Thick Steel Plates Research Articles

Microstructure and Hardness Properties of Hardfacing Overlays Deposited by Shielded Metal Arc Welding on Low Carbon Steel Plate

The aim of this study is to investigate the effect of applying various welding current parameters of shielded metal arc welding (SMAW) on microstructure and the hardness of the hardfacing overlays. The investigation was performed on a 12mm thick ASTM A36 steel plate weld overlaid by hardfacing electrode HV-450 of 3.2 mm diameter at various welding currents, 90, 110, and 130 amperes, respectively. The investigation was conducted by using optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and hardness test on the hardfacing overlay. The results showed the hardness of the hardfacing overlay is higher than the base metal, indicating higher strength of the weld overlay. From the three welding currents applied, the highest hardness in the weld overlay is obtained at the lowest current.

Response of axial-loaded steel-concrete composite walls under low-velocity impact

Steel-concrete (SC) composite walls consisting of two external steel plates and sandwiched concrete core have been employed in various engineering structures such as nuclear facilities, protective structures and high-rise buildings. Impact resistance performance is an important aspect for designing this type of structures. This paper experimentally and numerically studies the low-velocity impact response of axial-loaded SC composite walls. A total of six SC composite walls were fabricated and tested by using drop hammer to obtain damage mode, impact force and mid-span deformation. Effects of impact height (impact energy), steel plate thickness, shear connector type and axial-load ratio were analyzed. The specimens experienced severe local indentation at the impact location. As the axial-load level increased from 0 to 0.2, the indentation area, concrete cracking and global deformation was reduced, indicating the axial-load could effectively enhance the impact-resistant capacity of the SC walls. Additionally, finite element (FE) models were developed and validated using test data. The verified numerical models were then employed to analyze the impact process and energy dissipation mechanism as well as the influences of key parameters on the dynamic responses. After that, a simplified formula was suggested to estimate the maximum mid-span deformation of SC composite walls under impact loading.

Seismic performance of precast column-beam joint with artificial plastic hinge

To improve the seismic performance and repairability of precast structures, an artificial plastic hinge (APH) was proposed for precast beam-column joint. The proposed APH was made from a combination of steel and high-strength-concrete (HSC), and the AHP will dissipates energy through metal plastic deformation when the earthquake occurs. To carry out the research, three full-scale beam-column joints were designed and fabricated, including one cast-in-place joint and two precast joints with APH. By using hysteretic loads, the seismic performance of joint was examined. For more systematic research, the finite element models were established and verified, and the parameter analysis was carried out. The findings demonstrate that the proposed joint performs well in terms of ductility and energy dissipation. It is recommended to use 12 mm steel plate thickness in the actual design, and to ensure the number of connecting bolts to avoid connection damage under earthquake. Through design optimization, the damage to the APH will be revealed at the location of the replaceable steel components, so as to achieve rapid repair after the earthquake.

The evaluation on performance of narrow- gap welding thick steel plates under the influence of main welding parameters

This work presents the experimental results of narrow gap butt welding of steel plates with large thickness by using the Metal Active Gas (MAG) welding method.The typical defects are accompanied with this process such as the infusion in the side wall and the porosity due to the narrow gap which affect on the melting process. Thus, some publications noted the results of welding for the thickness up to 20−30 mm and the chamfer angle about 30° using GMAW/MIG, GTAW/TIG, SMAW and new development such as laser – arc hybrid, laser multi- pass technique, super -TIG welding etc. But the production requires the solution to save the costs by the reduction of time, labour and investment keeping the standard quality. That is the aim of this study. In order to improve the quality of weld joint and increase the productivity of the process, is it suggested to develop the innovative welding process, in which the welding voltage – Uw, the translational velocity of the tip – Vt, and rotational velocity of the tip – Vr, are changing. This helped to increase the thickness of steel plates up to 50 mm and the chamfer angle decreased at 15°, providing the satisfied quality of the weld. The micrography study serve as the preliminary proof of this hypothesis.
 The microstructures in 4 regions, such as the weld center zone, heat-affected zone (HAZ), parent metal region, and the boundary between the weld metal and the HAZ were examined. The microstructures of 13 positions from different experiments are investigated using the optical microscope (Axiovert 25).These experiments covered all specific points (node) locating accordingly to three layers from bottom to top of the weld joint . The findings proved the welding quality is similar in case of narrow gap but the chamfer angle is twice lower and the thickness is increased. The result of the study enhances the productivity due to saving the labour cost and the welding materials. It is recommended to consider the effect of other factors (such as cooling conditions, dwell time when the arc approaching the side walls) to optimize the weld quality. There is the huge volume of the heavy steel constructions with the thick steel construction and specific narrow gap in industry. The results of this study with the optimization and more deeper evaluation the influence of main parameters of welding process to eliminate the typical defects will be the valuable reco mmendation for the managers and engineers in the production of metallic constructions

