Diameter Of Steel Tube Research Articles

Forming limit in burring process of large diameter steel tube

Forming limit in burring process of large diameter steel tube

FEM Analysis and Forming Limit in Burring Process of Large Diameter Steel Tube

FEM Analysis and Forming Limit in Burring Process of Large Diameter Steel Tube

Behavior of Hollow-Core FRP-Concrete-Steel Columns under Static Cyclic Flexural Loading

This paper presents the seismic behavior of hollow-core fiber-reinforced polymer (FRP)-concrete-steel (HC-FCS) columns comparable with the conventional RC column. The typical HC-FCS column consists of a concrete shell sandwiched between an outer FRP tube and an inner steel tube. The HC-FCS column represents a compact engineering system; the steel and FRP tubes act together as stay-in-place formworks. The steel tube acts as a flexural and shear reinforcement. This paper studies three large-scale columns—one RC column having a solid cross section and two HC-FCS columns. Each column has an outer diameter of 610 mm (24 in.) and a shear span-to-diameter ratio of 4.0. The steel tube is embedded into the reinforced concrete footing with an embedded length of 1.6 times the steel tube diameter, whereas the FRP tube only confines the concrete shell and truncates at the top of the footing. The HC-FCS columns exhibits high lateral drift reaching 15.2% and fail gradually due to concrete crushing and local steel tube buckling, followed by FRP rupture. The reference RC column fails at a drift of 10.9% due to rebar fracture. Simple beam theory overpredicts the flexural strength of the columns by an average of 9%.

Surfactant Alternating Carbonated Water Injection (SACW) is a New Process for Enhanced Oil Recovery

Surfactant alternating carbonated water (SACW) injection is a novel mode for Enhanced Oil Recovery (EOR), a method to produce residual oil by injecting surfactant solution slug followed by carbonated water slug. Dissolving carbon dioxide (CO2) in brine water injection may overcome the shortcomings that seriously associate with the tertiary process of CO2 injection such as high CO2 mobility, viscous fingering and gravity override, poor sweep efficiency. The surfactant solution (S) slug alternating carbonated water (CW) slug might reduce the gas mobility at displacement front and retard CO2 breakthrough. In addition, surfactant and CO2 can reduce interfacial tension between oil and water reservoir. The sodium dodecyl sulphate (SDS) surfactant was used in surfactant flooding. In addition, the sand pack flooding experiments has been performed in this work. Glass beads were packed into 34.5 cm length and 3.8 cm diameter of stainless steel tube (sand pack) with small holes in both sides. The synthesized sodium chloride solution (brine water) and crude oil saturated the sand pack to establish Swi and Soi. Thereafter, the sand pack was aged at reservoir temperature of 60 °C and pressure of 2500 psi for 4 days to create actual oil reservoir conditions. Furthermore, different injection strategies were carried out including with different slug sizes in pore volume (pv) of SACW such as 0.25 pv (S) followed by 0.75 pv (CW), 0.5 pv (S) followed by 0.5 pv (CW) and 0.75 pv (S) followed by 0.25 pv (CW) in order to find out the optimum injection strategy to obtain the highest oil recovery factor. The obtained results illustrated that the scenario of 0.75 pv of surfactant slug alternating 0.25 pv of carbonated water showed the highest oil recovery factor of 86.58%. This is may be attributed to the efficiency of surfactant slug is higher than carbonated water slug.

Behaviour of Small Diameter Steel Tubes Under Axial Compression

Small diameter steel tubes are used in many civil engineering applications. Recently, the behaviour of concrete columns reinforced with small diameter steel tubes was experimentally and analytically investigated. This study explores the effect of unsupported length to the outside diameter (L/D) ratio on the axial compressive behaviour of small diameter steel tubes, which has not yet been adequately investigated. Galvanized and cold-formed steel tube specimens with L/D ratio of 2 to 12 were tested. It was observed that for specimens with L/D ratio of 2 and 4, the compressive failure occurred due to local elephant's foot buckling. However, the compressive failure mode changed to global buckling for specimens with L/D ratio≥6. The ultimate compressive strength was found to be lower than the ultimate tensile strength for specimens with L/D ratio≥6.

