Steel Rectangular Hollow Sections Research Articles

Nonlinear analysis of concrete-filled steel SHS and RHS columns

This paper presents an accurate nonlinear finite element model for the behaviour and design of axially loaded concrete-filled square hollow section (SHS) and rectangular hollow section (RHS) steel tube columns. The nonlinear material models for confined concrete and steel tubes were carefully modeled in the finite element analysis. The column strengths and load-axial shortening curves were evaluated. The results obtained from the finite element analysis were verified against experimental results. An extensive parametric study was conducted to investigate the effects of different concrete strengths and cross-section geometries on the strength and behaviour of concrete-filled SHS and RHS steel tube columns. The study was conducted over a wide range of concrete cube strengths ranged from 30 to 110 MPa. The overall depth of the steel tube-to-plate thickness ratio ranged from 10 to 40 covering compact SHS and RHS steel tube sections. The column strengths predicted from the finite element analysis were compared with the design strengths calculated using the American, Australian and European specifications. Based on the results obtained from the parametric study, it is found that the design strengths calculated using the American Specifications and Australian Standards are conservative, while the design strengths calculated using the European Code are accurate, except for the concrete-filled RHS compact steel tube columns having the overall depth of the steel tube-to-plate thickness ratio of 40.

Behaviours and Strengths of Concentrically Loaded Short Concrete-Filled Steel HS Columns with Different Cross-Section Geometries

This paper presents the stress distribution, confinement distribution and complete average longitudinal stress-strain curves for concentrically loaded short concrete-filled steel circular, octagonal, square and rectangular hollow section (HS) columns using 3-D finite element (FE) analyses. The curves predicted by FE analyses are in good agreement with those obtained from previous experimental work. The compressive design strengths and the compressive moduli of concrete-filled steel HS columns are also obtained. A unified method is proposed for the design of concentrically loaded short concrete-filled steel HS columns with different cross-section geometries.

Analysis of thin-walled steel RHS columns filled with concrete under long-term sustained loads

The present study is an attempt to predict the time-dependent behavior of concrete-filled thin walled steel RHS (rectangular hollow section) columns by means of a model that is proposed by the ACI Specifications (ACI Committee 209,1992) [1]. A theoretical model of analysis to account for shrinkage and creep effects on concrete-filled steel RHS columns under sustained loading is presented, and is a development of the analysis used for short-term loading (Han et al, 2001a) [2]. A comparison of results calculated using this model shows good agreement with test results. The main objectives of this paper were threefold: firstly, to report a series of tests on the behavior of concrete-filled steel RHS columns under long-term sustained loading, in addition to providing further tests on the static ultimate strength of the composite columns. Secondly, to analyze influence of several parameters, such as changing steel ratio, long-term sustained load level, slenderness ratio, strength of the materials and depth-to-width ratio on the capacities of the concrete-filled steel RHS columns. And finally, to develop formulas for the calculations of the ultimate strength of the concrete-filled steel RHS columns with long-term sustained loading effects are considered, such formulas should be suitable for incorporation into building codes.

Connection stiffness and natural frequency of DuraGal lightweight floor systems

This paper reports a series of component tests on a lightweight floor system and a method to predict the natural frequency of the floor using a frame analysis program. Full-scale floor tests are also briefly described. DuraGal steel Rectangular Hollow Sections (in-line galvanised RHS) are used as joists, bearers and piers in DuraGal lightweight floor systems. A structural grade particleboard is used as decking. Connection stiffness between different components (bearer, joist, pier and floor decking) was determined. A 40% composite action was achieved between the RHS joist and the particleboard. Both 2D and 3D models were developed to study the effect of connection stiffness on predicting the natural frequency of DuraGal lightweight floor systems. It has been found that the degree of shear connection between the bearer and the joist has a significant influence on the floor natural frequency. The predicted natural frequencies are compared with measured values from full scale floor testing.

Rotational Stiffness of Rectangular Hollow Sections Composite Joints

Joints in steel rectangular hollow sections filled with concrete present the added difficulty of involving the deformability of the connected faces in bending. This implies that, unless a good estimate of the moment-rotation curve can be obtained, complex and expensive detailing is required to ensure a fairly rigid response of the joint. A first step to achieve the objective of predicting the behavior of such a joint corresponds to an assessment of the initial stiffness of the joint. Starting with a brief review of the current state-of-the-art in the behavior of joints in hollow sections, this paper presents and discusses an analytical model based on an equivalent strip of the loaded face. A simple solution based on this model that has been calibrated with numerical simulations is also derived. The main parameters considered are the thickness of the loaded face and the dimensions of the loading area. Comparisons with some available numerical and experimental results are quite encouraging.

Experimental Investigation of Cold-Formed Stainless Steel Columns

An experimental investigation into the column strength of cold-formed stainless steel rectangular hollow sections is described in this paper. The columns tested displayed four cross-section sizes and were compressed between fixed ends. The tests were performed over a range of column lengths in order to obtain a column curve for each series of tests. The failure modes of the columns involved local buckling, overall flexural buckling, and combined local and overall buckling. The test strengths are compared with the design strengths predicted using the American, Australian/New Zealand, and European specifications for cold-formed stainless steel structures. The design strengths were calculated using the material properties obtained from both tensile coupon and stub column tests. It is concluded that the design strengths predicted by the three specifications are generally conservative. Reliability analysis of the design rules in the three specifications is performed. It is shown that the design strengths predicted by the Australian/New Zealand Standard are generally more reliable than the design strengths predicted by the American and European specifications.

