Rectangular Hollow Section Columns Research Articles

Development of component stiffness equations for thread-fixed one-side bolt connections to an enclosed rectangular hollow section column under tension

Development of component stiffness equations for thread-fixed one-side bolt connections to an enclosed rectangular hollow section column under tension

Stiffness of Loaded Face of Steel Rectangular Hollow Section Columns with and without Concrete Infill in Beam-column Endplate Connections

This paper presents a new analytical approach for calculating the stiffness of the loaded face of a rectangular hollow section RHS column in beam-column connections with and without concrete infill, as well as with flush and extended endplates, to determine the behavior curve of these types of connections. The approach, based on Eurocode 03's component method, offers efficient analytical formulas for accurately determining the loaded face's stiffness. A comparison with existing methods demonstrates its remarkable simplicity and efficiency, allowing a simple beam model to represent the RHS column's behavior with all relevant parameters considered. Comparison of the new approach to existing ones from the literature demonstrates their reliability and efficiency. Furthermore, when compared to 32 experimental tests presenting nearly the entire range of probable connection configurations, as well as attachment techniques commonly used in construction practice, the margin of error does not exceed 12 percent on average and a maximum of less than 25 percent.

Numerical study on compressive behavior of a 3D-printed sand mold-cast S-CN connector

This paper presents a novel approach for steel modular structures, incorporating the S-CN connector – a hybrid tie rod and connector connection method – along with rectangular hollow section (RHS) steel members. The study numerically investigates the mechanical behavior of S-CN connectors and their application in beam–column connections under compressive loading. The compressive load-bearing capacity of the proposed connection is determined following AISC 360-16 guidelines, predicted through a finite element analysis approach and validated by experimental data. Parametric analysis reveals the impact of local buckling in modular nodes on the connector’s load-bearing capacity. The results demonstrate that tie plate thickness has a minimal effect, while reducing the modular node thickness leads to a linear decrease in load capacities. Furthermore, the failure mode of the beam–column connection depends on the compressive capacities of both the RHS column and the S-CN connector.

Stability and design of stainless steel hollow section columns at elevated temperatures

This paper investigates the stability and design of stainless steel circular, elliptical, square and rectangular hollow section (CHS, EHS, SHS and RHS) columns at elevated temperatures. Nonlinear shell finite element models are employed to conduct comprehensive parametric studies whereby extensive benchmark structural performance data on the behaviour and resistance of stainless steel hollow section columns at elevated temperatures is generated. In total, 26,760 cold-formed and hot-rolled austenitic, duplex and ferritic stainless steel CHS, EHS, SHS and RHS columns at elevated temperatures are taken into account, considering various member slendernesses, cross-section geometries, cross-section slendernesses and elevated temperature levels. New flexural buckling design rules are put forward for stainless steel hollow section columns in fire, which consistently considers the elevated temperature strength at 2% total strain f2,θ as the reference material strength for all cross-sections classes. The accuracy, safety and reliability of the proposed new design rules are assessed for a wide range of cases. Comparisons are also made against the results obtained through the column fire design rules of the European structural steel fire design standard EN 1993-1-2 [1]. It is demonstrated that the proposed new design rules furnish more accurate, safe-sided and reliable flexural buckling resistance predictions for stainless steel hollow section columns at elevated temperatures relative to the column fire design provisions of EN 1993-1-2 [1].

Innovations for Bolted RHS Column Splices

AbstractTwo novel concepts, recently developed in North America, are presented for bolted splices between Rectangular Hollow Section (RHS) column members. Single‐sided bolting through the RHS wall is performed, but using regular high‐strength bolts rather than “blind bolts”. The first concept employs nut‐holding devices, called “Shurikens”, that are pre‐installed on four splice plates fitted to the inside of the two RHS columns. The second innovation is a custom‐designed, hollow, cast steel insert – made of nut‐quality steel – that extends into both the upper and lower columns and has threaded holes to receive the inserted bolts, in lieu of nuts. This “internal plug” is a pre‐engineered solution, tailored to a particular RHS size, and requires no connection design. For both concepts, a bolted shear connection with little protruding steelwork is the result.

Structural response and design of stainless steel hollow section columns at elevated temperatures

AbstractThis paper investigates the flexural buckling behaviour and design of stainless steel circular, elliptical, square and rectangular hollow section (CHS, EHS, SHS and RHS) columns at elevated temperatures through numerical modelling. Shell finite element models are utilised to perform numerical parametric studies whereby benchmark structural performance data are generated. A large number of cold‐formed and hot‐rolled austenitic, duplex and ferritic stainless steel CHS, EHS, SHS and RHS columns at elevated temperatures are taken into account, considering various cross‐section and member slendernesses. Since the fire design provisions provided in the European fire design standard EN 1993‐1‐2 for stainless steel columns are largely based on those originally developed for carbon steel columns, they typically lead to rather inaccurate ultimate resistance predictions for stainless steel columns at elevated temperatures. To address this, in the present study, a new flexural buckling design method for stainless steel hollow section columns at elevated temperatures is put forward. The accuracy, safety and reliability of the proposed design method and the provisions in EN 1993‐1‐2 are assessed. It is observed that the proposed fire design method leads to more accurate, safe‐sided and reliable flexural buckling resistance predictions for stainless steel hollow section columns at elevated temperatures relative to the provisions in EN 1993‐1‐2.

