Search Results (253)

Steel wire ropes (SWRs) are exceptional load-bearing elements. However, conventional designs often treat them as passive structures, lacking strategies to actively program their ultimate load-bearing capacity and failure behaviors. To address this gap, this study systematically investigates the tunable load capacity and fracture characteristics of SWRs by developing a simplified power-law hardening elastoplastic constitutive model and a finite element framework integrated with a ductile-damage criterion. Following material parameter calibration via single-wire tests and independent experimental validation of the baseline model using 1 × 7 strand tensile tests, comprehensive numerical parametric studies were conducted to evaluate the simulation-based influence of core diameter (d_core), overall rope diameter (D), layer count (F), and strand configuration (S) on mechanical responses. The numerical results reveal that these geometric parameters act as effective tuning knobs that govern internal stress transfer pathways and ultimate load-bearing capacity. Specifically, simulations predict that increasing the $d_{\mathrm{core}}$ to 1.00 mm elevates the peak tensile force by 9.6% while maintaining a 90.07% tensile force efficiency (TFE, defined as the ratio of mean to peak tensile force). Furthermore, implementing a hybrid multi-strand architecture (SWR-S3) achieves an optimized TFE of 99.76%. These structural modifications facilitate internal strain synchronization, which effectively buffers localized stress peaks and dictates the progressive fracture sequence. Ultimately, this study demonstrates the potential of complementing traditional material enhancement strategies with active geometric parametrization. Rather than offering immediate industrial design rules, it provides a conceptual theoretical framework for exploring custom-tailored tensile strength profiles and predictable failure behaviors. However, because these advanced structural configurations are evaluated using idealized quasi-static finite element models, further experimental validation addressing real-world manufacturing constraints, residual stresses, and dynamic loading is required before practical engineering deployment. Full article

Advanced analysis has been shown to improve material efficiency in statically indeterminate steel-framed structures compared with member-based linear elastic design methods. However, limited research has investigated its applicability to geometrically nonlinear steel structures where residual stresses are induced by the bending process. In this study, the material optimization potential of advanced analysis has been quantified for two arch-based structures by comparing the volume of steel required to satisfy the criteria of both the system and member-based analysis methods in accordance with AS 4100:2020. The two structures were analyzed using the finite element analysis software Strand7 (R3.1.6) and subjected to combined gravity and wind loading in alignment with the serviceability and ultimate limit states specified in AS 1170.0:2002. System behavior was analyzed through the Arc-length plastic zone method. The results indicate that in one of the arch-based structures, advanced analysis can improve material utilization by 8.1%. Provided that future research both validates the use of the reduced stiffness method for treatment of initial geometric imperfections and verifies system reliability factors for structures with curved geometries, advanced analysis presents a practical design method for this structure. Comparison of the two case studies found that advanced analysis has the potential to improve material efficiency only when linear elastic failure is governed by ultimate limit state criteria. It is therefore evident that the material optimization findings of this research cannot be generalized to all arch-based structures, as they are contingent upon the geometry of the model analyzed, the loading scenarios considered, and the deflection limits adopted. Full article

The structure comprising precast prestressed concrete components (SCOPE joint) is widely used in prefabricated buildings. For this type of joint, insufficient anchorage of U-shaped reinforcing bars can lead to premature core failure. To address this, finite element models of SCOPE joints are developed in ABAQUS for parametric and mechanical analysis of U-shaped bars, and an improved joint with steel-strand-embedded anchorage is proposed. Comparisons of seismic performance and frame performance are conducted. The results indicate that in the conventional SCOPE joint, the strain of the U-shaped reinforcing bars concentrates within 100–150 mm outside the column, and the anchorage effect of the vertical segments is not mobilized; the yield penetration phenomenon further aggravates bond failure. In the improved joint, steel strands are anchored into the core and lapped in opposite directions, leading to a superior failure mechanism and plastic hinge formation sequence, enhanced capacity and ductility, and better conforming to the strong-joint–weak-component principle. This research offers a theoretical basis and detailing reference for seismic optimization of the SCOPE system. Full article

