Round Steel Research Articles

Experimental investigation into the properties of crumb rubberized concrete incorporating corrugated round steel fibers

This paper presents an experimental study on how crumb rubber particles from waste tires and corrugated round steel fibers affect the mechanical behavior of concrete. In addition to the standard plain mix and five combinations of mixes composed of 0.5%, 1.0%, and 1.5% ratios, three steel fiber and crumb rubber mixes, 0.5%, 1.0%, and 2.0% weight of sand, coarse aggregate, cement, and silica fume were evaluated. The percentage of silica fume that replaced the weight of the cement in this study was 8%. The fresh properties of the 12 mixtures in terms of slump and density were studied. After 28 days of curing 36 cubes, 36 cylinders, and 12 prisms, the hardened properties were determined by evaluating the mean compressive, split, and flexural strengths. The results indicate that a synergetic effect is observed for the combination of crumb rubber and corrugated round steel fibers to improve the fresh and hardened properties of concrete. Adding fiber reinforcement to concrete can mitigate the negative impacts of rubber, and vice versa. According to the combination content, increases in compressive strength, tensile strength, and flexural strength of up to 49.04%, 38.60%, and 75.76%, respectively, were achieved compared with the control combination. This validates the applicability of the proposed mathematical prediction formulation to evaluate the compressive strength, split tensile strength, and modulus of rupture of rubberized fibrous concrete in terms of fiber and rubber ratios. Based on these results, a promising solution for tire disposal is to recycle waste rubber for fibrous concrete applications.

Structural Characteristics of Steel Pipe Piles Using CLSM

Recently, as underground construction becomes larger and deeper, temporary facilities must be designed, and methods suitable for the construction environment, such as the shape of surrounding structures and ground conditions, must be applied. Among them, the importance of self-contained earth retaining wall temporary facility construction is growing. Therefore, the installation method and construction technology of the self-contained earth retaining wall temporary facility structure must be improved. In this study, to evaluate the structural behavior of steel pipe piles for self-contained earth retaining wall, a full-scale specimen was fabricated, the steel pipe ends were welded with round steel plates, and CLSM was filled through the sand compaction inside the steel pipe. Subsequently, compressive and flexural strength tests were conducted on the specimen in which both ends of the steel pipe were welded with round steel plates. Additionally, a finite element analysis of the vertical displacement of the bending specimen according to the load was performed based on the results from the ANSYS finite element analysis, and the results were compared.

Testing and Analysis of Frictional Performance of Carbon Fiber/Metal Composite Materials

In order to enhance the friction and wear performance of carbon fiber/steel composite structures, experiments were conducted to adjust the ratio of thermosetting epoxy resin and C12-C14 glycol ether. A modified liquid was developed that could fully fill the gaps in the carbon fiber and enhance the adhesion characteristics between the fiber surface and 18CrMnTiH round steel material. The effects of self-made modified epoxy adhesive and single-component epoxy adhesive on the mechanical properties of composite materials were compared using ISO814-86 determination of the bond strength of sulfur-cured rubber to metal—two-plate method and international standard ISO1747-1976 determination of the shear strength of sulfur-cured rubber bonded to rigid metal plates—four-plate shear method. The friction and wear performance test analyzed the friction coefficient of composite materials under different pretreatment times. The results showed that the pretreatment treatment effectively reduced the friction coefficient of carbon fiber and effectively extended the service life of the material. This study has certain reference significance for extending the friction and wear resistance performance of carbon fiber-reinforced relative motion metal parts.

Comparative Evaluation of Durability and Hygiene Between Multistrand Round Dead Soft and 8-Braid Flat Dead Soft Stainless Steel Retainer Wire

Aim and Objectives The present study aims at evaluation and comparison of durability and hygiene between 2 different lingual retainer wires bonded between premolar to premolar, that is, maxillary or mandibular arch in the same patient. Materials and Methods Eighty retainer wires were placed in 40 patients. They were assigned to 2 groups and subjected to 2 different types of retainer wires (multistrand round and 8-braid flat). Results The mean durability of multistrand round retainer wire (235.7 ± 67.28 days) was more than 8-braid flat retainer wire (153.5 ± 43.85 days) irrespective of arches to which they were bonded, which was statistically significant. Scores for plaque index, calculus index, and gingival index were found more with 8-braid flat retainers and in lower arch than multistrand round retainer and in upper arch but these are statistically not significant. Conclusion The mean durability of multistrand round retainer wire was more than 8-braid flat retainer wire. The analysis did not find any statistical significant association for deposition of plaque, calculus, and gingival inflammation between different retainer wires and between arches.

