Tension Steel Research Articles

Design and application of inclined tensioned steel cantilevered scaffolding

Design and application of inclined tensioned steel cantilevered scaffolding

Buckling-restrained behavior of woven steel strip shear walls: Experiment and numerical simulation

A novel woven Buckling-Restrained Steel Strip Shear Wall (WBR-SSSW) is proposed for low and medium-rise buildings in this study. The proposed shear wall, comprising inclined arrangements of steel strips with varying dimensions, is categorized into compression and tension steel strips under horizontal loads. By weaving the steel strips, the out-of-plane buckling deformation of the compression strips is significantly alleviated. Cyclic tests were carried out on two 1/3-scaled single-story single-span SSSW specimens to investigate the seismic behavior of woven and non-woven SSSW. Finite element models of two types of SSSW were established and validated by test results. The results showed that the WBR-SSSW exhibited a distinct stress transfer path and stable bearing capacity, with the tension steel strip bearing the majority of the shear load. Compared to specimen SSSW, the WBR-SSSW reduced out-of-plane displacement by over 35 % at each loading level. Parametric analysis of the thickness, number, and width-to-spacing ratios of the steel strips was conducted to optimize the woven-net size. Additionally, a simplified theoretical model for WBR-SSSW was developed, showing good accuracy compared to finite element results, which can be used to estimate the structural shear bearing capacity.

Espérance Bridge

Espérance Bridge is one of the final infrastructure elements to be delivered on the King’s Cross estate in central London. The 25 metre footbridge spans over the Regent’s Canal to connect the major railway stations and Pancras Square in the south with shopping and eating hotspots, Granary Square and Coal Drops Yard in the north. As part of the original King’s Cross master plan, the bridge strengthens the link between the two halves of the site, enabling visitor flow and giving residents better access to public transport. The bridge also enlivens the canal corridor, providing a platform to observe Camley Street Natural Park to the west and the Ghat Steps to the east. Designed and constructed during a global pandemic and opening in the summer of 2021, the bridge is an innovative take on a traditional warren truss bridge that uses tapering and folded steel plates to create an elegant and sculptural form. The bold pomegranate red carbon steel plates set against the diagonal stainless steel tension ties illustrate the structural behaviour of the warren truss. Re-use of existing foundations to support the bridge ensured a seamless integration of the abutments into the setting, whilst also providing cost and carbon benefits.

Dynamic mechanical properties and uni-axial constitutive model of S30408 stainless steel

This paper investigates its mechanical properties at different strain rates and the uni-axial constitutive model of S30408 (S30408 known as 1.4301 in EN10088:1, 304 in ASTM standard) stainless steel. Firstly, the tensile and compressive mechanical properties of S30408 stainless steel were tested at four strain rates (0.001 s−1, 1000 s−1, 3000 s−1, 5000 s−1) by performing quasi-static tests as well as split Hopkinson tension bar (SHTB) and split Hopkinson pressure bar (SHPB) tests. Based on the tests, the stress-strain curves of S30408 stainless steel under tensile and compressive conditions at different strain rates were obtained. The results show that S30408 stainless steel revealed a significant strain rate strengthening effect, and there were some differences in the mechanical properties of S30408 stainless steel in tension and compression under different strain rates. Then based on these test results, a modified Johnson–Cook model was established under tensile and compression conditions. The accuracy of the proposed modified Johnson-Cook model was verified by the finite element software LS-DYNA. The modified model can provide a reference for the study of mechanical properties and computational simulation of S30408 stainless steel under high strain rate conditions such as impact and blast load.

Blast resistant performance and damage mechanism of steel reinforced concrete beams under contact explosion

To investigate the blast resistance of steel reinforced concrete (SRC) beams under contact explosion, contact explosion tests on four SRC beams were carried out. The damage modes and dynamic response of SRC beams and the effect of structural steel and studs were analyzed. Finite element models of SRC beams and the corresponding RC beams were established to compare and analyze the different stress wave propagation in the middle-span cross-section and stress-time history curves of critical nodes in the section to reveal the damage mechanism of SRC beams. The results show that under contact explosion, U-shaped craters were formed on the blasting surface of the SRC beams, and the depth of the crater center was the distance from the top surface of the beam to the top surface of structural steel. The cover concrete on upper half side surfaces and bottom surface was spalled off. However, the concrete protected by structural steel flanges was not damaged, and comparing with RC beams, the setting of structural steel reduced the compressive stress in concrete protected or shielded by structural steel flanges and tension stress waves in concrete near the side and bottom surfaces of SRC beams. So, the concrete spalling on the side and bottom surfaces suffered less severe damage, and concrete protected by structural steel flanges was not damaged for SRC beams. Besides, when larger structural steel was used, the effects were more significant.