Internal steel-core damage hidden within aluminum conductor steel-reinforced (ACSR) compression components may threaten the mechanical integrity of ultra-high-voltage transmission lines. This laboratory study evaluates metal magnetic memory testing (MMMT) responses to artificial discontinuities in seven-strand ACSR steel cores under four nominal lift-off distances, two nominal orthogonal specimen orientations, and a simplified aluminum-tube-covered condition. One intact specimen and five artificially damaged 1 m specimens were preloaded to 16 kN for 2 min, unloaded, and scanned using the normal magnetic-field component recorded by Channel 1 of a TSC-1M-4 detector. Quantitative descriptors included peak-to-peak amplitude, abnormal-field width, maximum gradient, and short-term within-specimen repeatability. At 5 mm lift-off, peak-to-peak amplitudes ranged from 18.7 to 91.4 A/m. Across three repeated repositioning scans, amplitude coefficients of variation ranged from 0.83% to 8.04%. Relative to 5 mm, the descriptive mean amplitude loss reached 66.3%, 81.9%, and 89.8% at 20, 30, and 40 mm, respectively. Orientation changed signal polarity and amplitude in a specimen-dependent manner. Anomalies remained visible under the aluminum-tube configuration, although covering and effective lift-off effects could not be separated. The results provide preliminary laboratory evidence for further evaluation of MMMT as a screening approach; the reported feature values are not field detection thresholds. Full article

To address delayed attitude correction, limited adaptability of single-actuator systems, and reduced tunneling efficiency in full-face shaft-boring machines (SBMs), this study proposes a PSO-LSTM-based hybrid steel strand–support shoe attitude correction strategy. A coupled dynamic model with a 45° offset configuration is developed to enable coordinated multi-actuator control. A PSO-optimized Long Short-Term Memory (PSO-LSTM) network is employed to predict inclination deviation over a 5 s horizon, providing anticipatory information for proactive control. Based on this prediction, a hierarchical control strategy with adaptive torque allocation is designed to seamlessly coordinate fine correction via steel strand cables and high-torque correction via support shoes. Simulation results demonstrate that the proposed model achieves a prediction accuracy within ±0.02°. Under inclination conditions of 0.05°, 0.3°, and 1.0°, rapid attitude correction is achieved. Compared with independent support shoe control, the maximum horizontal displacement is reduced from 64 mm, 131 mm, and 160 mm to 6.3 mm, 65 mm, and 100 mm, corresponding to reductions of 90.2%, 50.4%, and 37.5%, respectively. The results further indicate that small-angle deviations can be compensated by the steel-strand system without additional support-shoe operations, while medium- and large-angle deviations can be regulated through coordinated actuation of multiple correction systems according to deviation magnitude. Simulation results demonstrate that the proposed method improves attitude correction performance and dynamic response under the investigated simulation conditions. The proposed framework provides a potential solution for intelligent attitude control of SBMs, while further field validation is required before practical engineering deployment. Full article

The overhead ground wire (OGW) may fracture at the suspension clamp under short-circuit faults, posing a serious threat to the safe operation of transmission lines. However, the dominant damage mechanism—whether Joule heating or arc discharge—remains unclear. This study investigates a 110 kV OGW breakage accident through combined experimental and numerical approaches. Fracture analysis using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) revealed composite damage featuring both melting and tensile necking, with no fatigue characteristics. A real-scale short-circuit test platform was constructed, which, for the first time, directly captured intense arc discharge phenomena inside the suspension clamp during current flow. A multi-physics finite element model was then developed to decouple and quantify the thermal contributions of Joule heating and arc heating. Results show that Joule heating alone raises the local temperature to only 49.27 °C—far below the melting points of aluminum (660 °C) and steel (1450 °C). In contrast, arc heating elevates the temperature to over 26,000 °C locally, causing rapid melting of aluminum strands and heating of the steel core above 1450 °C within milliseconds. This extreme heat reduces the effective load-bearing cross-section and tensile strength, ultimately leading to fracture under normal operating tension. The findings demonstrate that arc discharge, rather than Joule heating, is the decisive factor in such failures. This study provides a quantitative theoretical basis for fault protection and hardware design optimization of overhead transmission lines. Full article

