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High Strength and High Performance Steels and Their Use in Bridge Structures,” Journal of Constructional Steel Research, 58(1): 3-20
Abstract
This paper reviews the histories of the development and use of high strength and high performance steels for bridge structures in Japan.
... Recently, the technology of high strength steel (HSS) develops quickly and it has been employed in some large-span or high-rise buildings or bridges. For example, different grades of HSS with the yield strength varies from 600 MPa to 800 MPa are employed in the Seto Ohashi Bridge [1]. Compared with ordinary steel, specimens fabricated from HSS have some considerable advantages, such as higher yield strength, less economic cost, and less carbon emission [2][3][4]. ...
... All columns have the slenderness of 15.00, which in ac-cordance with the requirement of stub column in AISC 360-16 [21], and the design length of columns can be calculated from Eq. (1). (1) where λ is the slenderness of column; r is the cruciform-section polar radius of gyration; and L e is the effective length of specimens. ...
In this work, the experiment of welded cruciform-section columns fabricated from high strength steel (HSS) with the yield strength of 550 MPa subjected to axial compression is performed, and the local buckling behavior including failure modes, local buckling load, and the ultimate load is investigated. Two different failure modes, such as the local buckling of plates and the torsion of column, are found, and the width-to-thickness ratio (WTR) of the flange significantly affects the local buckling load and the stress ratio of σ cr /f y. The ultimate stress of the cruciform-section column decreases as the WTR of plates increases. A finite element method for predicting the mechanical behavior of HSS welded cruciform-section columns is developed using ANSYS. New limit for the WTR of plates in HSS welded cruciform-section columns is suggested. AISC 360-16 is conservative for estimating for the ultimate load of HSS welded cruciform-section columns. A new model modified from AISC 360-16 is proposed , and it makes good agreement with experimental and numerical results. Reliability analysis for AISC 360-16 and the proposed model is carried out in accordance with EN 1990.
... Steel structures are an important part of civil infrastructures, and the demand for high-performance materials in engineering structures is on the rise due to the development of longer span building structures and the consideration of structural mass reduction. The HPS (High-performance steel) is the steel has higher ductility, better fracture toughness, better weldability, better cold formability, better corrosion resistance besides higher strength (Miki et al., 2002). The HPS has been widely used in engineering structures due to its excellent properties, such as higher strength, better ductility, and a lower thickness effect than ordinary steel (Gang et al., 2015;Miki et al., 2002;Schröter & Lehnert, 2014). ...
... The HPS (High-performance steel) is the steel has higher ductility, better fracture toughness, better weldability, better cold formability, better corrosion resistance besides higher strength (Miki et al., 2002). The HPS has been widely used in engineering structures due to its excellent properties, such as higher strength, better ductility, and a lower thickness effect than ordinary steel (Gang et al., 2015;Miki et al., 2002;Schröter & Lehnert, 2014). ...
The main goal of this study is to investigate the effect of local corrosion at the mid-span region on the flexural behavior of HPS (high-performance steel) beams. Four Q550E HPS beams were designed and subjected to electrochemically accelerated corrosion. The 3D scanning technology was used to analyze the geometric characteristics of corrosion regions. After the four-point flexural test, the relationship between the degradation of flexural behavior and the corrosion ratio or corroded location (right side of pure bending section and lower half of pure bending section) was studied in details. The FE (finite element) model of corroded HPS beams was established and strictly verified by comparing with the tested results. Additionally, different heights and thicknesses of the corroded parts were considered in the FE models. Failure modes and bearing capacity degradation of the HPS beams caused by local corrosion were studied by analyzing above parameters. The results shows that the corrosion at the compressive flange of bending section has a greater influence on the ultimate bearing capacity than tension flange and web. The HPS beam corroded in right side of pure bending section has the most significant compressive flange buckling compared. The failure mode of HPS beams with corrosion in lower half of pure bending section changes from obviously compressive flange buckling and local web yielded to all web yielded with the increase of corrosion ratio. The influence of bottom flange corrosion on remaining critical buckling load of beam is slightly more significant than the ultimate load, but the influence degree of top flange corrosion on above two loads are basically the same.
... High strength steel (HSS) with nominal yield stress in the range 460 MPa into 960 MPa has been used many times worldwide in the construction of modern building and bridge structures (Miki et al., 2002). The advantage of these materials is a particularly favorable strength/weight ratio. ...
... Computational [9,13,14,16,17,20,[46][47][48]53,67,69,75,76,[81][82][83][85][86][87]90,94] [ [102][103][104]108,112,118,119,125,126,[130][131][132][133][134] Experimental [1,11,28,29,33,49,50,55,56,58,59,65,76,78,93,96,98,106,110,117,121] [122] Computational + Experimental [7,30,38,39,41,43,54,[57][58][59][60][61][63][64][65][66]68,78,79,92,95,99] [100, [113][114][115][116]123,[127][128][129]135,136] Review [10,12,15,21,[23][24][25]27,31,32,34,36,37,40,77,80,84,91,97,101,105] [ 107,109,111,120,124] homogeneous beams of 400 MPa and 500 MPa, respectively. The hybrid beam, with a web yield strength of 500 MPa and flange yield strength of 400 MPa, does not attain its section's yield moment. ...
Although it is still common practice to use homogeneous steel girders (same yield strength in the flanges and web), implementing hybrid configurations seems to be an excellent alternative to improve the performance and sustainability of this type of structural element. Therefore, this paper provides a comprehensive review of the current state of knowledge on hybrid steel girders. The objective is to improve our understanding of this innovative and sustainable alternative to traditional homogeneous steel elements, with a focus on updating the theoretical basis for future design projects. The study analyzes 128 publications, from which information is extracted on five categorical variables, reflecting the current situation of hybrid elements. In addition to studying each variable separately and highlighting the most relevant research to date, a more in-depth statistical analysis is performed. It is based on simple correspondence analysis, which allows identifying the underlying relationships among the variables. Results summarize the design methods implemented to calculate these structures. Furthermore, the recommended hybrid ratios to achieve the best performance are presented. However, it is found that there are gaps in the research. Consequently, several promising lines of investigation are proposed.
... When compared with those commonly used S355 steel, i.e. structural steel with a nominal yield strength at 355 N/mm 2 , these S690 steel offer significant advantages because of their superior strength per unit weight of steel, i. e. doubled strength-to-self-weight ratios. Many design and construction engineers are keen to exploit the potential use of these S690 steel in a wide range of engineering applications [38,17,40,34,47,6] because of significant savings in materials, time and costs. An obvious application is high strength S690 columns of circular hollow sections. ...
... High strength steel (HSS) has been widely employed in civil engineering [1][2][3] as it has many advantage, such as high strength, light weight, and so on. The application of HSS can save construction cost and decrease energy consumption [4][5][6][7]. ...
