为探究拉(缆)索护套破损尺寸对索内高强钢丝腐蚀扩散模式以及缆索承载性能的影响规律，本研究首先采用人工加速腐蚀试验模拟不同开口尺寸下拉索索内钢丝腐蚀扩散模式。之后，对锈蚀后的钢丝进行腐蚀等级评估，建立钢丝腐蚀扩散三维数学模型。最后，对锈蚀高强钢丝进行力学试验，探究非均匀锈蚀下高强钢丝的力学性能退化规律及其与截面损失率间的关系，结合腐蚀三维扩散模型建立拉索剩余承载力评估模型，评估拉索承载力。研究结果表明：腐蚀初期，护套开口尺寸对索内钢丝腐蚀扩散速度影响显著，随着腐蚀时间的延长，开口尺寸的影响逐渐减小；通过COMSOL有限元软件验证腐蚀扩散模型，结果显示本腐蚀扩散模型可较准确地表征索内钢丝的腐蚀扩展规律；根据拉索承载力模型计算得腐蚀4周后，20mm和30mm开口尺寸的拉索承载力退化明显，当腐蚀12周时，30mm开口尺寸拉索的外层钢丝锈蚀率大于12％，拉索剩余承载力低于规范限值。

斜拉索是斜拉桥的主要传力构件,索内高强钢丝腐蚀致使拉索承载性能退化,严重时将影响到大跨度斜拉桥的安全性和耐久性。为了精确高效地评估拉索承载性能,本文首先提出一种考虑腐蚀致使索内高强钢丝强度沿轴向和横截面方向随机分布的三维随机场模型来评估腐蚀斜拉索的剩余承载力。之后,采用某实桥的1号斜拉索和2号斜拉索的现场试验结果对本评估模型的有效性进行了验证,结果表明本评估模型可以准确地估算腐蚀拉索的承载性能,与试验误差小于5%。

Corrosion fatigue is a major factor leading to the high strength steel wire deterioration of bridge cables. In this study, accelerated corrosion and fatigue stress were simultaneously applied to high-strength galvanized steel wires using a combination of a fatigue testing machine and an electrochemical workstation. While accelerated corrosion was achieved by galvanostatic polarization, the dissolution progress of galvanized coating layer was monitored using potential-time curves. Metallographic analysis of the galvanized high-strength steel wires for cables was conducted using scanning electron microscopy. The zinc-iron alloy structure within the coating was characterized by energy-dispersive spectroscopy. The relationship between the potential-time curves and the corrosion progression of the coating was established by combining microscopic corrosion morphology. Tafel curves for different steps were derived, and the corrosion kinetic parameters of various zinc-iron alloy phases were analyzed. The fatigue effects on the corrosion of the galvanized coating layer on high-strength steel wires were investigated based on the potential-time curves, considering factors such as the maximum stress, stress range, and loading frequency. The results indicate that under corrosion fatigue, the consumption rate of galvanized coating layer may be more than three times faster than under general corrosion conditions. © 2025 Elsevier Ltd

This paper presents a coupled experimental-numerical study aimed at understanding the mechanical behavior of corroded high-strength steel wires. Accelerated corrosion tests were conducted on steel wires to achieve varying corrosion levels, and the mechanical properties of the corroded wires were characterized by tensile test. The surface morphology of the corroded wires was derived by 3D optical scanning and point cloud models was generated that precisely captured the surface pits. These models were then converted into solid models by surface reconstruction and finite element discretization. Numerical simulations, based on reconstructed surface morphology, effectively predict key mechanical characteristics and align closely with experimental data. The research establishes relationships between statistical pit parameters and macro-mechanical properties, providing valuable insights for predicting the mechanical performance of corroded wires and evaluating the integrity of structures compromised by corrosion. © 2024 Elsevier Ltd

The steel corrosion in Ultra-High Performance Concrete (UHPC) would cause degradation of structural performance or even structural failure. It is an urgent need to monitor and predict the steel corrosion in UHPC, however it is still a tough task. In this paper, Fiber Bragg Grating (FBG) sensors are applied for monitoring the steel corrosion process in UHPC, by combining with steel bar, which is equidistant winding with the sensors, and connected with power supply for accelerating corrosion. The UHPC specimens embedded with steel bars are surrounded by sodium chloride (NaCl) solution, and the steels are artificially corroded with different current densities for investigation. The steel corrosion in Original C60 and Marine Concrete 60 (Marine C60) are applied for comparison. The volume expansion coefficient for monitoring the steel corrosion process, is carried out by FBG sensors, and further comprehensively monitored by three grating sensors. The results suggest that the steel corrosion process in UHPC is slowly with current density lower than 100 μA/cm2, and largely increases with current density higher than 500 μA/cm2, the volume expansion coefficient of corroded steel in UHPC is in range of 2.02–2.62 in this test, which is much different from Original C60 and Marine C60. © 2024 Elsevier Ltd

The bridge of Shanghai Metro Line 10 over Metro Line 6 is a U-shaped concrete single-box double-cell concrete box beam continuous bridge. A novel method is applied to construct the asymmetric cantilever prefabricated and assembled continuous bridge due to the limited construction space and the complex environment. Four mechanical state control methods are applied during the T-shape structure construction process: tensioning pre-stressed steel strand, jacking by the axial force servo system, adjusting the leg reaction force, and setting the auxiliary leg. Auxiliary measures such as the compressive column, side-span counterweight, and temporary pre-stressing are also taken into consideration. The finite element method simulations are performed to measure effects of the four control methods during the construction process. The front leg force of the bridge erection machine and the deflection of the bridge are then monitored. It was deduced that the simulated and measured values of the cantilever T-shape structure are controlled within the limit range during the construction process.