Multiscale homogenization numerical study on the mechanism of interface debonding detection for steel–concrete composite structures with multichannel surface wave measurements

In order to understand the interface debonding detection mechanism for steel–concrete composite structures (SCCSs) efficiently using multichannel analysis of surface waves (MASW) when the heterogeneity and randomness of the mesoscale structure of concrete are considered, mesoscale homogenization numerical analysis on surface wave propagation in SCCSs is carried out. Firstly, for exploring the theoretical dispersion characteristics of surface waves in SCCSs, dispersion curves of both Lamb wave and Rayleigh wave of three different layering scenarios, including single-layer, two-layer, and three-layer composite models where concrete is treated as homogeneous material, are investigated. Meanwhile, the effect of the steel plate thickness on the dispersion curves is studied. Secondly, to evaluate the effect of mesoscale structure variation of concrete in SCCSs on surface waves, a random aggregate method (RAM) is employed to establish the mesoscale model of concrete composed of randomly distributed aggregates with different shapes. Thirdly, for enhancing numerical simulation efficiency on surface wave propagation, an equivalent homogenization approach and Voigt parallel model are developed to establish the mesoscale homogenization models of SCCSs. Dispersion curves from forwarding analysis on surface wave measurement of the mesoscale models are compared with the corresponding theoretical dispersion curves to reveal surface wave attribution and optimum layering scenarios of SCCSs for MASW method. The influence of mesoscale concrete variation on surface wave fields in SCCSs using equivalent homogenization models is investigated comprehensively and compared with that of the corresponding mesoscale models. Finally, the feasibility of the proposed MASW method for interface debonding length estimation is validated, and wavelength selection criteria of excitation signals considering interface dimension, as well as steel plate thickness, are discussed. The results from the mesoscale homogenization numerical study can provide helpful guidance on the practical application of MASW-based debonding detection for SCCSs where concrete is heterogeneous.

Calibration-free SH guided wave analysis for screening of wall thickness in steel with varying properties

Guided shear horizontal (SH) ultrasonic wavemodes show promise for fast screening of wall thinning and other defects, with miniaturised electromagnetic acoustic transducers (EMATs) offering the potential for automated robotic inspection. However, the use of guided waves for full defect characterisation is strongly affected by mode conversions, changes in lift-off from the sample, variations in material properties and other effects, and these are not typically considered when reporting laboratory results. We show that these factors can have a significant effect on the data as one moves towards industrial implementation, but that a combination of different analysis methods on the SH0 and SH1 wavemodes can offer a high reliability of detection, and mitigate some of the issues with changes in experimental conditions and mode conversions. For inspection of 10 mm thick steel plates, the proposed processing of the signals is shown to reliably detect 40 mm diameter flat bottomed holes with 5%–50% wall loss. A rough, approximately 20 × 20 mm square defect with up to 20% wall loss is also detected.