Carbon Fiber Reinforcement Polymer (CFRP) has been widely utilized in repairing and retrofitting engineering. The purpose of this work is to study the buckling behavior of high strength steel (HSS) welded T-section column strengthened with CFRP using experimental and numerical method. The experiment of six specimens of 800 MPa HSS welded T-section column strengthened with CFRP under axial compression is performed. The influences of three main parameters (i.e., the number of CFRP layers, the slenderness of columns, and the width-to-thickness of plates) are observed in this work. All columns fail by the debonding of CFRP layers and the flexural-torsional buckling of specimens. CFRP layer can effectively delay the local buckling of plate or the torsional buckling of specimen. CFRP layer and slenderness has significant influences on the bearing capacity of specimens. The flex-ural and torsional displacement of columns strengthened with CFRP is much smaller than that of columns without CFRP. A finite element (FE) method for estimating the bearing capacity of HSS welded T-section column strengthened with CFRP is developed using ANSYS software. It is found that the confining effect of CFRP is more effective for stub columns. A more accurate model modified from Cadei et al.'s model for estimating the bearing capacity of 800 MPa HSS welded T-section column strengthened with CFRP under compression is proposed.
... The rapid development of industry and construction has increased the demand for new materials and structures. Due to the advantages of high material strength, satisfactory plasticity, and easy welding, high-strength steel has been widely employed in building structures, bridge structures, automotive frame structures, and other fields [1][2][3]. However, fracture failure is the common failure form of steel structures under compression, and the ultimate bearing capacity of steel structures under compression must be taken into account during the design and manufacturing process. ...
High-strength steel (HSS) columns are widely used in industry and construction because of their outstanding properties. Predicting the ultimate bearing capacity of HSS columns is not an easy task due to many nonlinear factors such as geometry and material properties. In this paper, a Cluster and Search Stacking Algorithm (CSSA) model based on the cluster algorithm, search algorithm, and Stacking algorithm is proposed to predict the ultimate bearing capacity of HSS columns. Specifically, the clustering algorithm is used to cluster the base models, and the search algorithm is implemented to find the best combination of base models in the Stacking algorithm. Results show that the proposed CSSA model is more effective than base models optimized by the Bayesian Optimization algorithm. Furthermore, the Bland–Altman approach is utilized to examine the consistency of the CSSA model to validate its reliability. Finally, the Shapley additive explanation (SHAP) method is introduced to analyze and explain the ultimate bearing capacity predicted by the CSSA model.
... The tensile strength of the welded joints in the pile legs is required to be greater than 770 MPa, and the low-temperature impact energy at −40 • C is required to be greater than 69 J [5]. Q690E high-strength steel is widely used as the structural material of pile legs because of its high strength and low ductile-brittle transition temperature [6]. ...
An 80%Ar-10%CO2-10%He ternary gas mixture was used as the shielding gas during the narrow-gap welding of thick Q690E high-strength steel plates. Complete and defect-free welded joints were obtained, and the microstructure and mechanical properties of the welded joint were investigated. The weld zone consists of a solidification area and interlayer zone, and the heat-affected zone consists of a coarse-grain heat-affected zone (CG-HAZ) and a fine-grain heat-affected zone (FG-HAZ). The microstructures of the weld zone are mainly lath bainite (LB), acicular ferrite (AF), and granular bainite (GB). The microstructure of the CG-HAZ is lath martensite (LM) and the microstructure of FG-HAZ is GB. Methods with different heat inputs were used to study their effects on the mechanical properties of the welded joint. It was found that the microstructure and mechanical properties of the welded joints are better with lower heat input. With tandem wire narrow-gap GMA welding, the tensile strength of the joints declined from 795.3 to 718.3 MPa and the impact toughness at −40 °C resulted in a weak position in the weld zone, which declined from 76~81 J to 55~69 J, when the welding speed reduced from 350 to 250 mm/min. With oscillating-arc narrow-gap GMA welding, the tensile strength achieved 853.4 MPa and the impact toughness at −40 °C was around 69~87 J. The results indicated that, under the appropriate heat input, the tensile strength of the joint exceeds 770 MPa and the low temperature impact toughness at −40 °C exceeds 69 J. A 155 mm-thick Q690E steel welded joint was obtained and the mechanical properties of the welded joint meets the requirements of the offshore drilling platforms.
... In recent years, there has been a large growth in the construction of steel structures using UHSS due to their relatively low cost and good availability [9,10]. Especially in lightweight structures and for extremely loaded components, UHSSs are heavily used. ...
Large-scale usage of high and ultra-high strength steels is strongly linked to the availability of suitable joining techniques ensuring consistent properties throughout the welded structure. For conventional structural steels, fusion welding techniques, such as gas metal- or submerged arc welding, are well established and widely used. In many cases these welding processes can also be utilized for high and ultra-high strength steels. Likewise, high energy density welding processes, e.g. laser beam or electron beam welding, can also be suitable choices for welding these materials. However, constraints such as missing filler metals, missing standardization, and small processing windows, especially in terms of allowed heat input, still limit their application. In this review scientific literature on fusion welding of various ultra-high strength structural steel grades, i.e. steels with a yield strength in the range of 690 to 1300 MPa, is reviewed and discussed. The main focus lies on experimental results regarding mechanical properties, such as tensile strength, hardness, impact toughness, fatigue, etc. as well as residual stresses and microstructural transformations.
... They have been developed to increase the strength to weight ratio and meet the need for higher strength construction grades [2]. These alloys are used in heavy gauge applications, including line pipe, building construction, wind towers, storage tanks, bridges, and pressure vessels [1,3,4]. While each of these applications has different performance requirements, toughness and fatigue are critical for all of them [5][6][7]. ...
Toughness and fatigue resistance of welds and associated heat-affected zones (HAZs) in high strength steels are important design parameters in structural applications. Acicular ferrite microstructures, which can be achieved through control of weld process and nucleant (inclusions or precipitates) characteristics, are often regarded as key to enhancing weld metal and HAZ properties of welded steels. This paper addresses the transformation characteristics of acicular ferrite related to alloying and weld processing as well as the specific role of acicular ferrite in weld performance, along with future research needs to identify weld processes suitable to specific alloying strategies.
... Another advantage of high strength steel is the possible increase in absorbed energy in a collision or crash scenario, see Ehlers [1]. Comprehensive reviews of the potentials of high-strength fine-grained steel for structural design were presented by Miki et al. [2] or van Es et al. [3]. ...
Fatigue strength of welded joints is typically independent of the parent material static strength; however, there are two exceptions from this rule—post-weld treated joints and high-quality joints. The reason for both is the absence of sharp weld transitions. Thus, fatigue life is not fully governed by fatigue crack propagation but also by fatigue crack initiation. This is intensified by the fact that crack initiation behaviour is proportional to static strength properties. Commonly, this effect is not accounted for by design guidelines and typical fatigue assessment methods for welded joints. This study hence investigates the applicability and accuracy of different local fatigue assessment methods for high-quality welded joints made of high-strength steel. For this purpose, fatigue test results of S500 structural steel joints with weld toe and weld root failure are assessed using a variety of local approaches and then compared to the nominal stress approach. Finally, the transferability of results to large-scale structures are discussed and recommendations are given for practical applications.
... High strength steel (HSS, nominal yield strength y ≥ 460 MPa) is one of the promising structural material to gain considerable convenience and economy [1][2][3]. However, the corresponding test results showed that the increase in yield strength generally synchronizes increase in yield-to-tensile ratio, which will lead to the decrease of the rotation capacity and plastic hinge length of steel beam-column joints [4]. ...