Concrete filled double circular steel tube (CFDCST) stub columns

Concrete filled steel tube (CFST) columns are deployed as the main load carrying members in high performance structures as they integrate the beneficial properties of constituent materials. In recent years, there has been an increased interest in the literature to further improve the performance of the CFST columns. The work presented in this paper, for the first time, investigates through experimental and statistical analyses the potential of concrete filled double circular steel tube (CFDCST) columns to improve the efficiency of the composite members. Experimental results validated the capability of CFDCST columns in performing high strength, stiffness and ductility properties which can be utilized in challenging design scenarios. Employed statistical analysis characterized the impact of parameters on the collapse performance of the CFDCST column. To establish whether the configuration of CFDCST members could be used in repairing process of highly stressed and deformed CFST columns, a further set of experimental work was undertaken. Deformed CFST stub columns were centred in a larger diameter steel tube and the region between the existing CFST column and the larger diameter tube was filled with concrete. Repaired forms of the columns were tested and the performances were compared against the performances of the CFDCST counterparts. Results show that it is possible to employ such a repairing, since the repaired CFST columns exhibit performances very close to that of CFDCST counterparts. The findings are quite revealing for design purposes and have important implications for advancing the knowledge on composite compression members.

Seismic Performance of Innovative Hollow-Core FRP–Concrete–Steel Bridge Columns

This paper presents the seismic behavior of hollow-core fiber-reinforced polymer–concrete–steel (HC-FCS) columns. The typical HC-FCS column consists of a concrete wall sandwiched between an outer fiber-reinforced polymer (FRP) tube and an inner steel tube. The inner steel and outer FRP tubes provide continuous confinement for the concrete shell; hence, the concrete shell achieves significantly higher strain, strength, and ductility than unconfined concrete in conventional columns. Three large-scale HC-FCS columns were investigated in this study. Each column had an outer diameter of 610 mm (24 in.) and a height-to-diameter ratio of 4.0. The steel tube was embedded into a reinforced concrete footing with an embedded length of 1.6–1.8 times the steel tube diameter, whereas the FRP tube only confined the concrete wall thickness and truncated at the top of the footing level. In general, the columns exhibited high lateral drift, reaching to 11.6%, and failed gradually as a result of concrete crushing and local steel tube buckling. An equation to determine the steel tube development length of HC-FCS columns was introduced based on an extensive finite-element study. The finite-element analysis was validated with finite-element models. In addition, this paper introduces a quick-repair technique for HC-FCS columns. Guidelines for the preliminary design of HC-FCS columns under seismic loading are also presented to help implement this new technology.

Circular concrete-encased concrete-filled steel tube (CFST) stub columns subjected to axial compression

Circular concrete-encased concrete-filled steel tube (CFST) consists of the circular inner CFST and circular outer reinforced concrete. In this paper, the axial compressive behaviour of the composite column is experimentally and analytically investigated. Ten concrete-encased CFST specimens, four reference CFST specimens and two reference reinforced concrete specimens were tested; the parameters include the ratio of the steel tube diameter to the column diameter and the concrete strength. The influence of these parameters on the axial load in relation to axial strain, ultimate compressive strength and ductility is discussed. A finite-element model is established, where a stress against strain model is suggested for the concrete confined by circular stirrups located outside the steel tube. The predictions are verified against the test results of the stub columns. Analysis is then performed to investigate the internal force distribution and stress development during the loading process. Parametric analysis is conducted to discover the influence of critical parameters. Finally, simplified superposition methods are suggested to predict the ultimate compressive strength.

