Local Buckling Of Steel Plates Research Articles

Research on the axial compressive behavior of double skin composite wall with steel truss

This paper presents a research on the axial compressive behavior of double skin composite wall(DSCW) with steel truss, which is a novel type of composite wall. The steel truss is constructed by two angles and kinked rebar is acting as the interface connector. Experimental study was introduced briefly and software ABAQUS was adopted for numerical simulation analysis. By comparing with the experimental results, the accuracy of the finite element model was verified and then structural behavior of the walls was comprehensively evaluated. A parametric study was carried out to investigate the influences of the strength of steel plate and infilled concrete, truss horizontal spacing to thickness ratio on the compression responses of the composite wall. The results show that the better ductility of the composite wall can be achieved by the lower concrete strength and higher steel plate strength. Besides, the strength of the concrete and the steel plate tends to have a linear correlation with the load-carrying capacity. The horizontal spacing to thickness ratio has the significant influence on the failure mode of the composite wall and local buckling of steel plate can be avoided when the ratio is less than a certain value. In addition, the calculation formula for the axial compressive load-carrying capacity of the composite wall was proposed to provide a reference basis for the application of this type of composite walls in practice.

Elastoplastic Analysis of Circular Steel Tube of CFT Stub Columns under Axial Compression.

Composite action between the components of the concrete-filled steel tube (CFT) is complex and it is difficult to accurately obtain the experimental relationship between the steel tube and the core concrete of CFT columns. The triaxially stressed core concrete has been studied by hydrostatic test in past research, while little research has been focused on the mechanical behavior of steel tube of CFT columns. It is difficult to obtain the experimental constitutive relationship of the steel tube of CFT columns to reflect the real-time influence of biaxial stress state and local buckling of steel plate on the steel tube. To clarify the mechanical behavior of the steel tube of CFT columns, this paper proposed an elastoplastic analytical method considering biaxial stress state and local buckling of steel tube to obtain the stress-strain curve of the steel tube. This method applied the Hook's law and the plasticity theory to interpret the information conveyed by the measured vertical and hoop strain histories of the steel tube. To verify its effectiveness, 11 circular concrete-filled steel tube stub columns were fabricated and tested under axial compression. Superposition results of the axial load-strain of steel tube and core concrete were compared against the experimental curves. The widely used Sakino-Sun model of the confined concrete was adopted to calculate the axial load-strain curve of the core concrete. Satisfactory agreements between the calculated and experimental results confirmed the rationality of the proposed method in tracing the constitutive relation of the biaxially stressed steel tube even after the occurrence of the local buckling. The obtained stress-strain relationship is critical for establishment of mathematical constitutive model and finite element model of steel tube.

Study on the shear mechanism and resistance of single-side concrete-encased composite plate shear wall

Concrete-encased composite plate shear walls (C-PSW/CEs) are effective structural elements for the lateral load-resisting. With the restraints from concrete panels and headed studs, the shear yielding of infill steel plate can be realized. In service, concrete panel can also provide a significant shear resistance to C-PSWCEs. Especially for the single-side concrete-encased ones, the post-buckling strength for the local buckling of steel plate can be utilized in ductility. However, research on the in-plane behavior of concrete panel or the post-buckling behavior of steel plate in the single-side C-PSW/CE is limited. In this paper, the shear behavior of single-side C-PSW/CE under lateral loading was studied by experiment and finite element analysis. The damage process and shear resistance of C-PSW/CE with different concrete thicknesses were tested. The extended finite element method (XFEM) was employed in the finite element model (FEM) to simulate the cracking of concrete panel. The internal forces in the horizontal and inclined cross sections of steel plate and concrete panel and in the pure shear zones and diagonal tension fields of steel plate were investigated to reveal the shear mechanisms of C-PSW/CE. Based on the parametric analysis results, formulas for the shear stiffness and yield shear force and a mechanics-based model for the shear force-drift ratio response of single-side C-PSW/CE were proposed.