Comparison of nail-holding performance of Pinus massoniana and Cunninghamia lanceolata dimension lumber based on round steel nails

In this study, the influence of the diameter of round steel nails, the guiding bores, and the wood sections on the nail holding performance of Pinus massoniana and Cunninghamia lanceolata dimension lumber was explored. The results showed that the nail-holding power of round steel nails mainly came from their friction with wood fibers, while the radial and tangential sections were also affected by the shearing action of wood fibers. The tangential section reached the largest nail-holding power, followed by the radial section and cross section. Greater wood density was associated with higher nail holding power. Under a large nail diameter, however, high-density wood was prone to plastic cracking, which influenced the nail holding power greatly. Prefabricated guiding bores could prevent plastic cracking in wood to some extent and improve the nail holding power of Pinus massoniana and Cunninghamia lanceolata dimension lumber when diameter of round steel nails was more than 3.0 mm. For Cunninghamia lanceolata characterized by low density and rigidity, the wood fiber was in close contact with the round steel nail and internal cracking could not be easily generated under a large diameter of round steel nails.

Experimental and Theoretical Studies of the Thermal Contact Conductance for Bundles of Round Steel Bars.

The paper presents investigations devoted to the analysis of the thermal contact conduction in a bundle of round steel bars. The phenomenon can be expressed quantitatively with the use of thermal contact conductance (hct). The starting points for the presented analysis were the results of the experimental measurements of the effective thermal conductivity. The measurements were performed for samples of a medium in the form of flat packed beds of bars with three different arrangements: staggered, in-line, and crossed and four bar diameters: 10, 20, 30, and 40 mm. Next, a mathematical model was developed, thanks to which the values of the hct coefficient were calculated for the analyzed cases. This approach consists in analyzing thermal resistances in the medium model, which is defined with an elementary cell. It was established that the value of the hct coefficient in the temperature range of 50-600 °C changes within the range of 50-175 W/(m2·K), and it decreases with an increase in the bar diameter. The final effect of the present study was to develop generalized approximation equations describing changes in thermal contact conductance in the heated bar bundle simultaneously in the temperature and bar diameter function.

Calculation Model of Ultimate Bearing Capacity of Concrete Short Column of CFRP Round Steel Pipe

Calculation Model of Ultimate Bearing Capacity of Concrete Short Column of CFRP Round Steel Pipe

Bond assessment between rebars embedded into a parent material using a single-function bond-slip model

The pull-out test is usually used to evaluate the local bond behaviour between a rebar such as a ribbed steel rebar or a Fiber Reinforced Polymer (FRP) and a parent material, like concrete or timber. Although some codes recommend using a piecewise bond-slip model for ribbed or round steel rebars embedded in concrete, there is no globally accepted bond-slip model for FRP composites. Consequently, this piecewise bond-slip model is usually adapted for FRP composites embedded in a parent material (substrate). The present work therefore aims to propose a novel single-function bond-slip model that may be calibrated and used to model the pull-out test and the detachment process of an embedded rebar from a parent material. The model requires the calibration of three parameters that may vary according to the type of rebar and its parent material. Since the governing equation of the detachment between the rebar and the parent material during a pull-out test has no known analytical solution, the Finite Difference Method (FDM) was applied to find the interfacial slips throughout the embedded length. The results were compared and validated with the experimental pull-out tests of ribbed steel rebars embedded into a concrete block as well as with the numerical results obtained from the use of the Finite Element Method (FEM). To cover a broader range of materials and show the versatility of the novel bond-slip model, the results were also compared with other experimental data available in the literature. The results showed a very high precision of the new bond-slip model when applied to several pull-out tests especially when ribbed steel rebars-to-concrete and FRP-to-concrete interfaces or FRP-to-timber interfaces were used.

Study on the Damage Characteristic of Ununiform Corroded SFRC by 3D Mesoscale Numerical Simulation

Steel fiber reinforced concrete (SFRC) will appear ununiform corrosion under chloride environment, resulting in corrosion-induced crack. However, the mechanism of corrosion-induced crack of ununiform corroded SFRC is not clear. In this paper, the 3D mesoscale numerical model of SFRC structure is established, the generation algorithm of round straight steel fiber is provided, and the corrosion-induced crack are simulated by XFEM, at the end the damage characteristic of ununiform corroded SFRC are studied. The result shows with the increase of rebar corrosion area, the number of corrosion-induced cracks increase gradually. The width of each corrosion-induced crack decreases linearly with the thickness of the protective layer, and the width of the penetrate crack decrease to 0.08 mm~1.2 mm.