In order to produce long-span precast bridge members and reduce the transport pressure of precast members, the lightweight design of bridge components has become a key area of research. In this study, utilizing retard-bonded prestressing technology and high-strength concrete, a full-scale thin-walled box girder measuring 30,000 mm in length and 1600 mm in height was designed and fabricated. A shear test with a shear-span ratio of 2.5 was conducted to investigate the failure mode and shear carrying capacity. Subsequently, an Abaqus finite element (FE) model was established and validated with experimental data. Based on the FE model, numerical investigations were conducted to examine the influence of bonding between prestressed steel strands and concrete, stirrup ratio, web thickness and bottom flange thickness at the end of the box girder, concrete strength and length of UHPC end zone on the shear performance of thin-walled box girder. The results indicate that the retard-bonded prestressed box girder exhibits acceptable mechanical performance. Additionally, intensifying the ends of the box girder with ultra-high-performance concrete (UHPC) can further reduce the wall (i.e., web and bottom flange) thickness of the girder, enhance its shear carrying capacity, and achieve lightweighting. This discovery provides new insights into the lightweight design of bridge components. Full article

The effects of practical parameters on the flexural behavior of reinforced concrete (RC) beams strengthened with steel strand mesh-reinforced engineered cementitious composite (ECC) were investigated, based on the finite element (FE) simulation. First, an FE model for strengthened RC beams was developed. The model was validated by comparing it with existing experimental data. Subsequently, the model was employed for parametric analysis on the flexural performance of the strengthened beams. The results showed that steel strand mesh-reinforced ECC significantly enhanced the flexural capacity, stiffness, and ductility of the RC beams, with improvements ranging from 7.81% to 61.84%, 6.35% to 40.90%, and 5.92% to 50.16%, respectively. As the reinforcement ratio of longitudinal steel strand, ECC thickness, and cracking strength increased, the flexural capacity increased. However, an increase in the reinforcement ratio of the longitudinal steel bars and the section height of the RC beam reduced the improvement in flexural capacity. The increase in the thickness of the strengthening layer and reinforcement ratio of the longitudinal steel strand enhanced the improvement of stiffness. Differently, an increase in the reinforcement ratio of longitudinal steel strand, concrete strength, and height of the RC beam diminished the improvement of stiffness. The enhancement of ductility increased with the concrete strength. Finally, formulas for calculating the bearing capacity and stiffness of RC beams strengthened with steel strand mesh-reinforced ECC and the limit of steel strand quantity were proposed. These formulas agreed well with experimental and numerical simulation FE results. Full article

This paper investigates the in-plane bending stiffness of light timber-framed (LTF) and light steel-framed (LSF) wall elements with different sheathing materials (fibre-plaster board (FPB) and oriented-strand board (OSB)), focusing on the influence of the fastener spacing (s) on the wall elements’ structural response. The analytical model accounts for bending, shear, and slip deformations in the sheathing-to-frame connection, while boundary conditions are assumed to be rigid in accordance with the Eurocode 5 standard. The results indicate a strong dependence of global stiffness on fastener spacing. Increasing the fastener spacing from 37.5 mm to 300 mm reduced the racking stiffness by approximately 42% in LTF–FPB walls and by 31% in LSF–FPB walls. The highest stiffness was obtained for LSF–FPB wall elements (6514 N/mm), while the lowest stiffness was observed for LTF–OSB elements (1236 N/mm). LSF wall elements generally exhibited stiffness values approximately two times higher than comparable LTF systems, although both framing systems showed similar trends with increasing fastener spacing. This study provides a solid basis for the design and optimization of lightweight wall systems and supports the development of efficient structural solutions in both timber and steel construction. Full article