Behaviors of improved multi-cell T-shaped concrete-filled steel tubular columns under eccentric loads

The improved multi-cell T-shaped CFST section is composed of four square or rectangular cavities infilled with concrete, in which the steel plates added in the section are developed as stiffeners to avoid or delay local buckling of the tube wall. In practical engineering, columns are generally subjected to eccentric load. A total of eleven multi-cell T-shaped concrete-filled steel tubular (CFST) columns were tested under eccentric loads in the symmetric axis. Effects of the web height, the slenderness ratio, the load eccentricity, and the eccentric direction of load on the mechanical behaviors of the specimens were investigated. The experimental results showed two failure modes of the specimens: before the peak load, local buckling was observed in the specimen ET-11 owing to the relatively large width-to-thickness ratio of steel plates in the web; before the peak load, slight local buckling occurred at the mid-span of the other specimens but was not observed during the test, and after the peak load, the local buckling gradually increased, which resulted from the large bending deformation. The improved multi-cell T-shaped CFST columns exhibited a better restraint effect of steel tubes on core concrete and the local buckling of steel plates was delayed or restrained. The ultimate bearing capacity of the specimen under eccentric load located on the flange (y-) was relatively larger. Furthermore, finite element (FE) models were developed to simulate the mechanical behaviors of multi-cell T-shaped CFST columns under eccentric loads and verified with the experimental results. The stress and strain analyses of core concrete at the ultimate state were conducted by using the FE models. Based on both experimental and finite element methods, the simplified calculation formulae for predicting the ultimate bearing capacity of multi-cell T-shaped CFST columns subjected to axial and eccentric compression were put forward. The calculated results agree well with the results of the test and the FE models.

Local buckling of rectangular concrete-filled steel tubular columns with binding bars under eccentric compression

Based on the energy method, this article presents a theoretical study on the elastic local buckling of steel plates in rectangular concrete-filled steel tubular columns with binding bars subjected to eccentric compression. The formulas for elastic local buckling strength of the steel plates in eccentrically loaded rectangular concrete-filled steel tubular columns with binding bars are derived, assuming that the loaded edges are clamped and the unloaded edges of the steel plate are elastically restrained against rotation. Then, the experimental results are compared with these formulas, which exhibits good agreement. Subsequently, the formulas are used to study the elastic local buckling behavior of steel plates in rectangular concrete-filled steel tubular columns with binding bars under eccentric compression. It is found that the local buckling stress of steel plates in eccentrically loaded rectangular concrete-filled steel tubular columns with binding bars is significantly influenced by the stress gradient coefficient, width-to-thickness ratio, and the longitudinal spacing of binding bars. With the decrease of width–thickness ratios or the longitudinal spacing of binding bars or with the increase of the stress gradient coefficient, the local buckling stress increases. Furthermore, the influence of the longitudinal spacing of binding bar is more significant than the stress gradient coefficients. Finally, appropriate limitation for depth-to-thickness ratios ( D/ t), width-to-thickness ratios ( B/ t), and binding bar longitudinal spacing at various stress gradient coefficients ( α0) corresponding to different cross-sectional aspect ratios ( D/ B) are suggested for the design of rectangular concrete-filled steel tubular columns with binding bars under eccentric compression.

Experimental compressive behavior of novel composite wall with different width-to-thickness ratios

Double skin composite wall system owns several structural merits in terms of high load-carrying capacity, large axial stiffness, and favorable ductility. A recently proposed form of truss connector was used to bond the steel plates to the concrete core to achieve good composite action. The structural behavior of rectangular high walls under compression and T-shaped high walls under eccentric compression has been investigated by the authors. Furthermore, the influences of the truss spacings, the wall width, and the faceplate thickness have been previously studied by the authors on short walls under uniform compression. This paper experimentally investigated the effect of width-to-thickness ratio on the compressive behavior of short walls. Compressive tests were conducted on three short specimens with different width-to-thickness ratios. Based on the test results, it is found that the composite wall shows high compressive resistance and good ductility. The walls fail by local buckling of steel plates and crushing of concrete core. It is also observed that width-to-thickness ratio has great influence on the compressive resistance, initial stiffness, and strain distribution across the section. Finally, the test results are compared with the predictions by modern codes.