The flexural behavior of bolted extended stiffened (ES) end-plate joints with high strength steel (HSS) is crucial in order to avoid brittle fractures in earthquakes. A total of three types of ES joints with different failure mode were carefully designed to cover commonly used types of joints, namely the full strength, equal strength, and partial strength joints. They were tested under cyclic loading to further investigate their seismic performance, and to evaluate the suitability of the design equations specified in European Code (EN 1993: 1-8 and EN 1998-1). Experimental results showed that the energy dissipation zone of the extended stiffened full (ESF) strength joints with HSS is mainly concentrated in the reduced section, while the one of the extended stiffened equal (ESE) strength joint using HSS is mainly distributed in the end-plate and the reduced section, both of them belong to ductile failure mode; the extended stiffened partial (ESP) strength joints with HSS only rely on the crack propagation and closure between the end-plate and the beam flange, and the limited plastic deformation of the end-plate to dissipate seismic energy, which presented brittle fracture; The failure mechanism and energy dissipation capacity of ES end-plate joints with HSS are closely related to the capacity design parameters αd, The capacity design calculation model of the ES joints based on the EN 1993: 1-8 code component method can accurately predict its failure mode, but the reasonable parameter αd needs to be further studied in European Code. Finite-element analysis was performed and showed good agreement with the experimental results. It was found that a higher likelihood of fracture in transition length rather than in the connection area was reconfirmed in both ESF and ESE joints, while for ESP joints, it is in the CJP weld of the beam flange end.
... Although there is often no significant increase in Young's moduli of these highstrength structural steels, when compared with those of the normal-strength steels, many structural engineers believe a wide adoption of these high-strength structural steels will lead to a major advancement in structural engineering and steel construction technology (Bjorhovde, 2015;Hegger & Doinghaus, 2000;Miki, Homma, & Tominaga, 2002;Ricles, Sause, & Green, 1998;Sedlacek & Muller, 2001;Willms, 2009) because of a significant reduction in self-weights of structures. There are also associated savings in materials and time in construction of their supporting structures and foundations. ...
This chapter presents a new design method for considering the bracing effect of sheathing boards that are attached to CFS (cold-formed steel) structural members. It also presents a detailed summary of history, development, and flaws of the available sheathing braced design guidelines of the American Iron and Steel Institute. Previous investigations have shown that the current American Iron and Steel Institute (AISI) design specification for sheathing bracing design of CFS wall panels is unconservative (design predictions>experimental strength) due to exaggerated sheathing stiffnesses calculated from ideal loading conditions rather than worst-case loading conditions. Therefore a new design method is suggested based on the performance (strength and stiffness) of the individual sheathing-fastener connections. The current test setup of the AISI is improved to simulate realistic failure modes of the sheathing-fastener connections. The test results revealed: (1) the prominent influence of tensile modulus of the sheathing board and the geometric dimensions of the CFS stud (lever arm), (2) the sudden and catastrophic failure modes and they should be considered in the form of coefficients in the design expressions to prevent an unsafe design, and (3) the sheathing thickness did not influence the performance of the sheathing board (strength, stiffness, and failure mode). Based on test results, new expressions are formulated to predict the stiffness and strength of the individual sheathing-fastener connections. Finally, the effectiveness of the proposed simplified design method is illustrated by a design example, which quantifies the benefit of adopting this method in AISI design guidelines.
... The application of high strength and structural steels with elevated strength has been growing in the last two decades. 1 In the present paper, low-frequency and high-frequency fatigue tests are presented. The present paper shows a comparison of the data obtained during these two types of tests and brings reliable data for designers as the inputs to lifetime assessments and numerical simulations. ...
The paper brings results of high‐cycle fatigue and very‐high‐cycle fatigue tests of the steel S355 tested during low‐ and high‐frequency loading. Two grades of structural steel (S355J0 and S355J2) were tested to gain fatigue properties that serve as inputs to reliable finite element calculations of cyclically loaded structures. Experimental measurements of both steel grades were performed on low‐frequency hydraulic and high‐frequency ultrasonic fatigue testing systems. Both low‐ and high‐frequency loading showed higher lifetime for the grade S355J2. The difference between the two studied steel grades was more apparent during low‐frequency loading. The significant difference between the results of low‐ and high‐frequency loading tests can be explained by the fact that the resistance to plastic deformation increases with an increasing rate of deformation. Fracture surfaces were studied by electron microscopy, where they exhibited both surface and internal crack initiation. The fatigue life of the studied steels exhibited strong dependence on loading frequency. The life under fatigue ultrasonic loading is much higher than the life under low frequency. The purity of the S355 steels has a significant impact on their fatigue life. The fatigue life of the steels S355J0 and S355J2 is in correlation to their ultimate strength.
... In the construction industry, high-strength steels can be used for either entire load-bearing structures, or key (high-stressed) structural components only. With this advantage, they are used in structures such as silos, tanks, hoppers, towers, and masts; for load-bearing structures in manufacturing facilities; and for loadbearing elements in bridges and footbridges [1]. These applications are implied by their high strength, which allows the transmission of high-intensity loads while using more economically sized elements [2]. ...
Modern high-strength steels achieve their strength exclusively through the manufacturing process, as the chemical composition of these steels is very similar to the composition of standard-quality steels. Typically, hot-dip galvanizing is used to form a protective zinc layer on the steel parts of structures; nonetheless, the material is exposed to high temperatures during the process. With high-strength steels, this can lead to deterioration of the mechanical properties. This study aims to experimentally examine and evaluate the extent of deterioration of the mechanical properties of high-strength-steel members. The effect was studied on specimens made of three different types of steel with the yield strength ranging from 460 to 1250 MPa. For each type of steel, selected mechanical properties—yield strength, tensile strength, and hardness—were determined on specimens with and without hot-dip galvanization, and the obtained results were mutually compared. Our study shows a significant impact of the hot-dip galvanization process on the mechanical properties of some high-strength steels. With the studied types of steel, the yield strength decreased by up to 18%, the tensile strength by up to 13%, and the hardness by up to 55%.
... Due to their excellent strength, fracture toughness, and high-temperature performance, steels are considered a crucial structural engineering material [1]. They are widely used in different industries such as automotive, aerospace, nuclear, chemical, oil and gas, military, construction, transportation, etc. Different categories of steel are used, depending on the application. ...
Friction stir processing (FSP) technology has received reasonable attention in the past two decades to process a wide range of materials such as aluminum, magnesium, titanium, steel, and superalloys. Due to its thermomechanical processing nature, FSP is used to alter grain structure and enhance mechanical and corrosion behavior in a wide range of steels. The refinement in grains and phase transformations achieved in steel after FSP affects hardness, tensile properties, fracture toughness, fatigue crack propagation rate, wear resistance, and corrosion resistance. A number of review papers are available on friction stir welding (FSW) or FSP of nonferrous alloys. In this article, a comprehensive literature review on the FSP/FSW of different types of steels is summarized. Specifically, the influence of friction stir processing parameters such as advancing speed, rotational speed, tool material, etc., on steels’ performance is discussed along with assessment methodologies and recommendations.
... The improved methods for producing high-strength steel [1], [2], the creation of appropriate welding technologies [3], [4], [5], and the increased consumption for construction of infrastructure [6], the manufacturing of heavy industry equipment, pressure vessels and vehicles [7], leads to an increase in the usage of S700MC steel. ...