In CSP thin slab casting, high casting speeds promote excessive columnar grain growth, leading to low equiaxed grain ratios in non-oriented silicon steel and resulting in wrinkling defects. This study employs a box-type electromagnetic stirrer (B-EMS) to address this issue. A multiphysics model was established, in which grain transformation and its associated effects were neglected. The effects of B-EMS on the flow of molten steel, temperature distribution and evolution of solidified shell were analyzed, and industrial trials were conducted to verify the influence of B-EMS on grains. Results show that B-EMS generates asymmetric magnetic fields and electromagnetic forces, driving width-directional flow that enhances scouring of the solidification front. Compared with the experiment and simulation, the error in the magnetic field excited by B-EMS is within 5%. Under 800 A current, narrow-face center shell thickness increased from 22.88 mm (no stirring) to 23.62 mm (starting side) and 23.21 mm (pushing side). The central mushy zone area and liquid fraction decreased significantly, indicating accelerated solidification and more uniform shell growth. Industrial trials confirmed that the equiaxed grain ratio increased to approximately 30%, with significantly improved internal strand quality. This study demonstrates B-EMS’s metallurgical effects in regulating solidification structure, optimizing shell morphology, and improving continuous casting slab quality. The numerical simulation can be correlated with the industrial production process to better guide manufacturing practices. Full article

During continuous casting, the flow behavior of liquid steel in the tundish directly affects the temperature distribution of liquid steel, inclusion removal, and billet quality. In tundish-related research, water model experiments remain an intuitive method for investigating the flow process in the tundish. However, water model experiments are often conducted in different seasons, and variations in experimental temperature can change fluid properties such as density and viscosity, thereby affecting flow characteristics and the comparability of experimental results. In this study, a 1:3.57 transparent bare single-strand tundish model made of acrylic was used, and the differences in tracer transport processes at 7 °C and 20 °C, as well as the influence of different tracer dosages on the experimental results, were systematically investigated through flow visualization and stimulus-response experiments. The results showed that, under the 7 °C condition, the upward transport tendency of the pure ink tracer was weakened, the overall flow remained closer to the tundish bottom, the transport speed decreased, and the time required to reach the outlet was significantly prolonged. For the saturated KCl solution tracer, a lower temperature enhanced its transport along the bottom toward the outlet and suppressed its diffusion toward the liquid surface. The RTD results showed that, after the temperature was increased, the curves shifted to the left as a whole, and both the peak time and the mean residence time were shortened. The outflow percentage of tracer results showed that the difference for the 10 mL saturated KCl solution between the 7 °C and 20 °C conditions was the most significant. At 7 °C, the total outflow percentage of the 10 mL salt solution tracer at 1500 s was 76.86%, which was 22.97% lower than that at 20 °C. As the tracer dosage increased, the differences in the transport process, RTD curves, and outflow percentage curves under different temperature conditions gradually decreased, indicating that the effect of dosage on the experimental results gradually became stronger than that of temperature. These results indicate that the combined effects of experimental temperature and tracer dosage cannot be neglected in tundish water model experiments. Full article

With the rapid expansion of urban underground space in China, anti-floating has become a critical challenge, and uplift piles are a key solution. Previous studies on composite anchor-cable uplift piles have primarily focused on small-diameter single-pipe types (≤600 mm), often simplifying the pile as an integral component, leaving the multi-interface stress transfer mechanisms of large-diameter piles inadequately understood. This study proposes a back-analysis method based on orthogonal experiments, implemented using Abaqus 3D finite element software, to determine interfacial mechanical parameters for three critical contact pairs (strand-grout, grout-steel pipe, steel pipe-concrete) in large-diameter multi-pipe composite anchor-cable uplift piles. These parameters are then implemented in a refined 3D finite element model to simulate the load-deformation behavior of such piles. Quantitative results show that the back-calculated parameters are highly reliable, with maximum simulation errors for pile head displacement limited to 13.0% and 9.6% for fully bonded and semi-bonded piles, respectively. Unlike conventional piles, stress and strain in this new pile type transfer progressively from the inner steel strands outward and from the top downward, resulting in reduced pile-soil displacement mismatch, fuller mobilization of side interfacial strength, and effective mitigation of concrete cracking. This study provides a systematic parameter-calibration framework and numerical platform, offering theoretical and technical support for optimized design and engineering application of large-diameter composite uplift piles. Full article