Local buckling of steel plates in composite members with tie bars under axial compression

Tie bars have been frequently used in square or rectangular concrete-filled steel tubular (CFST) columns and concrete-filled steel plate (CFSP) composite shear walls for delaying local buckling of the steel plates and also improving the concrete confinement. This study investigated the entire response of steel plates in composite members with tie bars. Twelve specimens were designed and tested under axial compression. In these specimens, only the steel plates resisted the axial load, and the concrete was only used to restrain the inward buckling of the steel plates. The effects of the width-to-thickness ratio of the steel plate and the ratio of the vertical spacing of the tie bars to the steel plate width (abbreviated as vertical-spacing-to-width ratio) were investigated. It was found that the increase in the performance of the steel plates due to the tie-bar restraint was quite limited when the vertical-spacing-to-width ratio was 1/2 and became more significant when this ratio decreased to 1/3. The elastic buckling stresses of rectangular plates having boundary conditions similar to those in composite members were computed using the finite element method for further strength evaluation of the steel plates. It was found that the effect of the columns of tie-bars on the elastic buckling stress increased as the vertical-spacing-to-width ratio decreased and was negligible when this ratio was larger than 0.6. Simplified equations for estimating the maximum strength and reserved strength (defined as the average stress corresponding to the average strain of 3%) of the steel plates in composite members with tie bars were developed based on the test results and elastic buckling analyses.

Hysteretic model for steel piers considering the local buckling of steel plates

The pier is a vital structural component of bridges and thus critically considered in the seismic design. In order to provide an accurate and efficient methodology in the analysis of seismic response, a hysteretic model considering the effect of local buckling of steel plates is proposed for steel piers. In the hysteretic model, the Giuffre-Menegotto-Pinto hysteresis model is employed to establish the hysteresis curve equation, and the energy-based Ibarra-Krawinkler degradation rule is followed to describe the deterioration rule of structural bearing capacity and stiffness. In this study, a widely used Chinese steel Q345qC was taken as an example to illustrate the proposed model for steel piers. At first, the seismic performance of steel piers under horizontal cyclic load was analyzed. Then, the empirical formulae of the vital limit state points for evaluating the structural seismic performance were established, and further the identification of the decisive parameter (degradation parameter) of the hysteretic model was carried out. Morever, the verification on the effectiveness of the proposed model was verified, and the results showed its applicability and accuracy for steel piers under horizontal cyclic loads. Finally, the application of the proposed model in the seismic calculation of steel piers was interpreted.

Local Buckling of Steel Plates in Composite Structures under Combined Bending and Compression

Local Buckling of Steel Plates in Composite Structures under Combined Bending and Compression

A refined model for local buckling of rectangular CFST columns with binding bars

This paper presents a refined model for local buckling of rectangular concrete-filled steel tubular (CFST) columns with binding bars under axial compression due to a deficiency in the previous model i.e. the influences of horizontal spacing and diameter of binding bars were not considered. The influences of longitudinal spacing, horizontal spacing and diameter of binding bars on the critical local buckling stress can be reasonably considered in the proposed model, which is applicable to both elasto-plastic phase and elastic phase. The refined model is verified against the experimental results, showing better agreement than the previous model. Then, the proposed model is employed to investigate the influences of longitudinal spacing, horizontal spacing, diameter of binding bars and cross-sectional aspect ratios on the critical local buckling stress. It is found that the critical local buckling stress increases considerably with the decrease of the spacing of binding bars. Furthermore, the influence of longitudinal spacing of binding bars on the critical local buckling stress is more significant than that of horizontal spacing. It is also found that the critical local buckling stress increase modestly with the increase of diameter of binding bars in the case of small spacing of binding bars. In addition, the cross-sectional aspect ratio have little influence on the critical local buckling stress, which can be ignored. Aiming at delaying the occurrence of local buckling of steel plates in rectangular CFST columns with binding bars, it is suggested that decreasing longitudinal spacing as an efficient measure has priority over other measures.