Machine-vision-based intelligent robotic replacement system of grinding-wheel-saws for steel round bar sawing machine

In the factory, the steel round bar sawing machine is applied to finish the sawing mission. Due to the process of the sawing steel is operating in high speed, the grinding-wheel-saw (GWS) is quickly worn by the friction and replaced frequently. The automatic replacement system of GWSs is seldom built yet. To improve the efficiency of the replacement for GWSs, the machine-vision-based intelligent robotic replacement system (MIRRS) for GWSs is developed and reported in the study. The MIRRS is mainly consisted of the six degrees-of-freedom (DOF) manipulator and the six-axes mechanical arm system to successfully complete the task of the replacement. The finite element method (FEM) is applied to analyze and design the subsystem of the MIRRS. Besides, the machine-vision positioning system associated with the digital camera are also setup to provide the required feedback detections for the MIRRS. The hardware system architecture and the control flow chart are described in detail and the hundreds of realistic testing results are collected to verify the reliability and offer the well working efficiency of the designed MIRRS.

Study on Mechanical Properties of Concrete-Filled Steel Tubular Members under Axial Tension

At present, the concrete-filled steel tube structure has been widely used in various practical projects. Due to the low tensile strength of the core concrete of round steel tube concrete (CFST) specimens, the axial tensile performance of CFST specimens is far from superior to its compressive performance. However, in practical projects, the concrete-filled steel tube members bearing tensile load often appear. In order to study the axial tensile properties of CFST specimens, the axial tensile tests of 5 CFST specimens and 1 pure steel tube specimen were carried out with steel tube diameter and concrete strength as variation parameters. The results show that the bearing capacity of CFST specimens is increased by 7.5%–16.3% compared with that of pure steel tube specimens with the same cross-sectional area, mainly because the core concrete limits the circumferential shrinkage of the outer steel tube. The larger the cross-sectional area of CFST specimens is, the higher the bearing capacity is. In this paper, the stress-strain relationship and the overall failure mode of CFST members under tensile force are studied, and the deformation characteristics and stress of steel pipe and core concrete are analyzed, which is expected to provide a reference for the application of CFST specimens in practical engineering.

Numerical convergence and error analysis for the truncated iterative generalized stochastic perturbation-based finite element method

The main aim of this work is to present a numerical analysis of convergence and accuracy of the selected generalized perturbation-based schemes in linear and nonlinear problems of solid mechanics. An algorithm for determining the basic probabilistic characteristics has been developed using the iterative generalized stochastic higher-order perturbation method adjacent to symmetrically truncated Gaussian random variables. It has been confirmed that usage of a sufficiently high order of the Truncated Iterative Stochastic Perturbation Technique (TISPT) allows for achieving any desired accuracy in determining up to the fourth-order probabilistic characteristics of static structural response. The semi-analytical probabilistic approach is the reference solution in this study, which is based upon the same composite response functions determined with the use of the Least Squares Method created using specific series of FEM experiments. The entire methodology has been provided for the given extreme value of the coefficient of variation αmax of the input uncertainty source. On the other hand, a selection procedure of the stochastic perturbation method order to achieve 1% numerical accuracy in all up to the fourth-order probabilistic moments has been proposed. Computational experiments include simply supported elastic Euler–Bernoulli beam, a set of steel diagrid structures, nonlinear tension of steel round bar as well as homogenization procedure of some particulate composite.

Experiment Study on the Effectiveness of Various and Mixed Kinds of Low Expansion Foam of 120# Gasoline Pool Fire Suppression