Evaluation of inclusion agglomeration behavior in molten steel based on the modified model of cavity bridge force

Inclusion agglomeration behavior in molten steel is a key factor that affecting steelmaking process and steel quality. In this work, the modification on the Laplace pressure of cavitation interaction between inclusions has been made according to the calculation model of cavity bridge force. The effects of the distance between inclusions, the diameter of inclusions, the surface tension of molten steel, and the contact angle between inclusions and molten steel on the cavity bridge force were quantitatively investigated by using this modified model. The results show that the contact angle between inclusions and molten steel has a significant influence on inclusions agglomeration. The inclusions cannot agglomerate by cavity bridge force when the contact angle is less than 90°. Subsequently, the agglomeration tendency of different inclusions was calculated and compared. The order of cavity bridge force and critical agglomeration distance of inclusions in molten steel is MgO·Al2O3 < CaO < MgO < Ti2O3 < AlN < Al2O3. Then the high temperature experiments were carried out to investigate the evolution of inclusions sizes in molten steel. It is found that the average size of Al2O3 is larger than that of AlN, which indicates that the agglomeration tendency of AlN inclusions is much weaker than that of Al2O3 inclusions. This calculation model can accurately evaluate the agglomeration behavior of inclusions and provide theoretical guidance for inclusions control.

Design and Analysis of Novel Anti-Rocking Bearing

To address the issue of severe rocking phenomena under seismic conditions in structures equipped with steel spring isolation bearings, this paper investigates a novel type of anti-rocking bearing. Firstly, the structural configuration and working principle of the novel anti-rocking bearing are introduced, and a design method for bearing parameters is proposed. Secondly, a finite element analysis model is established using SAP2000-v20 software to conduct nonlinear dynamic time–history analysis under seismic loading. The analysis results show that the structural arrangement of the novel anti-rocking bearing reduces both the vertical displacement difference and the rocking angle of the isolation layer. The bearing exhibits a certain level of anti-rocking effect, but it may cause significant tensile forces in some bearings. The effectiveness of the anti-rocking effect improves as the stiffness of the steel tension rod in the bearing increases. For structures equipped with the novel anti-rocking bearing, the acceleration amplifies under most cases, with amplification coefficients ranging from 0.82 to 1.55. Through the finite element simulation of the bearing, the mechanical properties of the bearing are essentially the same as the theoretical analysis results.

Experimental flexural investigation of RC beams with impeded steel truss using smooth steel angels

This paper emphasizes on testing the flexural capacity of Hybrid Steel Truss Reinforced Concrete Beam (HSTRCB), where a prefabricated steel truss is embedded into concrete beam instead of conventional rebars, forming a composite section. Five doubly reinforced concrete beams were designed, casted, experimentally tested and analyzed to investigate the flexural behavior of HSTRCB, in comparison to ordinary reinforced concrete beam. All beams were designed according to ACI 318, having same flexural capacity. First beam is ordinary reinforced concrete beam while the other four HSTRCB were designed having identical smooth steel angles, as compression and tension reinforcement, with different shear reinforcement alignment, and spacing. Different smooth truss typology were used as reinforced rebar replacement in the RC beams to determine the significant truss configuration that has highest flexural behaviour. The results showed that HSTRCB improves cracking moment, stiffness, energy absorption and effective cracked moment of inertia during the entire loading stages.

Effect of high-strength and stainless steel reinforcement on the flexural behavior of UHPC beams

Ultra-high performance concrete (UHPC) is an advanced cement-based composite which shows remarkable properties including very high compressive strength, increased tensile resistance, impressive toughness and excellent durability. One promising application of UHPC is in heavily-loaded beams and slabs where its use can allow for increased design efficiency and improved durability. Conversely, the high bond capacity of UHPC can lead to early bar fracture failures, especially when using low amounts of ordinary steel reinforcement. This paper examines the influence of reinforcement grade on the flexural ductility of UHPC beams. As part of the study, three beams built with either Grade 400 MPa ordinary steel reinforcement, Grade 690 MPa high-strength reinforcement or Grade 520 MPa stainless steel reinforcement, are tested under flexural loading. The key test parameters include the influence of concrete type (UHPC vs. conventional high-strength concrete) and steel type (high-strength or stainless steel vs. ordinary steel). The results show that the flexural strength and ductility of the UHPC beams is influenced by the steel grade/type. The beam with ordinary steel shows a well-defined yield point but fails by bar rupture. Increased resistance by 47% is observed when using high-strength bars, however bar rupture occurs owing to the low strain-capacity of this steel type. Combining UHPC with higher ductility stainless steel does not increase capacity, but leads to remarkable ductility by 75%. As part of the numerical study the behaviour of the beams is predicted using FE modelling and the effects of tension steel ratio, UHPC tensile strength and high-strength or stainless steel type are investigated.