Local buckling of steel plates in concrete-filled steel tubular columns at elevated temperatures

Local buckling remarkably reduces the strength of steel plates in rectangular thin-walled concrete-filled steel tubular (CFST) columns at ambient temperature. This effect is more remarkable at elevated temperature. However, there have been very limited experimental and numerical investigations on the local and post-local buckling behavior of steel plates in CFST columns at elevated temperatures. This paper presents numerical studies on the local and post-local buckling behavior of thin steel plates under stress gradients in rectangular CFST columns at elevated temperatures. For this purpose, finite element models are developed, accounting for geometric and material nonlinearities at elevated temperatures. The initial geometric imperfections and residual stresses presented in steel plates are considered. Based on the finite element results, new formulas are proposed for determining the initial local buckling stress and post-local buckling strength of clamped steel plates under in-plane stress gradients at elevated temperatures. Moreover, new effective width formulas are developed for clamped steel plates at elevated temperatures. The proposed formulas are compared with existing ones with a good agreement. The effective width formulas developed are used in the calculations of the ultimate axial loads of rectangular CFST short columns exposed to fire and the results obtained are compared well with the finite element solutions provided by other researchers. The initial local buckling and effective width formulas can be implemented in numerical techniques to account for local buckling effects on the responses of rectangular thin-walled CFST columns at elevated temperatures.

Strength of double skin steel-concrete composite walls

Double skin steel-concrete composite walls have been increasingly used in civil engineering applications. However, the advantages of these walls have not been fully recognized due to the lack of appropriate technical guidelines for capacity design. In this paper, the local buckling strength of steel plate were firstly reviewed in terms of specifications incorporated in several modern codes. A methodology to predict the strength of steel plate with restraint of both concrete and shear studs was proposed based on the explicit solution for local buckling of steel plate in composite shear walls subjected to uniform axial compression and with elastically rotational restraint at loaded and unloaded edges. The results were compared with various previous experimental data and good agreement was observed. Furthermore, the load carrying capacity of composite walls was derived from the superposition of the contribution of steel plate and concrete. The predicted values from the proposed equations, together with the resulted determined from modern codes, were compared with the experimental results. It was found that both the proposed method and JEAG 4618 offer reasonable predictions while AISC 360 and KEPIC-SNG always underestimate the actual values.

Structural Performance of Composite Shear Walls under Compression

In order to research the effect of different layout forms of steel plate on the axial compression behavior of a steel plate-concrete composite shear wall, this paper presents the experimental results and analysis of the axial compression behavior of a composite shear wall, with different layout forms of steel plate. A total of three tests were carried out, composed of two composite walls with built-in steel plate, and one composite wall with two skins of steel plate. The gross dimensions of the three specimens were 1206 mm × 2006 mm × 300 mm. Experimental results show that the composite wall with two skins of steel plate has an optimal ability of elastic-plastic deformation, and the maximum axial compressive bearing capacity among the three specimens. Using the energy method, the critical local buckling stresses of steel plate were calculated, and compared with the yield stresses. According to different confined actions of concrete, concrete constitutive models were proposed, and the axial compressive strengths of confined concrete were calculated. Considering the local buckling of steel plate and confined concrete, the calculation formula of the axial compression of the composite wall was put forward, and the calculated results were in good agreement with the test results. Therefore, the different layout forms of steel plate have a great influence on its buckling, and on the concrete inhibition effect, which can affect the axial compressive bearing capacity of the composite wall.

