Hollow Steel Columns Research Articles

Research on eccentric-compressive behavior of steel stub columns with localized corrosion

To explore the impact of localized corrosion on the mechanical properties of hollow steel columns under eccentric loads, a specialized localized immersion-accelerated corrosion apparatus was developed. This device facilitated the creation of 17 locally corroded specimens, all subjected to eccentric loading. A systematic examination was conducted on various corrosion parameters including corrosion length, corrosion angle, localized corrosion rate, and corrosion location as well as loading conditions, which encompassed eccentricity and loading angle. Surface corrosion morphology and statistical parameters of the specimens were obtained using a 3D scanner. Subsequently, a nonuniform corrosion model, based on element displacement, was formulated through finite element analysis. Both experimental findings and numerical simulations indicate that localized corrosion does not alter the failure mode of locally corroded circular steel tubes (LCCSTs), which predominantly undergo local buckling in the compressed region. However, it was noted that localized corrosion leads to the elimination of the ascending segment in the load-displacement curve of the LCCSTs, thereby reducing both the ultimate load and ductility. Interestingly, the ultimate load of the LCCSTs was found to be relatively unaffected by variations in corrosion length and location but significantly influenced by factors such as localized corrosion rate, corrosion angle, eccentricity, and loading angle. Furthermore, through a comparative analysis of existing calculation models for the ultimate load of LCCSTs in major specifications, a practical model that accounts for localized corrosion is proposed. This model demonstrates high accuracy and is expected to enhance the understanding and prediction of the ultimate load capacity of LCCSTs in real-world applications.

Experimental and Numerical Research on the Behavior of Steel Columns with Circular Hollow Cross Sections

A circular, hollow tubular steel column is introduced for experimental and analytical analysis in this study. A series of axial compression tests for the variation of static schemes are reported in this study. All theoretical, numerical, and experimental analyses are based on the European Standards for the steel structure, respectively EN 1993-1-1. The experimental models of steel columns are conducted on actual steel columns with a length of 3000 mm and a circular hollow section of 114.3/2.8 mm. To assess the behavior and stress values of the columns, various schematically supported systems are modeled, starting from the axial-centered columns to the symmetrical eccentric load and asymmetrical loaded columns. 3D modeling of the steel columns using the finite element program SEISMOSOFT is also developed for such elements. The accuracy of the model is compared with the experimental results using numerical analysis by the finite element method. Finally, the numerical comparison of the results provides a recommendation for the engineers regarding the design and construction of such columns. Doi: 10.28991/CEJ-2024-010-05-014 Full Text: PDF

Experimental Study on Hollow Steel Sections Under Elevated Temperature

Structures known as modular buildings are made in factories and then moved to construction sites, where they are assembled. The efficacy of modular structures under many uncertainties has to be thoroughly investigated as demand rises; fire is one such uncertainty. The purpose of this study is to ascertain how high temperature affects the components of modular constructions. In the current study, hollow steel columns and beams were taken into account as components of a modular construction. Using ABAQUS, several situations were examined depending on the span length to determine the important locations of the members. Experimental research was conducted on the critical regions identified by the analysis, and the results were contrasted with those of the analysis. A high-temperature localized heating furnace was used for the experimental testing. The findings demonstrated that for spans of 250 mm and 500 mm, the central area of the beams was essential, and the load-carrying capacity was six times less than that of heating at the extremities of the beams. Similar to the beams, columns exhibited less fluctuation than the beams and were weaker in the bottom area when exposed to high temperature. When compared to other places, the capacity was reduced by 1.1 times, and in Case 1, the capacity reduction with regard to loading was 1.68 times greater. Doi: 10.28991/CEJ-2024-010-03-014 Full Text: PDF

Numerical simulation of corroded circular hollow section steel columns: A corrosion evolution approach

