Hollow Steel Research Articles

Seismic performance of a GFRP–concrete–steel hollow section segmental column with SMA bars and replaceable ED devices

This paper investigates the seismic behavior of a novel precast segmental bridge column (PSBC). Glass fiber reinforced polymer (GFRP)-concrete-steel hollow section segments were used to construct the column. Hybrid energy dissipation (ED) system consisted of shape memory alloy (SMA) bars and replaceable external ED devices was proposed to increase the ED capacity of the PSBC. The SMA bars have a large deformation capacity, which makes them not easy to be damaged. They were therefore installed inside the column to absorb energy and more importantly to keep the residual displacement small. External ED devices were used to increase the overall ED ability of the PSBC. The external arrangement of the ED devices made it possible and easy for the post-earthquake replacement. A reference PSBC with steel-reinforced precast segments was also constructed and investigated. The test results demonstrated that, compared with the traditional PSBC, the proposed column exhibited appealing seismic performance, including better self-centering capacity, higher post-yield stiffness, and better ED ability. Furthermore, the proposed PSBC experienced minimal concrete damage during the test. One of the external ED devices fractured, however, they could be uninstalled and replaced easily. Numerical models were developed and used to conduct parametric studies. The results demonstrated the feasibility of using the hybrid ED system and the GFRP–concrete–steel​ hollow section segments to improve the performance of the PSBC under seismic loadings.

Experimental investigation on the behaviour of FRP strengthened square hollow section steel members under monotonic and cyclic loading

Strengthening and rehabilitation of square hollow sections (SHS) are a major concern nowadays as SHS may fail due to higher service loads, fabrication and construction errors, degradation of material over time and adverse effects of the cyclic loading due to earthquakes. In this study, a detailed experimental investigation has been carried out for the implications of using carbon fibre reinforced polymer (CFRP) and glass fibre reinforced polymer (GFRP) as a strengthening measure to mitigate the failure of SHS members under monotonic and cyclic loadings. Strengthened members displayed lower moment degradation and higher moment and energy dissipation capacities and higher stiffness and ductility compared to the bare steel members. Although the amount of CFRP and GFRP fibres were almost equal, CFRP strengthening can result in higher capacity sections due to having higher strength material properties compared to GFRP strengthening. The cyclic responses of the GFRP-strengthened member were close to that of the CFRP-strengthened member and can be more effective for strengthening steel SHS under cyclic flexural loading. The established theoretical model in the current paper can predict reliably the ultimate moment capacities of the strengthened SHS members. This study confirmed that strengthening SHS members with fibre composites will be effective for structures in seismically active regions.

Axial stress measurement method for hollow cylindrical steel structures based on non-dispersive characteristics of T (0,1) guided waves

This article presents an equivalent sound propagation model for hollow cylindrical structures subjected to axial stress, which yields theoretical solutions for sound velocity changes in steel pipes under varying stress levels. To enable the excitation and detection of T (0,1) mode guided waves in hollow steel pipes, an electromagnetic ultrasonic transducer (EMAT) array based on the principle of magnetostriction is designed and tested. To accurately extract nanosecond-level sound time changes due to stress, this study devises the LMS-Gabor algorithm, which exploits the non-dispersive properties of T (0,1) mode guided waves to process the echo signal. Experimental results demonstrate that this stress measurement approach can achieve high accuracy, even in the presence of noise and signals in the same frequency band.

Post-fire behavior of RC columns repaired with square hollow section steel tube and RC concrete jackets

Post-fire behavior of RC columns repaired with square hollow section steel tube and RC concrete jackets

Tensile behavior of improved CFRP-square hollow steel tube composite member strengthened with thick-walled steel tube

An improved CFRP-square hollow steel tube (CFRP-SHST) composite member strengthened with a thick-walled section at each end of the steel tube was proposed to prevent premature debonding of CFRP. The square hollow section (SHS) steel tube in the proposed composite member is composed of two thick-walled SHS at both ends and a thin-walled SHS at the center. The test of six proposed CFRP-SHST composite member specimens and one conventional CFRP-strengthened equal-thickness SHS composite member specimen under axial tension load was carried out. Test results indicated that the proposed CFRP-SHST composite member had a better bonding performance, as well as higher ductility than the conventional composite member due to the presence of the thickened sections. The failure mode was the exterior CFRP rupture and interfacial debonding near the end section of the loading side for the improved composite member. Besides, finite element analysis (FEA) was developed to investigate the interfacial stress distribution and the evolution of adhesive layer damage. In addition, a simple calculation approach for tensional carrying capacity was proposed, which was verified by test results.

