Structural Steel Plates Research Articles

Simulation analysis of intake transition section steel lining for hydropower station penstock

To improve the bending stiffness of steel plate structure, anchor bars and stiffeners are used to anchor the thin steel plate in the intake transition section in the concrete. In this paper, the finite element method is used to simulate the steel lining at the penstock intake transition section of hydropower station. The analysis results show that, the overall deformation of steel lining structure is small, which can meet the requirement of stiffness, the stress of steel lining structure is complex, the stress concentration at the stiffening ring is very high, the stress value of other parts is low, and the general stress value does not exceed 43.0 MPa, and the stress distribution is more uniform. The structural stress value of dam in the gate section is relatively low, through conventional reinforcement can meet the design requirements.

Transmission of ultrasonic guided wave for damage detection in welded steel plate structures

The ultrasonic guided wave-based technique has become one of the most promising methods in non-destructive evaluation and structural health monitoring, because of its advantages of large area inspection, evaluating inaccessible areas on the structure and high sensitivity to small damage. To further advance the development of damage detection technologies using ultrasonic guided waves for the inspection of welded components in structures, the transmission characteristics of the ultrasonic guided waves propagating through welded joints with various types of defects or damage in steel plates are studied and presented in this paper. A three-dimensional (3D) finite element (FE) model considering the different material properties of the mild steel, high strength steel and austenitic stainless steel plates and their corresponding welded joints as well as the interaction condition of the steel plate and welded joint, is developed. The FE model is validated against analytical solutions and experimental results reported in the literature and is demonstrated to be capable of providing a reliable prediction on the features of ultrasonic guided wave propagating through steel plates with welded joints and interacting with defects. Mode conversion and scattering analysis of guided waves transmitted through the different types of weld defects in steel plates are performed by using the validated FE model. Parametric studies are undertaken to elucidate the effects of several basic parameters for various types of weld defects on the transmission performance of guided waves. The findings of this research can provide a better understanding of the transmission behaviour of ultrasonic guided waves propagating through welded joints with defects. The method could be used for improving the performance of guided wave damage detection methods.

Analytical Study on Structural Behavior of Bolted Connections in Corrugated Steel Plate Structures

Analytical Study on Structural Behavior of Bolted Connections in Corrugated Steel Plate Structures

Local and post-local buckling of fabricated high-strength steel and composite columns

High-strength structural steel plates are being increasingly used as composite columns in tall buildings, bridges and large infrastructure. The presence of concrete infill in these composite sections enhances their local buckling strength, and thus very slender steel plates can be used in their fabrication. This paper presents the results of an experimental study and numerical investigation of the local buckling slenderness limits for high-strength steel plates. A set of sixteen tests were conducted on both hollow steel and steel-concrete composite sections to explore their local and post-local buckling behaviour under axial compression. A numerical model which accounts for the effects of residual stresses and initial geometric imperfections was developed to predict the local buckling and post-local buckling response of box and I-section columns. This model was verified against the test results. Yield slenderness limits obtained from numerical results were compared with existing codes of practice for both hollow steel and composite sections incorporating high-strength steel plates.

A Study in the field of Welding of Different Materials

Objectives: The investigation was done with the aim of studying the influence of basicity index on mechanical properties of the structural steel. Methods/Statistical Analysis: In this experiment, influence of Basicity index on the welding characteristics was analyzed in the submerged arc welding by keeping all other variables like current, voltage and welding speed constant. The effects of wire/flux (Basicity index) on ultimate tensile strength, Microstructure and impact strength of the weld metal was investigated. Weld deposits on structural steel plates were made at different flux composition. In these experiment plates of dimension 14x125x250 mm was used for welding. The specimens were cut out from the welded plate to carry out various tests after performing the saw operation. Five different types of fluxes were used to weld the plates. Findings: The impact toughness values at room temperature increases with increase in basicity index of flux and highest micro hardness values are formed at the Heat Affected Zone (HAZ) regions for welded specimens. Keywords: Dissimilar Metals, Steel, Welding

An empirical formulation for predicting welding-induced biaxial compressive residual stresses on steel stiffened plate structures and its application to thermal plate buckling prevention

ABSTRACTThe aim of this paper is to derive an empirical formulation for predicting welding-induced biaxial compressive residual stresses in welded steel plate panels. A test database for full-scale models of welded steel plate structures is developed. Elastic-plastic finite element method solutions, associated with thermal stresses in welded steel plate panels, are also developed. The proposed formula is derived by a curve fitting of the databases obtained from both full-scale measurements and numerical computations as a function of plate thickness and weld leg length. The paper demonstrates an applied example of the derived formulations to prevent the thermal buckling of thin steel plate panels that occurs during the welding process.