Restoration of two-span RC beams with severely corroded reinforcement using C-FRCM composites

The feasibility and viability of using carbon fabric-reinforced cementitious matrix (C-FRCM) composites for restoration of continuous reinforced concrete (RC) beams with severely corroded reinforcement were examined. Five large-scale dual-span RC beams were fabricated and tested. One beam was not corroded to serve as a control. Four beams were subjected to accelerated corrosion that corresponded to a tensile steel cross-sectional loss of 40% in either the sagging or the hogging region. Such a steel cross-sectional loss would cause a comparable reduction in the yield load of bare steel reinforcing bars. Two of the corroded beams were repaired with C-FRCM composites. An analytical model was formulated and utilized to design the number of C-FRCM layers required to fully restore the original load capacity. Experimental results verified the redistribution of moments between the sagging and hogging regions due to yielding of the tensile steel at critical sections. Both sagging and hogging sections contributed to the load-bearing capacity, and hence, the reduction in the load capacity caused by corrosion in one of the critical sections was smaller than the tension steel cross-sectional loss caused by corrosion. It was possible to predict the load capacity of the tested beams with reasonable accuracy considering the residual cross-sectional area of the corroded tension steel bars while keeping their yield strength and Young’s modulus unaltered in addition to implementing other conventional assumptions adopted by international codes and guidelines. As predicted analytically and verified experimentally, rehabilitation of corroded continuous beams with appropriate number of C-FRCM composite layers fully restored their original load capacity. Research findings would assist practitioners in conducting a proper analysis of continuous RC beams with corroded reinforcement before and after repair with C-FRCM composites.

The Role of Powder Used in the Continuous Molding of Alloys

Abstract In this paper, a technology for obtaining powdery materials with special characteristics, in the metallurgical field, is presented. The compositions of these powders are from the calcium oxide - alumina - silica system, by adding CaF2, Na2O and C. The choice of oxide compositions will be made according to a series of parameters: the composition of the cast steel, the casting speed, the viscosity or the surface tension of molten steel.

Dependence of a Steel-concrete-Steel Sandwich Structure Behavior under Pure In-Plane Shear Loading on the Reinforcement Ratio

This paper deals with failure modes of a steel-concrete-steel sandwich loaded by pure in-plane shear. Current research together with the developed models imply that increase of reinforcement ratio leads to decrease of ductility and possibly to change a failure mode from yielding of steel in tension to crushing of concrete in compression which results in brittle failure. In order to give a reader basic information about in-plane shear behavior of a steel-concrete-steel sandwich, an analytical model is introduced. Japanese experimental program that researched a behavior of SCS panels with reinforcement ratio 2.3%, 3.2% and 4.5% is also shown. In addition to the effect of changing the reinforcement ratio, the experimental program also investigated the effect of the transverse steel plate on the ductility of test panels with a degree of reinforcement of 3.2%. The next chapter describes the methodology used by the author to model the individual parts of the model, the loads, and especially the method of supporting the model. This is followed by the presentation of the results of the analysis on the calibration and extrapolation models. Finally, a discussion is conducted on the agreement of the analysis results on the calibration models with the Japanese experimental results, followed by an evaluation of the analysis results on the extrapolation models. According to the results on the extrapolation models the critical degree of reinforcement at which a change in the failure mode of the structure occurs under in-plane shear loading is around 13%.

Simulation and design model for reinforced concrete slabs with lacing systems

Lacing reinforcement plays a critical role in the design and performance of reinforced concrete (RC) slabs by distributing the applied loads more evenly across the slab, ensuring that no specific area of the slab is overloaded. In this study, nine slabs, divided into three groups according to the investigated parameters, were meticulously designed and evaluated to study the interplay between the lacing reinforcement and other key parameters. Each slab was crafted for simple support and was subjected to both static and repeated two-point load tests. The lacing reinforcement had an angle of 45° with various tension and lacing steel. The repeated-tested specimens with lacing reinforcement experienced smaller ductility than those of similar static-tested specimens, where the reduction in ductility factor ranged between 8.4% and 22.3% for all specimens. Additionally, the tested slabs were analyzed numerically using the ABAQUS software package. The validated FE test program was used to study the effect of varying the lacing reinforcement ratio, the compressive strength of concrete, and the material types of the tension and lacing reinforcements. The lacing reinforcement becomes more effective in increasing the slab capacity when using the higher compressive strength of concrete.