Reflections on Mechanisms Affecting the Behavior of FRP-Concrete-Steel Double-Skin Tubular Columns

This paper presents the results of 20 hollow and concrete-filled double-skin tubular columns (DSTCs), which were tested as part of a comprehensive experimental program that was undertaken at The University of Adelaide on FRP-concrete steel DSTCs. The paper is aimed at providing important insights into the influence of two key parameters, namely the diameter of inner steel tube and presence/absence of a concrete-filling inside the inner steel tube, which play major roles in the column behavior through their influences on a series of interacting mechanisms that govern the complex system behavior. A detailed examination of the results yielded a number of important insights into the mechanisms that influence the compressive behavior of DSTCs.

Orthogonal analysis and optimization of a K4-rating auto-lifting anti-ram bollard system

The anti-ram bollard system (ABS) is installed around the perimeter of buildings and infrastructures to prevent the penetration of unauthorized vehicles and reduce the blast and debris caused by the vehicle-borne improvised explosive devices (VBIED). Comparing with the fixed anti-ram bollard system (FABS), the auto-lifting anti-ram bollard system (AABS) has the advantage to be set down automatically to allow authorized vehicles passing on. In this paper, a configuration of K4-rating AABS is proposed and a finite-element model is developed to simulate its performance. Differences between vehicle model and real vehicle, effects of boundary conditions are both taken into account. The effectiveness and accuracy of the numerical simulation are validated through predicting the results of relevant experiments. Based on the verified numerical model, 32 groups of numerical experiments of K4-rating AABS are investigated using an orthogonal array L32 (48×81). The order and significant levels of nine affecting factors are identified on the basis of the range analysis and variance analysis, respectively. It shows that gaps between substructure and outer sleeve, wall thickness of substructure, wall thickness of steel tube, diameter of steel tube and thickness of stiffening ribs have significant influences on the behavior of AABS. The optimal design is proposed according to the orthogonal analysis.

Behavior of hybrid GFRP–perforated-steel tube-encased concrete column under uniaxial compression

This study presents an experimental investigation on concrete confined by glass fiber reinforced polymer (GFRP) and perforated-steel tube subjected to uniaxial compression. The compressive behavior of this hybrid structure is compared with GFRP tube encased concrete and steel tube encased concrete. The three key experimental parameters were investigated: the layers of GFRP tube (1, 2, 3 and 4), the perforation diameter of porous steel tube (5mm and 10mm), and the grid form of perforated steel tube (axial type and helical type). The effects of these parameters on the failure mode, stress–strain relationship and ductility of the specimens were discussed. A simplified design model was proposed for the specimens and the predictions were in good agreement with the experimental results. In addition, the interactive function between steel and GFRP on the confined concrete was analyzed which considered an influence factor provided by these two confinement materials. This study showed that the hybrid GFRP–perforated steel tube exerts the full potential of these two materials, i.e. GFRP with its high tension strength enhanced the loading carrying capacity and the perforated-steel with its high elastoplasticity enhanced the deformation performance in hardening segment, softening branch and residual strength plateau of the concrete, respectively. This study therefore demonstrated that the combination of GFRP and perforated steel tubes is a new effective method to confine concrete.

Influence of Inner Steel Tube Diameter on Compressive Behavior of Square FRP-HSC-Steel Double-Skin Tubular Columns

FRP-concrete-steel double-skin tubular columns (DSTCs) are a new form composite column system that effectively combines the advantages of the constituent materials. The performance of this column system has been experimentally investigated in a number of recent studies. However, apart from a single study reported on square DSTCs, all of the existing studies have been concerned with DSTCs with circular external tubes. This paper reports on part of an ongoing experimental program at the University of Adelaide on FRP-concrete-steel composite columns. The results from 12 square hollow and concrete-filled DSTCs and six companion hollow concrete-filled FRP tubes (H-CFFTs) that were tested under axial compression are presented. Results of the experimental study indicate that hollow DSTCs with larger inner steel tube diameters develop similar ultimate axial stresses to but significantly larger axial strains than companion DSTCs with smaller inner steel tubes. The results also show that, in concrete-filled DSTCs with similar Ds/ts ratios, an increase in the steel tube diameter leads to an increase in both axial stress and strain of concrete. It was observed that H-CFFTs perform significantly worse than both hollow and filled DSTCs under axial compression, and their behavior further degrades with an increase in the diameter of their inner voids.

