used to take into account the nonlinear strain of elements. Piecewise approximation of the dependencies between components of the stress–strain state is used for this purpose. Linear regression equations are subjected to feature binarization to improve the efficiency of nonlinearity projections. The identification of weight coefficients without laborious search optimization methods is a distinguishing characteristic of the proposed models of steel blocks for modular buildings. A modular building block is used to illustrate the effectiveness of the proposed models. Its purpose is to accommodate a gas compressor of a gas turbine power plant. These machine learning models can accurately spot the stress–strain state for different design parameters, in particular for different corrugated web thickness values. As a result, ensemble models predict the stress–strain state with the coefficient of determination equaling 0.88–0.92. Full article

Interlocking Inter-Module Connections (IMCs) in Modular Steel Buildings (MSBs) have garnered significant interest from researchers. Despite this, the optimisation of plate thicknesses in such structures has yet to be extensively explored in the existing literature. Therefore, this paper focuses on optimising the thickness of interlocking IMCs in MSBs by leveraging established experimental and numerical simulation methodologies. The study developed various numerical models for IMCs with plate thicknesses of 4 mm, 6 mm, 10 mm, and 12 mm, all subjected to compression loading conditions. The novelty of this study lies in its comprehensive parametric analysis, which evaluates the slip prediction model. A random forest regression model, trained using the ‘TreeBagger’ function, was also implemented to predict slip values based on applied force. Sensitivity analysis and comparisons with alternative methods underscored the reliability and applicability of the findings. The results indicate that a plate thickness of 11.03 mm is optimal for interlocking IMCs in MSBs, achieving up to 8.08% in material cost reductions while increasing deformation resistance by up to 50.75%. The ‘TreeBagger’ random forest regression significantly enhanced slip prediction accuracy by up to 7% at higher force levels. Full article

The previous research introduced an innovative retrofitting technique for reinforced concrete beams using modularized steel plates. This technique enhances structural performance, offering a lightweight solution compared to conventional retrofitting methods using steel plates, and accommodates construction errors. However, a challenge arises due to the lack of integrity between unit steel plates. To address this, this study proposes a novel method of connecting each steel plate with bolts. The experimental results show that retrofitted beams achieved a maximum load of 311.9 kN, roughly 1.6 times that of non-retrofitted specimens, with the ductility of retrofitted beams being 3.3 times that of the non-retrofitted beams. Additionally, there was a 25% increase in load capacity for beams retrofitted with interconnected steel plates compared to those without connections between unit steel plates. Full article

Steel–concrete–steel (SCS) sandwich structures have gained increasing interest in new constructions. The external steel plates increase the stiffness, the sustainability, and the strength of the structures under some extreme solicitations. Moreover, the use of these plates as lost prefabricated formwork makes SCS structures modular, enabling higher construction rates. However, for a better understanding of the complex behavior of these structures up to failure, refined numerical simulations are needed to consider various local phenomena, such as concrete crushing in compression and interface interactions. Indeed, the highly non-linear steel–concrete interaction around the dowels is the key point of the composite action. In this contribution, a refined methodology is first proposed and applied on a push-out test. It is especially demonstrated that a regularization technique in compression is needed for the concrete model. Interface elements are also developed and associated with a nonlinear constitutive law between steel connectors and external plates. From this refined methodology, simplified numerical modeling is then deduced and validated. Directly applied to an SCS wall-to-wall junction, this simplified strategy enables the reproduction of the overall behavior, including the elastic phase, the degradation of the system, and the failure mode. The response of each component is particularly analyzed, and the key points of the behavior are highlighted. Full article

Modular steel buildings show high assembly degree and fast installation speed. The inter-module connection (IMC) is one of the key technologies that restrict the robustness of modular steel buildings. An innovative IMC with a cross-shaped plug-in connector is proposed, and the connection consists of end plates of columns, the cross-shaped plug-in connector, bolts, cover plates, and one-side bolts. The proposed IMC is easily constructed, and the cross-shaped plug-in connector can improve the shear resistance of the core area. The mechanical model of the proposed IMC is presented, and the panel zone volume modified factor and initial rotational stiffness modified factor are proposed for calculating the shear capacity of the panel zone and the initial rotational stiffness. Numerical simulation was conducted considering the influences of axial compression ratios, sections of beams and columns, and the thickness of the tenon plate of the connector. The bearing capacity of the proposed IMC was analyzed, and the values of the two factors mentioned above were calculated, and their regression formulas are presented. The results show that the sections of beams and columns and the axial compression ratios show great influences on the bearing capacity of the proposed IMC, while the thickness of the tenon of the cross-shaped plug-in connector shows almost no effect. In addition, the sections of beams and columns show great influences on the shear capacity of the panel zone, as well as the initial rotational stiffness of the proposed IMC, while the thickness of the tenon of the cross-shaped plug-in connector and the axial compression ratios show little effect and almost no effect, respectively. Furthermore, the bending moment limit of the beam end of the proposed IMC is suggested to be 0.6 times the resistance bending moment, and the proposed IMC is considered to be a rigid connection or inclined to a rigid connection The proposed IMC has good mechanical performance, and design recommendations are presented. Full article

This paper presents the results of a shear test on a reinforced concrete beam retrofitted with modularized steel plates. A total of five retrofitted concrete beams with various span-depth ratios as a variable were fabricated and tested. A companion beam without retrofitting was used as the control specimen. The results of this experiment confirmed that the method proposed in this study improved the shear performance by approximately 1.8 times compared with the non-retrofitted reinforced concrete beam. The test results indicate that the shear retrofitting method using modularized steel plates can be effective in retrofitting the concrete beams, resulting in improvement in the strength, stiffness and deformations. Full article