Effect of variations in concrete quality on the crack width in rigid pavement

Cracks pose a significant issue in rigid pavement, leading to substantial damage. The manual mixing and casting of road pavement concrete underscore the importance of concrete quality as a critical parameter. This study investigates crack behavior by varying concrete quality. Loading is performed statically using line loads, shedding light on the impact of concrete quality on crack development. The concrete to be used has a quality fc' of 15 MPa, 25 MPa, and 35 MPa. The fine aggregate used in this study was Lumajang black sand, while the coarse aggregate used was machine crushed stone, and Portland Composite Cement (PCC) was used in all concrete mixes. The reinforcing steel used had a quality fy of 480 MPa, with a reinforcement ratio of ρ=0.010, which was converted to 5-D16 reinforcement. The subgrade density used to support the specimens had a CBR value of 10 %. Specimen dimensions were 2×0.6×0.2 m for length, width, and thickness. Pavement plates, 30 cm thick, were placed on leveled subgrade soil in a steel box set to achieve a 6 % CBR reading. Hydraulic jacks, monitored by a load cell, applied monotonic static loading with 2 kN intervals, reaching a maximum load of 200 kN. Steel tension and plate settlement were measured using a tension sensor and Linear Variable Differential Transformer (LVDT), respectively. A data logger recorded readings, and crack widths were captured by a digital microscope with 0.01 mm accuracy. Experimental results show that low concrete compressive strength values result in larger crack widths, and vice versa. Cracks also occur at earlier loading of concrete quality fc' 15 MPa. In addition, experiments show that the reinforcement stress value has a significant influence on crack width in specimens with low concrete quality

Effects of UHPFRC jacketing and axial loading on the blast behaviour of reinforced concrete beams and columns

The objective of this study was to characterize the effects of axial loading and UHPFRC (ultra-high performance fiber-reinforced concrete) jacketing on the blast performance of reinforced concrete beams and columns. The test group included two as-built and strengthened columns with UHPFRC jacketing applied over the full span (FJ). The companion group included three as-built and UHPFRC-strengthened beams, with jacketing applied either over the full span (FJ) or in the middle hinge region (FJ-Mid). With the exception of axial load, the specimens in both groups had the same dimensions, reinforcement properties and boundary conditions. In both groups, the UHPFRC jacketing improved control of blast-induced displacements and damage when compared to the as-built specimens. Under equivalent blasts, axial loading was also confirmed to reduce the magnitude of the displacements in both the as-built and retrofit specimens. In addition, applying UHPFRC jacketing increased the blast capacity of the columns, but ultimately led to rupture of the tension steel bars. As part of the numerical study, finite element (FE) modelling was used to predict the blast behaviour of the test specimens, and to study the effects of parameters not considered in the experiments, including the effects of axial load ratio, boundary conditions, longitudinal steel ratio and jacket design on blast performance and failure mode.

Numerical Analysis Study on Seismic Performance of Semi-Rigid Steel Frame Infilled with Prefabricated Composite Wall Panels

The semi-rigid connected steel frame has good displacement ductility and energy dissipation capacity, and the interaction between the traditional steel frame and the filled wall is the critical factor affecting its seismic performance. In this paper, for the semi-rigid steel frame, the composite wall panel and the frame are separated by foam concrete mortar, and the effective connection is achieved by the tensioned steel bar. The premature brittle failure of composite wall panels can be prevented using friction energy dissipation between wall panels. By using ABAQUS simulation method, a semi-rigid steel frame composite wall is established. The failure mode, hysteresis curve and skeleton curve of simulation and test are compared and analyzed, and the reliability of the model is proved. The finite element model with the different number of wall panels is established to analyze its influence on the seismic performance of the structure. The results show that the frame structure realizes the effective connection between the composite wall panel and the concrete-filled steel tube frame, which jointly resists the earthquake action and reduces the damage of the earthquake action to the filled wall. With the increase in the number of composite wall panels, the ultimate load decreases gradually. The initial stiffness of the four layers of wall panels is more significant and decreases rapidly. When the wall panel has three or four layers, the energy dissipation capacity of the specimen is the strongest. The two are relatively close, stable at 24.48, and the increase is 5.15% compared with the second layer of the wall panel, and the increase is 12.72% compared with the third layer of the wall panel.

