Performance Of High Strength Steel Research Articles

Experimental study and finite element analysis on shear performance of high strength steel reinforced ultra-high performance concrete beam

This paper investigates the shear performance of high strength steel reinforced ultra-high (HSSUHPC). Test were carried out on seven beam specimens with the different parameters of web steel ratio, shear-to-span ratio, and steel fibres content in volume. The failure patterns and load-displacement curves were obtained. The bearing capacity, deformation capacity and strain variation laws of UHPC, steel web, stirrups, tensile longitudinal reinforcement and tensile flange of steel were analyzed. The experimental study established the finite element model of the shear performance of HSSRUHPC beams. The results of finite element fit well with the experimental results. Then parametric analysis was carried out. The results showed two shear failure patterns for the HSSRUHPC beam: shear diagonal compression failure and shear-compression failure. The mechanical process of the HSSRUHPC beam could be divided into four stages: the elastic stage, cracking stage, strengthening stage, and failure stage. There were two peak loads for the load-displacement curves. As the steel ratio of the steel web and yield strength of steel increased, the bearing capacity and deformation capacity of the HSSRUHPC beam increased. The shear-to-span ratio had a significant influence on the failure pattern of HSSRUHPC beam, and with the increase of the shear-to-span ratio, the bearing capacity of the HSSRUHPC beam decreased, but the deformation capacity increased. As fibre content increased, the crack resistance and deformation capacity of the HSSRUHPC beam were improved. With the increasing width ratio between the steel flange and beam, the bearing capacity of HSSRUHPC beam increased, but the change range decreased, so it is suggested that the width ratio between the steel flange and beam should not be larger than 0.6. As the stirrup ratio increased, the bearing capacity of the HSSRUHPC beam increased, but the availability of stirrups decreased, so it is suggested the stirrup ratio should not be over 3 %.

Behaviour and design of high strength steel circular hollow section member under pure torsion

The paper presents a detailed numerical investigation on the performance of high strength steel (HSS) circular hollow section (CHS) member subjected to pure torsion. Three grades of HSS, viz., S700, S900 and S1100, were considered in the study. Finite element (FE) models were initially developed and validated against the available test results. Further, the validated FE models were used for parametric study. Cross-sections of varying thickness and diameters, as well as HSS grades, were considered for the parametric study. The results generated from the parametric study were then utilised to assess the effect of steel grades on the torsional capacities and deformed shapes at ultimate and post-ultimate capacities. The effect of ratio of yield strength to ultimate ratio on the normalised member capacities has also been studied. Furthermore, the applicability of existing design equations for members subjected to pure torsion have been assessed against the FE generated member capacities. Based on the analysis, most of design predictions outlined in European and American Standards, as well as those proposed by various researchers were found unsuitable for design of HSS CHS under torsion. Hence, two modified design equations based on continuous strength method and direct strength method has been proposed. The modified design methods were found to predict more accurate and reliable torsional capacities.

Lateral-torsional buckling performance of high strength steel rectangular hollow section beam-columns

A new approach namely Plate-Beam theory was employed to perform the investigation into the lateral torsional buckling (LTB) performance of high strength steel (HSS) rectangular hollow section (RHS) beam-columns. Firstly, the total strain energy corresponding to the LTB failure mode of the beam-columns was established, and then the equilibrium differential equation was developed, through the variation of energy functional. Based on the Plate-Beam theory, the equivalent restrained torsional rigidity (warpage constant) that can simultaneously accounted for the secondary warping effect was derived, and the formulation process did not involve any sectoral coordinate operation. The deducing process of the total strain energy of RHS beam-columns was further discussed and recommended to describe the torsion performance of composite and irregular thin-walled members. Based on the FE program verified against test data and theoretical solution, the accuracy of the provisions of HSS RHS beam-columns given in Eurocode3 and GB50017-2017 was assessed. The comparison of numerical program against codified design provisions revealed that the resistance prediction in Eurocode3 was still serviceable for HSS RHS beam-columns, in conjunction with the torsional rigidity according to the Plate-Beam theory.