This study introduces a numerical simulation method for corroded circular hollow section steel columns, utilising a newly developed corrosion evolution model. This model was formulated by characterising the corrosion morphology and calibrating parameters throughout the entire corrosion process. An interpolation method was implemented to estimate the number of corrosion pits, based on experimentally measured corrosion ratios. Consequently, this allowed for the numerical prediction of the time-varying corrosion morphologies. Finite element (FE) models, incorporating this corrosion evolution model, were constructed. These corroded column models underwent validation through comparison with experimental findings. To further establish the effectiveness of the proposed FE models in predicting the structural behaviour of corroded members, FE models were also developed using the traditional uniform thickness reduction approach for comparative analysis. The results revealed that the proposed FE models for corroded structures offer a more accurate prediction of mechanical performance, particularly in instances of severe corrosion damage.

Experimental studies on the effect of nano silica modified novel concrete CFST columns

Under axial compression, the present article analyses and compares the behaviour of Plain Concrete filled and Nano Silica modified concrete filled with light gauge steel rectangular columns. In 18 work samples, plain and nano silica-modified concrete was tested on light gauge steel sections. Investigations were conducted into several essential variables, including the geometry of the cross-section, the tubular thickness of light gauge steel, the depth-to-thickness ratio, and the type of concrete infill used. From the experimental results, effects of flat width-to-thickness ratio (w/t), axial load-end shortening, axial load-deflection, axial load-strain characteristics, and failure modes have been studied under the linear stage. To evaluate their confinement effects, this study compared plain and silica-modified nano concrete tube columns with light gauge steel hollow hollow hollow columns. The experimental results are compared using BS5400, EC4, and ACI codes to determine the ultimate sectional capacity. Test outcomes showed that tested nano-silica modified concrete filled steel tubular (CFST) columns exhibited higher strength and outstanding ductility than the plain CFST and hollow light gauge steel columns. The nano silica-modified concrete in-filled columns showed a good yield plateau under the non-linear stage compared with the other columns.

Structural Performance of Nanosilica-Blended Square and Circular CFST Stub Columns

The study focuses on the structural behavior of concrete-filled steel tubular (CFST) stub columns with conventional cement concrete and nano-silica blended (doses of 4%, 6%, 8%, and 10% nano-silica by weight) concrete core infill of M25 grade under a pure axial compressive load. The strength and deformation capacities, as well as failure modes, of the CFST columns were assessed with reference to steel hollow and reinforced concrete (RC) stub columns. At optimum replacement of cement with nano-silica, the increase in strength from filling the hollow steel columns is about 1.6 and 1.5 times for square and circular sections, respectively. The addition of 6% nano-silica to the cement concrete core of CFST columns showed 2.55 and 1.19 times more strength as compared to RC stub columns with square and circular sections, respectively. As a result, adding nano-silica to the concrete mix increases the core’s axial compressive load carrying capacity and strengthens the nano-silica blended CFST stub column. The addition of the optimum doses of nano-silica increases the higher rate of hydration and rapid formation of hydrated products in the cementitious matrix due to its higher specific surface area. Due to its higher specific surface area, adding the right amount of nano-silica speeds up the formation of hydrated products in the cementitious matrix and makes the rate of hydration faster.

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.

Buckling analysis of non-uniform Timoshenko columns under localised fire

The buckling analysis of non-uniform steel columns with various boundary conditions under localised fire is investigated based on the Timoshenko beam theory (TBT). The temperature-dependent (TD) material properties are taken into account. First, based on the differential quadrature (DQ) method, the temperature field in the column is determined by solving the heat transfer equation considering the convection and radiation boundary conditions. Then, a segmented model is presented to solve the stability problem for the column with the variable flexural rigidity resulting from the non-uniform temperature distribution and cross-section. The transfer-matrix method is employed to obtain the critical buckling load and corresponding buckling mode. Finally, an example is conducted to study the temperature field and buckling response of tapered circular hollow steel columns under localised fire. The feasibility of the present method is verified by comparing the present results with those predicted by the finite element (FE) method and those reported in the literature. Numerical results show the influences of the localised fire and shear deformation on the buckling response of the column.