Optimal design of beam-column connections of plane steel frames using the component method

This paper presents a methodology for optimization of beam-column connections of plane steel frames. The objective is to obtain beam- column connections mechanically more efficient and with minimum cost by determination of the optimal dimensions for the components of the connection; satisfying mechanical constraints associated with the bending moment and the rotational stiffness of the connection, without compromising its safety and integrity. Minimum and maximum limits of geometric parameters are considered, according to current regulations. Algorithms were developed to calculate the bending moment and the rotational stiffness of the connection using the “Method of Components” of Eurocode 3. Initially, it was developed a digital database with structural profiles, steel plates and commercial bolts obtained from catalogs of manufacturers, with automatic access of the data by the computational modules of structural analysis and optimization. In the optimization model, it is adopted the connection with extended end plate without stiffeners, the design variables are the dimensions and the thickness of the end plate, the diameter and the location of the bolts. In the optimization process, we use genetic algorithms with continuous and discrete variables, with the discrete variables being associated to the database. In this way, this paper presents a computational tool fully developed in MATLAB® environment for analysis and optimal design of beam-column connections for plane steel frames. Applications that show quite satisfactory results when compared with results available in the literature are presented.

Effect of Impact Energy in the Esso Test (Part 1: Basic Experiments and Validation of FEM Analysis)

Abstract To enhance the integrity of manufactured steel plate structures, the arrest toughness is an important parameter and is actually required in several structural applications, e.g., shipbuilding, tankage, and power plants, where brittle cracking occurs. Currently, the Esso test is the most popular evaluation method for arrest toughness. In the Esso test, a notch located at the top of the specimen is forced open by impact energy. Generally, it is expected that the arrest toughness may be affected by impact. However, the effect of the impact has not been considered in the evaluation methods so far. Furthermore, the impact energy is selected arbitrarily and differs depending on the test organization. Considering the current situation, it is quite important to evaluate the effect of impact on the obtained results. In the present work, in order to clarify the effect of impact on the arrest toughness evaluation, changes in the driving force at the running crack tip are examined by finite element method (FEM) analyses including impact. In particular, the fundamental behavior of the specimen due to impact and the validation of FEM analysis are investigated.

An approach for evaluating tensile strength of painted steel plates from the surface rusting grade

ABSTRACTThe level of anticorrosive performance is easy to determine from visual inspections of painted steel structures, but the structural performance level is difficult to evaluate. In this study, a tensile test was carried out on structural steel plates with pitting corrosion. Artificial defects were made with percentages of rusted surface area of 0, 3, 10, 16, 33 and 50% and depth-to-radius aspect ratios of 0.25, 0.5 and 1.0. From the test results, the relationship among the percentage of rusted surface area, the aspect ratio and tensile strength was defined. Accordingly, a simple approach is proposed for evaluating the tensile structural performance level from the visual inspection of painted steel structures.

Effect of weld dilution on post-weld thermal conductivity of austenitic stainless steel clad layers

Cladding austenitic stainless steels are trendy these days 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. To facilitate this, composite clad layers are produced with 316L stainless steel deposits on low carbon structural steel plates based on the design of experiments. Results exhibit an incremental trend of thermal conductivity with respect to percentage of weld dilution. A linear mathematical relationship is established between the percentage of weld dilution and post-weld thermal conductivity of clad layers for the prediction of thermal conductivity of clad layer deposits. These results could be supportive in the fabrication industries for producing energy efficient thermal equipment.