Effect of 0.1 wt% Nb on the microstructure and corrosion fatigue performance of high strength steels

In this manuscript, the effect of 0.1% Nb addition on the corrosion fatigue behavior of the marine engineering steel has been studied through corrosion fatigue experiments, electrochemical hydrogen charging, and a series of microscopic characterization methods. The results show that BM steel has a high corrosion fatigue sensitivity in the marine environment. Compared to BM steel, the corrosion fatigue sensitivity of 0.1 Nb steel is reduced by 8% in the marine environment, and it reduced by 40% in the hydrogen charging environment. 0.1% Nb adding inhibits hydrogen concentration in local areas by forming irreversible hydrogen traps NbC and by improving the microstructure, and it lowers the diffusible hydrogen content and total hydrogen content inside the steel by inhibiting electrochemical hydrogen evolution reaction to hold back the corrosion fatigue crack initiation and propagation, thereby improving the ability of resisting corrosion fatigue cracking for the marine engineering steel.

In-Plane Interactive Buckling of High Strength Steel Welded Wide Web I-Section Beam-Columns

A numerical investigation on the overall-local interactive buckling performance of high strength steel (HSS) wide web I-section members was conducted using finite element (FE) models verified against experimental data. The effect of overall slenderness, the height-thickness ratio of the web h w / t w , and the width-thickness ratio of the flanges (bf/tf) on ultimate load was parametrically analyzed. The result demonstrated that (i) for the beam-columns with higher steel grade, the Pz-Uz curve presents a relatively obvious deformation plateau, meaning a certain degree of ductility. (ii) The ultimate load decreased essentially linearly resulting from higher h w / t w , and the trend was graphically consistent under various steel grades. (iii) bf/tf lower than 0.6 led to the failure mode of shearing buckling, and the corresponding ultimate load increased with an increase of bf/tf. In the case of bf/tf greater than 0.6, the ultimate load decreased as a result of the higher bf/tf. Based on the concept of the direct strength method, the local postbuckling strength prediction formula was fitted with stub beam-column FE results and examined with experiment data. The correlation formula of compression and bending moment was proposed to evaluate the resistance of the interactive buckling of the HSS wide web I-section underpinned by the FE results of beam-columns with intermediate length and experiment data.

Ductile fracture locus identification using mesoscale critical equivalent plastic strain

AbstractThe ductile performance of high strength steel (HSS) from different steel grades, producers, manufacturing processes varies a lot. It is also difficult to conduct all kinds of reliable experiments to generate different stress status through different initial specimen geometries or by applying different load combinations in the civil engineering sector. One of the common issues for HSS structures is to identify the parameters of the ductile fracture model conveniently from the uniaxial stress–strain relationship obtained from common coupon specimens. An attempt is made in this paper to use the proposed mesoscale critical equivalent plastic strain (MCEPS) to calibrate the fracture locus of the uncoupled phenomenological model based only on the engineering stress–strain relationship. The proposed method is successfully validated by the Sandia fracture challenge in 2014.

Effect of austenitizing and tempering on impact resistance of a hot rolled high strength steel

The aim of this study is to investigate the effect of heat treatments on the impact properties of hot rolled high strength steel and describes the effect of tempering temperature and quenching media on the microstructure, hardness, and impact resistance of plates. In the present study a high strength steel was austenitized at 900 °C with different quenching medium and followed by tempering at 300 °C, 500 °C. After thermal treatments, the values of Charpy impact resistance, hardness, and microscopic structure were evaluated from mechanical and metallographic analysis of metals respectively. The change of mechanical properties and microstructure of the metal with the existence of heat treatment with the ballistic performance of high-strength steel. Experimental results showed that tempering at 500 °C for 2 hours after water quenching medium it provides the best mechanical properties in conjunct on with an improved in microstructure.