Experimental Investigation on the Axial Compressive Behaviour of Cold-Formed Steel-Concrete Composite Columns Infilled with Various Types of Fibre-Reinforced Concrete

The exceptional structural strength and low cost of steel-concrete composite columns make them a popular choice for civil engineering structures. Numerous forms of composite columns, including steel tubes filled with concrete, have been produced recently in response to various construction situations. Cold-formed steel tubular columns with concrete filling have higher strength and ductility due to their capacity to withstand inner buckling and postpone outward buckling. The objective of this research is to determine the ductile and strength performance of composite columns containing various forms of fibre-reinforced concrete when subjected to axial compression. Several different kinds of fibre-reinforced concrete (FRC) are employed as additives in hollow steel columns, including steel FRC, carbon FRC, glass FRC, coir FRC, jute FRC, and sisal FRC. Axial compression tests were performed on 24 columns, including three hollow steel columns and 21 composite columns. Three distinct slenderness ratios were developed and used. Axial bearing capacity, compressive stress-strain curves, ductility, peak strain, axial shortening, and toughness were among the topics covered by the axial compression test. Experimental findings demonstrated that all conventional composite columns experienced failure through overall buckling, Local buckling and crushing of concrete infill, which was transformed into more ductile failure using fibre-reinforced concrete infills. The test results revealed that fibre-reinforced concrete-infilled steel columns outperformed conventional composite columns in terms of strength, ductility, and energy absorption capacity. The percentage increase in load-carrying capacity was observed as 203.88%, 193.48% and 190.03% when compared to hollow cold-formed steel tubular columns in medium, short and stub columns, respectively. Under assessment of stub, short, and medium columns, the load-strain plots demonstrated that the steel fibre-reinforced concrete in-filled columns performed well in terms of ductility. Localized buckling and crushing of the concrete infill caused the composite columns with low slenderness ratios to fail. In contrast, concrete-filled steel tube columns with higher slenderness ratios showed column failure through the overall buckling of the composite column.

Fire design of steel columns through second-order inelastic analysis with strain limits

A structural steel fire design approach through second-order inelastic analysis with strain limits is proposed and applied to the fire design of steel columns as a first step in the establishment of a novel fire design framework for steel structures in this paper. The proposed method is carried out using beam finite elements, utilising their computational efficiency. In the proposed design approach, the strength and stiffness deterioration of steel in fire, the spread of plasticity, global instability effects, indirect fire actions and thermal expansion are fully taken into account through second-order inelastic analysis, while strain limits are employed to consider the deleterious influence of local buckling on the ultimate resistance. Ultimate capacity of a steel member or system is determined by (i) the load or temperature level at which the predefined strain limit is attained or (ii) the peak load or critical temperature observed during the analysis, whichever occurs first. A systematic numerical parametric study is carried out through nonlinear shell finite element modelling, taking into account a high number of I-section and hollow section steel columns whose response is considered (i) using isothermal and anisothermal analysis techniques and (ii) with and without axial and rotational end-restraints. It is demonstrated that the proposed fire design approach consistently furnishes significantly more accurate capacity and limit temperature predictions for steel columns in fire relative to EN 1993-1-2 [1] design provisions.

Innovative inner sleeve composite bolted connections for modular steel constructions: Experimental and numerical studies