Modelling of the ductile-brittle fracture transition in steel structures with large shell elements: A numerical study

In this paper, the strain energy density (SED) criterion is proposed for predicting the ductile-brittle fracture transition (DBFT) in ships and offshore structures. In finite element simulations, these structures are discretized by relatively large shell elements which precludes the modelling of the local stress and strain states in the vicinity of a crack. Critical values of the SED are determined based on local simulations of fracture for a range of temperatures and plane stress states. The local simulations of fracture are based on combined use of the Gurson model for ductile damage and fracture and the Richie-Knott-Rice (RKR) criterion for brittle fracture. After calibrating the Gurson model and the RKR criterion to existing experiments on offshore steel, critical values of the SED are found by analysing a representative plate element with a generic through-thickness crack using a refined solid element mesh. The proposed failure model is evaluated by simulating drop tests on steel-plated structures found in the literature. The present study indicates that the SED criterion is a useful concept for practical design of ships and offshore structures at sub-zero temperatures, but further assessment against experimental data is necessary to fully establish its credibility.

Investigation of residual stresses in Q460GJ steel plates from medium-walled box sections

Residual stress is an important factor that can have considerable effect on the behaviour of steel structures. In the past, most of the research has been focused on determining the residual stress in members consisting of traditional normal strength and high strength steels. There has been little research on residual stresses in members fabricated from high performance steels such as GJ steel. The work detailed in this paper aims to experimentally investigate the residual stresses in welded box sections fabricated from Q460GJ high performance structural steel plates. A total of eight full-scale welded box sections, with nominal wall thicknesses of 12 mm and 25 mm, were tested using the sectioning method. Both the circular curve correction method and the straightening measurement method were used in this study to obtain the magnitude and distribution of the longitudinal residual stresses. In addition, the effects of steel plate thickness and the plate width-to-thickness ratio on the residual stress were investigated. A simplified residual stress distribution model, which would be of great assistance in investigating the buckling behaviour of GJ-type steel members, is proposed based on the experimental results.

Potassium sodium niobate (KNN)‐based lead‐free piezoelectric ceramic coatings on steel structure by thermal spray method

AbstractFor the first time, potassium sodium niobate (KNN)‐based lead‐free piezoelectric ceramic coating with strong piezoelectric response was fabricated on stainless steel substrates by thermal spray process, after introducing NiCrAlY and yttria‐stabilized zirconia (YSZ) intermediate layers. A large effective piezoelectric coefficient (d33) of 125 pm/V was obtained with the thermal‐sprayed KNN‐based ceramic coating on the steel substrates. The mechanisms of improving the structure and enhancing the properties of the KNN‐based piezoelectric ceramic coatings by introducing the intermediate layers were analyzed. Ultrasonic transducers were designed and fabricated from the KNN‐based coatings directly formed on a steel plate structure, and the feasibility for generation and detection of ultrasonic waves for structural health monitoring using the thermal‐sprayed lead‐free piezoelectric ceramic coating was demonstrated.

Simultaneous multi-objective optimization of stainless steel clad layer on pressure vessels using genetic algorithm

Metal cladding is a process of depositing a filler material to enhance the surface properties of base material using a suitable welding process. In this work the clad specimens are produced by surfacing a layer of filler material using weld cladding process to minimize the heat loss across the walls of the pressure vessels. It is done by depositing a low thermal conductivity austenitic stainless steel grade of 316L on structural steel plates used for boiler construction using flux cored arc welding process. The experimental study is carried out as per design of experiments availed for five factors five levels central composite design using response surface methodology. The mathematical models are developed for the prediction of clad layer height, clad layer width and depth of penetration. These models are employed in formulating fitness functions for multi-objective optimization of clad layer dimensions using genetic algorithm (GA). The set of optimal solutions suggested by response surface optimizer and genetic algorithm are compared and discussed. Conformity tests are conducted to validate the prediction capability of developed models and optimum settings. Optimum clad layer dimensions have been arrived and optimized stainless steel clad specimen has been produced. The heat transfer analysis is planned to be conducted in the next phase. The findings can be used in energy efficient design of pressure vessels.