This paper presents a finite element model of submerged arc welding. The modeling of the filler material has been performed by applying the technique for deactivation and subsequent activation of the finite elements involved in the welding seams. The nonlinear material properties are taken into account. The description of the peaks in the specific heat capacity in the phase changes has been done by introducing latent heat. The welding arc is modeled as a heat source with a constant heat flux density. Experiments have been conducted to validate and verify the numerical model. The influence of the ratio between surface and volume of the set heat sources has been studied. Tack welds have been taken into account. Data on the relationship between the accuracy of the obtained results and the number of passages has been presented.
... High/ultrahigh-strength steel has become an increasing choice for the manufacturing industries of machinery, marine structures, offshore structures, bridge structures, and other engineering facilities with excellent strength-to-self weight ratios and mechanical properties (Miki et al., 2002;Feng and Qian, 2018b;Ahola et al., 2019b;Chung et al., 2020). The integrity of these structures experiencing service cyclic loading under different environmental actions (e.g., wave, heavy traffic, wind, current, and seismic loadings) is directly dependent on the material fatigue properties and structural designs of local details. ...
Welding of steel is a technique frequently used in practical engineering applications; however, their mechanical performance is strongly dependent on the physical metallurgical status of the weldments. In the present study, fully reversed, strain-controlled low-cycle fatigue (LCF) tests were conducted on 10CrNi3MoV steel and its undermatched weldments with strain amplitudes varying from Δε ±0.5 to ±1.2%. Both base metal and weldments exhibited softening behavior at the beginning of the cyclic stage. Numerical investigations of cyclic stress-strain evolutions of the materials have been studied by the cyclic plastic model considering nonlinear hardening. The continuous damage mechanics (CDM) theory based on the experimental hysteresis stress-strain energy concept was employed to illustrate LCF failure, including damage initiation and deterioration. The damage mechanics approach calibrates the material parameters from the measured fatigue life for initiation and growth stages. Afterward, the combination of material cyclic plastic parameters and damage parameters was implemented to predict the LCF life. Good agreement can be observed between the experimental results and the FE results based on the CDM approach. Finally, the damage evolution of the materials under different strain amplitudes by this approach was assessed.
... High strength steels (HSS), which possess yielding strength greater than 460 MPa, have been gaining increasing attention due to their contribution to architectural space, structural efficiency and construction convenience [1][2][3]. Nevertheless, it has been well recognized that the yield ratio and elongation respectively increase and decrease with increasing yield strength. In order to ensure sufficient plastic deformability, most design codes provide specific limitations to constrain the yield ratio and elongation. ...
Recently structural members fabricated of high strength constructional steels in civil and building engineering has been widely explored. However, their usage in earthquake zones is still restricted by seismic standards worldwide due to its poor ductility. In order to attain potential seismic application, this paper conducted five cyclic lateral loading experiments on H-shaped beam-columns fabricated of Q690D high strength structural steel. The tested members were cyclically bent about the weak axis. It was recognized that the low-fatigue fracture of edge fiber around bottom cross-section was the main failure mode. Besides, the hysteretic curves, cyclic backbones and energy dissipation characteristics were thoroughly discussed. The ultimate inter-storey drift was greater than the limitation of 1/50. All tested beam-columns exhibit favorable cyclic deformability and energy dissipated ability. To further study the influence of several factors, a series of FEA simulations were performed through verified numerical models. Ductile damage behaviors and advanced cyclic constitutive relationships were considered to improve the simulation performance. The influences of plate component slenderness and axial load ratio on seismic performance of steel beam-columns were thoroughly discussed. It is concluded that there exist interdependence characteristics between different influential factors on seismic performance.
... It is further observed that the fatigue strength of AWJ cut components is enhanced by using HSS. However, this enhancement of fatigue properties is less pronounced in comparison to the increase in static properties [4,9]. This observation can be directly linked to the cutting process, which induces surface defects that act as initial cracks. ...
An analytical model for the fatigue probability of abrasive waterjet cut high strength steel as a function of surface roughness, surface residual stress, tensile strength and number of cycles to failure is presented. Based on the model, which is valid in the finite and infinite-life high cycle fatigue regime, the influence of the aforementioned parameters on the fatigue strength at different probability levels is studied. For validation, fatigue tests are performed on abrasive waterjet-cut dog-bone specimens manufactured from high-strength steel with a yield strength of 700 MPa. Residual stresses are measured parallel to the loading direction at the inlet, middle and outlet of the cut surface. Surface roughnesses are measured with laser line triangulation as well as a traditional contact stylus method, showing good agreement between both measurement techniques. The proposed probabilistic model shows good agreement with the experimental results with less than 4% error in the predicted mean fatigue limit. Furthermore, the applicability of the presented analytical expression in a probabilistic design framework is demonstrated. An engineering example is introduced demonstrating the implementation of the model in a finite-element simulation, accounting for both multiaxial loading and the statistical size effect.
... The improved methods for producing high-strength steel [1], [2], the creation of appropriate welding technologies [3], [4], [5], and the increased consumption for construction of infrastructure [6], the manufacturing of heavy industry equipment, pressure vessels and vehicles [7], leads to an increase in the usage of S700MC steel. ...
This paper presents a finite element model of submerged arc welding. The modeling of the filler material has been performed by applying the technique for deactivation and subsequent activation of the finite elements involved in the welding seams. The nonlinear material properties are taken into account. The description of the peaks in the specific heat capacity in the phase changes has been done by introducing latent heat. The welding arc is modeled as a heat source with a constant heat flux density. Experiments have been conducted to validate and verify the numerical model. The influence of the ratio between surface and volume of the set heat sources has been studied. Tack welds have been taken into account. Data on the relationship between the accuracy of the obtained results and the number of passages has been presented.
... ) ，ショットピーニング処理(間野他，2006) ， ワイヤピーニング処理(太田他，1980)， 低温変態溶剤の添加 (Miki et al., 2002) ( Kasuya and Sasaki, 2009) ，超音 波衝撃処理(UIT) (Abdullah et al., 2012) ( Statnikov et al., 2006) ...
The residual stress state inside the cruciform welded joints were measured using the pulsed neutron stress measurement method. The points of interest in this study are the weld toe and its interior. We also compared the cases with and without ultrasonic impact treatment (UIT), which is expected as a fatigue strength improvement technology. Furthermore, the case where tensile stress or compressive stress was applied after UIT treatment was also examined. The applied stresses at this time were 75 % or 85 % of the yield point, respectively. From the above, we considered the cause of the change in the residual stress on the surface after UIT treatment, which was clarified in the preliminary experiment, in the early stage of fatigue. As a result, the load after the UIT treatment caused plastic deformation in a part of the inside, which caused the redistribution of residual stress. It was also found that such changes in the internal residual stress state are the cause of the changes in the surface residual stress.
Nowadays, hot rolled steel sections are used in practice. The cross‐sectional dimensions are therefore fixed and catalogued by the steel manufacturers. However, when the span of the members and/or the applied load becomes significant, such hot rolled steel sections can no longer meet the ultimate and/or service design criteria and the use of a built‐up welded I‐beam should be considered. They are typically made of three steel plates welded together to form a monolithic I‐beam. By varying the dimensions of these plates, an infinite amount of cross‐section geometries can be defined. But face to this high variability of solutions, the designers encounter difficulties in identifying the most appropriate combination of geometrical and mechanical properties for the constitutive plates.