The application scenarios of modular steel constructions (MSCs) are becoming more and more extensive due to their exceptional advantages: minimum on-site work, and higher construction speed and quality. Inter-module connections are the critical components, which can significantly affect the integrity and seismic behavior of MSCs. This study proposed an innovative inner sleeve composite bolted connection which combines blind bolts, high-strength bolts and inner sleeve to improve the constructability and seismic behavior. Experimental tests on four full-scale cruciform connections composed of hollow structural steel (HSS) columns and H-section steel beams with different configurations were carried out under cyclic load. The failure modes, moment-rotation relations, initial rotational stiffness, ductility and energy dissipation were analyzed. GB 50011–2010 was used to evaluate the seismic performance and verify the applicability for the seismic design of the proposed connection, in which the lower limit of elastic inter-story drift ratio [θe] is 0.004 rad (or 1/250) and that of elasto-plastic inter-story drift ratio [θp] is 0.02 rad (or 1/50). The yield inter-story drift ratio, [θy] = 4.00–6.75[θe], and the ultimate inter-story drift ratio, [θu] = 1.00–2.00[θp] for the test specimens under cycle load, demonstrating the satisfactory deformation capacity and ductility. Furthermore, EC3 Part 1–8 was adopted to evaluate the stiffness characteristic of the proposed connection, indicating that the proposed connection can be classified as a “semi-rigid” and partial strength connection. Finally, refined numerical models calibrated against the experimental results were established and parametric evaluation was conducted based on the numerical models. The results demonstrate that the effect of the thickness of the inner sleeve and column in the panel zone and the diameter of the blind bolt and vertical high-strength bolt is insignificant. The presented research will provide useful references for further application and popularization of MSCs.

Numerical Investigation on the Axial Load Behaviour of Polygonal Steel Tube Columns

Hollow steel tubes members with different properties are being increasingly used for structural applications, such as columns in frame structures, roof structures, truss columns, and other applications. These structural members are primarily subjected to compressive and flexural loading. Due to the insufficient studies regarding the influence of the cross-section’s shapes on the axial load behaviour of hollow steel columns, this study has presented eight different cross-sections shapes and has indicated their effect on the axial load behaviour of the polygonal hollow steel columns. Eighty different FE models have been designed and analysed to find the effect of the cross-section shape, thickness, length, and materials on the axial load behaviour of the polygonal hollow steel columns. The FE results have proved that the cross-sectional shapes affect the ultimate axial load behaviour of the hollow steel tubes by 14%. The highest ultimate axial load resistance recorded by Rec. model has been followed by Squ. unlike Cir. model, which has presented the lowest ultimate axial load resistance followed by Ova. model. This study also demonstrates that when the cross-sectional shape of the hollow steel tubes is near to a rectangular shape, the ultimate axial load resistance will be higher, while, if it is near to a circular shape then low ultimate axial load has been registered. Moreover, there is a small effect of the steel tube thickness, length and material on the axial load behaviour of the hollow steel tubes with different cross-sectional shapes, with almost -2% to -14%.

Numerical Study of Hybrid Through Plate Connections to CFST Columns

The use of concrete-filled steel tube (CFST) columns is highly encouraged nowadays in modern multistory structures. The major reason is the extensive resistance offered by the hollow steel column to high compression. Nevertheless, further studies and data are desirable to exhaustively characterize these members and their connections to other members, such as beams. This paper investigated the behavior of concrete-filled columns connected to I-beams by through plates. Three simple types of plate connections (easy to assemble and construct) were proposed and evaluated. The behavior of these connections was examined under static loading by using advanced finite element based software (ABAQUS). The modeling techniques used in this study were validated by comparing the numerical results of a through plate connection model with the results of two relevant experimental studies. The proposed connections were classified as semi-rigid connections according to Eurocode-3. These connections were able to move the plastic hinge away from the column panel zone. The maximum plastic rotations of all connection types were greater than 40 mrad. The failure mode, and moment-rotation curves of the concrete-filled column to steel beam connections were discussed based on numerical results. The influence of through plate material and through plate thickness were evaluated via a parametrical study.

