Search Results (54)

During the fabrication of prestressed concrete beams, the quality and positional accuracy of the laid corrugated ducts (or prestressing ducts) directly influence the load-bearing capacity and durability of the beams. However, traditional manual inspection is inefficient, highly subjective, and difficult to achieve full coverage. To address this problem, this paper proposes an automated detection method that integrates improved YOLOv11-based pose estimation, robust curve fitting, and image stitching techniques. The method automatically identifies duct positions and evaluates laying quality. By incorporating the SE channel attention mechanism and the SPPFCSPC multi-scale pooling module, the SC-YOLOv11 model is developed, which significantly enhances the detection accuracy of slender corrugated pipe key points in environments with dense rebar occlusion. The RANSAC algorithm is employed to fit curves to the predicted key points, effectively suppressing the influence of outliers. Furthermore, the SIFT algorithm is used for precise stitching of drone-captured segmented images, which are then transformed into a unified front orthographic coordinate system of the entire box girder via perspective transformation, enabling accurate reconstruction of the corrected 2D layout of corrugated ducts across the full beam. Ablation experiments using 5-fold cross-validation demonstrate that SC-YOLOv11 improves mAP₅₀ and mAP_50–95 by 2.6% and 1.2%, respectively, with statistical significance (paired t-test, p < 0.01). The model achieves a per-image inference time of 6.37 ms, with 4.34 M parameters and 8.1 GFLOPs, meeting real-time requirements. In a 30 m prefabricated box girder field application, the measured section trajectory fitting curves of the corrugated ducts were compared with the design alignment, successfully identifying two abnormal locations where the laying deviation exceeded the allowable threshold. Cross-validation with on-site inspector records shows that over 92% of the measurement points agree within ±10 mm. This method achieves a fully automated analysis chain from key point detection and curve fitting to deviation quantification, providing an efficient, non-contact, and traceable intelligent tool for quality control of bridge prestressed systems. Full article

Horizontal annular channels are widely encountered in fluid mechanics. Extensive research has explored how wall roughness alters total pressure loss in circular pipe flows. Meanwhile, existing literature has thoroughly discussed artificially enhanced rough structures (e.g., ribs, helical strips, and axial corrugations) for turbulence control and modulation. By contrast, relevant research on the inner cylinder roughness of annular channels remains insufficient. In practical engineering like petroleum drilling, inner pipes are usually treated as hydraulically smooth in theoretical and numerical models. However, machining inevitably generates tiny surface asperities on inner walls. Though this manufacturing micro-roughness is minimal in size, its true impact on flow characteristics is still unclear and requires a systematic numerical study. This study numerically explores the effects of practical inner-wall roughness on the hydrodynamic performance of annular flow. The simulation results reveal that compared with a fully smooth inner wall, surface roughness significantly rearranges the spatial distribution of major turbulent parameters (e.g., flow velocity, turbulence intensity, turbulent kinetic energy and Reynolds stress), and changes both the magnitude and position of their peak values. When the inner wall roughness is 0.4 mm, the near-wall Reynolds stress increases by 153.5%, the turbulence intensity increases by 52.4%, and the turbulent kinetic energy increases by 133.0%; the velocity peak shifts to the outer ring side, and the critical roughness is 0.06 mm. The findings confirm that considering inner tube roughness is critical for improving the prediction accuracy of both microscale turbulent behaviors and macro flow parameters in practical annular flow engineering. This work distinguishes itself from existing studies by systematically quantifying the response of full first- and second-order turbulent statistics to pipeline manufacturing micro-roughness, revealing the symmetry-breaking turbulent transport mechanism of annular flow, and quantitatively determining the critical inner-wall roughness that shifts the velocity peak to the annular geometric midpoint, which provides a targeted quantitative database for the correction of annular flow numerical simulations that ignore native micro-roughness. Full article

While data fitting is extensively used in polymer processing to extract fundamental rheological properties, its application for direct macroscopic geometric transfer between complex operational dies remains largely unexplored. Optimizing extrusion dies for corrugated plastic pipes traditionally requires time-consuming offline laboratory rheology, creating a major development bottleneck when dealing with proprietary, undocumented blends. To address this gap, this study introduces a novel, data-driven protocol for predicting the die pressure drop that eliminates the need for independent laboratory rheometry. Unlike traditional in situ methods that seek pure material properties, our approach back-calculates lumped, effective Power Law parameters directly from macroscopic pressure drops of existing converging dies. This uniquely embeds both material and geometric flow characteristics under actual processing conditions. Experimental validation demonstrates that this workflow, supported by an iterative refinement strategy, yields prediction errors typically within 10%. Ultimately, this lightweight computational tool provides engineers with a rapid-iteration framework to significantly accelerate early-stage die design. Full article