Influence of concrete compaction on the strength of concrete-filled steel RHS columns

Abstract Concrete-filled steel tubular columns have better structural performance than that of bare steel or reinforced concrete (R.C.). The use of concrete-filled SHS (Square Hollow Section) and RHS (Rectangular Hollow Section) have become widespread in the past few decades. However, these members are susceptible to the influence of concrete compaction. It is expected that the influence of concrete compaction on R.C. columns and concrete-filled steel tubes is different. For R.C. columns, concrete compaction only affects the mechanical properties of concrete. But for concrete-filled steel tubes, it is well known that the interaction between steel tube and concrete is the key issue to understand the behaviour of this kind of column. The concrete compaction not only affects the properties of the core concrete itself, but also may influence the interaction between the steel tube and its concrete core, and thus influences the behaviour of the composite columns. The present study is an attempt to study the influence of concrete compaction on the strength of concrete-filled steel RHS columns. Tests on 35 concrete-filled steel RHS columns to investigate the influence of concrete compaction methods on the member capacities of the composite columns are reported. The main parameters varied in the tests are: (1) column section depth-to-width ratio, from 1.0 to 2.0, (2) tube depth to thickness ratio, from 34 to 136, (3) load eccentricity (e), from 0 to 31 mm and (4) column slenderness (λ), from 21 to 62. The main objectives of these tests were twofold: firstly, to report a series of tests on composite columns under different concrete compaction methods; and secondly, to investigate the influence of concrete compaction on the member capacities of the composite columns. Comparisons are made with predicted column strengths using the existing codes such as LRFD, American Institute of Steel Construction Inc-1997, AIJ-Architectural Institute of Japan-1997, Eurocode 4-1996 and GJB4142-2000. It was found that better compaction of concrete resulted in higher member capacities in concrete-filled steel RHS columns. The tests showed the importance of good concrete compaction for concrete-filled steel RHS columns.

An experimental study and calculation on the fire resistance of concrete-filled SHS and RHS columns

Abstract The behavior of concrete-filled steel square hollow section (SHS) and rectangular hollow section (RHS) columns with or without fire protection subjected to axial or eccentric loads has been experimentally investigated and the results are presented in this paper. The parametric and experimental studies provide information for the development of formulas for the calculation of the fire resistance and the fire protection thickness of the composite columns. The main objectives of this paper were threefold: first, to report a series of fire tests on composite columns with square and rectangular sections. Secondly, to analyze the influence of several parameters, such as fire duration time, sectional dimension, slenderness ratio, load eccentricity ratio, strength of steel and concrete on the residual strength index (RSI) of the composite columns. Finally, to develop formulas for the calculation of the fire resistance and the fire protection thickness of the concrete-filled steel SHS and RHS columns, such formulas to be suitable for incorporation into building codes. The concepts of this paper were used to provide data on the necessary fire protection measures for the concrete-filled steel SHS columns used in a high-rise building, Ruifeng, Shangye Building in Hangzhou City, in southern China.

Tests on slender composite columns

This paper describes two series of load tests on slender composite columns: eight tests on concrete filled rectangular hollow steel section columns and seven tests on concrete encased rolled steel joist columns, both with end eccentricities producing moments other than single curvature bending. In all tests, normal strength concrete of grade C25/30 and low strength steel of grade S275 were specified. The main objectives of these tests were twofold: first, to provide test information for the calibration of Eurocode 4 against BS 5400 for slender composite columns and secondly to assess the accuracy of a new design method for composite columns, based on the well established steel column approach in BS 5950. Comparisons are made between predicted column strengths using the three different methods and between various predictions and test results. It is found from these comparisons that all three methods are conservative and have similar overall accuracy. For concrete filled composite columns, the Eurocode 4 method appears to be more accurate than the BS 5400 method. The proposed design method, which is based on the steel column approach in BS 5950, gives predicted column strengths comparable to those from the Eurocode 4 method. It also gives a clear understanding of the behaviour of a composite column. However, the main advantages of the proposed method are its simplicity and the savings in design time.

冷間成形角形鋼管柱の最近の課題

冷間成形角形鋼管柱の最近の課題

Finite Element Model for RHS Double Chord K‐Joints

A finite element elastic‐plastic model for separated double chord gap K‐joints of steel rectangular hollow sections (RHS), is presented. The model treats a single chord member as composed of a plate representing the inner web and a channel depicting the top and bottom flanges and the outer web, respectively. Triangular and rectangular flat shell elements are used to discretize the inner web plate, whereas plane stress elements are employed for the branch members. The channel consists of a grillage of beam elements. The analysis extends beyond the elastic limit and accounts for strain hardening and material nonlinearity. A comparison of theoretical predictions with the experimental results of 12 K‐joint specimens of a previous study shows fair agreement.