International Journal of Steel Structures最新文献

Cold-formed steel C-shaped connectors are one of the most commonly used components in a connection e.g. track-to-stud connections which may be exposed to various destructive failure modes. This paper presents a detailed experimental study of 78 specimens to investigate the pull-out ultimate strength and force–displacement responses of C-shaped connectors subjected to tensile loading conditions. Effects of various design parameters were considered including plate thickness, screw diameter size, distance between the screw rows and formed corner of the C-shaped sections, number and arrangement of the screws, and internal screw rows. Then, a developed pull-out strength equation with a resistance reduction factor was proposed and the obtained results were compared against existing design standard equations. From the comparisons, the proposed equation can accurately predict the screw pull-out strength in C-shaped connectors’ webs. The results of this equation can be applied to analytical methods as mechanical characteristics of the component of C-shaped section’s web in tension or bending.

To reduce the significant losses caused by ship collisions on bridges, in this paper, a new combined anti-collision device set on a bridge pier is proposed., taking the 26# pier of Mingzhu Bay Bridge as the engineering background. To study the anti-collision performance of the anti-collision device, the failure mode, peak impact load, system energy conversion, and dynamic response of the ship and pier during the collision process of each working condition were compared and analyzed by finite element modeling. The results show that when the shipping speed is 5 m/s, compared with the unprotected condition; the new anti-ship collision device reduces the peak collision force by 35.13% and prolongs the collision time by 191%. The maximum deformation of the bow is reduced by 92.04%, and the maximum internal energy of the pier and the hull is reduced by 40.93% and 87.66%, respectively. The anti-collision device can significantly reduce the peak impact force and prolong the collision duration. It has good energy absorption ability, reduces the damage of ships and piers during impact, and effectively protects bridges and ships.

The increasing reliance on bridges in high-speed railway systems and the growing risk of earthquakes necessitate advanced seismic analyses of train–bridge interactions. This study addresses the dynamic behavior of a high-speed train and long-span cable-stayed bridge system under seismic ground motions, with a focus on the correlation effects among ground motion components in diverse directions. The analysis incorporates track irregularities, rigid wheel–rail contact, and a coupled equation of motion solved using the time integration method. Results reveal that correlated ground motions significantly influence the system’s stochastic responses, including estimated maximum accelerations of bridge spans and towers, wheel–rail contact forces, and offload factors. These findings underscore the importance of accounting for correlation effects in seismic assessments to ensure the safety and reliability of high-speed train operations on bridges during earthquakes.

The structural damage detection system comes under the vast field of structural health monitoring. This paper deals with the two-stage damage assessment approach, including identification and severity estimation of any damage present in the structure. Free vibrational analysis of the healthy and damaged state of the structure yields two important modal parameters: frequency and mode shape. Eigenvectors, which constitute the mode shape of the structure, are considered for evaluating a damage index by comparing the damaged state with the healthy state. A Normalized Damage Index (NDI)is estimated for the structure subjected to various damage case scenarios. The novel method of estimating NDI provides a unique pattern for each element in the structure. The variation of natural frequency with increasing damage percentage helps estimate damage severity. Support Vector Machine(SVM), with a statistical pattern recognition paradigm, is an efficient supervised Machine Learning (ML) algorithm capable of performing classification and regression analysis. The Kernel-based SVM algorithm effectively identifies damaged elements and estimates each element's severity. A four-storey, three-bay steel frame structure developed in the OpenSees framework is subjected to modal analysis. The results are validated with SAP and finite element-based ABAQUS software. The ability of the proposed model is also verified for a complex 3D structure. The viability of this model is also explored experimentally with a four-storeyed and single-bay steel frame structure. This approach provides an effective way of damage assessment.

