Structural Steel Plates Research Articles

Fracture Prediction of Steel-Plated Structures under Low-Velocity Impact

In this paper, a validation study of a recently proposed rate-dependent shell element fracture model using quasi-static and dynamic impact tests on square hollow sections (SHS) made from offshore high-tensile strength steel was presented. A rate-dependent forming limit curve was used to predict the membrane loading-dominated failure, while a rate-dependent ductile fracture locus was applied for predicting failure governed by bend loading. The predicted peak force and fracture initiation using the adopted material and fracture model agreed well with the experimental results. The fracture mode was also captured accurately. Further simulations were performed to discuss the importance of the inclusion of dynamic effects and the separate treatment of failure modes. Finally, the shortcomings of the common practice of treatment of rate-effects in low-velocity impact simulations involving fracture were highlighted.

Local electropulse-induced gradient and hierarchical architecture of soft-hard phase in 35CrMo steel

To improve the comprehensive mechanical properties while avoiding the overall heat treatment, this study provided a method to prepare structural steel with soft-hard phases arranged in complex gradient, hierarchical structures via processing a homogenous material using local electropulsing treatment (LEPT). The results show that ultimate tensile strength, elongation-to-failure, and curves area of the structural steel plate are about 1400 MPa, 15.93%, and 19,100 MPa·%, respectively, which are 16.5%, 34.7%, and 47.5% higher than the conventional quenched and tempered steel. The excellent mechanical properties of LEPTed specimens are mainly due to the local strengthening caused by the effects of pulse current, and the synergistic effect of hard and soft phases. The designed hardened units produced by LEPT exhibit hierarchical structure and gradient variations in texture and grain size. There also exists gradient hardness distribution in hardened units. These structures are produced due to the multi-scale effects of current and the gradient current density distribution. Moreover, due to the introduction of hardened units at another scale, there were four stages in the strain-hardening behavior of LEPT based on differential Crussard-Jaoul (DC-J) analysis, which deviates from the three stages of two-phase or multi-phase steels.

Prediction of Angular Distortion in Gas Metal Arc Welding of Structural Steel Plates Using Artificial Neural Networks

The manufacturing of structures ranging from bridges and machinery to all types of seaborne vehicles to nuclear reactors and space rockets has made considerable use of arc welding technologies. This is as a result of benefits including increased joint efficiency, air and water tightness, no thickness restriction (0.6 to 25 mm), decreased fabrication time and cost, etc. when compared to alternative fabrication methods. Gas metal arc welding (GMAW) is a frequently used welding technology in industries due to its inherent benefits, including deeper penetration, a smooth bead, etc. Local heating and cooling that takes place during the multi-pass welding process causes complicated stresses to develop at the weld zone, which ultimately causes angular distortion in the weldment. Angular distortion is a major flaw that affects the weld’s properties as well as the cracking and misalignment of the welded joints. The issue of angular distortion can be successfully solved by predicting it in relation to certain GMAW process variables. A neural network model was created in this research to predict angular distortion. A fractional factorial approach with 125 runs was used to conduct the exploratory experiments. A neural network model with feed forward and backward propagation was developed using the experimental data. To train the neural network model, the Levenberg–Marquardt method was utilised. The results indicate that the model based on network 4-9-3 is more effective in forecasting angular distortion with time gaps between two, three, and four passes than the other three networks (4-2-3, 4-4-3, 797 and 4-8-3). Prediction accuracy is more than 95 percent. The neural network model developed in this study can be used to manage the welding cycle in structural steel weld plates to achieve the best possible weld quality with the least amount of angular distortion.

Temperature Compensation for Reusable Piezo Configuration for Condition Monitoring of Metallic Structures: EMI Approach.