This study evaluates the effectiveness of reinforcement measures for a corrugated steel pipe arch bridge subjected to differential settlement induced by underground mining. Using a ten-span continuous corrugated steel pipe arch bridge in Shandong Province as the engineering background, a refined finite element model was developed based on 12 months of in situ settlement monitoring data. The mechanical performance of three reinforcement schemes–inner lining concrete, inner lining concrete with nested steel pipes, and laterally welded steel plates–was systematically compared. The results indicate that under differential settlement, the maximum stress of the unreinforced structure reaches 75.74 MPa, primarily concentrated at the arch foot. Reinforcement with an inner concrete lining significantly improves structural performance; in particular, the 200 mm-thick lining reduces the maximum steel pipe stress by 61.8%, achieves a maximum reduction of 22.1% in crown displacement and approximately 11.2% in sidewall displacement, and limits the circumferential displacement amplitude to 12–17 mm, representing a reduction of 11.7–15%. The nested steel pipe scheme delivers reinforcement effects comparable to the pure inner lining concrete scheme, with a maximum crown displacement reduction of approximately 17.3%, though its overall additional advantages remain limited. In contrast, the laterally welded steel plate scheme reduces the maximum structural stress by 28.3%. While it exhibits favorable control over local displacements, its overall reinforcement effectiveness is inferior to that of the inner lining concrete scheme. These findings provide a useful reference for the reinforcement design and engineering application of corrugated steel pipe arch bridges in mining-induced subsidence areas. Full article

Composite soil–steel corrugated bridges, which are widely used in road, railway, and civil engineering, are recognized as durable, sustainable, and cost-effective structures. Due to their interactions with the surrounding soil, relatively thin corrugated steel plates are usually used in these bridges. Larger spans are associated with larger cross-sections, and deep corrugations with a 500 mm pitch and a 237 mm depth are already in use worldwide. However, the behavioral benefits of high-strength steel and additional strengthening elements for CSS structures have rarely been investigated with regard to local buckling in the straight regions of the corrugation. This study analyzed the influence of high-strength steel and innovative corrugated cross-sections strengthened with circular steel pipes on the utilization ratio of steel plates in composite soil–steel structures. Two-dimensional numerical models of three bridges with spans of 26 m, 17.5 m, and 12 m and surrounded by soil were developed to identify internal forces from permanent and temporary actions. Plate utilization was designed according to the Swedish, Canadian, and American methods, considering local buckling in the 500 × 237 mm and 381 × 140 mm corrugation profiles. It was found that the use of higher-strength steel material, as well as the introduction of steel pipes, significantly reduced the plate thickness of regular corrugations. The results show that the use of higher-strength steel reduced the cross-section area of regular and innovative corrugations by 30–40%. Moreover, the cross-section area of the innovative profile was 5% to 36% lower than that of the regular corrugation profile. Nevertheless, the results show that the local buckling approach proposed by the Swedish design method could be considered conservative and should be revised. In addition, the method of preventing local buckling by reducing the plastic moment capacity could be neglected when using thicker plates and lower steel grades. Full article

Pulsating heat pipes (PHPs) are promising passive heat-transfer devices for compact thermal management; however, their performance is highly sensitive to channel geometry. In particular, the operating-condition-dependent influence of sinusoidal corrugation amplitude on the condenser side remains unclear, despite its importance for oscillation regulation and heat dissipation. This numerical study investigates a single-loop PHP with sinusoidally corrugated condensers (A = 0.25 and 0.5 mm) under heat fluxes of 5000–12,500 W/m² and filling ratios of 40–60%, using a uniform-diameter PHP as the baseline. The results show that the configuration with A = 0.25 mm exhibits better start-up performance, especially at low heat fluxes, whereas both corrugated configurations provide better thermal performance than the baseline. At a filling ratio of 50%, the thermal-resistance reductions for A = 0.25 and A = 0.5 mm are 14.5% and 9.2% at 5000 W/m² and 8.4% and 10.5% at 12,500 W/m², respectively. An operating-condition-dependent amplitude-matching relationship is identified: The smaller amplitude is more favorable for start-up under weak driving conditions, whereas the larger amplitude tends to provide lower thermal resistance and higher equivalent thermal conductivity under strong driving conditions. These findings provide useful guidance for condenser-geometry optimization in single-loop PHPs. Full article