Experimental and analytical study on the double steel plates-UHPC sandwich slabs under low-velocity impact

The upgrading of protective structures can be realized through the application of new materials or the innovation of structural forms. A novel double steel plates–concrete (DSC) sandwich structure constructed with an ultra-high-performance concrete (UHPC) core forming a DSUHPC sandwich structure could be applied in Arctic offshore platforms as protective layers. This structure can withstand dynamic pressure derived from impacting ice sheets and vehicles in serve cold regions. This paper presents the dynamic behavior of these DSUHPC sandwich slabs subjected to drop-weight impact load. The superiority of protective performance of DSUHPC sandwich structure was revealed in contrast with the perforation failure mode of reinforced concrete (RC) slabs subjected to the same impact energy. Moreover, the brittleness of concrete material under dynamic load was alleviated by adding steel fibers compared with double steel plates–normal strength concrete (DSNC) sandwich slabs, showing effectiveness in the improvement of material utilization and energy dissipation. Further, the diverse dynamic response of DSUHPC sandwich slabs with different steel plate thicknesses and under different impact velocities was also studied. Finally, a two-degree-of-freedom model was established to predict the time–history curves of impact force and displacement. The acceptable accuracy of the proposed analytical model was demonstrated.

Compressive performance of an innovative tall pier with composite box section

To improve the seismic performance of tall-pier bridges, an innovative tall pier with a composite box section, composed of four-limb concrete-filled steel tube (CFST) columns and low-yield-strength (LYS) steel plates, was proposed based on the principle of capacity design and the replaceable fuse concept. Both axial and eccentric compression tests were conducted on a series of specimens to study the compressive performance of the composite tall pier. Parametric analysis was performed to investigate the effects of load eccentricity, slenderness ratio, thickness, and yield strength of the LYS steel plates on the compressive capacity using validated finite element (FE) models. The main results indicate that the composite tall pier fails with global bending deformation and elastoplastic instability under axial or eccentric compression. The compressive capacity and initial stiffness of the composite tall pier decrease significantly with an increase in eccentricity or slenderness ratio, and the influences of eccentricity and slenderness ratio are essentially independent. Additionally, the increase in the thickness of the steel plates enhanced the flexural stiffness and compressive capacity, and reduced the uneven loading distribution for the pier. Under axial compression, the pier can be simplified as a CFST lattice column connected by steel beams and LYS steel plates. Finally, practical formulas for the compressive capacity are proposed considering the connection and restraint effects of the LYS steel plates on the CFST columns, which can be used to predict the compressive capacity of the novel composite tall pier.

Influence of steel plates on the compressive strength and pore structure of concrete

To accurately predict the strength of concrete in a combined structure, this paper analyzed the effect of steel plates on the pore structure and strength of concrete. Two concrete strengths and eight steel plate thicknesses were used for the experimental specimens, and their pore structures and strengths were tested at 3, 7, and 28 days. It was found that the pore structure of concrete increased with the increase in steel plate thickness. Additionally, the strength of concrete decreased with the increase in steel plate thickness. Besides, an equation was proposed to predict the strength of concrete in specimens with steel plates in this research.

Experimental Research of Welding Residual Stress of Butt Welded Joint of Thick Steel Plate

The thickness of steel plates used in the structure has gradually increased to meet the load-bearing capacity requirements of long-span steel bridges. Thick steel plate welded by arc welding process will result in considerable welding residual stress with complex distribution. Large welding residual stress will significantly impact the performance of steel bridges. At present; residual welding stress of thick steel plates is not considered enough in bridge engineering; which could lead to potential dangers in safety. In this paper; a butt welded joint with a thickness of 80 mm was designed; the residual welding stress was measured by X-ray diffraction method; and the distribution of residual stress in the direction perpendicular to the weld seam and along the direction of the weld seam is analyzed; and the distribution pattern of welding residual stress in thick steel plate is systematically studied. It is found that in the area near the weld; the stress in the direction along the weld seam is more significant than that in the perpendicular direction; the peak stress in the direction perpendicular to the weld seam usually appears in the weld seam and the heat-affected zone; and the maximum value tends to appear close to the last weld bead on the surface; on the path perpendicular to the weld seam; the stress in the direction perpendicular to the weld seam is distributed in a “Π” shape; the stress in the direction along the weld seam is distributed in an “M” shape; and the stresses in the direction along and perpendicular to the weld seam are symmetrically distributed; however the axis of symmetry may appear anywhere in and around the weld seam. The results could serve as a reference for welding residual stress analysis and guide optimization design of steel bridges made of thick steel plates.