Local-overall interactive buckling of high strength steel welded I-section columns under axial compression

In this study, the investigation on the overall-local interactive buckling performance of high strength steel welded I-section columns was carried out. Finite element models of steel columns of different yield strength (235 MPa, 460 MPa, 500MPa, 690 MPa, 800MPa, 960 MPa) were constructed considering geometric imperfection and residual stresses, and verified against the existing test results. Effect of geometric imperfection including global imperfection and local imperfection was found to be largely dependent on the nominal slenderness ratio of columns (λn). Local imperfection present prominent influence for the case of λn lower than 0.4, while global imperfection for the case of λn exceeding 0.95. Effect of four types of residual stress patterns on ultimate capacity were compared, the disparity of which was around 10%. Comprehensive effect of imperfections on local buckling load was found to be smaller resulted from higher steel grade; whilst that on stiffness became more pronounced. Based on the test data of stub columns, new predict formulas were proposed for the local post-buckling strength using effective width method and direct strength method respectively. Continuing the investigation of stub columns, the formulas for interactive buckling resistance of high strength steel welded I-section around the weak axis were studied, where column curve b in Eurocode3 was suggested to be adopted.

Probabilistic seismic performance evaluation of steel moment frame using high-strength and high-ductility steel

To shorten a steel building recovery time after an earthquake, a dual and damaged-controlled system is proposed, in which the seismic energy is absorbed by a highly ductile buckling restrained brace (BRB) and the gravity load is resisted by high-strength column. Because the seismic energy is mainly dissipated by the BRB, to accurately simulate the BRB hysteretic behavior is essential. Thus, kinematic hardening and two surface theories are adopted and coded as an ABAQUS user-defined material (UMAT). Particle swarm optimization (PSO) is used to find the optimal design equivalent to a corresponding traditional structure. The performance of the optimal frame is verified by nonlinear time history and fragility analysis. Based on the found optimum, a practical design guideline is recommended. The performance of high-strength steel and a high-ductility structural system such as the inter-story drift, maximum roof acceleration, property of BRB hysteresis, strength ratio between the main frame and BRB and cumulative fatigue damage are investigated. In addition, the economic feasibility of using high-strength steel in the structural system is compared to that using traditional steel materials.

Experimental study on fatigue performance of high strength steel welded joints

The welded joint of steel structure is prone to occur fatigue fracture under dynamic loads. In this paper, an experimental study on the fatigue performance of base material, butt weld, and cross fillet weld of high-strength steels were investigated. The S-N curve was fitted, and the corresponding fatigue life was predicted. Results corroborate that the base material of high-strength steel possess high fatigue resistance. AISC360 and EC3 standard design curves are applicable for the evaluation of the butt weld fatigue performance of Q460D and possess adequate safety margin, but only suitable for low-fatigue life estimation of Q690D butt weld. With respect to cross fillet weld, AISC360 design curve not only is suitable for the fatigue life analysis of Q460D and Q690D but also has enough safety margins, while EC3 and BS7608 codes possess relatively low fatigue limit. In addition, a quantitative analysis on fatigue fracture was conducted on the basis of fatigue damage theory, and the fatigue crack propagation law was disclosed on the basis of fracture morphology. The crack propagation law before instant fracture is consistent with damage development, and the fatigue striation width increases gradually with damage development. The fast crack propagation stage accounts for a small proportion in the fatigue life, thereby indicating that this stage is insufficiently developed.

Comparison and Analysis of Steel Frame Based on High Strength Column and Normal Strength Column

The anti-seismic performance of high strength steel has restricted its industrialization in civil buildings. In order to study the influence of high strength steel column on frame structure, three models are designed through MIDAS/GEN finite element software. By comparing the seismic performance and economic performance of the three models, the three different structures are comprehensively evaluated to provide some references for the development of high strength steel in steel structure.