A novel corrugated steel-reinforced concrete pipe that enhances electromagnetic shielding performance compared to the conventional reinforced concrete power pipes is developed and presented in this paper. In order to investigate the pipe’s behaviour under jacking and service conditions, the critical axial compression and flexural moment distributions were represented by two separate flat segments of a circular pipe cross-section, respectively. A total of six column specimens were designed for axial compression testing, while another four beam specimens were prepared for four-point bending tests to examine the bending behaviour. Prior to testing, all specimens were subjected to standard curing, and the material properties of steel and concrete were determined via standard tests. The load versus deformation curves of column specimens, the moment versus deflection curves of beam specimens, and the corresponding failure modes were obtained from the tested specimens. It was revealed that the load-carrying capacities of the corrugated steel-reinforced concrete cross-sections were comparable to those of the conventional reinforced concrete counterparts. Advanced finite element (FE) models incorporating the mechanical properties of encased corrugated steel plates (CSPs) and the damage development of concrete were developed and were validated against the experimental failure modes and load-carrying capacities. Based on both experimental and numerical results, the load-carrying capacity of corrugated steel-reinforced concrete cross-sections was evaluated by referring to Chinese standard GB/T 11836 and American standard ASTM C76. The experimental and numerical finding can pave the way for further research and applications of this novel type of corrugated steel-reinforced concrete pipe. Full article

Corrugated pipes are widely used due to their mechanical flexibility; however, their corrugated internal geometry is associated with increased hydraulic losses. Previous studies have reported a non-classical increase in friction factors with pipe diameter at identical Reynolds numbers, although the underlying mechanisms and related energy implications have not been fully clarified. In this study, turbulent flow behavior and pumping power requirements in stainless-steel corrugated pipes are investigated using a validated three-dimensional Computational Fluid Dynamics (CFD) framework based on the SST k–ω turbulence model. The numerical predictions show good agreement with available experimental data, with maximum deviations remaining below approximately 12% across the validated range. The results indicate that both friction factor and pumping power increase systematically with pipe diameter under dynamically similar flow conditions, demonstrating that Reynolds-number similarity alone does not ensure flow similarity in corrugated geometries. From an energy perspective, an Energy Penalty Factor (EPF) is introduced to quantify corrugation-induced pumping requirements, and a surrogate correlation is developed to relate EPF to Reynolds number and selected dimensionless geometric parameters. The proposed formulation exhibits strong predictive performance within the investigated parameter space (R² = 0.972) and enables rapid, CFD-free estimation of energy penalties for preliminary design and comparative evaluation of corrugated piping systems. Full article

This study presents the design and performance evaluation of an advanced inorganic filler system composed of calcite (CaCO₃) and talc (Mg₃Si₄O₁₀(OH)₂), modified with a polyolefin elastomer (POE), and integrated into a high-density polyethylene (HDPE) carrier resin with process additives such as erucamide, montan wax, pe wax, and PIB. The composite was developed to improve the structural integrity and longevity of HDPE double-wall corrugated pipes. Comprehensive characterization of the filler was performed using TGA–DSC, FTIR, SEM–EDX, XRD, and XRF analyses, confirming the presence of every individual component and homogeneous dispersion in the compound. Pilot-scale extrusion pipe trials confirmed uniform filler dispersion when evaluated by SEM-EDX analysis. The filler addition increased both the density and MFI values up to 1.03 g/cm³ and 1.5 g/10 min, respectively, while test results indicated oxidation induction times (OIT) reaching up to 40 min. The developed filler-added pipes demonstrated a significantly higher ring stiffness value of 12.20 kN/m², exceeding the minimum requirement of 8 kN/m² specified for the SN8 class pipes. The POE effectively attenuated rigidity and brittleness typically induced by mineral fillers, yielding this superior stiffness while maintaining adequate ring flexibility. These findings highlight the potential of this tailored filler system to advance the production of lightweight, mechanically robust corrugated piping solutions for demanding infrastructure applications. Full article