STRENGTH AND BEHAVIOR OF COMPOSITE STEEL TUBE CONCRETE BEAM

This paper deals with an experimental and analytical study to investigate the structural behavior of simply supported composite steel-concrete tube beams with external load, in which a concrete is connected together with steel circular tube by means of headed stud shear connectors. This type of structure not only inherits the characteristics of traditional concrete tube beams but also possesses its own unique attributes, such as advantageous mechanical performances, facilitating construction process, and low maintenance cost etc. Seven composite steel-concrete tube beams were tested to their ultimate strength. The effect of thickness and diameter of steel tube on structural performance of composite beams were investigated. Experimental results proved that, due to increase tube thickness from (2mm to 6mm), the strength increased by (63.5%) and the ultimate deflection increased by (75%). While the strength increased by (190.3%) and the ultimate deflection decreased by (47%) when the tube diameter increased from (75mm to 200mm). Based on the experimental results, a theoretical model for predicating the flexural resistance of composite steel- concrete tube beam is proposed. ANSYS computer program (version 13.0) has been used. The calculated flexural resistance based on proposed model has a high level of accuracy when compared with test results.

Behavior of Hollow and Concrete-Filled FRP-HSC and FRP-HSC-Steel Composite Columns Subjected to Concentric Compression

This paper presents an experimental study that was undertaken to investigate the effects of key parameters on the compressive behavior of fiber reinforced polymer (FRP)-concrete-steel composite columns that were manufactured with S-Glass FRP tubes. A total of 24 hollow and concrete-filled double-skin tubular columns (DSTCs), two concrete-filled FRP tubes (CFFTs), and six CFFTs with inner voids (H-CFFTs) were prepared and tested. The parameters examined included the inner steel tube diameter, influence of concrete-filling the inner steel tube, and the loading pattern. The results indicate that concrete-filling the inner steel tubes of DSTCs results in an increase in the compressive strength of confined concrete in DSTCs, compared to that of the companion specimens with hollow inner steel tubes. It was observed that cyclically loaded DSTCs exhibited slightly higher strength and strain enhancements compared to their monotonically loaded counterparts. The results also indicate that H-CFFTs perform significantly worse than DSTCs and CFFTs and their performance further degrades with an increase in the diameter of inner void. Comparison of the results from DSTCs and CFFTs indicate that both hollow and concrete-filled DSTCs exhibit improved compressive behavior compared to those of the companion CFFTs.

Reliability of threaded locking screws.

A frequent problem for interlocking nailing that affects the treatment of the fracture is locking screw deformation. The aim of this study is to determine whether bending resistance is different between high, low, and unthreaded locking screws of interlocking femoral nails. Ninety screws were used in this experimental study, with 10 screws used in each of 9 groups. Three-point bending tests were performed on 6 groups of 5 mm screws (titanium, stainless steel, crossed with unthreaded, low threaded, and high threaded) and the same 3 thread types of 5.5 mm stainless steel screws in a 30-mm inner diameter steel tube, imitating the level of the lesser trochanter. An axial compressor was used to determine the yield points for permanent deformation in the locking screws by way of 3-point bending tests. The mean yield point value of the 3-point bending tests of 5-mm low threaded stainless steel locking screws was 2071 N, 53% less than that of unthreaded screws (3169 N). The mean yield point value of 5-mm high threaded stainless steel locking screws was 556 N, 272% less than that of low threaded screws (2071 N). To avoid locking screw deformation, high threaded screws must not be used as locking screws. In cases of unreliable patients, 5-mm low threaded screws should not be used in the nailing of comminuted or oblique femur shaft fractures. All 5-mm unthreaded screws and 5.5-mm low threaded stainless steel screws can be used safely in full weight-bearing conditions of unreliable patients.