Storage tank fires can endanger society and the environment by generating intense heat radiation, rapidly spreading blazes, and cataclysmic explosions. Various types of foam and even two or more mixed foams are commonly used in storage tank fire disposal sites. This research aims to experimentally and analytically assess the efficacy of various and mixed forms of foam in putting out 120# gasoline pool fires. A series of foam fire extinguishing and re-ignition tests were conducted using a laboratory fire-extinguishing device that gently released low-expansion foam. In this work, a 2.4 m-diameter steel round tray was utilized to model the full-surface fire of an oilcan in a large oil depot base. The non-dimensional (T* = TExtinguishing/Tboiling point) average temperature of 0.62–0.66 is used in this study to represent the fire extinguishing temperatures of 120# gasoline fuel. The power law is still followed during the spreading phase as the length of the foam spreads further with time. When combined, 6% aqueous film-forming foam solution and alcohol-resistant aqueous film-forming foam solution (AFFF + AFFF/AR) have the highest flow velocity of 0.0189 m s−1. According to the results, synthesis foam solution combined with alcohol-resistant fluoroprotein foam (S + FP/AR) provided the greatest cooling effect, followed by S + S/AR (alcohol-resistant synthetic foam solution), AFFF/AR, S + AFFF, S/AR + AFFF, and finally S/AR + AFFF. According to the results, foam with an expansion ratio of 8.7:1 (FP (fluoroprotein foam solution) + AFFF/AR) has greater re-ignition resistance and burn-back protection. A referable tactic for choosing foam for liquid fire suppression is shown in this paper. The results suggested that FP and AFFF should be used for effective fire suppression in this hydrocarbon fuel fire rescue. Then, we can use synthetic foam and AR foams to provide continuous cooling and prevent the fire from re-igniting through efficient foam coverage.

A Butterfly-Like Connection Proposed for Bridge Pier Composite Protective System against Vessel Collision: Experimental and Numerical Analyses

Reliable connections are crucial for a bridge anti-collision protective system. Thus, this study proposes an innovative butterfly-like connection to tightly connect all segments of the pier composite protective system. The composite protective system is composed of four large segments, made of glass fiber-reinforced polymer (GFRP) panels, GFRP lattice plates, GFRP octagonal honeycomb tubes, round steel tubes, and polyurethane (PU) foam cores. The segments are jointed as a whole protective system by using eight proposed butterfly-like connections. First, the quasi-static tensile test is carried out to study the tensile strength and failure mechanism of the proposed connection. Then, a numerical model of the connection is established to determine the optimization parameter, and the numerical results are verified by experimental data. The optimal structural parameters for the connection are determined by parameter analysis using numerical results. Finally, a case study of a cable-supported bridge under vessel collision is numerically analyzed to comprehensively evaluate the overall protective performance and the dynamic reliability of the connection. It was found that the dynamic performance of the proposed connection is so reliable that it can ensure the protection system’s excellent performance. Also, the composite protective system can effectively reduce the collision force and the damage to both bridge and vessel.

A hybrid strategy blending primal‐dual interior point and return mapping methods for a class of hypoelastic‐plastic models with memory surface

AbstractBy blending the primal‐dual interior point method (PDIPM) and the return mapping algorithm, we propose a hybrid strategy of implicit stress update for a class of hypoelastic‐plastic models with the hardening rule whose evolution is restricted by the memory surface. The inequality constraint relevant to the memory surface is replaced by the equality constraint by the introduction of a slack variable, and the duality gap is gradually reduced by using path‐following method. First, we formulate an optimization problem corresponding to the principle of maximum plastic dissipation for the standard von‐Mises plasticity with isotropic and kinematic hardening rules and its variant for the model with the memory surface. Next, after function forms employed for the elastic‐plastic model are specified, the PDIPM to realize an implicit stress update is briefly reviewed and then applied to the model involving the memory surface to replace the relevant inequality constraint by the equality constraint by the introduction of a slack variable. Then, we present a hybrid scheme that combines the standard return mapping algorithm with the PDIPM. The numerical accuracy of the proposed stress update algorithm for the conventional elastic‐plastic model is verified in comparison with the standard return mapping algorithm using iso‐error map. Also, targeting a notched round steel bar under cyclic loading with three different amplitudes, we demonstrate the performance for the stress update using the elastic‐plastic model with the memory surface. Finally, the capability of the proposed algorithm is proven through a typical real‐life example such that a steel bridge is subjected to earthquake for which the residual load carrying capacity must be estimated.

Computer modeling of the process of siphon casting of a large metal cylindrical ingot