Mechanical properties of fast-growing poplar glulam columns reinforced with steel plate

Fast-growing poplar with characteristics of fast growth, convenient processing, and strong adaptability is widely planted all over the world, but it is difficult to be directly used as structural timber due to its loose fibers and low strength. In order to enhance mechanical properties of fast-growing poplar, a new type of steel plate reinforced glulam fast-growing poplar is developed. Nine columns are tested including one fast-growing poplar column, two glued-laminated timber (glulam) columns and six steel plate reinforced glulam columns. The influencing factors include the steel plate thickness and eccentricity. Based on test results, axial stiffness, failure mode, load-displacement and load-strain relationships were investigated. Test results indicate that ultimate load and axial stiffness of steel plate reinforced glulam columns were respectively increased by 134.5–177.5% and 168.5–244.1% compared to fast-growing poplar column. With the increase of steel plate thickness and decrease of eccentricity, ultimate load increased by 10.9–18.3% and 27.2–92.3%, respectively. It was found that steel plate thickness and eccentricity have great impacts on bearing capacity of steel plate reinforced glulam columns. In addition, bearing capacity equation for steel plate reinforced glulam columns was established and test results coincide quite well with calculated results with difference of less than 5%.

INVESTIGATION ON CONCRETE FILLED SKINNED BEAMS

Steel-Concrete-Steel Sandwich (SCSS) beam is a relatively new and innovated form of construction consisting of a layer of concrete, sandwiched between two relatively thin plates of steel which are connected to the concrete by shear connectors. In this project we investigated the difference between conventional Beam strength & concrete filled skinned beams strength. These skinned beams consist 1.5mm thick Steel plate and 1m in length, welded with 4 nos of 8mm diameter bar using shear connector consists of 12mm dia bar placed at spacing of 150mm in two rows of longitudinal section. It is a composite sandwich concrete section. Key Words: 1.5mm Steel plate 1m, 4 nos of 8mm diameter, M25 concrete.

Effect of Mill Scale on Laser Cutting Quality of Various Thick Steel Plates

Laser cutting provides more precise and higher quality cuts than other thermal cutting processes, and is adaptable to automation requirements. On the other hand, laser cutting with oxygen assist gas of thick steel plates is a complex process in which various factors affect laser cutting quality compared to the thin plates. When laser cutting of the plate with mill scale is performed, the mill scale on the surface of plate generally plays a role in supporting stable laser cutting, although self-burning may also occur due to peeling of the mill scale. Therefore, this paper focuses on the mill scale and investigates the effects of the adhesion, thickness, and surface roughness of the mill scale on the laser cutting quality. As a result, it was found that the laser cutting quality is higher when the adhesion of the mill scale is high, the thickness of the mill scale is between 20 μm and 40 μm, and the surface roughness is small.

Structural Behavior of Short Thin-Walled Steel Columns Filled with High Strength Concrete Made of Recycled Aggregate

This paper introduces an experimental work to study the behavior of 12 recycled aggregate concrete-filled steel tubular (RACFST) short columns with high-strength concrete grade subjected to axial compression loading. These columns formed from six different cross-sections involving triangle, elliptical, and hexagon, whereas the other three sections included traditional forms for control purposes, involving square, rectangular, and circular. All RACFST columns used are made of mild steel plates. These columns were divided into two groups. The steel tube thickness was the only parameter modified to study its effect properly. In addition, the study included the search for the best effective section concerning the properties of stability and confinement, so these columns were designed so that the cross-sectional areas of steel tubes were approximately equal. Also, composite action and level of ductility for these columns were studied. The ultimate failure axial load, the reduction in the axial column length, the failure pattern of cross-section shape, and lateral displacement were recorded during the test. Regarding the two groups of columns with (1 and 2) mm thick steel plates, testing data obtained from RACFST columns with elliptical and circular cross-sections respectively showed better stability and confinement of concrete and the ability to withstand a higher ultimate failure stress. Moreover, columns with polygonal sections showed when the number of ribs for the steel plates of the model or increased the angle between the two sides is (90°) or more, column cross-sections can achieve more stability and confinement, respectively. In general , increasing the thickness of the steel tubes increases. Finally, for all columns, the higher values of the concrete contribution ratio (C.C.R) led to an increase in the strength index (S.I.) values. An increase in values of final failure stresses accompanied this increase.