To investigate the deformation behavior of corrugated steel pipe arch bridges subjected to differential foundation settlement, this study examines a ten-span continuous corrugated steel pipe arch bridge as the engineering background. A one-year field monitoring program was conducted to record the settlement of each span, and the spatial distribution pattern, annual cumulative settlement, and settlement growth rate were evaluated. Numerical analyses were then performed to compare the deformation response of the bridge under ideal foundation conditions, differential foundation settlement, and vehicle loading. Based on the numerical results, the effectiveness of a concrete lining installed inside the corrugated steel pipe was further assessed. The results show that the settlement of the side spans is significantly larger than that of the middle spans due to the differential foundation settlement in the mining area. The maximum annual cumulative settlement at the side span (span 2) reaches 21.66 mm, which is approximately 4.1 times that of the middle span (span 6). During the monitoring period, the settlement growth rate was high in the early stage (1~3 months), reaching up to 30 percent, and gradually stabilized to about 10 percent per month in the later stage. Compared with the ideal foundation condition, differential settlement increases the pipe stress by a factor of 3.4 and amplifies the deformation by a factor of 9.1. Vehicle loading has a pronounced effect on the deformation of the pipe crown, increasing the settlement by approximately 9 percent, while its influence on the pipe invert is relatively small, with an increase of about 4 percent. Installing a 100 mm thick concrete lining inside the corrugated steel pipe has limited influence on the overall load-carrying behavior but reduces the deformation by 10~20 percent. This reinforcement method is suitable for applications in existing bridges. Full article

Corrugated metal pipe (CMP) culverts are key pieces of infrastructure in drainage and waterway management, but many are reaching their end of life and require rehabilitation. While existing repair methods have a long track record of success, they can be cost prohibitive and may significantly affect the hydraulic properties of culverts. Ultra-high performance concrete is internally reinforced, stronger, and more durable than conventional concrete, offering a modern solution to culvert deterioration. The seven mockups described include trials with top-formed UHPC, thixotropic UHPC, and a UHPC shotcrete placement. Shotcrete UHPC was not found to be viable at this time due to challenges with maintaining mix consistency and adhesion to the substrate. Top forming and thixotropic UHPC were found to be the best options for building a consistent invert lining for culvert rehabilitation but posed unique challenges in design, construction, and material consistency. This paper describes the methods of construction, challenges during construction, and the results of each test. It is the author’s intent to give owners a new tool for culvert rehabilitation, provide designers with each of the variables in implementation, and help contractors mitigate risks by discussing the challenges encountered for UHPC invert linings. Full article

Corrugated pipes are extensively used in engineering applications that require flexibility and enhanced heat exchange, such as drainage and compact heat exchangers, and recently as inner layers in cryogenic flexible hoses for offshore liquid ship-to-ship transfer. The great flexibility of these hoses makes them well-suited for deployment in dynamic and harsh marine environments. However, the corrugated geometry also induces flow separation, elevated turbulence, and intricate heat transfer behaviors. This study focuses on the flow and heat transfer characteristics in corrugated pipes with various geometries, addressing the current lack of systematic comparative studies on the performance of different Reynolds-Averaged Navier–Stokes (RANS) models in such configurations. Despite their limitations in accuracy compared to high-fidelity methods, RANS models remain the workhorse for engineering analysis due to their computational efficiency. This study employs several RANS models to simulate flow and heat transfer in three corrugated pipe geometries—sinusoidal (Sin), C-type, and U-type—over a Reynolds number range of O(10⁴) to O(10⁵) and assesses their performance against high-fidelity Large Eddy Simulation benchmarks. The results show that prediction accuracy decreases with increasing corrugation depth, with the most significant errors in trough regions where reverse flow dominates, and that the choice of turbulence model has a strong influence on the predicted flow and heat transfer behavior. Among all models, the $k-ϵ$ models overall provide the most consistent and accurate predictions for friction factor, velocity distribution, and Nusselt number, while the $k-\omega$ models perform the worst. The Reynolds Stress Model improves friction factor prediction accuracy at high Reynolds numbers and provides marginally better accuracy in mean Nusselt number prediction, but its advantages are limited relative to its substantially higher computational cost. The Standard $k-ϵ$ model with Enhanced Wall Treatment demonstrates robust and balanced performance across geometries and flow regimes, making it a practical choice for engineering use. This work provides engineers and researchers guidance for choosing RANS models that balance accuracy and computational efficiency in simulations of LNG ship-to-ship transfer, compact heat exchangers, and other industrial systems that employ corrugated pipes. Full article