斜拉索是斜拉桥的主要承重结构,由于保护层破损,腐蚀介质进索体导致斜拉索用高强钢丝腐蚀,斜拉索用高强钢丝腐蚀是斜拉索失效的主要原因之一,高强钢丝性能退化最终导致斜拉索失效。在实际工程中,若只是斜拉索稍微破损而内部高强钢丝尚未腐蚀便进行换索,这会大幅提高桥梁的维护成本,同样会导致原材料的浪费。因此,为了更好地保护桥梁安全、人身安全和社会财产,本文通过对斜拉索用的高强钢丝进行人工加速腐蚀,对腐蚀后的高强钢丝进行力学性能测试,并对相关数据进行统计分析,为斜拉索的换索提供依据,从而更好的解决桥梁维护问题。本文对高强钢丝进行盐雾腐蚀,按照腐蚀天数分为:30d、50d、70d、90d、120d、150d、180d、220d、260d、300d和350d,实验温度为45℃。采用XRD、EDS对锈蚀产物进行分析,结果表明,锈蚀产物中Zn元素逐渐减少、Fe元素逐渐增多,对腐蚀后的高强钢丝进行酸洗,得出Zn含量与腐蚀率之间的关系并依此对不同腐蚀天数的高强钢丝进行分类。对腐蚀后的高强钢丝进行静载试验,结果表明:随着腐蚀率的增加,高强钢丝的极限强度、断后伸长率和屈服强度逐渐降低,弹性模量基本保持不变,采用最小二乘法对腐蚀率与极限强度、屈服强度进行回归分析,得出腐蚀率与极限强度、屈服强度的关系。同时,对不同腐蚀率的高强钢丝进行疲劳试验,通过实验发现,当疲劳寿命在10000与100000期间时,高强钢丝的残余应变增加比较大。当腐蚀率小于4%时,高强钢丝可以达到200万次,符合工程要求;在大于4%时,高强钢丝的疲劳寿命逐渐减小;当腐蚀率达到15%左右时,高强钢丝的疲劳寿命将小于50万次。本文通过人工加速腐蚀和自然腐蚀的高强钢丝进行了系统的试验研究,为保障大跨径斜拉桥的服役性能和安全水平提供了试验与理论基础,具有比较高的社会意义。

Steel corrosion in concrete is harmful but invisible. Until now, it is still very hard to measure the steel corrosion condition by non-destructive method accurately. In this paper, Fiber Bragg Grating (FBG) sensors include single and three grating sensors, are proposed to bond with steel bar and embed in concrete for monitoring the steel corrosion condition. The steel corrosion condition is evaluated by the corrosion ratio and volume expansion coefficients of steel, which are derived from the wavelength shift of FBG. Bonding materials and bonding ways are investigated in detail for improving the accuracy of FBG sensors. The mechanism of bonding effects on FBG sensor for optimizing the accuracy, has been discussed. The results suggested that the steel corrosion condition is successfully monitored by calculating the corrosion ratio of 2.02–4.24%, and volume expansion coefficient of 2.18–2.65 in this test. The research work is more quantify than the traditional methods for monitoring the steel corrosion condition in concretes. It is helpful for ensuring the safety operation of infrastructures efficiently. © 2023 Elsevier Ltd

Tires are one of the indispensable components of automobiles,and different automobiles have different requirements for tire performance.After the tire leaves the factory,the identifier on the tire is the only information for the owner to identify the type of tire.Therefore,character detection must be carried out on the tire before the tire leaves the factory to ensure the safety of consumers.because the Tire image has the characteristics of low contrast between characters and background,diverse text forms and high character density,so the traditional manual feature extraction method is difficult to meet the industrial application conditions of tire detection.Therefore,the character detection of tire manufacturers mainly relies on manual detection.In order to solve this problem,in this paper,Halcon’s deep learning object detection model is used to design a tire character detection system to realize automatic tire image character detection.

The corrosion morphology of artificially galvanized high-strength steel wires and its effect on mechanical behavior was presented. The corrosion morphology was obtained by 3D optical scanner. Four typical pit mor-phologies on corroded wires were identified, namely conical pit, hemispherical pit, combined pit and secondary pit. The probabilistic density function of cross-sectional parameters under different corrosion degree were modeled by normal distribution, and the evolution of model parameters was obtained. Based on the proposed evolution model, the maximum cross-sectional area loss was estimated by '3 sigma rule' of normal distribution function. Subsequently, the effect of corrosion pits on the mechanical behavior of corroded wires was discussed. It shows that the ductility degradation of corroded wires is much greater than that of strength, the ductility degradation is closely related to the ratio of pit depth to residual radius. Besides, it was found that the proba-bilistic density function of the ratio of pit depth to uniform corrosion depth tends to stabilize when the corrosion loss is more than 10%, which indicates that the surface of corroded wire with corrosion pits is uniformly thinning.