This paper presents a novel algorithm for compensating the changes in conductance signatures of a piezo sensor due to the temperature variation employed in condition monitoring using the electro-mechanical impedance (EMI) approach. It is crucial to consider the changes in an EMI signature due to temperature before using it for comparison with the baseline signature. The shifts in the signature due to temperature can be misinterpreted as damages to the structure, which might also result in a false alarm. In the present study, the compensation values are calculated based on experiments on piezo sensors both in a free boundary condition and in a bonded condition on a metallic host structure. The values were further validated experimentally for damage detection on a large 2D steel plate structure. The variation in first natural frequency values for the unbonded piezo sensor at different temperatures has been used to develop the compensation algorithms. Whereas, in the case of the bonded sensor, the shift in structural peaks has been used. The developed compensation relations showed promising results in damage detection. Lastly, a finite element-based study has also been performed, supporting the experimental findings. The outcome of this study will aid in the compensation of the signatures in the structure due to temperature variation in the conductance signature.

Cracking failure analysis on a high-frequency electric resistance welding pipe in buried fire water pipeline

Leakage of a buried fire water pipeline occurred after in service of 15 years. It was manufactured from a Q235B carbon structural steel plate by high-frequency electric resistance welding. The water pressure increased from 0.8 MPa at a normal operating condition to 1.2 MPa at the tube burst moment. Cracks propagate along the weld and incomplete fusion defects are observed. This paper aims to explore the cracking failure through a combination method of experimental tests and theoretical analysis. The metallographic analysis clearly shows that the crack is located in the fusion zone and grains are coarse in that zone. Mechanical property tests indicate tensile properties of the anti-corrosion layer meet requirements. Finite element analysis reveals that the pipeline with an incomplete fusion can safely operate under a pressure of 0.8 MPa, while fracture occurs under the pressure of 1.2 ∼ 1.3 MPa. The results indicated that the deep unfused defect of the welded joint was the root cause of cracking, and selective seam weld corrosion also played an important role. The failure progress and mechanism were discussed in details.

The Effect of Using Different Cross-Sectional Shapes of Steel on the Flexural Performance of Composite Reinforced Concrete Beams

Various types of structures can be constructed using reinforced concrete, including slabs, walls, beams, columns, foundations, frames, and more. The incorporation of structural steel and reinforcements in concrete enhances the strength and durability of structural elements while compensating for the tensile weaknesses in the concrete material. This study aimed to investigate the behavior of reinforced concrete beams utilizing structural steel of different shapes. Four types of concrete beams were prepared: a standard beam with normal reinforcement, and three composite beams, each featuring structural steel with different sectional shapes – T-section, I-section, and channel section. The consistent parameters included the cross-sectional area of the specimens, each measuring 100x150x450 mm, a steel reinforcement percentage of 2% of the total volume, and the compressive strength of the concrete. The conducted tests involved applying a concentrated load at the mid-span of each beam to examine the specimens’ behavior in terms of strength, flexural load capacity, deflection, crack patterns, and failure mode. The results of this study reveal that, given the same steel ratio, the load capacity of beams reinforced with structural steel of a channel shape has surpassed that of the other beams. Additionally, specimens with structural steel plates exhibited higher maximum deflections before failure compared to the beams with conventional reinforcement.

Fillet welding of skewed reinforcing steel to steel plate

Connecting or anchoring reinforcing steel to structural steel plate or shapes using fillet welds is a common detail in precast concrete construction. However, there is currently no guidance on the effects of skewing the reinforcing bar with respect to the plate. This paper reports findings from a study of the effects of a skewed reinforcing bar on both the effective weld area and the overall connection strength. Thirty-two samples of reinforcing bars welded to steel plates at various skew angles were fabricated and tested in tension to failure. These results were compared with an analysis based on the instantaneous center of rotation method presented in the American Welding Society’s Structural Welding Code—Steel (AWS D1.1-20). Recommendations are presented to revise the Structural Welding Code—Reinforcing Bars (AWS D1.4) to account for the effect of skewed reinforcing bars welded to structural steel plate or shapes.