Numerical analysis of encased granular pile with vertical hollow steel pipe

Numerical analysis of encased granular pile with vertical hollow steel pipe

DESAIN RAK TEMPAT PENYIMPANAN TABUNG GAS ARGON DENGAN KAPASITAS MAKSIMUM 3 TON

Gas tungsten arc welding (GTAW) uses argon gas as a protective gas in the welding process. Argon gas cylinders weigh 100 kg, making it difficult to mobilize in large quantities when the welding work is at a certain height. Therefore it is necessary to create a storage area that is able to accommodate and withstand the load of gas cylinders and their contents and can be mobilized at a certain height. In order to get a suitable storage area, a design has been carried out, which includes calculating the strength of the frame, determining the material and design of the lifting lug, and calculating the welding connection of the lifting lug and hollow steel. The rack material used is SS400 type, the compressive stress that occurs due to the force acting on the hollow iron is 91.124 MPa and the stress received by the base plate is 127.5 MPa, while the allowable compressive stress for the material is 152 MPa. The load received by the lifting lug is 33,866.6 N, and the tensile stress due to the force acting on the lifting lug is 76.88 MPa, while the allowable tensile stress is 152 MPa, so the lifting lug is declared safe to use.
 

Buckling performance of thin-walled filled steel columns

Concrete-filled composite elements have recently gained popularity as beams and columns all over the world. They have advantages similar to reinforced concrete elements, such as the moulding process and the lack of maintenance of the filled concrete, as well as advantages similar to hollow steel elements, such as enhancing compressive strength and bending capacity by using smaller sections. In this paper, the buckling behaviour of thin-walled steel columns with circular cross-section and different filling materials was investigated under uniaxial load. Six different materials (concrete produced using normal aggregate, concrete produced using waste aggregate, waste fine aggregate, waste coarse aggregate, waste iron dust and polyurethane) were used as filling. Filled columns were compared experimentally with hollow thin-walled steel columns that had the same height and diameter. All specimens had the same length (750 mm), same diameter (60.3mm) and the same wall thickness (3mm). Experimental results were compared with analytical results obtained from a calculation done using the national steel design code, Design, Calculation and Construction Principles of Steel Structures 2016. Additionally, columns specimens were modelled in Abaqus software. Conservative and consistent results were obtained from comparing experimental, analytical, and numerical results.

Behavior of self-cured self-compacting concrete filled short channel columns under axial compression

Composite columns have been suggested as a preferable option for parking lots, submarine pipelines, multi-story structures, and bridge piers. The advantages of the inherent material qualities of both materials make the combination of cold-formed steel and concrete noteworthy. A hollow steel tube with a concrete core inside of it, with or without extra reinforcing, makes up a column made of steel tubes and concrete. Columns made of steel tube which is filled with concreteare constructed using steel tubes with normal geometric sections or eccentric geometric sections. Furthermore, there isn't yet a published Indian design standard that is specifically for the construction of such composites. The objectives of this lab is to investigate the structural behavior of simple & lipped cold-formed steel constructed shortcolumns filled with concrete with respect to the load–deflection graph, maximumcapacity to carry loads, concrete containment, and plasticity. It has been determined that a unique form of self-compacting concrete that partially replaces cement with fly ash and waste granite dust can be used for structural purposes. The failure pattern of the box configuration is explored by testing a total of three constructed lipped sectionsand three constructed plain sections. The load against axial shrinking curve is illustrated, and its specific impact just on capacity to carry loads is discussed. For specimens aforementioned, the analytical analysis yielded the relationship between load and axial shortening. Equations with distinct constants and their upper and lower bounds for the relevant specimens are derived using MATLAB. These formulas can be utilized to calculate how axial shortening and load for each specimen relate to one another. The lipped sections are better capable of withstanding loads than plain sections, according to the study outcomesof the column made of steel filled with concretespecimens.