Torsional Behavior of Steel-Concrete-Steel Sandwich Beams with Welded Stirrups as Shear Connectors

The structural performance of a steel-concrete-steel sandwich beam (SCSSB) with welded stirrups to the steel skin plates as shear connections exposed to a pure torsion load was studied in this paper. Eight SCSSB specimens were fabricated and tested under pure torsion. The effects of the compressive strength of the concrete core, 26 and 35 MPa, the thickness of the top and bottom steel skin plates, 2 and 4 mm, and the degree of shear interaction, which represents the number of beam stirrups, between the steel skin plates and the concrete core are 75, 100, and 125%. The experiment beams revealed a similar mode of failure for all SCSSB specimens regarding all considered variables, which started with inclined cracks along the specimens’ side faces and ended with local separation between one of the steel skin plates (top or bottom) and the concrete core. In addition, the experiment results showed an increase in the torsional strength with the increase in the shear connection ratio and the thickness of the steel skin plate, as well as with the increase in the strength of the concrete core. However, it was observed that the torsional ductility of the tested beams is proportional directly to the steel skin plate thickness and degree of interaction and inversely with the concrete compressive strength. The results showed that the use of steel skin plates with welded stirrups as a shear connection could reduce the negative effect of increasing the compressive strength of the concrete core on the torsional ductility of SCSSB. Doi: 10.28991/CEJ-2023-09-01-016 Full Text: PDF

Quantitative thermal investigation of a fayalite particle and a Si-rich layer in oxide scale formed on steel

Fayalite (Fe2SiO4) is a major component of olivine and is often formed in the surface oxide layer (oxide scale) on steel plates owing to its high-temperature oxidation. The thermal conductivity of the oxide scale and its constituents, including fayalite, is essential for controlling the cooling rate of hot steel plates. Therefore, this study uses modulated thermoreflectance microscopy to determine the thermal effusivity/conductivity of fayalite particles with diameters smaller than 180 μm because the sample commercially available is such a small size. This thermal optical microscopy enables the measurement of thermal effusivity for small areas, such as 10 μm. The thermal effusivity and conductivity were found to be 4.1 ± 0.2 kJs-0.5K-1m-2 and 6.0 ± 0.5 Wm-1K-1, respectively. These values are representative of the bulk value. Additionally, the thermal conductivity of fayalite is shown to be higher than that of wüstite (Fe1-xO), which is the main component of the oxide scale. The oxide scale formed on the thick steel plate comprises a Si-rich layer, a wüstite layer, and a magnetite layer. Furthermore, the Si-rich layer comprises fayalite, wüstite, and pores. The effective thermal conductivity of the Si-rich layer was calculated by observing the oxide scale formed on the steel plate. The low thermal conductivity of the Si-rich layer indicates that the thermal conductivity of the layer is strongly affected by the porosity of the oxide scale. Furthermore, although the Si-rich layer is thin, it significantly contributes to the heat resistance of the oxide scale.

Structural damage assessment of RC slab strengthened with POZD coated steel plate under contact explosion

To reveal the anti-explosion capacity of polyisocyanate oxazodone (POZD)-coated steel RC composite structural slabs, a explosion test was carried out for 2 test models. Using ANSYS/LS-DYNA, the damage mode and maximum mid-span deflection of steel plate-RC plate and POZD coated steel plate-RC plate were explored, and the experimental results were compared. Parametric analysis of the charge, POZD, steel plate and concrete slab thickness on the anti-explosion performance of the POZD-steel plate-RC slab. The results show that increasing the thickness of POZD, steel plate and RC slab can effectively reduce the POZD-steel – RC slab mid-span deflection. The POZD coating and steel plates increased the tensile area of concrete and improved the flexural and load carrying ability of the concrete slabs.