Treatment of severe medial tibial bone defect in primary total knee arthroplasty with autogenous bone graft and plate fixation

To explore the technique of autogenous bone graft combined with plate fixation in total knee arthroplasty(TKA) with severe proximal medial tibial bone defect. From March 2012 to October 2018, 21 patients (9 males and 12 females) with severe bone defects in the proximal medial tibia during primary total knee arthroplasty were treated with autogenous structural bone grafting and steel plate fixation, with an age of 61 to 77 years old with an average of (69.6±9.1) years and a course of 64 to 257 months with an average of (73.6±170.7) months. According to Rand classification, there were 13 cases of type Ⅲb and 8 cases of type Ⅳb. Postoperative complications were observed, and knee joint function was evaluated by the Hospital for Special Surgery (HSS) score and SF-36 quality of life score. All 21 patients were followed up for 37 to 64 months with an average of (49.5±13.7) months. The incisions of all patients healed smoothly, and 2 patients developed lower limb intermuscular venous plexus thrombosis after operation. There were no periprosthetic infection, loosening of prosthesis and other complications. The autogenous bone grafts of all patients achieved bony healing during postoperative X-ray follow-up, and the healing time was 8 to 13 months with an average of (10.1±2.3) months. The HSS score of patients increased significantly from 30 to 48 with an average of (53.4±4.2) before operation to 75 to 92 with an average of (81.2±8.4) at the final follow-up (P<0.05). The SF-36 quality of life score of patients after operation was significantly different from that before operation (P<0.05). The technique of autogenous bone graft combined with steel plate fixation can achieve satisfactory osseointegration effect in the treatment of severe proximal tibial bone defects in primary knee arthroplasty, with less complications and obvious improvement in knee function.

Experimental Research on a Hybrid Algorithm for Localisation and Reconstruction of the Impact Force Applied to a Rectangular Steel Plate Structure.

Impact force is the most common form of load which acts on engineering structures and presents a great hidden risk to the healthy operation of machinery. Therefore, the identification or monitoring of impact forces is a significant issue in structural health monitoring. The conventional optimisation scheme based on inversion techniques requires a significant amount of time to identify random impact forces (impact force localisation and time history reconstruction) and is not suitable for engineering applications. Recently, a pattern recognition method combined with the similarity metric, PRMCSM, has been proposed, which exhibits rapidity in practical engineering applications. This study proposes a novel scheme for identifying unknown random impact forces which hybridises two existing methods and combines the advantages of both. The experimental results indicate that the localisation accuracy of the proposed algorithm (100%) is higher than that of PRMCSM (92%), and the calculation time of the hybrid algorithm (179 s) for 25 validation cases is approximately one nineteenth of the traditional optimisation strategy (3446 s).

Bearing performance of high-strength bolted corrugated steel longitudinal seams

The assembly-type corrugated pipes have been widely used in underground pipeline construction owing to their rapid construction speed and strong adaptability to deformation. However, research with respect to the bearing performance and design methods of their longitudinal seams is lacking. In this study, axial compression tests were conducted on a single high-strength bolted seam of longitudinal seams of galvanised middle-wave corrugated steel plate structures to investigate the damage characteristics and bearing performance of the seams in different failure modes. A finite element analysis was also conducted to verify the test results and perform parametric analysis. The results showed that, to realise the maximum seam strength, the plate thickness should be matched to the bolt diameter. The torque coefficient hardly affects the ultimate bearing performance of the longitudinal seam, and the ultimate bearing capacity of the plate bearing failure seam is significantly influenced by the slip resistance coefficient. With the increase in waveform, the bearing capacity of seams increased by approximately 8.8% and 17.1% for the bearing failure of the plate, while it increased only slightly for bolt shear failure mode. Finally, several codes of bearing capacity calculation methods were compared with the test and simulation results. The revised Eurocode BS EN 1993-1-8:2005 accurately reflects the true bearing performance of corrugated steel plates with high-strength bolted connections. This study provides relevant reference data and design recommendations for seams that are easily overlooked in the design of assembly-type corrugated pipe projects.