To study and optimise these profiles, a MATLAB ® routine has been developed at the University of Liege. It allows, for different load cases, to find suitable cross‐sectional dimensions that minimise the weight and/or the total cost of the element. This routine follows the current recommendations prescribed in prEN1993‐1‐5 and evaluates the possibility of using transverse stiffeners along the web to further reduce the weight and cost of the element. The so‐developed routine is presented in the present paper. Also, the advantage of considering the use of high strength steels for such structural members is discussed to propose recommendations to the designers for the selection of the most appropriate steel grade.
The existing research mainly considers the fatigue properties of steel structures under the influence of the environment, corrosion rate, and load conditions without considering the effect of corrosion locations and areas. However, corrosion can happen to a steel structure in a practical engineering setting at any position. This paper investigates the fatigue behavior of high-performance steel beams (Q550E) subjected to different corrosion conditions through various tests. Results show that the fatigue life of the wholly corroded steel beams decreases as the frequency increases and increases as the stress ratio increases. Additionally, local corrosion has a greater impact on flexural stiffness than whole corrosion, and the lower half area has a greater impact than the right half area. Other corroded steel beams, with the exception of SCU-10, have fracture positions that are within the corrosion area. Because, despite the corrosion in the bending shear section, the fatigue strength of the corrosion area is higher than that of the fracture location. In addition, the degradation curves of the mid-span flexural stiffness of other steel beams under cyclic loading have not observed S-shaped curve characteristics, with the exception of GC-10B and SCU-20.
There has been an increase in the use of high-strength steel in several countries, as they provide design lightweight structural members by satisfying environmental and economic issues. This paper aims to implement high-strength steels in the web-post buckling resistance equation, which was based on the truss model according to EUROCODE 3, presented previously by the authors. For this task, a finite element model is developed by geometrically and materially nonlinear analysis with imperfections included. A parametric study is carried out, considering the key geometric parameters that influence the web-post buckling resistance. Three high-strength steel grades are studied (S460, S690 and S960) and in total, 13,500 finite element models are processed. A new factor for adapting high-strength steels to the equation proposed previously was presented. The finite element results agree well with the new proposal. The statistical parameters calculated, via the ratio between the numerical and analytical models, considering the regression, mean, standard deviation and variance, were 0.9817, 0.986, 8.32% and 0.69%, respectively. In conclusion, a reliability analysis was presented based on Annex D EN 1990 (2002).
Corrosion is nearly unavoidable phenomenon in most of the metal materials. In this paper, its effect on the sharp edge crack propagation under tensile loading is investigated. A rectangular plate with a perpendicular crack and an elliptical corrosion pit nearby is modelled via finite elements and fracture behavior of the crack is analyzed. The multi-parameter fracture mechanics concept is applied, i.e. the higher-order terms of the Williams expansion are calculated by means of the over-deterministic method and utilized for tangential stress approximation in the vicinity of the crack tip. Thus, the generalized MTS criterion could be used for estimation of the crack deflection angle. The calculations were performed for a selected corrosion pit size and location considering various crack lengths. The results are discussed and a crack length with the highest probability to deflect from its original perpendicular propagation direction is found.
The behaviour and design of high strength steel (HSS) beams are addressed in the present study. Six in-plane three-point bending tests on three different welded I-sections − two homogeneous S690 steel welded I-sections and one hybrid welded I-section with S690 steel flanges and an S355 steel web, were first conducted. The beam tests were carried out in major axis bending and a bespoke restraint system was designed and employed in the test programme to prevent lateral-torsional buckling. Following the experimental investigation, a thorough finite element (FE) modelling programme was performed, which included a validation study confirming the accuracy of the developed FE models in replicating the flexural behaviour of HSS welded I-section beams, and a parametric study generating additional FE data on HSS welded I-section beams over a broader range of cross-sectional slendernesses, steel grades and loading configurations. The test results obtained in the present study and collected from the literature, together with the generated FE data from the parametric study, were used to evaluate the suitability of the current Eurocode 3 cross-section slenderness limits for HSS homogeneous and hybrid welded I-sections in bending. It is shown that the current Eurocode Class 2 and Class 3 slenderness limits are suitable for the classification of the outstand flange (in compression) and internal web (in bending) elements Zhu, Y. F., Yun, X. and Gardner, L. (2022). Behaviour and design of high strength steel homogeneous and hybrid welded I-section beams. Engineering Structures, 275, Part B, 115275. 2 of both HSS homogeneous and hybrid welded I-sections subjected to major axis bending, while stricter Class 1 slenderness limits are considered necessary to achieve sufficient rotation capacity for plastic design. The findings from the present study indicate that plastic design can be used for HSS structures, provided the proposed stricter Class 1 slenderness limits are employed.
High-strength steel structures have favorable mechanical properties and perform economically, but their application in seismic design is limited owing to their poor deformation capacity. In order to evaluate the hysteretic performance of Q690 high-strength steel box-section beam–columns and to assess the rationality of applying Eurocode 3 (EC3) to classify cross-sections of high-strength steel, three non-thin-walled welded box-section beam–columns were designed, and horizontal cyclic loading tests under constant axial force were undertaken. The hysteretic response of the specimens was analyzed from the standpoint of the failure mode, the degree of plastic evolution in the cross-section, energy dissipation capacity and ductility. Following this, numerical models verified from the experimental results were used for a parametric analysis to obtain the hysteretic response over a wider range of variables. The test results show that the local buckling failure of the plate at the base of the beam–column determines the failure mode of all three specimens. For a low axial compression ratio, a section with small width to thickness ratio may experience fracture. The parameter analysis showed that there is a flange-web interaction, and the evolution of cross-section plasticity under axial force is also related to the plate width to thickness ratio. In addition, through an analysis of the degree of plasticity in the cross-section under different parameter combinations, it is found that the classification of high-strength steel box-sections by the current specification is not rational, and that EC3 may be unreliable for 690 MPa box-section columns with Class 1 and Class 2 cross-sections, especially with a large axial compression ratio. A new cross-section classification method suitable for high-strength steel columns considering the influence of web-flange interaction and axial compression should be explored.
This study presents an experimental investigation of the fatigue performance of non-load-carrying transverse fillet-welded attachments made of high-strength steel (HSS). Four typical HSSs were selected, with steel yield strength of 460 MPa, 550 MPa, 690 MPa, and 960 MPa. A total of 88 high-cycle fatigue tests were conducted. Based on the analysis of the morphological details of the fracture surfaces and the failure modes, three different methods for fatigue assessment, such as the nominal stress method, the effective notch stress method and the strain energy density method, were applied to directly compare the fatigue performance of HSS and conventional strength steel (CSS, with a yield strength of approximately 235–355 MPa). HSS transverse fillet-welded attachments have demonstrated excellent fatigue resistance compared with specifications (FAT 80) in the design codes by using the nominal stress method, the natural slope of the S–N curves is nearly 4.0, rather than 3.0 prescribed in the current design codes for fatigue assessment of welded structures. For the notch stress method, HSS transverse fillet-welded attachments show a greater increase in fatigue life for low notch stress ranges (approximately Δσk≤ 400 MPa). However, for high notch stress ranges (approximately Δσk > 400 MPa), the increase in fatigue life is limited. The results with the strain energy density method are similar to those with the notch stress method.