The cold roll-forming process is a continuous technique used to shape metal strips into desired cross-sectional profiles without altering the sheet thickness, achieved by passing the strip through a series of rotating rollers. Multi-layer metal and composite sheets offer unique properties, combining high strength with corrosion resistance. This study focuses on numerically investigating the cold roll-forming of three-layer metal sheets and Al/ABS/Al composites. Utilizing ABAQUS finite element software, the research examines the influence of layer thickness ratios on key parameters such as springback, edge longitudinal strain, thickness variation in the bend area, and energy requirements. Findings indicate a significant increase in sheet thickness reduction with ABS core thickness below 2 mm. Decreasing Acrylonitrile Butadiene Styrene (ABS) core thickness at the forming stage reduces sheet stretching in the bending area, thereby mitigating thinning in that region.

Steel structures exposed to marine environments are vulnerable to corrosion, significantly deteriorating the structural capacity. Specifically, column base plates are crucial components in many steel structures, which are susceptible to corrosion-induced reduction in bending resistance. This study aims to evaluate the remaining bending resistance of steel column base plates considering the effects of metal corrosion. Three environmental conditions, which are rural, urban, and marine areas, were considered in the evaluation. Two proposed procedures were employed, in which the deterministic and random approaches were considered. The deterministic approach used the component method in EN 1993-1-8 to design the bending resistance of corroded steel column base plates. Meanwhile, the corroded steel structure’s reliability was evaluated using the hybrid Artificial Neural Network-Monte Carlo Simulation (ANN-MCS) method. The reliability of the steel column base plate up to 100-year life-service was evaluated. Moreover, Sobol’s indices were employed to calculate the sensitivity of the input variables. The results revealed that the structural capacity of the steel base plate was reduced by approximately 50% after 100 years in a strongly corrosive environment. The probability of safety of the steel base plate decreased significantly from the rural and urban areas to marine environments.

Stabilizing effects of deviators on flexural and lateral-torsional buckling behaviors of pre-stressed simply-supported/cantilever beams due to initial tension are re-examined using an analytical approach. A flexural and lateral-torsional buckling formulation of mono-symmetric steel beams with discrete deviators at irregular intervals pre-stressed by a rectilinear cable is presented based on total potential energy. Also, some interesting properties on spatial buckling loads and their mode shapes of the pre-stressed beams such as determination of effective buckling length and laterally un-supported length, buckling loads of pre-stressed simply-supported/cantilever beams and difference of two buckling mode shapes by a rigid body rotation, are addressed in a general form and rigorously proved through mathematical process.

Modular floating islands are a promising option for ocean space utilization, offering affordability and sustainability. In this study, the motion response and connector load of a modular floating island in waves were numerically investigated based on potential flow theory. Numerical analysis was performed by adopting a Higher-order Boundary Element Method with the wave Green function. First, the motion response and connector loads of floating islands with different number of outer-module layers were studied. It was found that the single-layer island shows a significant advantage in terms of motion response and has a wider peak frequency range of the vertical load compared to the double-layers island. In addition, it was numerically confirmed that substantial horizontal connector loads can be induced by the horizontal motion responses associated with several dominant Eigen-modes of the floating island. Then, the effect of connector stiffness on the connector loads of the floating islands was also investigated. It was confirmed that the horizontal and vertical connector loads within the floating island can be reduced by adjusting the connector stiffness.

Non-irradiated and proton-irradiated stainless steel (SS) 304L samples were subjected to corrosion tests in various concentrations of Cl⁻ ions at room temperature. The electrochemical impedance spectroscopy techniques were used to investigate the corrosion behavior, and X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the phase composition and surface morphology. After irradiation, the open circuit potential (OCP) of SS 304L shifted from the passive state to the active dissolution state. It caused the shift of the anodic current peak towards the lower potential, demonstrating the reactivity of the surface and it may increase the corrosion process. The lower semi-circle of impedance for the irradiated SS 304L confirms the localized corrosion process and breakdown of passive films, it enhanced the localized corrosion as indicated by SEM. XRD peak shows a slight shift in the negative direction and formation of Fe₃O₄, for irradiated SS 304L samples. The surface morphology of the irradiated sample consisted of tiny pieces of corrosion product in the surroundings of pits. In contrast, the number and size of pits increased with the concentration of Cl⁻ ions in the solutions. Higher Cl⁻ ions are aggressive towards pitting corrosion for the non-irradiated SS 304L, however, irradiation accelerated the pitting initiation process for SS 304L.