Investigation on the influence mechanism of polyurea material property on the blast resistance of polyurea-steel composite plate

The application of polyurea in the field of anti-blast has attracted extensive attention. To study the influence and mechanism of polyurea with different mechanical properties on the blast resistance of steel plate structure, two types of polyurea with different mechanical properties (high hardness and ductility) were selected and coated on a carbon steel plate. The mechanical properties of two types of polyurea under quasi-static and dynamic conditions were quantitatively compared. A series of field tests of composite plates subjected to blast load were conducted. The macro damage characteristics of targets with different configurations were obtained. Combined with metallographic microscopy and scanning electron microscopy, the micro failure characteristics of the steel plate and polyurea were confirmed. The energy absorption mechanism of different types of polyurea was revealed by Fourier transform infrared. The results show that high hardness polyurea can only slightly improve the blast resistance of the steel plate when it was coated on the front. Coating polyurea on the back face of the steel plate had the best effect on improving the blast resistance, but it would produce backward flying fragments, which may lead to secondary injury. The high ductility polyurea can effectively improve the blast resistance of the steel plate without fragments, no matter coated on the front or back. The response process of polyurea with high hardness was transient. While the response process of polyurea with high ductility was relatively continuous. From the perspective of chemical bonds, the energy absorption mechanisms of different types of polyurea were also different. Finally, the mechanisms of various effects of polyurea with different mechanical property on the blast resistance of steel plate were discussed using the propagation law of stress wave. This study can provide a reference for the application of polyurea spraying technology under the anti-blast protection of metal structure.

3D vision‐based out‐of‐plane displacement quantification for steel plate structures using structure‐from‐motion, deep learning, and point‐cloud processing

AbstractIn this paper, a novel accurate and economical 3D computer vision‐based framework is proposed to quantify out‐of‐plane displacements of steel plate structures. First, a sequence of image frames of the steel plate structures of interest is collected. Second, using image association, structure‐from‐motion, and multi‐view stereo algorithms, a 3D point cloud of the steel plate structures and their surroundings is created. Third, an efficient 3D object detection method based on convolutional neural networks is developed and implemented to identify the steel plate structures in the 3D point cloud. Last, the out‐of‐plane displacements of the steel plate structures are quantified using point cloud postprocessing algorithms. The proposed framework has been implemented on a steel plate damper and a full‐scale steel corrugated plate wall panel, which are commonly used in structural and earthquake engineering applications. The results indicate the developed framework can successfully localize the steel plate components in the 3D scene and accurately quantify the out‐of‐plane structural displacements with an average accuracy of ∼1 mm. The implementation shows the proposed framework can accurately and efficiently quantify the out‐of‐plane displacements of steel plate structures in realistic engineering applications.

Mechanical Performance Test and Numerical Simulation Analysis of Building Steel Plate and Concrete Composite Structure.

The study aims to continuously improve the level of the construction industry, such as the improvement of construction capacity and efficiency and reduction of the project cost and construction period, and find a specific way to improve the development of the construction industry. First, the study analyzes the research status of mechanical properties of horizontal joints, vertical joints, and the overall structure of worldwide prefabricated buildings. Next, the built-in steel fabricated concrete shear wall model is established. Moreover, the quasi-static experimental analysis is conducted on the joints of the fabricated shear wall with built-in section steel. The finite element software is used to analyze the numerical simulation test of the new built-in shear wall. According to the relevant test parameters, the finite element model is constructed, and the parameters are set. Finally, the shear wall model is established and tested by a simulation experiment, and the simulation results are compared with the numerical simulation results. The final results show that the proposed connection mode of the reinforced skeleton and new fabricated joints improves the stability of prefabricated buildings. The use of the quasi-static test to test the relevant performance parameters has a short calculation time, high efficiency, and high parameter optimization accuracy. It can better simulate the actual working conditions and the actual stress-strain and damage failure conditions. Moreover, the conclusion is drawn that the shear wall structure with steel plate concrete has good ductility and deformation capacity. The study has a certain reference significance for the construction optimization of steel plate concrete prefabricated buildings and related research in the future.