Performance of rubberized concrete-filled hollow steel column under monotonic and cyclic loadings

Performance of rubberized concrete-filled hollow steel column under monotonic and cyclic loadings

Experimental and theoretical modeling for predicting bending moment capacity of T-head square-neck one-side bolted endplate to tube column connection

One-side bolting technology is expected to play an important role in the bolted connection between H-beam and Hollow Section Steel Column (HSSC). By evaluating the possible defects of the existing one-side bolts in terms of cost, installation, and mechanical properties based on plentiful reported studies, a new type of T-head Square-neck One-side Bolt (TSOB) was proposed, which has a simple construction, can adapt to the rough installation manners in the construction site, and no additional auxiliary tools are required. The bending performance of four T-head Square-neck One-side Bolted Connections (TSOBCs) for a beam to a HSSC and a Standard Double-sides Bolted Connection (SDBC) for comparison was experimentally studied, in which two arrangement patterns for the slotted bolt holes and two strengthening measures of stiffeners on the endplate and inner concrete in the HSSC was explored. The results show that the TSOBC with vertical bolt holes has nearly the same yield moment, and the horizontal bolt holes have more excellent post-yield performance, compared with the SDBC. Besides, three yield line patterns and an analytical model for calculating the bending bearing capacity of the HSSC and the concrete strengthened HSSC are proposed, respectively. • Tests on beam-to-column connections using TSOBs under bending were conducted. • TSOBCs have no less than 85% of the bending moment capacity of the traditional SDBCs. • Three novel yield line patterns of tube column wall were proposed. • A novel bending moment capacity calculation model of CFST column was presented. • Design methods of TSOBC were recommended.

EXPERIMENTAL STUDY ON BEHAVIOR OF UNPROTECTED FOAMED CONCRETE FILLED STEEL HOLLOW COLUMN UNDER FIRE

Reduction in self-weight and achievement of full fire resistance requirements are some of the important considerations in the design of high-rise structures. Lightweight concrete filled steel tube (CFST) column provides an alternative method to serve these purposes. Recent studies on lightweight CFST columns at ambient temperature have revealed that foamed concrete can be a beneficial and innovative alternative material. Hence, this study investigates the potential of using foamed concrete in circular hollow steel columns for improving fire resistance. A series of nine fire test on circular unfilled hollow and foamed concrete filled hollow section column were carried out. ISO 834 standard fire exposure test were carried out to investigate the structural response of these columns under fire. The main parameters considered are load level and foamed concrete density; foamed concrete density used are 1500 kg/m3 and 1800 kg/m3 at 15%, 20%, and 25% load level. All the columns tested are without any external fire protection, with concentrically applied load under fixed-fixed boundary conditions. The columns dimension was 2400 mm long, 139.7 mm diameter and steel tube thickness of 6 mm. The fire test result showed that foamed concrete increases the fire resistance of steel hollow column up to an additional 16 minutes. The improvement is more at load level above 15%, and the gain in fire resistance is about 71% when 1500 kg/m3 density foamed concrete is used. Generally, foamed concrete filled steel hollow column demonstrate a good structural fire behavior, based on the applied load and foamed concrete density. Also, inward local buckling was averted by filling the steel hollow column with foamed concrete. General method for composite column design in Eurocode 4 adopted to calculate the axial buckling load of 1500 kg/m3 foamed concrete filled columns. These type of columns can be used for structures like airports, schools, and stadiums; taking the advantage of exposed steel for aesthetic purpose and high fire resistance. It can also be used for high rise structures; taking advantage of high fire resistance and reduction in self-weight of a structure.

Seismic response on T-head square-neck one-side bolted endplate connection of beam to square tubular column

Totally four T-head square-neck one-side bolted connections (TSOBCs) for H-beam to hollow section steel column (HSSC) and a standard double-sides bolted connection (SDBC) for comparison were tested under cyclic load to evaluate the seismic performance of TSOBC. Two arrangement patterns of the slotted bolt holes and two strengthening measures for the connections were studied in the tests, especially the comparison between the TSOBCs and the SDBC. The test results show that the failure mode of the TSOBCs is the same as that of the SDBC, which is endplate fracture. The TSOBC with Type-V bolt holes has higher rigidity, bending moment capacity, and energy dissipation capacity than the TSOBC with Type-H bolt holes. Overall, the TSOBCs have no less than 85% of the bending moment capacity and more than 130% of the ductility coefficient, and 145% of the energy dissipation capacity of the SDBC in whole cycle life, which indicates that TSOBC can replace SDBC under certain conditions. Moreover, the strengthening measures of endplate stiffener and concrete filled in the HSSC can significantly improve the yield bending moment of TSOBC by 13.2% and 50.8%, respectively, but the latter will weaken the ductility coefficient of the joint by 35.2%. Test results on the bending moment capacity and failure mode of TSOBC under static and cyclic loads agreed well with calculated results by currently available computational models.