Robust omniphobic ceramic hollow fibre membrane with leaf-like copper oxide hierarchical structure by membrane distillation

Omniphobic membranes have recently shown promising performance in water desalination using MD due to their ability to repel all liquid drop types and keep the membrane surface dry. This study successfully modified the surface of robust hydrophilic mullite-stainless steel hollow fibre membranes (M-SS HFMs) to omniphobic properties. The omniphobic layer was achieved through surface grafting with copper oxide (CuO) rough layer by a hydrothermal technique at different hydrothermal reaction times of 1, 2, 3, 4 and 5 h, followed by fluorination step using 1H,1H,2H,2H-perfluorode-cyltriethoxysilane (C8, 97 %). Next, the omniphobic membranes were characterized in terms of membrane morphology, roughness, mechanical strength, pore size/distribution, liquid entry pressure, contact angle and fouling accumulation. The prepared omniphobic M-SS HFMs were also tested through the DCMD system at 80 °C using a feed solution containing 35 g/L of NaCl and 10 mg/L of humic acid as a foulant agent. The results indicated that M-SS HFMs subjected to a 4 h hydrothermal reaction time, resulting in a leaf-like surface structure, exhibited superior characteristics compared to other omniphobic HFMs reported in the literature that used titania (SiO2), zinc oxide (ZnO), and cobalt (Co3O4) as roughing material. These superior features included higher roughness of 0.798 μm, liquid entry pressure of 5.40 bar, and enhanced liquid repellence and contact angles towards DI water of 167°, olive oil of 152°, and ethanol of 145°. Additionally, the M-SS HFMs at 4 h hydrothermal demonstrated remarkable performance in terms of rejection performance (99.99 %) and vapour flux stability of about 29 kg/m2.h in DCMD operations, surpassing the performance of omniphobic HFMs fabricated using mullite-ball clay, mullite-kaolinite, and alumina (Al2O3). Notably, no fouling/wetting on the membrane surface and elements leaching was observed throughout the MD operation. These findings highlight the potential of this omniphobic HFM for seawater desalination using DCMD systems, even in the presence of organic contaminants.

Test on Compressive Performance of Hollow Concrete-Filled Sandwich Circular Steel Tubes Connected by Thread

The connection method of lengthening the steel tube of hollow concrete-filled sandwich circular steel tubes and threaded connections is proposed. The length, depth and position are the basic parameters. Twelve hollow concrete sandwich circular steel pipes with threaded connections were designed and subjected to axial compression tests. The axial compressive loading–longitudinal compressive displacement curves, axial compressive loading strain of steel tube curves and failure mode of the specimens are analyzed, and the effects of different parameters on the axial compressive-bearing capacity and stiffness of the specimens are studied. The results showed that within the range of parameters studied, the axial compression load–longitudinal compression displacement curves of the specimens were the linear elastic stage and the elastic–plastic stage, which can be divided into a yield-strengthening stage and a decreasing stage. The bearing capacity and strength of the lined threaded connection specimen are not inferior to those of the ordinary specimen or the welded specimen. The bearing capacity and strength of the specimen increase with the increase of the thread length. The bearing capacity and strength of the specimens connected with inner liner screws at the ends are higher than those connected with inner liner bolts at the middle.

Low cycle fatigue behavior of 316LN stainless steel hollow specimen in air and liquid lead–bismuth eutectic

A hollow specimen, which can be filled with lead–bismuth eutectic (LBE), was designed to study the low cycle fatigue behavior of 316LN stainless steel (SS) in air and LBE at 400 °C. The fatigue life of 316LN SS in liquid LBE only reduced at high strain amplitude (≥0.8%). The fatigue cracks initiated at outer surface in liquid LBE at low strain amplitude and the opposite is true at high strain amplitude. The oxygen concentration has no impact on the fatigue life of 316LN SS in liquid LBE. The corrosion fatigue damage mechanism for 316LN SS in liquid LBE is discussed.