Effect of Residual Stress on Hydrogen Diffusion in Thick Butt-Welded High-Strength Steel Plates

Thick high-strength steel plates are increasingly being used for ship structures. Moreover, hydrogen enters the process of manufacturing and service, and large residual tensile stress occurs near the weld. Such stress can facilitate the diffusion and accumulation of hydrogen in the material, leading to hydrogen embrittlement fracture of the shell. Therefore, residual-stress-induced diffusion and accumulation of hydrogen in the stress concentration region of thick butt-welded high-strength steel plate structures need to be studied. In this study, manual metal arc welding was realized by numerical simulation of residual stress in a thick butt-welded high-strength steel plate model using the thermoelastic–plastic theory and a double ellipsoidal heat source model. To analyze residual stress, a set of numerical simulation methods was obtained through comparative analysis of the test results of relevant literature. Residual and hydrostatic stress distributions were determined based on these methods. Then, hydrogen diffusion parameters in each region of the model were obtained through experimental tests. Finally, the results of the residual stress field were used as the predefined field of hydrogen diffusion to conduct a numerical simulation analysis. The distribution of hydrogen diffusion under the influence of residual stress was obtained based on the theory of stress-induced hydrogen diffusion. The weak area of the welding joint was found to be near the weld toe, which exhibited high hydrostatic stress and hydrogen concentration. Further, the maximum hydrogen concentration value of the vertical weld path was approximately 6.1 ppm, and the maximum value of the path parallel to the weld centerline and 31 mm away from the weld centerline was approximately 6.22 ppm. Finally, the hydrostatic tensile stress in the vertical weld path was maximized (~345 MPa), degrading the material properties and causing hydrogen-related cracking. Hence, a reliable method for the analysis of hydrogen diffusion according to residual stress in thick high-strength steel plates was obtained. This work could provide a research basis for controlling and eliminating the adverse effects of hydrogen on the mechanical properties of ship structures and ensuring the safe service of marine equipment.

Stochastic Evaluation of Structural Steel Plates Corrosion in Offshore Platforms

This study presents the structural reliability of steel plates on offshore platforms exposed to corrosion during their design period and beyond. The reliability-based design of steel plates exposed to corrosion was carried out with First Order Reliability Method coded in a computer based program, (FORM 5) and a Finite element method in a software (ABAQUS). The rate of corrosion of the steel plates was determined using a standard expression for extreme marine environment. From the results obtained using FORM 5, the safety indices ranged from 1.18 to 11.0, and a non-linear relationship exist between safety indices and thickness for different parameter variations. However, it was also noted that the design formulation is robust enough to exceed the design life prediction in the code by about 20% of the current prediction.

Investigation on air blast resistance of POZD-coated composite steel plates: Experiment and numerical analysis

This study aimed to evaluate the anti-blast performance of polyisocyanate-oxazolone (POZD) coated composite steel plates. First, experiments were conducted on monolithic steel plates and POZD-coated steel plates under close-range air blast loading to determine the damage deformation and failure modes of the steel plates under different POZD coating methods. Secondly, numerical simulations were performed to analyze the damage evolution and energy absorption characteristics of different structural POZD-coated composite steel plates. Finally, parametric analyses were performed to evaluate the anti-blast performance of POZD-coated composite steel plates with different coating methods and to explore the relationship between different thickness POZD coatings and different charges and the overall anti-blast performance. It was found that regardless of the explosive load strength and the POZD coating methods, the steel plate layer played the main role in energy absorption in the POZD-coated composite steel plates. Under the same POZD thickness, the anti-blast performance of the steel plates with POZD coating at the back face was the best, and as the thickness of the POZD increased, the anti-blast performance of the structure was also improved. An empirical expression on the dimensionless deflection was obtained which considered both the thickness of the POZD coating and the scaled distance.

Effect of austenitic stainless steel weld clad layers on conduction heat transfer across the walls of pressure vessels

Cladding austenitic stainless steels are popular nowadays in pressure vessels to enhance surface qualities. In this work, austenitic stainless-steel clad layers deposited by flux cored arc welding process on structural steel plates used in boiler construction are investigated in the direction of heat energy conservation. This study is vital, as the low thermal conductivity of austenitic stainless-steel clad layer is capable of reducing heat transfer across walls of pressure vessels. Heat transfer studies were performed using theoretical approach, computational simulations and experimental approach. Results of these studies exhibit a heat conservation of 10.6% owing to the stainless-steel clad layers with optimum clad thickness. The results of theoretical and computational method are having good agreement with the experimental results. These dual-benefit findings of the present work could be supportive to impart corrosion resistance and energy conservation, thereby, in energy efficient design of the thermal equipment.