Dual-concentrically Braced Frames Using High Strength Steel – Seismic Response

The recent technological advances on steel production process allowed introducing in construction market steel grades with significantly high yield strength. These new materials are known as High Strength Steel (HSS). The use of these steel grades offers economical and mechanical benefits compared with mild carbon steel (MCS). Consequently, their use is constantly increasing especially for seismic applications that are the rational field to exploit the high performance of HSS, by means of the “dual-steel” concept, which combines the HSS with MCS in order to provide overstrength to non-dissipative element and ductility to dissipative ones, thus controlling the global frame behaviour into a ductile overall failure mode. In this paper, a comprehensive parametric study devoted to investigate the seismic performance of Eurocode 8 compliant dual-steel chevron Dual-Concentrically Braced Frames (D-CBF) is presented and discussed. This structural typology is composed of two dissipative sub-systems acting in parallel, namely Moment Resisting Frames (MRFs) and Concentrically Braced Frames (CBFs). Static nonlinear pushover analyses were carried out in order to assess the seismic performance of the D-CBFs. The examined parameters cover both geometric and mechanical variables, as the type columns, span length, number of storeys and spectral shape. The analyses showed that the use of HSS in Eurocode 8 compliant D-CBFs is effective to avoid the damage in non-dissipative members. On the other hand, the use of HSS leads to design flexible members, especially for the braced-intercepted beams, resulting in poor performance of bracing members due to significant damage concentration. The economic evaluation shows that the use of HSS allows reducing the material consumptions and dropping the total constructional costs.

Fracture performance of high strength steels, aluminium and magnesium alloys during plastic deformation

A series of uniaxial tension tests were performed for 5052 and 6061 aluminum alloys, AZ31B magnesium alloy, TRIP600 and DP600 steels, to obtain a better understanding of their fracture performance. Scanning electron microscope (SEM) observation of the microstructure evolution was conducted. The dimple structure, orientation relationship between the fracture surface and tensile direction, necking behavior were analyzed. The fracture mechanism and fracture mode of each material was discussed in detail. The results show that TRIP600 steel is subject to a typical inter-granular ductile fracture combined by shear fracture. DP600 steel belongs to mainly ductility mixed with normal fracture. Both 5052 and 6061 aluminum alloys are subject to a mixed ductility fracture and brittle fracture. AA5052 and AA6061 belong to a typical shear fracture and a normal fracture, respectively. Magnesium AZ31B is typical of a brittle fracture combined with normal fracture.

Weight and cost optimization of welded high strength steel beams

In this study, economical use of high strength steel in welded beams is considered. The purpose is to compare the performance of high strength steels of grades S500 and S700 with the reference grade S355, when employed in simply supported, geometrically double-symmetric I-beams under uniform transverse loading. The beams are optimized separately for weight and cost under the design rules of Eurocode 3. Bending and shear resistances are considered, but lateral torsional buckling is neglected. Hybrid beams, where the flanges and the web may be of different steel grades, are also treated. The cross-section can belong to any of the four classes of Eurocode, which means that both plastic and elastic design is considered. The cost function takes into account fabrication, transportation and erecting the beam on site. The results indicate that while significant weight reduction can be obtained by high strength steels, rather limited cost savings are achieved compared with S355. On the other hand, hybrid cross-sections display promising potential as the most economical solution.

Seismic behavior of high strength steel welded beam-column members

This study presents the evaluation of seismic performance of high strength steel (HSS) beam-columns. Quasi-static experiments were carried out on four welded H-section and four box-section beam-column members fabricated from flame-cut Q460C HSS. The specimens were subjected to combined constant axial load and cyclic lateral load. The axial load was held at 30% of the yield strength of specimen during the loading history. The effects of width to thickness ratio and height to thickness ratio on the seismic behavior of HSS beam-columns were evaluated. It is found that component plate slenderness ratio has a significant effect on the deterioration behavior of beam-column under cyclic loading. According to the test results, welded Q460C HSS beam-columns with compact cross-sections show a good capacity of energy dissipation. No significant degradation was observed for the moment capacity of very compact cross-sections as class 1 under large inelastic rotation. The moderate compact cross-section belonging to class 2 shows a decrease in the moment capacity accompanied with the occurrence of local buckling when storey drift ratio is around 1/30. In addition to the obtained end moment–rotation hysteretic curves, the end moment–curvature hysteretic curves were developed to achieve more accurate descriptions of the cyclic performance of HSS specimens. Based on the generalization of experimental hysteretic curves, a trilinear hysteretic model was proposed in terms of the normalized moment–curvature relationship. This model was further compared with the experimental study to validate the accuracy in predicting the seismic behavior of HSS beam-column members.