Seismic behavior of steel plate concrete composite shear walls with PEC columns and WRGs

An innovative shear wall was proposed by introducing partially encased composite (PEC) columns and welded reinforcement grids (WRGs) into steel plate concrete composite shear wall. This work conducted an experimental investigation of the seismic behavior of seven 1/3-scale proposed walls subjected to cyclic lateral loading. The design parameters included the forms of distribution reinforcement, axial compression ratio, thickness of the built-in steel plate, shear-to-span ratio and thickness of the PEC column-section steel flanges. The results revealed that the specimens had good bearing capacity, deformation ability, energy dissipation capacity, and stiffness under a reasonable axial compression ratio. Compared with a specimen featuring orthogonal distribution reinforcement, the cracking load and ductility of a specimen with diagonal cross-distribution reinforcement were increased by 6.5% and 13.6%, respectively. And increasing the thickness of the built-in steel plate and the PEC column-section steel flanges could augment the bearing capacity and ensure the late stiffness of the specimens. Then, the residual displacement fitting formulae were presented herein to assess post-earthquake repairability. Besides, the bearing capacity calculation formulae of the novel shear wall with certain prediction accuracy were proposed. Finally, finite element models of the tested specimens were established in ABAQUS and validated with experimental results. Also, further investigations regarding the influence of axial compression ratio and shear-to-span ratio were implemented by finite element analysis and engineering recommendations for the designed axial compression ratio limits of the novel shear were given.

Structural performance of perforated steel plate-CFST arch feet in concrete girder-steel arch composite bridges

This paper investigates the mechanical behavior of perforated steel plate-concrete-filled steel tubular (P-CFST) arch feet in concrete girder-steel arch composite bridges. A total of thirteen arch feet specimens, varying testing parameters of the length, thickness and arrangement of perforated steel plates, and the wall thickness of steel tubular, were prepared and tested. Failure modes, load-slip curves, strain history, and ductility of the P-CFST arch feet were presented and discussed. Experimental results indicate that introducing perforated steel plates to traditional CFST arch feet prevented the early-age cracking of the concrete abutment, and the P-CFST with triple-line-shaped perforated plates gave the largest resistance among all specimens. Compared to the P-CFST using a 4 mm-thick perforated steel plate, the cracking resistance of the P-CFST with a perforated plate thickness of 5 mm and 6 mm were increased by 26.9% and 69.4%, respectively, while the improvements for the ultimate resistance of the structure was not obvious. It also magnifies that the cracking resistance of the P-CFST using a 5 mm- and 6 mm-thick steel tubular was increased by 24.3% and 32.9%, respectively, compared to those with a 4 mm-thick steel tubular. Moreover, an analytical model considering the end-bearing effect of the combined tubular-to-plate steel member, the supporting effect of the SRC core column, and the shear effect between the SRC core column and surrounding concrete to predict the capacity of the P-CFST arch feet was proposed. The capability of the developed model was verified by experimental results.

Study on the Seismic Behavior of a Steel Plate–Concrete Composite Shear Wall with a Fishplate Connection

The steel plate–concrete composite shear wall (SPCSW), having been widely applied to several super high-rise buildings, is currently regarded as a new type of lateral load-resisting structure. The SPCSW design does not consider the connection to the surrounding structure, normally envisaged as a buttweld connection, while the fishplate lap connection tends to be applied in construction. To explore the fishplate lap connection to achieve the performance standard of SPCSW, in this paper, an SPCSW with a fishplate connection is modeled using ABAQUS to investigate the hysteretic behavior under constant axial force and horizontal cyclic loads. Through the hysteresis curve and a load–displacement skeleton curve, the effects of fishplate thickness and lap length on its hysteretic behavior are studied. The results show that increasing the fishplate thickness contributes to a slight increase in the bearing capacity and energy dissipation and has little influence on stiffness degradation. When the fishplate thickness is more than half the steel plate thickness, the strength and energy dissipation of an SPCSW with a fishplate connection can reach the level of an SPCSW without a fishplate connection. The bearing capacity and stiffness of the SPCSW increase with the increase in lap length. When the lap length is greater than 50 mm, the strength, stiffness and energy dissipation capacity of an SPCSW with a fishplate connection are superior to those without fishplate connections. Finally, engineering suggestions on fishplate connections are put forward.