Influence of Air Gap Size to Mechanical Properties of Laser Welded Lap Joints

The paper is focused on the effects of air gap size to mechanical properties of laser welded lap joints. Structural steel plates of 3 mm thickness were used in the laser welding experiments. The laser welding experiments were conducted at two very different energy inputs (EI) of 60 and 320 J/mm. The weld geometries were investigated using optical microscopy. The shear strength of the lap joints was evaluated by uniaxial tensile tests. Results showed that with low EI of 60 J/mm the size of air gap had significant effect on the width of the interface as the larger air gap size increased the width of the interface. At high EI of 320 J/mm, the width of the weld at the interface did not change significantly as the air gap increased. The hardness of the weld metal was greater than the hardness of the base material at both EIs. The shear strength of the joint increased significantly with low EI of 60 J/mm, as air gap size increased. The size of the air gap did not have a large effect on the shear strength of the joint with higher EI of 320 J/mm.

Analysis of fire-induced progressive collapse for topside structures of a VLCC-class ship-shaped offshore installation

ABSTRACT This study extends the authors’ previous numerical and experimental studies simulating the progressive collapse of steel stiffened-plate structures in fire events (Paik JK, Ryu MG, He KH, Lee DH, Lee SY, Park DK, Thomas G. 2021a. Full-scale fire testing to collapse of steel stiffened plate structures under lateral patch loading (part 1) – without passive fire protection. Ships Offsh Struct. 16(3):227–242; Paik JK, Ryu MG, He KH, Lee DH, Lee SY, Park DK, Thomas G. 2021b. Full-scale fire testing to collapse of steel stiffened plate structures under lateral patch loading (part 2) – with passive fire protection. Ships Offsh Struct. 16(3):243–254; Ryu MG, He KH, Lee DH, Park SI, Thomas G, Paik JK. 2021. Finite element modeling for the progressive collapse analysis of steel stiffened-plate structures in fires. Thin-Walled Struct. 159:107262). Specifically, this study demonstrates that the computational models developed in the earlier studies can be applied to the analysis of the heat transfer and fire-induced progressive collapse behaviour of the topside structures of a ship-shaped offshore installation. To this end, a hypothetical VLCC-class floating, production, storage and offloading (FPSO) unit hull structure is considered, and transient thermal elastic-plastic large-deformation finite element models are used. The novelty of this study and its contribution to industry are the development of a practical procedure to ensure the fire safety of large-scale steel-plated structures with complex geometries.

Hybrid laser-arc welding of laser- and plasma-cut 20-mm-thick structural steels

It is already known that the laser beam welding (LBW) or hybrid laser-arc welding (HLAW) processes are sensitive to manufacturing tolerances such as gaps and misalignment of the edges, especially at welding of thick-walled steels due to its narrow beam diameter. Therefore, the joining parts preferably have to be milled. The study deals with the influence of the edge quality, the gap and the misalignment of edges on the weld seam quality of hybrid laser-arc welded 20-mm-thick structural steel plates which were prepared by laser and plasma cutting. Single-pass welds were conducted in butt joint configuration. An AC magnet was used as a contactless backing. It was positioned under the workpiece during the welding process to prevent sagging. The profile of the edges and the gap between the workpieces were measured before welding by a profile scanner or a digital camera, respectively. With a laser beam power of just 13.7 kW, the single-pass welds could be performed. A gap bridgeability up to 1 mm at laser-cut and 2 mm at plasma-cut samples could be reached respectively. Furthermore, a misalignment of the edges up to 2 mm could be welded in a single pass. The new findings may eliminate the need for cost and time-consuming preparation of the edges.