This thesis evaluates the potential of laser-based additive manufacturing (AM) for the processing of two representative bulk metallic glass-forming alloys as well as their microstructure evolution and mechanical properties. It is demonstrated that both laser powder bed fusion (LPBF) and direct energy deposition (DED) exhibit great potential in the production of bulk metallic glass-forming alloys including bulk metallic glasses (BMGs) and bulk metallic glass composites (BMGCs). Our findings can provide some important fundamental and technological clues for the preparation of BMG and BMGC products with large dimensions, complex geometries, customized microstructures, and excellent properties by means of AM technologies. Laser-based AM technologies, due to their layer-by-layer forming manner and the processing principle without molds, are characterized by i) a rapid cooling rate and ii) flexible processing characteristics. The two outstanding advantages over traditional casting methods make them possess great potential in the production of BMGs and BMGCs without dimensional and geometric restrictions. In the literature, the successful fabrication of some bulk metallic glass-forming alloys through laser-based AM technologies, including LPBF and DED, have already been reported. However, there is a lack of information on the LPBF preparation of low-cost and high-strength Fe-Co-B-Si-Nb bulk metallic glass-forming alloys as well as a lack of knowledge of DED processing of high-strength and corrosion-resistant alloys of the Zr-Cu-Al-Nb system. In this thesis, {(Fe0.6Co0.4)0.75B0.2Si0.05}96Nb4 (at.%) and commercially available Zr59.3Cu28.8Al10.4Nb1.5 (trademark: AMZ4) are chosen as model alloys for LPBF- and DED-processing, respectively. The relationship between processing conditions, microstructure, and mechanical properties of bulk metallic glass-forming alloys by laser-based AM is investigated systematically. It is found that almost fully amorphous Fe-Co-B-Si-Nb BMGs can be obtained in LPBF-processing via the optimization of laser power and scanning speed, although microcracks form in all processing conditions. This demonstrates that LPBF is a promising but also challenging technology to process Fe-Co-B-Si-Nb BMGs, due to the extremely high brittleness of this FeCo-based BMG alloy and the large thermal stress involved in the processing. To overcome these challenges, Cu was introduced into LPBF fabrication of the FeCo-based alloys. Cu is almost immiscible in both Fe and Co, which leaves the glass-forming ability of the BMG alloy nearly unaffected. The role of the Cu in the processing of the forming BMG composite is two-fold: Alleviating thermal stresses through plastic deformation and increasing the cooling rate due to its high thermal conductivity. After processing optimization and systematic characterizations it was observed that all FeCoBSiNb-Cu samples presented an interpenetrating composite microstructure, which mainly comprises an amorphous Fe(Co)-rich phase and a fcc Cu-rich crystalline phase. The origin of this interpenetrating composite microstructure was analyzed and discussed on the basis of thermodynamic calculations, which indicate that a liquid-liquid phase separation and the high cooling rates during LPBF could be the primary reason for its formation. Nearly crack-free and high relative-density FeCoBSiNb-Cu BMGCs were prepared successfully at a moderate area energy density, and they exhibited a large plasticity and a relatively high fracture strength. Interestingly, compared with these highly dense and low-defect FeCoBSiNb-Cu BMGCs, LPBF-processed porous bulk samples at a low energy input showed a higher plasticity despite exhibiting a slightly lower fracture strength. In addition to the investigation on LPBF production of bulk metallic glass-forming alloys, DED fabrication of BMGCs was explored. In samples of DED-processed single-track, double-track and multiple-layer Zr-Cu-Al-Nb bulk metallic glass-forming alloys, a periodical composite microstructure with different crystalline features was observed. The periodical composite microstructure grows successfully coarser against the building direction as a result of the thermal cycling and the relatively high heat accumulation during DED processing. The microstructural evolution leads to a change of mechanical properties parallel to the building direction of the BMGC samples. The results imply that DED is promising to process BMGCs. However, further work is yet to be carried out to DED-fabricate fully amorphous BMGs or in-situ BMGCs with tailored microstructures and mechanical properties.
Plastic hinge beam-column model is widely used in the direct design method, but it cannot directly simulate the elastic unloading and cumulative damage effect in hysteresis analysis. This paper presents a theoretical study on the cyclic performance of high strength steel box-section columns. Firstly, the second-order effect and the additional axial strain due to the element bending are incorporated in the stiffness matrix formulation of the beam-column element. Then, the plasticity development in box section under axial force and bending moment is analyzed and a practical calculation method for the rotational stiffness of plastic hinges considering the cumulative damage effect is derived. Based on a new hysteresis criterion, an improved refined plastic hinge method is proposed for beam-column element to predict the hysteretic behavior. Existing experimental results of Q460 high strength steel welded box-section columns under cyclic loads are adopted to verify the reasonability and accuracy of the proposed method in which only one element per member is required. The proposed improved refined plastic hinge method is shown to be an efficient tool ready to be implemented into the design practice.
To study the flexural behavior of high-strength steel-precast concrete slab (HSS-PCS) composite beams with steel block shear connectors (SBSCs), seven HSS-PCS beam specimens subjected to a single concentrated load were tested, considering the parameters of concrete strength, steel strength, and shear connection degree. Through this experiment, the primary specimen information of vertical load, deflection, mid-span section strain, and interface slip were established. The HSS-PCS composite beam with steel block shear connectors has good overall working performance with high bending capacity and stiffness, and three failure modes are recorded including cracking at the tongue and groove joints, crushing of mid-span concrete slab, and failure of shear connections. The composite beams show a high degree of brittleness under these three failure modes, which should be considered in practical design. The existing design theory and standards are generally suitable for predicting the bending capacities of the novel prefabricated composite beams, in which the Eurocode 4 is slightly conservative, while the Chinese design specification has relatively good prediction results for the composite beams with partial shear connections.
This paper presents an experimental study on the elastic-plastic behavior of high-strength steel beam-to-column panel zones with the columns being formed by matching or under-matching welding conditions. Four column cross-sections, including built-up H-shape, built-up box-shape, cold-formed square, and cold-formed circular, are considered. The test involves eight beam-to-column joints subjected to cyclic loading with lateral displacements imposed at the beam ends. The failure modes, hysteretic curves, shear strengths, and shear strain distributions of panel zones are discussed. The test results indicated that all the specimens showed the linear elastic behaviors until the panel shear yield deformation angle and the panel zones exhibited stable hysteretic behavior even for large shear deformations. Regardless of welding conditions, the panel zones formed by built-up box-shape columns have the highest shear strength and initial stiffness among the four column types. The failure modes of specimens composed of built-up box-shape or cold-formed square columns were dependent on the welding conditions. In addition, the welding condition has negligible effect on the shear strength of panel zones formed by built-up H-shape or built-up box-shape columns; whereas, comparing to the matching welding, the under-matching welding resulted in a strength decreasing of about 8.96–12.67% for the panel zones formed by cold-formed square and cold-formed circular pipes.
Stainless-clad bimetallic steel is a high-performance steel with the advantages of cost and mechanical resilience. As the low-cycle fatigue characteristics of a material is essential for the seismic performance of structures, this paper investigates the low-cycle fatigue properties of a stainless-clad 304+Q235B bimetallic steel plate through a series of strain-controlled fatigue tests to gain a comprehensive understanding of the cyclic response, failure mode and fatigue strength of this material. Fatigue test results indicate that most of the fatigue cracks initiate and propagate in the side of substrate layer Q235B carbon steel, and no interface debonding is found till the fracture occurrence of the test coupons. The different applied strain ratios have negligible effects on the fatigue life of the 304+Q235B bimetallic steel due to the effect of the mean stress relaxation. The level of the observed cyclic hardening shows positively related with the cycled strain amplitude. Comparison of the Coffin-Manson strain-life curves between different steel grades further proves this 304+Q235B bimetallic steel possesses excellent low-cycle fatigue resistance. Finally, the calibration and verification of the nonlinear isotropic/kinematic hardening model parameters for this bimetallic steel are conducted and provide a good description of the experimental results.