Performance of concrete-encased CFST box members under bending

This paper described a series of tests and finite element analysis (FEA) on large-scale concrete-encased concrete-filled steel tube (CFST) box members under bending. Eight full-scale specimens, including six concrete-encased CFST box and two corresponding reinforced concrete (RC) box members were tested to investigate the influence of variations in diameter of steel tube (from 74.9mm to 102.2mm) and sectional height (from 840mm to 1260mm) on the performance of concrete-encased CFST box members under bending. The failure modes and performance of concrete-encased CFST box members under bending were investigated and compared with those of corresponding RC box members. A finite element analysis (FEA) model was developed to analyse the flexural performance of concrete-encased CFST box members, including full-range analysis of moment–curvature relation, loading transfer and effect of shear-span-to-depth ratio. Finally, a parametric study was carried out based on the FEA modelling, and a simplified model was proposed for predicting the flexural capacity of concrete-encased CFST box members.

Study on Section Temperature Field of Concrete-Filled Double Steel Tubular Columns under Fire

Finite element model was built in order to study the section temperature field of concrete-filled double steel tubular columns through the software of ANSYS. Moisture of concrete and thermal contact resistance were considered in the model. Based on the Eurocode 2, specific heat of concrete was modified in order to consider the effect of moisture. Contact elements were created in the interface between steel tube and concrete in order to consider the effect of thermal contact resistance. The effects of diameter of steel tube and type of aggregate to section temperature field were studied. Distribution of section temperature field is given on the concrete-filled double steel tubular columns, which provides the basis for the analysis of fire resistance capability.

Evaluation of Electromagnetic Inspection of Outer Side Defect on Small Diameter and Thick Steel Tube With Steel Support Using 3-D Nonlinear FEM

Steel tubes are used in the heat exchanger in the petrochemical plant. Since these steel tubes are grouped in a bundle by the support steel plate, it is necessary to inspect the existence of defects from the inside of each tube. In these steel tubes, the corrosion or the defects are generated by the friction with the support steel plate at the outer side of steel tube. In this paper, the electromagnetic inspection method using only ac magnetic field is proposed. The behavior of ac flux in the steel tube and support steel plate is examined using 3-D nonlinear finite element method taking account of eddy current. It is shown that the detection of outer side defect is possible without being influenced by the support steel plate with high permeability. The usefulness of this proposal inspection method is shown by verification experiment.

Experimental Study and Theoretical Analysis of Ultimate Strength for Steel Tubular Joint of UHV Transmission Towers

Both experimental research and theoretical analysis of ultimate strength for steel tubular tower joint are developed. The experimental data comprise four different specifications of steel tube, that is, without ribbed plate, with 1/4 annular ribbed plate, with 1/2 annular ribbed plate and with annular ribbed plate. This paper considers that the ultimate strength of steel tubular joint depend on the following four parameters, that is, the ratio of length of joint plate to outer diameter of steel tube B/D, outer diameter D, axial force and ratio of length of annular plate to outer diameter of steel tube R / D as well as the ratio of thickness of annular plate to thickness of steel tube. Furthermore, a recommended formula of the ultimate strength of steel tubular joint is derived by the potential energy principle and the principle of virtual work in elasticity and plasticity based on the failure modes of experimental specimens. It is demonstrated that the applicability of the recommended formula is better.

Temperature Field Analysis of Circular Concrete Filled Steel Tube Reinforced Concrete Column under Fire

A three-dimensional finite element analysis model was developed using ABAQUS to simulate the temperature distributions of circular concrete filled steel tube reinforced concrete column in this paper. The influence of main parameters on the temperature distribution, such as heating time, section diameter, and steel tube diameter, was analyzed. This provides valuable information about structural fire resistance and structural behaviour of concrete filled steel tube reinforced concrete column structure under fire.