Fire resistance of concrete-filled steel plate composite (CFSPC) walls

Concrete-filled steel plate composite walls (CFSPC walls) have recently emerged as promising alternatives to conventional reinforcement concrete shear walls due to the benefits of effective space use, less construction time/effort, and higher ductility. While the basic load carrying capacity and seismic performance of CFSPC walls have been receiving great attention, little work has been conducted so far on their fire performance. This paper aims to bridge the knowledge gap by performing 12 fire tests on CFSPC walls, where shear stud spacing, wall height, wall thickness, steel ratio, and fire scenario (uniform or single-sided fire) were considered as the main test parameters. For the uniform fire tests, the specimens exhibited reasonably good fire resistance, where the fire resistance time exceeded 2h. Three dominating failure modes were observed, namely, local buckling of steel plates (LB), severe cracking (‘tearing’) of the weld along the corner line of the wall (WC), and global instability (GI). For the specimens subjected to single-sided fire, minor local buckling of the heated steel plate accompanied by tie bar failure in the buckled areas were observed, but no further load bearing failure was induced by the end of the heating process. The fire resistance time, which exceeded 2.5h for the specimens exposed to single-sided fire, was governed by the ‘thermal insulation criterion’. After 2.5h of heating, some specimens lost their thermal insulation capacity. Based on the test phenomena, preliminary design recommendations are proposed, and future research directions are also outlined.

Shear strengthening of fire-damaged reinforced concrete beams using bolted-side plating

Abstract Six reinforced concrete (RC) beams were fabricated and exposed to fire in accordance with the international standards ISO834 temperature curve, four of which were retrofitted employing the bolted side-plating (BSP) technique. The shear tests of two control beams and four beams strengthened with BSP after fire were carried out. The influence of the plate depth and bolt spacing on the shear strength, ductility and stiffness was investigated. The testing results indicated that the BSP method can significantly increase the shear capacity of fire damaged RC beams and improve the overall shear and flexural performance. The strengthening effect increases as the increase of plate depth and the decrease of bolt spacing. When the external load is very large, local buckling of steel plate will occur under the combined action of bending and shearing. Both longitudinal and transverse slips coexist on the plate–RC interface of BSP beams. The bolt spacing exerts an important influence on the degree of partial interaction between the plate and the concrete. In the design of BSP reinforcement, the relative relation between the number of anchor bolts and the plate depth should be taken into consideration.

Comprehensive stress-strain model of square steel tube stub columns under compression

A stress-strain model is proposed to define the relationship between axial compressive stress and strain for square steel tube stub columns, which have been widely used as predominant gravity-sustaining structural components in high-rise buildings and skyscrapers. The proposed model consists of two equations, defining the ascending branch and descending branch of the stress-strain curve, respectively, and has a significant advantage over previous models in that it can trace effects of both the residual stress induced during manufacturing process and the local buckling of steel plate on the compressive stress-strain behavior of square steel tube stub columns. Another feature of the proposed model is that it can be used to the stub columns made of very thin steel plates. In order to calibrate the new stress-strain model and verify its reliability and accuracy, sixty-eight hollow square steel tube stub columns under monotonic axial compression are collected. The previous tests cover a wide range of structural factors such as yield strength and width-to-thickness ratio of steel plates. In particular, the previous tests include stub columns made of steel plate with high yield strength of up to 835MPa. Comparisons between the experimental results and the calculated ones indicate that the proposed model cannot only predict the local buckling strength and the corresponding strain very well, but also trace the compressive stress-strain behavior of square steel tube stub columns up to large strain with high accuracy.