Effect of Plate Curvature on Blast Response of Structural Steel Plates

In the present work an attempt is made, through simulation studies, to determine the effect of plate curvature on the blast response of a door structure made of ASTM A515 grade 50 steel plates. A door structure with dimensions of 5.142 m × 2.56 m × 10 mm having six different radii of curvatures is analyzed which is subjected to blast load. The radii of curvature investigated are infinity (flat plate), 16.63, 10.81, 8.26, 6.61 and 5.56 m. In the present study, a stand-off distance of 11 m is considered for all the cases. Results showed that the door structure with smallest radius of curvature experienced least plastic deformation and yielding when compared to a door with larger radius of curvature with same projected area. From the present Investigation, it is observed that, as the radius of curvature of the plate increases, the deformation mode gradually shifts from indentation mode to flexural mode. The plates with infinity and 16.63 m radius of curvature have undergone flexural mode of deformation and plates with 6.61 and 5.56 m radius of curvature undergo indentation mode of deformation. Whereas, mixed mode of deformation that consists of both flexural and indentation mode of deformations are seen in the plates with radius of curvature 10.81 and 8.26 m. As the radius of curvature of the plate decreases the ability of the plate to mitigate the effect the blast loads increased. It is observed that the plate with smaller radius of curvature deflects most of the blast energy and results in least indentation mode of deformation. The most significant observation made in the present investigation is that the strain energy absorbed by the steel plate gets reduced to 1/3 rd when the radius of curvature is approximately equal to the stand-off distance which could be the critical radius of curvature.

Experimental and model investigation on residual stresses in Q460GJ thick-walled I-shaped sections

Residual stresses can occur through a variety of mechanisms, and welding is one of mechanisms. This kind of stress variation through materials can be very complex and can vary between compressive and tensile stresses from layer to layer. A new type of high performance structural steel named by Q460GJ has been increasingly utilized in many large scale steel constructions in China, such as the National Stadium of China in Beijing (Birds Nest) and Canton Tower in Guangzhou. Q460GJ structural steel has a nominal yield strength of 460 MPa, which does not decrease significantly with the increase of steel plate thickness. Thus, Q460GJ structural steel is normally used in thick-walled welded sections. Nevertheless, the residual stresses on thick-walled sections may be more complex. Currently, only limited knowledge is available on the residual stress distribution of the members fabricated from high performance structural steel plates, especially for thick-walled sections. In this paper, the residual stresses in four welded medium-walled and four thick-walled H-section specimens fabricated from Q460GJ structural steel plates were studied by experimental tests. Residual stresses were measured by sectioning method, and the variation of residual stress through plate thickness was determined by slicing method. This study provides the magnitude and distribution of the longitudinal residual stresses. This paper also explores the effect of plate thickness on residual stress distribution and the interaction between flanges and webs. Finally, based on the statistical evaluation of the experimental results, a simplified multilayer residual stress model is proposed for predicting residual stress.

Numerical simulation and experimental validation of residual stress and welding distortion induced by laser-based welding processes of thin structural steel plates in butt joint configuration

Thin plates are extensively used in automotive, shipbuilding, and railway industries. Welding technology is the main assembling method to manufacture thin plate structures because of its high productivity and ease of use. Consequently, residual stress and distortion induced by welding are an inevitable part of the manufacturing process in welding thin plate structures. Relatively low stiffness, and a high amount of heat input are the main reasons for distortion of the welded structures. In order to decrease the heat input, laser-based welding processes that generate highly localized heat with a very high intensity can be a good choice as an alternative to traditional fusion welding. To predict residual stress and distortion in welding thin plate structures, a three dimensional, thermo-metallurgical-mechanical finite element method was developed. The results of three different laser-based welding processes including aspects of Autogenous Laser Welding (ALW), Cold Wire Assisted Laser Welding (CWLAW), and Hybrid Laser-Arc Welding were compared with traditional Submerged Arc Welding (SAW) from both predicted and experimental perspectives. SYSWELD commercial code was used for the simulations in which both large and small deformation theories were employed to predict the residual stress and the final deformation. Experiments were executed to verify the simulation results. A digital high-resolution microscope was used to visualize and measure the weld cross- sectional shape and bead geometry. To measure the residual stress, an X-ray diffractometer was employed. A digital Vernier Caliper and a 3D laser-handheld scanner were used to measure displacement in the z-direction. Moreover, the mechanical properties of welds obtained by different welding processes were also verified by tensile and micro-hardness tests. It was concluded that lower heat input can markedly influence the final distortion of the welded structure. This conclusion can strongly support the idea of replacing traditional arc welding method with a laser-based one. Simulation and experimental results were matched fairly.