Non-linear analysis of CFRP-wrapped steel box sections under biaxial load

The effect of biaxial compressive loading on hollow steel box column (HSBC) and concrete-filled steel box column (CFSBC) sections wrapped with low-modulus carbon-fibre-reinforced polymer (CFRP) was studied. The CFSBC and HSBC sections were simulated using Abaqus finite-element software and validated using available experimental data. Biaxial compressive loading was considered for different eccentricities (i.e. eccentricity to depth ratio (e/D) ratio of zero to 0.32). The results indicated that, for CFRP-wrapped HSBCs at low eccentricity (e/D = 0.08), compact and non-compact sections were effective at carrying higher load, while a slender section was effective for concentric loads. For the CFRP-wrapped CFSBCs, compact and non-compact sections were effective for all the eccentric loads (e/D = 0–0.32). It was also found that the low-modulus CFRP layer wrapping the CFSBC sections had no significant effect on strength. An empirical relationship was developed based on trend analysis, which gives the load-carrying capacity of any section. For the CFSBC sections, axial compression–uniaxial moment (P–M) interaction curves are presented to validate the simulation results under biaxial loading.

Strength enhancement and stub-column behavior of cold-formed stainless steel elliptical hollow sections

This paper aims to investigate the strength enhancement, local geometric imperfections, and stub-column behavior of cold-formed (CF) stainless steel elliptical hollow sections (EHS) by using finite element methods. In the present study, an advanced numerical approach was used to conduct a comprehensive parametric study for CF stainless steel EHS with a wide range of cross-section dimensions and slenderness values as well as different stainless steel alloys. By analyzing the generated numerical data from the parametric study, the effects of cold-forming and material parameters on the strength enhancement were examined. Predictive models of the strength enhancement as well as the local geometric imperfections for CF stainless steel EHS are proposed. The slenderness limits for CF stainless steel circular hollow sections (CHS) and CF steel EHS in the existing design methods were assessed for CF stainless steel EHS. New slenderness limits are proposed for CF stainless steel EHS. In addition, the existing equivalent diameter method, the Continuous Strength Method (CSM) and the Direct Strength Method (DSM) were evaluated for the design of CF stainless steel EHS. Modifications on these existing design methods are proposed for CF stainless steel EHS, which can improve their accuracy.

Experimental investigation on the square and rectangular hollow section stainless steel portal frames

Cold-rolled hollow sections are the most commonly used stainless steel sections in the construction industry, because the production of this type of profile is the most cost-effective in smaller volumes. However, very little experimental research has been carried out so far on whole structures made of these sections. Therefore, experiments on stainless steel frames were carried out. In total, 5 portal frames made of austenitic stainless steel SHS/RHS were tested. These tests are described in detail, including the layout of auxiliary elements and measuring devices. The aim of the experiments was to capture the effects of material nonlinearity on the global behaviour of the stainless steel frames. The load–displacement diagrams are presented in tables, enabling their use for the validation of numerical models. Tensile coupon tests were carried out and parameters for common material models were determined. Numerical models of the studied frames were developed and validated using the experiments performed. These numerical simulations have been shown to be able to capture the general load–displacement response in a global, in-plane mode. Linear buckling analysis was carried out. Resulting elastic critical load factors indicated a high susceptibility of the frames to second order effects. In addition, modified elastic critical load factors were determined, showing the large influence of material nonlinearity on second order effects.

Baseline-free absolute strain estimation for cylindrical structures

The total strain induced by forces in a structure, known as absolute strain, provides crucial information about structural integrity. The unexpected variations in absolute strain can compromise the overall safety of the structural system. In this paper, a baseline-free absolute strain estimation technique is developed based on the acoustoelastic effect of ultrasonic guided wave for in-service cylindrical structures. To generate and sense ultrasonic guided waves, two macro-fiber composite (MFC) transducers were installed on the surfaces of cylindrical structures subjected to tensile force. Additionally, a strain gauge was used to measure the relative strain generated after installing the MFC transducers and the strain gauge. The absolute strain was estimated using the velocity of the ultrasonic guided waves and the relative strain, without the need for calibration tests and baseline data obtained from known absolute strain levels. The effectiveness of the developed technique was experimentally examined using blind data obtained from a hollow steel cylinder and an aluminum mooring cable from a submerged floating tunnel model.