Theoretical study on local buckling of rectangular CFT columns under eccentric compression

The local buckling of steel plates in rectangular concrete-filled steel tubular (CFT) columns subjected to eccentric compression is investigated based on the energy method. The formulas for elastic local buckling stress of the steel plates in rectangular CFT columns under eccentric compression are derived, assuming that the unloaded edges of the steel plate are elastically restrained against rotation, whereas the loaded edges are clamped. Subsequently, the formulas are calibrated with the experimental results and compared with calculated results by the empirical method, which exhibit good agreement. Then, these formulas are applied to investigate the local buckling behavior of steel plates in eccentrically loaded rectangular CFT columns. It is found that the local buckling stress of steel plates in eccentrically loaded rectangular CFT columns is significantly influenced by the stress gradient coefficients and width–thickness ratios while it is slightly influenced by cross-sectional aspect ratios (D/B). Finally, the reasonable ranges for width–thickness ratios (B/t) and depth–thickness ratios (D/t) at various stress gradient coefficients corresponding to different cross-sectional aspect ratios are suggested for the steel plates in eccentrically loaded rectangular CFT columns. Furthermore, the appropriate relationship for the thickness of the steel plates at various stress gradient coefficients is suggested for the design of rectangular CFT columns under eccentric compression.

Experimental Research on Seismic Behavior of Wall Component with Double Steel Plates and Infill Concrete

In order to study the seismic performance of wall component with double steel plates and infill concrete,three wall components with double steel plates and infill concrete were tested.The deformation performance and failure modes were observed under low cyclic lateral loads with high axial compression ratio.Valuable results were obtained for the hysteretic curves,skeleton curves,rigidity degeneration,ductility and energy dissipation capacity.The results indicate that Stud spacing is the key factor to prevent local buckling of steel plate, Steel plate and concrete stress as a whole;Setting stiffening rib, can improve the overall stiffness, bearing capacity and ductility, but had little effect on delaying wall cracks.

Development and Application of CFT without Fire Protection using High Performance Steel and Concrete

Concrete filled tube (CFT) columns, which consist of a steel tube filled with concrete, combine the benefits of the two materials. The steel tube provides a confining pressure to the concrete, while the local buckling of steel plate can be prevented by the concrete core. CFT columns also have a high fire resistance due to the heat storage effect of concrete under fire. For this reason, it is possible to develop CFT columns without fire protection measures. CFT columns without fire protection have many advantages, including quality control, cost reduction, better space efficiency and a shorter construction period. Due to these advantages, studies on the development of CFT columns without fire protection measures have been performed. However, CFT columns lose their bearing capacity under fire because the steel tube is exposed to the outside. As a result, the structure is collapsed, causing significant damage. In this research, we made a CFT column using high strength concrete (100 MPa) and high strength steel (800 MPa). We use steel fiber and nylon fiber with concrete to provide fire resistance. We perform the fresh concrete experiment and investigate the fire resistance of the CFT column (<TEX>${\Box}400{\times}400{\times}15{\times}3000mm$</TEX>) under loading. To investigate the effect of steel fiber on increasing fire resistance, we compare the fire resistance time according to the steel fiber. Through the test, it was found that the CFT specimen with steel fiber had better fire resistance performance than other cases.

Flexural behaviour of steel plate-masonry composite beams

Steel plate-masonry composite structure is a newly-developed type of structural technique applicable to existing masonry buildings by which the load-bearing walls can be removed for large spaces. This kind of structure has been used in practice for its several advantages, but experimental investigation on its elements is nearly unavailable in existing literature. This paper presents an experimental study on the flexural behaviour of four steel plate-masonry composite beams loaded by four-point bending. Test results indicate that failure of the tested beams always starts from the local buckling of steel plate, and that the tested beams can satisfy the requirement of service limit state. In addition, the assumption of plane section is still remained for steel plate prior to local buckling or steel yielding. By comparative analyses, it was also verified that the working performance of the beam is influenced by the cross-section of steel plate, which can be efficiently enhanced by epoxy adhesive rather than cement mortar or nothing at all. Besides, it was also found that the contribution of the encased masonry to the flexural capacity of the composite beam cannot be ignored when the beam is injected with epoxy adhesive.