Based on auxetic foam: A novel type of seismic metamaterial for Lamb waves

Seismic metamaterial (SM) has lately received significant attention in the field of vibration isolation and damping due to its wave manipulation and bandgap properties. However, the limitations of unit cell size and the difference of the material parameters of each component have made it challenging to generate an ultra-low frequency bandgap. In order to overcome this challenge, a novel type of 2D SM composed of auxetic foam and steel is proposed to attenuate seismic waves at ultra-low frequencies. Firstly, the band structure of the SMs and the vibration modes of the upper and lower bounds of the first complete bandgap are calculated and analyzed by using the finite element method, and the mechanism of the bandgap generation is clarified. The transmission spectrum under the Lamb wave incident on the SM is investigated. It is validated that Lamb waves have a good attenuation effect in the frequency range below 10 Hz. Secondly, a parametric study of the SM with auxetic foam-coated hollow steel columns is carried out. The numerical results show that the shape and height of the unit cell, the elastic modulus, density and Poisson’s ratio of the auxetic foam play important roles in the formation of the bandgap. Finally, the numerical simulation verifies that adding through holes in the matrix which reduces the equivalent mass density of the matrix could widen the bandgap and enhance the effective attenuation of seismic waves. Based on theoretical model and combined with the exceptional material characteristics of auxetic foam, the focus of the study is to achieve a wide bandgap coverage for the seismic peak spectrum of 2 Hz which causes the principal damage of surface buildings.

Cyclic behavior of T-stub connection to hollow section steel column using TSOBs

The One-side bolts are widely used in the connection of the closed section members in the prefabricated buildings. As a novel type of one-side bolt, T-head Square-neck One-side Bolt has the advantages of the simple structure, the convenient installation, and no need for special installation tools. In this paper, the sub-model for the tension region of the T-stub bolted beam-column connection was selected as the research object, and the cyclic test was conducted on four T-head Square-neck One-side Bolted Connections (TSOBCs) for T-stub to Hollow Section Steel Column (HSSC) and two Traditional High-strength Bolted Connections (THBCs) for comparison. The results of the test including the failure modes, the applied force-displacement hysteretic curves, the applied force-displacement envelope curves, the deformation capacity and ductility, the strength degradation, the stiffness degradation, the energy dissipation, and the strain evolution are discussed and analyzed in this paper. The experimental results denote that: (1) There are two failure modes in the test, mode i, HSSC wall yielding and mode ii, T-stub flange yielding; (2) The initial stiffness and peak bearing capacity of the TSOBCs decreased by 2.5% ~ 35.6% and 21.7% ~ 39.4%, respectively, compared with those of the THBCs; (3) When the failure mode ii occurred, the ductility and the equivalent damping coefficient of the TSOBC with vertical mounting holes are 42.5% and 5.4% higher than those of the THBC, respectively. Besides, the plastic deformation, rigid displacement, and bolt offset in the TSOBCs are analyzed using finite element models.

Numerical Investigation of FRP-Strengthened CHS Columns

The use of external CFRP jacket is examined as a retrofitting technique that improves the ductility and the load carrying capacity of the steel tube. The study focuses on the interaction between the steel and the jacket, which is treated as a contact problem. The contact conditions in the steel-CFRP interface are represented by interface laws. Finite element modeling is used to simulate the physical problem and the results of the numerical analysis are presented and discussed. CFRP-jacket is proved to be an effective strengthening method for hollow steel columns.