The accurate installation position of corrugated pipes is critical for ensuring the quality of prestressed concrete box girders. Given that these pipes can span up to 30 m and are deeply embedded within rebars, manual measurement is both labor-intensive and prone to errors. Meanwhile, automated recognition and measurement methods are hindered by high equipment costs and accuracy issues caused by rebar occlusion. To balance cost effectiveness and measurement accuracy, this paper proposes a method that utilizes an RGB-D camera and deep learning. Firstly, an optimal registration scheme is selected to generate complete point cloud data of pipes from segmented data captured by an RGB-D camera. Next, semantic segmentation is applied to extract the characteristic features of the pipes. Finally, the center points from cross-sectional slices are extracted and curve-fitting is performed to recognize and measure the pipes. A test was conducted in a simulated precast factory environment to validate the proposed method. The results show that under the optimal fitting scheme (BP neural network with circle fitting constraint), the average measurement errors for the three pipes are 2.2 mm, 1.4 mm, and 1.6 mm, with Maximum Errors of −5.8 mm, −4.2 mm, and −5.7 mm, respectively, meeting the standard requirements. The proposed method can accurately locate the pipes, offering a new technical pathway for the automated recognition and measurement of pipes in prefabricated construction. Full article

This article focuses on the microstructural evolution and mechanical property changes of AISI 304 austenitic stainless steel corrugated pipes after aging treatment and solution treatment. The influence of different heat treatment processes on the microstructural evolution, second phase precipitation behavior, mechanical properties, and corrosion resistance of corrugated pipes was analyzed through metallographic microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), fatigue testing, hardness testing, and corrosion resistance experiments. The results showed that after aging treatment at 600 °C, carbides precipitated at the grain boundaries and twin boundaries of the corrugated tube, leading to corrosion behavior. The average microhardness value was 266.08 HV, and the work hardening problem of the corrugated tube was not improved. After solution treatment at 1050 °C, a single-phase austenite structure was obtained in the corrugated tube, and the carbides at the grain boundaries were completely dissolved. The average microhardness value was 66.02 HV, significantly improving the work hardening problem of the corrugated tube. Simultaneously, excellent comprehensive fatigue performance and intergranular corrosion resistance were exhibited. The solid solution treatment process is more suitable for the manufacturing of corrugated pipes that require high formability and corrosion resistance, while the aging treatment requires strict temperature control to avoid the sensitization temperature zone. This study provides a theoretical basis for optimizing the heat treatment process of AISI 304 austenitic stainless steel corrugated pipes. Full article

The small-loop transient electromagnetic method (TEM) refers to a system in which the coil frame length or diameter is less than 2 m. Due to the inductive effects of the multi-turn coils used for both transmission and reception, the induced electromotive force in the measuring coil increases, causing a reduction in the decay rate and an extension of the shutoff time. This results in coupling between the primary and secondary fields in early-time signals, making them difficult to separate and creating a detection blind spot in the shallow subsurface. The opposing coil TEM transmission and reception method can significantly reduce early-time signal distortion caused by coil inductance. However, this approach is constrained by the physical symmetry of the coil dimensions, which makes it challenging to achieve balance in a zero-field space. By performing both forward and reverse measurements at the same location using the opposing coil setup and calculating the difference between the signals, the inductive coupling between coils at the measurement site can theoretically be eliminated. This eliminates the induced potential of the TEM signal, enhancing the induced electromotive force from the formation. As a result, more accurate resistivity values are obtained, detection blind spots are eliminated, and the resolution in shallow TEM exploration is improved. Field experiments were conducted to validate the method on both high-resistivity and low-resistivity anomalies. The results demonstrated that this method effectively identified a high-resistivity corrugated pipe at a depth of 1.2 m and two low-resistivity gas pipelines at a depth of 2 m, thereby essentially eliminating detection blind spots in the shallow subsurface. Full article