Prestressed steel strands transfer structural loads through complex anchorage systems. During through-anchorage ultrasonic guided-wave inspection, strong reflections generated in the anchorage segment may obscure defect-related echoes and create blind zones in the received signals. This study investigates the generation mechanisms of these anchorage-induced reflections and evaluates the relative roles of stress-induced acoustoelastic impedance variation and load-dependent interfacial contact evolution. An acoustoelastic finite element model is first used to estimate the reflection contribution caused by stress concentration alone. The results show that the stress-induced reflection remains weak, with the reflection coefficient remaining below 0.0125 even at 80% of the ultimate tensile strength. A sensitivity-based equivalent spring-contact model is then employed to examine whether effective strand–wedge and wedge–anchorage interfacial stiffness variations can generate anchorage reflections with comparable order of magnitude and load-dependent trends. The contact-based model produces much stronger reflections, and roughness-sensitivity analysis indicates that the load-dependent trend is not governed by a single nominal roughness assumption. Multi-specimen stepwise tensioning experiments show repeatable load-dependent reflection trends at both 80 kHz and 240 kHz. The results therefore suggest that, within the investigated geometry and loading range, interfacial contact evolution is a more plausible dominant contributor to anchorage-induced guided-wave reflections than stress-induced acoustoelastic impedance variation. This work focuses on the physical origin of anchorage reflections and provides a mechanistic basis for interpreting anchorage-induced interference in future through-anchorage defect detection. Full article

Four-point bending tests were conducted on precast ultra-high-performance concrete (UHPC) segmental beams reinforced with unbonded prestressing tendons. A nonlinear finite element model was established and rigorously validated against the experimental data to simulate their flexural behavior. The experimental results show that compared with monolithic beams, the segmental beams experience a slight reduction in flexural capacity of 9.22% and 12.44% for the double-joint and triple-joint configurations, respectively. Nevertheless, the segmental beams possess greater ductility reserves; specifically, their average peak displacements increased from 9.83 mm for the monolithic beams to 11.60 mm and 14.78 mm for the double-joint and triple-joint beams, respectively, demonstrating substantially improved ductility. Based on the validated finite element model, extensive parametric analyses were performed. The numerical results indicate that concrete strength and steel strand reinforcement ratio significantly enhance the load-carrying capacity. Furthermore, shifting the joint positions away from the loading points increases the beam’s bending capacity, though this enhancement aggressively flattens out beyond a critical distance threshold of 0.25 L (L is the effective span). Finally, segmental beams with shear-resistant keyed joints exhibit higher overall stiffness and ultimate load-carrying capacity compared to those with plain flat joints. Full article

Sulfur-containing medium-carbon microalloyed steel blooms are widely used for high-load automotive components, and reducing surface defects is important for improving product yield and lowering downstream processing costs. To address surface defects such as star cracks and microcracks in the continuous casting of these steel blooms, this study redesigned the mold flux on the basis of the steel’s solidification characteristics and crack susceptibility and carried out a twin-strand industrial comparative casting trial. Thermodynamic and thermophysical analyses indicated that the relatively high contents of S, Mn, and Ti/N in the steel promoted the precipitation of MnS and TiN–MnS complex inclusions along grain boundaries, severely weakening grain boundary cohesion. Meanwhile, the high specific heat capacity and low thermal conductivity further intensified thermal stress concentration in the solidifying shell, rendering the steel highly susceptible to cracking. Evaluation of the originally used mold flux (Flux A) revealed that its high melting temperature (1189 °C), long melting time (106 s), high break temperature (1170 °C), and poor crystallization behavior resulted in an excessively thin liquid slag layer (<5 mm) within the mold, making it difficult to provide adequate lubrication and stable heat transfer; these were key external factors inducing surface defects. Accordingly, the optimized mold flux (Flux B) was designed and prepared by increasing the basicity from 0.95 to 1.1, raising the Al₂O₃ content from 9.48% to 11.16%, increasing the F content from 4.93% to 5.58%, and reducing the carbon content from 13.85% to 6.97%. The rheological and crystallization properties of the flux were optimized in a coordinated manner, allowing uniform heat transfer through the crystalline slag layer while maintaining adequate lubrication. Industrial comparative trials demonstrated that Flux B stabilized the liquid slag layer at 8–10 mm, increased slag consumption to 0.56 kg/t, and significantly reduced surface defects such as star cracks and microcracks on blooms. The ultrasonic testing acceptance rate for rolled products increased to 98.6%, thereby meeting stringent quality requirements for the continuous casting of sulfur-containing, medium-carbon, microalloyed steel blooms. Full article