Electroslag remelting is one of the main ways to obtain high-quality large ingots from special steels and alloys, and in particular for the needs of power engineering. Casting in a mold is the most common way to obtain large-sized consumable electrodes for electroslag remelting. Computer modeling was carried out to determine the rational parameters of the process of casting large cylindrical ingots by the uphill casting. This paper presents the simulation results of the movement of liquid metal flows during the filling of a mold with liquid metal and the process of forming a crust of solid metal at that time under the conditions of the uphill casting of a round steel ingot with a diameter of 1 m with a height-to-diameter ratio of 6.5 and a mass of about 40 tons. Analysis of the results of computer simulation shows that in the bath of liquid metal in the mold there is a non-stationary hydrodynamic picture, which changes as the internal volume of the caster is filled with liquid metal. Solidification of the metal begins already at the initial stage of filling the mold. However, under the influence of liquid metal flows, the formation of a crust of solidified metal occurs unevenly due to the uneven distribution of the heat flow from the liquid-metal bath around the perimeter and height of the mold wall, which creates conditions for the hot surface cracks occurrence. To prevent the formation of surface defects, it is recommended to take measures to stabilize the upward flow of liquid metal. The effect of mold preheating on the intensity of metal solidification during the filling of the mold with liquid metal was also investigated. Preheating reduces the amount of solid phase formed during the filling of the mold with liquid metal. The most significant inhibition of the formation of a solid phase with a decrease in the solidified metal volume fraction of 40 % is observed under the condition of preheating the mold wall to at least 550–600 °C.

Fractional order adaptive MRAC controller design for high-accuracy position control of an industrial robot arm

Most of conventional feedback controllers become inefficient in hard industrial environments like in steel industry, because of uncertainties in the plant model, or process dynamics variation due to nonlinear actuators, and changes in the character of the disturbances. This paper proposes an adaptive control design based on fractional order model reference adaptive control (FOMRAC) strategy in order to deal with an uncertain horizontal positioning control of an unloading machine in a rotary hearth furnace for hot rolling operation. The proposed FOMRAC scheme uses the MIT rule as an adaptive mechanism with two main modifications comparatively to the conventional MRAC: the reference model is an adequate fractional order system and the parameter adjustment rule contains a fractional order integrator. Stability analysis of the proposed control scheme is performed using the Lyapunov stability theorem. Numerical simulations are presented to show the effectiveness of the proposed fractional adaptive schemes applied to an industrial robot arm loading round steel blocks from inside a rotary hearth furnace. After comparison with the conventional MRAC, it is shown that the performances of FOMRAC are superior to classical control schemes.

Experimental study on slender buckling-restrained knee braces with round steel bar cores

Experimental study on slender buckling-restrained knee braces with round steel bar cores

Nonlinear analysis of axial-compressed corroded circular steel pipes reinforced by FRP-casing grouting

In this paper, ABAQUS software is used to carry out finite element simulation on the axial compression performance of corroded round steel pipe members reinforced by FRP casing grouting. Moreover, its working mechanism and failure mode are analyzed. A typical load-displacement curve of the component is obtained. Furthermore, the effect of FRP pipe thickness, grouting thickness, corrosion rate, concrete strength, and slenderness ratio on the mechanical performance of the component is explored. The research results indicate that the component load-displacement curve can be characterized by bilinear and trilinear models. The former corresponds to the overall buckling failure mode, while the latter corresponds to the strength failure mode for the bare ends of a round steel tube. After reinforcement, the component bearing capacity increases up to 166.83%. Moreover, the increase is positively correlated with FRP pipe thickness, grouting thickness, and corrosion rate. The component bearing capacity first decreases and then increases when modifying the slenderness ratio, while concrete strength has a minor effect on it. Moreover, the bending stiffness ratio equation and the stability bearing capacity correction equation of the axial compression reinforced components are proposed. The aforementioned provides reference suggestions for practical engineering applications of corroded steel structures reinforced by FRP casing grouting.

Experimental Comparison of Fibers and Nanomaterials in Compression Test and Cost of High Strength Concrete in Egypt

Abstract The present work addresses conducting an experimental comparison between different types and dosages of fibers and nanomaterials in compressive tests and the cost of mixes for high-strength concrete (HSC). This study investigated the materials used in the construction sector in Egypt. The experimental work was carried out to select the optimum percentage of each type of the used nanomaterials, and fibers to achieve the highest compressive strength and low cost. In this work, nineteen concrete mixes were prepared. Nano silica (NS) and nano clay (NC) were used at 0, 1, 2, and 3 % by weight of cement. Also, nano- fumed silica (FS) was used at 0, 1, 2, 3, 5, and 10 %, while silica fume (SF) was used at 10 % by weight of cement. Each type of corrugated round steel fiber (STF), and polypropylene fibers (PPF) were used at 0.5, 0.75, and 1.00 % by concrete volume. The results indicated that the compressive strength of the HSC increases as the percentage of adding nano-fumed silica increases up to 3 % and the economic feasibility of nano-fumed silica in concrete is better than in other nanomaterials such as nano silica and nano clay. Also, using 1 % steel fiber in HSC increases concrete strength significantly compared to conventional concrete without considerably increasing the cost.