This study presents a bolted built-up H-section column using high-strength steel with a yield stress higher than 770 MPa. Ten specimens were tested under axial compression loading to study the failure modes, load–deformation behavior, strength and stiffness, and strain characteristics. Test variables included bolt pitch (200, 400, 600, 800, and 1200 mm) and column slenderness ratio (17.8, 39.7, 63.4, and 87.1). When the slenderness ratio is small, the specimens show a local buckling dominated failure; when the slenderness ratio becomes larger, the specimens show an overall buckling dominated failure. The ultimate strength and axial stiffness increase with the decrease in slenderness ratio and bolt pitch, and the calculated axial stiffness is consistent with the test results. The axial compressive strengths were calculated according to AIJ 2002, ANSI/AISC 360-16 and GB 50017-2017 design codes; in addition, the equivalent slenderness ratio parameters were also compared and discussed. The results show that the design method suggested by AIJ 2002 provides good predictions for the ultimate strength of tested bolted built-up H-section columns.
To evaluate local buckling and its effect on the hysteretic performance of high-strength Q690 thin-walled H-section beam-columns, cyclic testing was carried out on four H-section columns composed of plates with a nominal yield strength of 690 MPa. Based on China’s standard for the design of steel structures (GB 50010-2017), the four H-section columns are categorized as S4 and S5 sections, and the axial load ratio of the columns is 0.2 and 0.35. After the test, the failure mode, second-order effect of bending moment, hysteresis curve, bearing capacity, backbone curve, energy dissipation, ductility and stiffness degradation of the specimens were investigated. The failure mode of the specimens is elastic–plastic local buckling of the column bottom flange and web. The ductility coefficient of the specimens is 2.08–3.04, and they have certain specific deformation and energy dissipation capacities. Following this, a finite element model was established to simulate the hysteretic performance of the Q690 thin-walled H-section beam-columns. The failure mode and hysteresis curve obtained by the finite element simulation corresponded well with the tests. Based on this agreement, a parametric study was carried out to investigate the influence of the flange width-thickness ratio, web width-thickness ratio, and axial load ratio on the local buckling and hysteretic performance of H-section beam-columns. The variation trend of the backbone curve and the bearing capacity were further investigated by the finite element parametric analysis. Finally, a prediction formula for the beam-column bearing capacity was proposed based on the finite element results. The comparison with the test results shows that the proposed formula has sufficient accuracy and can be used in engineering design.
In this study, experimental and numerical analysis were performed to investigate the stability of 16 circular hollow section (CHS) 7A04-T6 extruded aluminum alloy columns under eccentric load. The analyzed parameters included cross section size, eccentric distance and slenderness ratio. The ultimate strength, mid-span displacement and strain were recorded, and the results showed that all specimens failed due to overall flexural buckling. The experimentally-validated finite element model was established by ABAQUS considering the impact of initial imperfections. A large number of parametric analyses were carried out via this model to investigate the effects of cross section size, eccentric ratio and slenderness ratio on ultimate strength. The results of experiment and parametric analyses were compared with the design strengths predicted by EN 1999-1-1, the results showed that EN 1999-1-1 was conservative in predicting the ultimate strength of specimens with an eccentricity ratio above 0.6, however, when the eccentricity ratio was lower than 0.4 and the slenderness ratio was higher than 60, the EN 1999-1-1 would overestimate the strength.
This chapter presents a comprehensive experimental and numerical investigation into the structural behavior of both stocky and slender columns of the high-strength S690 welded H-section under axial compression. These members were expected to behave in an essentially similar fashion to those columns of the normal-strength S355 welded section columns, and a total of 24 axial compression tests on both stocky and slender columns have been conducted. This has permitted the specific effects of initial imperfections, namely, (1) welding-induced residual stresses and (2) member out-of-straightness, accurately on the structural behavior of these particular sections under axial compression to be assessed. The effects of residual stresses on the deformation characteristics of these S690 welded sections are generally considered to be proportionally less pronounced than is the case for S355 welded sections. Hence, an improvement to the current design rules recommended in EN 1993-1-1 is highly desirable. To develop representative numerical models that simulate the structural behavior of these S690 welded H-sections with an accurate incorporation of the welding-induced residual stresses, an integrated numerical modeling technique for the thermal, thermomechanical, and structural responses of these high-strength S690 welded H-sections has been developed. Compatible three-dimensional finite element models with both heat transfer and stress elements are employed to perform sequentially coupled thermomechanical analyses, followed by structural analyses. Through a rational simulation of the welding process, highly nonlinear welding-induced residual stresses in the vicinity of the flange/web junctions are fully incorporated into the structural models of these welded H-sections together with geometrical initial imperfections when examining the structural behavior of both stocky and slender columns under axial compression. These models have been carefully calibrated against transient surface temperature histories during welding, surface residual stresses after welding, and deformation characteristics under axial compression. A comprehensive parametric study was then performed to generate a total of 80 numerical data that served as the basis for a rational improvement to the current design rules given in EN 1993-1-1, using suitably selected material-dependent parameters.
Superior high-performance (SHP) steel is a kind of advanced steel with high strength and ductility, fire-resistant, and corrosion-resistant performance. It is especially suitable for structural engineering resistant to natural disasters such as fire, earthquake, environmental corrosion, etc. This paper aims to investigate the hysteresis behaviour of SHP steel welded I-section beam-columns. Four full-scale specimens under the combined action of constant axial load and horizontal reciprocating load were tested, and finite element models were developed accordingly. Based on comparisons of the test phenomena, failure modes, hysteretic curves, strain curves, energy dissipation capacity and ductility, effects of flange and web width-to-thickness ratio on the performance of the specimens were clarified. In addition, a 3-D finite element model was developed and further validated against the test results. Variation ranges of flange width-to-thickness ratio, web width-to-thickness ratio and axial load ratio were increased to further analyze the influence of critical parameters on the seismic performance of SHP steel beam-column in the parametric analyses. Finally, according to the test and finite element modelling results, whether the seismic performance of the SHP steel welded I-section beam-columns complies with the relevant provisions of the national standards Eurocode 3 and GB 50011–2010 was evaluated, and design suggestions were proposed accordingly. Research outcomes showed that the SHP steel beam-columns with good energy dissipation capacity and ductility could be applied to seismic steel frames in practical engineering; the failure modes of the specimens are local buckling rather than member instability; a smaller width-to-thickness ratio of the specimen could lead to a plumper hysteresis curve, more sufficient development of plasticity, a greater total energy consumption, and better ductility performance; the web and flanges have certain restrained effects, which should be comprehensively considered in seismic design of the SHP steel beam-columns. The research findings herein may provide an important basis for understanding the hysteresis behaviour of the SHP steel beam-columns as well as for their application in practice.