Comparison of the Bearing Capacity of Dry and Wet Cutting Surfaces

The performance of high strength steels is sensitive to the surface quality of machined surfaces. The effect of cutting condition on the variation of surface roughness in turning of 30CrMnSiA steel has been investigated through a serial of dry and oil-lubricant cutting tests. The characters of an amplitude characteristics set, Ra, Ry and tp, which are associated with the general shape of the machined surface profiles, are investigated in this study. It is concluded that, in the aspect of Ra and Ry values, dry cutting condition provides a similar surface roughness as in wet cutting condition under the experimental conditions of the present research; the bearing capacity of both kinds of machined surfaces, characterized by the bearing length rate tp, could be different according to the cutting parameters combinations.

Optimizing the Prestrain Fatigue Performance of Transformation-Induced Plasticity-Aided Steel

The cut-edge properties of automotive structures formed during the manufacturing processes significantly influence fatigue and formability performance of high-strength steels. This factor is becoming increasingly important as advanced high-strength transformation-induced plasticity TRiP-aided DP600 steels under examination exhibit an increased sensitivity to fatigue cracks initiating from mechanical cut-edges. It was determined that under prestraining, the effects of plastic deformation of the microstructure can be used to optimize fatigue life. This was particularly the case where the prestraining significantly improved the fatigue lives of mechanical cut-edges up to a prestrain level of 5%. It is proposed that the effect of prestraining can be used to optimize the fatigue lives of even damaged mechanical cut-edges. These parameters can be used in the manufacture of structures with both optimum formability and fatigue lives.

Post-fire performance of very high strength steel S960

For the time being, high strength steels and very high strength steels have gained employment in some significant structural components of landmark constructions, where the strength can be fully utilized. However the available research on structural and material performance of high strength steels and very high strength steels is very limited in literature, especially for very high strength steels. The potential advantage and low research level of very high strength steels call for more researches. The steel members made of very high strength steels in constructions are sometimes inevitably exposed to fire hazards, after fire whether they are reusable or not, it needs a reliable evaluation. In order to reveal post-fire material performance of very high strength steel S960, an experimental study was carried out, which serves for the evaluation of post-fire performance of structures with components made of S960. Tensile tests were undertaken on specimens made of S960 after cooling down from temperatures up to 1000°C. Its post-fire elastic modulus, yield strength, ultimate strength, and stress–strain curves were obtained. It is found that the post-fire performance of structural steels is dependent on steel grade. Some unique predictive equations were proposed for evaluating the mechanical properties of S960 after fire.

Key Technology to Reduce Residual Stress Level of High Strength Steel

Given that the traditional hot temper passing process cannot fulfill the demand of high strength steel on residual stress level and stable processability, leveler and temper passing process with dual servo valve (LTP-DSV) is developed to solve this technical problem. LTP-DSV process employs leveler to reduce residual stress level of high strength steel; uses dual servo valve variable gain rolling force control technology to improve performance stability of high strength steel; improves surface quality of high strength steel by means of temper passing. The residual stress level of products is substantially reduced on condition that the performance of high strength steel is ensured. The actual production data shows LTP-DS process is able to improve the performance and quality of high strength steel from all aspects.

Characteristics of abrasive waterjet cut-edges and the affect on formability and fatigue performance of high strength steels

The characteristic surface properties and internal workpiece transformations formed during the Abrasive Waterjet (AWJ) cutting process influences the formability and fatigue performance of steel cut-edges. This relatively established cutting technology is used in industry to generate specialist low production components, which may undergo continual loading cycles under operational service conditions. The fatigue performance of AWJ cut-edges can be critical since individual notch defects produced by the cutting process can act as initiation sites from where fatigue cracks can propagate. Due to the increased sensitivity of high strength structural steels to cut-edge fatigue, AWJ cut-edge defects have an ever more significant influence on fatigue performance. The relationship between the traverse cutting speed and the influence on the resulting properties of the cut-edge has been the critical area of investigation. The affects of traverse cutting speed on the surface roughness properties and cut-edge hardening through a process of plastic deformation of grains in the near edge region were observed to be influenced by the traverse cutting speed. It is these characteristic factors that were determined to influence the cut-edge ductility and fatigue performance of steel components. It is a combination of the AWJ properties that produces cut-edges, which are positive for the Hole Expansion Capacity (HEC) but negative for stress life and cyclic stress strain life fatigue performance of AWJ cut high strength steels.