Structural Behavior Comparison on Earthquake Resistance of High-Rise Mall Building (Framed Structure,Flat Slab and PT Flat slab)

The rate of urban population growth and the amount of available space had a significant impact on the construction of high-rise mall buildings in developing countries like the USA, UK, Australia, and Hong Kong. These high-rise mall constructions may be constructed using a variety of structural techniques. Today, RC Frame structures are often employed in constructing. Usually, these structures are employed to counteract the sizeable moments brought on by applied stresses. On the other hand, flat slab structural systems, in which the slab is directly supported by columns, have lately been adopted in many buildings because they have the advantage of greater clear floor-to-floor heights to satisfy the economical, easier form-work, quicker construction duration, and architectural needs. On the other hand, with a post-tensioned slab, the PT flat slab Structural System uses high-strength tensioned steel strands to compress the slab, maintaining the bulk of the concrete in compression. When compared to RC framed structural system, this results in a very efficient construction that minimizes partial consumption and reduces the economic span range. Three cellar+Ground+9 higher floors structural models of a high rise mall building with RC framed structure, flat slab, and PT flat slab structural system arrangement are taken into consideration in the current study. The study is completed by taking into account seismic zone II and type I soil condition, and it takes into consideration the susceptibility of purely RC framed structures, solely flat slab, and completely PT flat slab systems. The structural behavior of an RC-framed structure, a flat slab, and a PT flat slab are being compared for earthquake loads. The response spectrum approach is used to do the analysis.With the use of analytical tools, parameters such as storey displacement, storey drift, base shear, and storey shear are calculated. The findings are then compared between three structural system.

FAILURE ANALYSIS OF PRESTRESSED CONCRETE STEEL BAR DURING THE INITIAL DRAWING PROCESS

Reinforced concrete is a common structural material used in the modern era. High tension steel provides strength to the concrete structure to reduce internal tensile forces and eliminate cracking. Failure of reinforcing steel causes the reinforced concrete to not have optimal strength and has the potential to cause failure in the main structure. The present paper describes the investigation of the failure case in the prestressed concrete bar (PC bar) during the manufacture of prestressed or pre-tensioned concrete. The failure occurred in the head section area during the initial drawing process. The chemical composition and tensile test showed the raw material complied to the manufacturer's specification. The fractography and microscopic examination of the failure area showed the characteristics of brittle fracture. Stress concentration in the head section and the tempering process of PC bar after quenching process at an inappropriate temperature caused temper embrittlement to be the cause of failure during the initial drawing process.

Experimental and numerical evaluations of load settlement response of helical piles in soft clay

Use of helical piles has become increasingly popular since last few decades for numerous advantages and installation convenience. They may consist of isolated helical plate welded to a central shaft or continuous screw type piles. The load transfer mechanism of helical piles is complex compared to the conventional vertical driven piles. Although limited contributions are available on the performance of helical piles including theoretical and experimental studies, still there are major scopes for further research. The authors have conducted a series of laboratory experimentations on axial load-settlement characteristics of model helical piles made of high tension steel in soft clayey soil, followed by 3D finite element analysis using ABAQUS. The numerical results were found to be close to the experimental observations. Using the numerical model, extensive parametric studies were conducted. The load-settlement response was found to be mostly logarithmic. The pile capacity was found to be influenced significantly by the pitch and embedded pile length. The FEM analysis revealed maximum plastic strain and displacement to develop adjacent to the pile-tip and the interface, while negligible at the boundaries. The interface shear stress distributions are also studied. From the entire investigation, a set of important conclusions are drawn.

Revision of the standard EN 1993‐1‐11 and background information

AbstractWithin the framework of the development of the second generation of Eurocode 3, Part 1‐11, related to the design of steel tension components, was completely revised.This paper introduces the main developments in the prEN 1993‐1‐11:2023 regarding the basis of design for the three groups of tension components: A ‐ Rods, B ‐ Ropes, and C ‐ Parallel strand or wire systems. For each of the three groups, complete information on the “Material”, “Ultimate limit state” (including fatigue) and “Serviceability limit state” requirements are provided. Improved formulas for the design of saddles and clamps are presented, including new saddle solutions for group C. Reference is made to the new group D ‐ Parallel wire tension components for suspended structures, included in new Annex C. Annex A “Product requirements for tension components” was completely revised to reflect modern testing requirements. Informative Annex B has been also updated with new figures that reflect the state of the art in tension elements and terminations.