We calculate the parameter that governs the width of the transition zone by molecular dynamics (MD) simulation and use it in a phase-field crack (PFC) simulation with the mechanical properties of iron. First, a quantitative evaluation of intactness is conducted by examining the change in atomic conformation induced by crack propagation, whose numerical data are taken from the result of the MD simulation. The spatial distribution of the intactness is fitted to the same function as the damage parameter in the PFC model, namely, an exponential function, by the least-squares method. From this distribution, the transition zone parameter is estimated. The result of the PFC simulation using this newly determined transition zone parameter is discussed in terms of the crack path by comparison with the result of crack propagation analysis based on the MD simulation.
This paper presents an experimental investigation into mechanical properties and fatigue performance of butt-welded high strength steel plates. Four typical high-strength steels (HSSs) were selected, with steel grades of 460, 550, 690, and 960 MPa. Mechanical properties were measured through monotonic tensile tests, cold bending tests, Charpy V-notch impact tests and hardness tests. A total of 114 fatigue tests were conducted on butt-welded high-strength steel plates. Comparisons of mechanical properties and fatigue performance are made among HSSs tested and conventional strength steels (CSSs) with a yield strength around 235 to 355 MPa. The natural slope of S–N curves for HSS butt-welded connections varied from 3 to 5. Two fatigue design approaches are recommended with one based on natural slope and one based on a fixed slope of 3 as for CSSs.
High strength structural steel (HSSS) can be divided into TMCP (Thermo-Mechanical Controlled Process) and QT (Quenched and Tempered) types according to the manufacturing process. Most previous studies on the post-fire mechanical properties of HSSS were conducted on QT HSSS, while few studies were conducted on TMCP HSSS. In order to identify the effect of manufacturing process on the post-fire mechanical properties of HSSS, experimental studies were carried out on TMCP Q550 and TMCP Q690 HSSS and the results were compared with the previous studies on corresponding QT Q550 and QT Q690 HSSS. The static tensile tests were conducted at ambient temperature on TMCP Q550 and TMCP Q690 HSSS specimens heated up to nine pre-selected temperatures ranging from 200 to 900°C and then cooling in air and water respectively to simulate various post-fire situations. It can be found that the heating and cooling process had little influence on elastic modulus but significant effect on strength and ultimate elongation once the heated temperature exceeded 600°C, and the cooling way and manufacturing process became critical once the heated temperature exceeded 700°C. In general, the post-fire strength and ultimate elongation was always less for TMCP HSSS than QT HSSS.
This study investigates the fatigue behavior of trusses. Various types of panel-point-structures were designed for the purpose of obtaining compact and strong nodal joint, and fatigue tests of the structural models on the scale of about one quarter were carried out. Based on the previous study, details of nodal joint were improved and the process of corner weld was changed from manual shielded arc welding to submerged-arc welding. The local stresses distribution in the vicinity of nodal joint and their influences on the fatigue strength are also shown through the finite element stress analysis.
本研究は, 各種の構造用鋼材に対して歪時効を発生させ, その後, シャルピー試験を行って, 歪時効によるシャルピー吸収エネルギーと遷移温度の変化を実験的に検討したものである. 橋梁における冷間曲げ加工半径は, 塑性歪を受けた鋼材の歪時効脆化を防止する観点から, 板厚の15倍以上とすることが規定されてきた (3%の塑性歪以下に対応). 本研究では, 最近の構造用鋼材を対象として歪時効脆化の実験を行い, 許容される冷間曲げ加工半径の検討を行った. その結果, 従来の許容値 (3%) より大きな塑性歪 (7.5%～10%) を与えても, 必要な靱性が確保されることが明らかになった. そこで, 鋼材のシャルピー吸収エネルギーレベルに応じた冷間曲げ加工半径の許容値を提言するものである.
The expansion work of the Tokyo International Airport is now going forward which will increase its capacity. Nine bridges are being constructed there to link terminal buildings and car parks as well as main roads. The Air-Side Bridge is a 2-span continuous steel cable-stayed bridge with a center span of 88.5m. This bridge has been designed taking its landscape into full consideration, particularly to match surrounding facilities, the characteristics of the airport itself, and so on. As the results, the bridge has been fabricated by all-weldind work at every joint on the site. Since the bridge is the first all-welded one in Japan, the execution has been fully controlled. This report presents the structural features and the work control system of that bridge and its results.
One box section member whose dimensions were almost equal to the truss chord of the Akashi Strait Bridge was tested under repeated bending by using a 4MN fatigue testing machine. The four corner joints consist of partially penetrated groove welds from outsides and fillet welds from insides. These corner joints contain blowholes with various sizes at the roots. The fatigur strengths of corner joints decrease remarkably with the increasing of blowhole size at the root of corner joints.
IN THE PRESENT STUDY, FATIGUE TESTS OF PARTIALLY-PENETRATEDLONGITUDINAL WELDED SPECIMENS OF WHICH ROOTS CONTAIN VARIOUS SHAPES AND SIZES OF BLOWHOLES ARE CARRIED OUT TO INVESTIGATE THE INFLUENCES OF BLOWHOLES ON THE FATIGUE STRENGTHS OF JOINTS. THE ACTUAL BEHAVIOR OF INITIATION AND PROPAGATION OF FATIGUE CRACKS EMANATING FROM BLOWHOLE IS CLARIFIED BY THE BEACH MARK TESTS OF THESE SPECIMENS. FURTHER, THE APPLICABILITY OF FRACTURE MECHANICS CONCEPTS OF FATIGUE CRACK GROWTH TOTHE PREDICTION OF FATIGUE LIFE OF THE JOINTS CONTAINING BLOWHOLES IS STUDIED. IN ENGLISH.
By rearranging existing fatigue test results, fatigue performance of typical welded joints, (longitudinal, cruciform and out-of-plane gusset welded joint) are discussed with respect to the dependence on steel strength and on joint size. The relationship between fatigue strength and steel strength was not clear for longitudinal welded joints of small specimens and large-scale girder specimens. For cruciform welded joints and out-of-plane gusset welded joints, fatigue strength of small joint specimens is independent of the steel strength, but that of girder specimens decreases with increase in steel strength. In addition, fatigue strengths of these two types of welded joints decrease with increase in joint size, especially for girder specimens.In order to discuss these relationships in detail, fatigue tests with out-of-plane gusset welded joint specimens and large-scale girder specimens, including web gusset joints made of JIS SM570 and 900 MPa class steel were carried out. From the fatigue tests, similar tendencies were found to those obtained from existing test results. Although fatigue tests of joint specimens showed no difference in fatigue strength, crack initiation life and crack propagation rate between the steel strengths, fatigue strength of girder specimens made of 900 MPa class steels is much lower than for JIS SM570. In addition, fatigue strength of the girder specimens is considerably lower than that of the joint specimens. This difference results mainly from an increase in stress concentration due to joint geometry, and combination of nominal stress and shear stress in the girder specimens. It was found that the influence of the combination can be approximately evaluated from the nominal principal stress.
Fatigue strength improvement of welded joint by additional welding with low temperature metallurgical transformation electrode
- Miki K C Anami
- Higushi
Anami K, Miki C, Higushi Y. Fatigue strength improvement of welded joint by additional welding with low temperature metallurgical transformation electrode. Proc JSCE 2001.
A study on fracture toughness properties of strain-aged structural steels
- Mori