Modeling and Pile-Driven Scaled Tests for Windfarm Foundations

One of the main problems associated with the generation of wind energy in offshore wind platforms is the analysis of the behavior of the soil when the pile is driven into the seabed. Nowadays, due to the large dimensions of the foundations (hollow steel piles up to 8 m in diameter and 15–20 cm thickness), there are no scale studies carried out that analyze the mechanical and deformational behavior of soil where piles are driven as well as the material of the pile that supports the motor. This paper presents the results obtained from scale submerged tests in a steel pool to analyze the behavior of sand in the presence of water where piles were installed. These tests use a hydraulic press to carry out the penetration of the steel tube in the sand. The results were compared with three different speeds for three tubes with different diameters and two types of termination at the end of the tested element. The results of the submerged tests were compared with the tests in dry conditions and with the results obtained through the finite element Plaxis program.

The correlation of fractal dimension to fracture surface slope for fatigue crack initiation analysis under bending-torsion loading in high-strength steels

In this study, the fractal dimension of fatigue fracture surfaces is investigated in order to find an alternative failure loading indicator. Some of many metrological factors are generalized by reducing the fracture surface structure to one factor and develop an entire fracture surface procedure by analyzing the impact of surface slope and calculation resolution. Three notched geometries are studied under cyclic bending-torsion: 34CrNiMo6 high-strength steel bars with transverse blind holes; (ii) 34CrNiMo6 high-strength steel bars with lateral U-shaped notches; and (iii) 18Ni300 maraging steel hollow bars with transverse holes produced by selective laser melting. The surface topographies of fatigue fractures were measured with an optical profilometer. The bending-torsion ratio, maximum local von Mises equivalent stress and the number of cycles to crack initiation are examined using the fractal dimension. Moreover, a comparison was also made for conventional surface topography parameters such as root mean square height and void volume. A fatigue crack initiation model based on surface topography and loading conditions is proposed. The model relies on the product of the maximum local von Mises equivalent stress and the fractal dimension divided by the root mean square height to void volume ratio. The results show that the fracture plane geometry, expressed by the fractal dimension Df, can facilitate the estimation of post-failure loading history. In particular, the analysis based on the enclosing boxes method (EBM) is more accurate when it is used as an extra-fine resolution without any plane leveling.

Performance of Hollow Concrete Filled Circular Steel Tube Column Subjected Axial Loading

To improve the behavior of hollow concrete filled steel tube, a novel type of reinforced hollow concrete circular steel tubular member (RHCFST) was put forward and its axial behavior was studied. The finite element analysis model of 12 RHCFST short columns under axial compression was established by using ABAQUS. The influence of steel tube’s strength and wall thickness, diameter of steel bar with normal strength, sandwich concrete’s thickness and strength on the mechanical properties of members were investigated. The results showed that the loading process can be defined as five stages: elastic, elastoplastic, descending, strengthen and gentle stage. The new composite structure has good cooperative performance. The ultimate bearing capacity increaseswith the increase of yield strength and wall thickness of steel tube, thickness and strength of sandwich concrete and diameter of steel bar with normal strength.

Structural behaviour of HST and RCC stub columns under axial compression

The use of Hollow Steel Tubes (HST) as structural members is gaining in popularity due to their excellent properties regarding loading in compression, torsion and bending in all directions. This paper presents a comparison study through an experimental and a Finite element (FE) study of HST and RCC stub columns. The ultimate loads, load–displacement curves and failure modes from the tests were used for the validation of finite element (FE) models developed through FE software package Abaqus. Parametric finite element analyses were then performed. It was also observed that the strength capacity of the HST columns is about 0.45 times of RCC columns for slender sections and 1.35 times of RCC columns for stocky sections.