A Simplified Model for the Effect of Weld-Induced Residual Stresses on the Axial Ultimate Strength of Stiffened Plates

The present work investigates the compressive axial ultimate strength of fillet-welded steel-plated ship structures subjected to uniaxial compression, in which the residual stresses in the welded plates are calculated by a thermo-elasto-plastic finite element analysis that is used to fit an idealized model of residual stress distribution. The numerical results of ultimate strength based on the simplified model of residual stress show good agreement with those of various methods including the International Association of Classification Societies (IACS) Common Structural Rules (CSR), leading to the conclusion that the simplified model can be effectively used to represent the distribution of residual stresses in steel-plated structures in a wide range of engineering applications. It is concluded that the widths of the tension zones in the welded plates have a quasi-linear behavior with respect to the plate slenderness. The effect of residual stress on the axial strength of the stiffened plate is analyzed and discussed.

Local strain energy based fatigue assessment of cruciform welded joints: experimental data analysis and influence of hot-dip galvanization

Performing the fatigue assessment of a welded joint using the Notch Stress Intensity Factors [1] presents two major challenges. The first is the necessity of a precise reconstruction of the stress field around the notch tip, thus needing an extremely refined discretization with an evident computational cost. The other, is that the dimensions of the N-SIFs and so their critical values, vary accordingly to the William’s solution [2] depending on the notch-opening angle. Consequence of this is that the mechanical properties necessary for the assessment vary as a function of the geometry treated. The research to overcome this issue has led to the use of the local Strain Energy Density [3]. The power of this parameter, used as a tool to perform fatigue assessment, consists of having a very low mesh refinement sensitivity [4], being the energy computed directly from nodal displacements and stiffness matrix [5], and having constant dimensions, so constant critical value for a given class of materials. In this paper, the local energetic method is applied to the analysis of the results of a series of tests performed on cruciform load carrying and non-load carrying specimens realized by S235 JRG2 structural steel plates. If load carrying, the fillet welded joints are made of S355 J2+N structural steel. The fatigue testing has been performed in atmosphere at room temperature in as welded condition both with and without the corrosion protective zinc layer. Particularly, the interest is focused on the influence of the zinc layer of the fatigue properties of the joint and on the capability of the local energetic approach, confronted with the classic nominal stress approach, to accurately predict the fatigue failure. To conclude, the investigation of the tests executed reveals no significant difference in the fatigue life for the coated samples, compared with the uncoated specimens and the predictions according to the IIW recommendations [6].

Experimental and numerical study for the post buckling behaviour of plate girders subjected to bending and shear

This research offers experimental and numerical study for the ultimate strength analysis and post buckling behaviour of plate girders subjected to shear and bending stresses. Two Plate girders of length 2.5m are designed consisting from three separate structural steel plates welded together to form I - section. The dimensions of the first girder section is 512 mm × 120 mm while the second girder section is 412mm × 120 mm. Mechanical properties for plate girders components were found by testing three samples of each plate. The ultimate shear strength was found by examining two plate girders in the laboratory under concentrated load applied at the middle span. A numerical study of the tested plate girders was carried out by using the software program (ANSYS) to study the behaviour of girders steel under the influence of loads application. The results showed that the ratio of the experimental ultimate load strength to the numerical ultimate load strength is 97% 94% for plate girders 1 and 2 , respectively. For the part of using theoretical study. The results obtained from the equations , it was observed that the ratio of the experimental ultimate load strength to the theoretical ultimate load strength is 83% for plate girders1 and 90% for the plate girder 2.Through comparison between experimental, numerical and theoretical results it was observed good andacceptable agreement. Thus confirming the accuracy of the modelling between this methods and obtain convergent results in all cases. Also it was found when an increase in the depth of the web has effect in increasing the ultimate shear strength for plate girder by about 19%.