I‐beam to RHS‐column joints with welded studs under cyclic loading

AbstractThe design of removable beam‐column joints between open structural steel beams and rectangular hollow section (RHS) columns is not easy because of the inaccessibility to the tube interior from outside. I‐beam to RHS‐column joints with threaded welded studs are of great interest due to their low‐cost assembling technique and easy on‐site execution. This study examines the cyclic performance of these joints with welded studs. A quasi‐static experimental study on the cyclic response of eight joint specimens is described. The strength of the joint and the failure modes were revealed. The ductility of the joints was also evaluated according to the rotation capacity after yielding, classifying all of them as having intermediate ductility and, therefore, implying some capacity to withstand limited plastic deformations when subjected to seismic forces. Some equations were also used to classify the joints according to the components that mainly govern the deformation of the full joint. In addition, the energy dissipation rate was assessed for all the specimens, finding the highest energy dissipation rates in the most rigid joints.

Post-earthquake damage detection of local buckling in rectangular hollow section columns based on local stiffness calculated by strain response

Local buckling of rectangular hollow section (RHS) columns can occur during strong earthquakes. However, it is difficult to determine quantitatively the magnitude of the load by visual inspection after an earthquake because of the small residual deformation caused by buckling. In this study, it was confirmed that the occurrence and progress of local buckling could be quantified by measuring the strain responses at the ends of the RHS columns when subjected to small aftershocks or microtremors. Furthermore, the change in the local stiffness distribution calculated by dividing the strain amplitude by the displacement amplitude was also investigated. It is suggested that the local stiffness can be used to detect small damages that cannot be visually observed. The shaking table test results show that the change in local stiffness is more pronounced in the convex buckling shape part compared with that in the concave buckling shape part; this finding is consistent with the finite element analysis outcomes. For strain measurements, it is recommended to determine first a few locations near the local buckling sections, based on which it may be necessary to make a comprehensive judgment.

Testing, modelling and design of 7A04-T6 high-strength aluminium alloy RHS columns under axial compression

The buckling behaviour and resistances of extruded 7A04-T6 high-strength aluminium alloy rectangular hollow section (RHS) columns under axial compression are reported in this paper. Nineteen RHS columns with member relative slenderness of 0.44–2.70 and cross-sections of Class 2–4 were conducted. Finite element (FE) models were developed and verified against the test failure modes, axial load-end shortening or mid-height lateral displacement curves and buckling resistances, and parametric analyses with a wide range of member and cross-section slenderness were performed. The generated test and FE results of 7A04-T6 high-strength aluminium alloy RHS columns were compared with current design methods specified in Chinese, European, American and Australian/New Zealand codes. The results indicated that the former three standards yielded conservative flexural buckling resistance predictions by about 9%, while slightly unsafe results were found for Australian/New Zealand standard, with all satisfactory reliability level. However, Chinese code resulted in the most conservative local-flexural buckling resistance predictions by about 35%, while conservative results under smaller member slenderness and overestimated ones under larger member slenderness were observed for other three standards, leading to scattered data and failing to reach target reliability indices. A series of improved design approaches shown to be safe and efficient for 7A04-T6 high-strength aluminium alloy RHS columns were suggested and validated by reliability analyses, including modified design curves for RHS columns to flexural buckling on Chinese and American standards, and three ways of proposals to imperfection terms with new coefficients as well as the direct strength method (DSM) in the framework of Chinese standard for RHS columns to local-flexural buckling.

Local buckling of cold-formed high-strength steel hollow section columns at elevated temperatures

A numerical investigation is conducted on the local buckling behavior of cold-formed square hollow section (SHS) and rectangular hollow section (RHS) columns made of normal and advanced high-strength steels at elevated temperatures. Shell finite element models validated against experimental results are used in a parametric numerical study to evaluate the local buckling strength at ambient and elevated temperatures of SHS and RHS columns fabricated with G450, dual-phase, and martensitic steels. The modeling uses recent experimental data on the elevated temperature behavior of advanced high-strength steels. The numerical results are compared with the design strengths calculated by the Direct Strength Method in AISI S100. Results show that the current method in AISI S100 consistently captures the trend but overestimates the ultimate capacity of G450 cold-formed columns both at ambient and elevated temperatures by about 10% for the SHS columns and 6% for the RHS columns. The current Direct Strength Method also yields higher estimates of capacity than the finite element models for advanced high-strength steel grades. Therefore, a modification to the method for local buckling capacity is proposed for these sections. The modified Direct Strength Method proposed herein can be used to evaluate the local buckling strength of cold-formed SHS and RHS columns made of normal and advanced high-strength steels at temperatures up to 700 °C.

Behavior and Design of Power-Actuated Fastener Connections in Cold-Formed Steels Subjected to Shear

This study proposes an innovative type of simple connection utilizing power-actuated fasteners to join a cold-formed steel channel to a rectangular hollow section column via a web-side plate or a T-section. An experimental program composed of 26 specimens was carried out to investigate the behavior of the connections under the combination of shear and rotation. The experimental results are discussed in two limit states including bearing and pull-out by shear. An analytical model is proposed to predict the shear strength of the connections based on the provided information of vectorial force at a fastener, displacement, and rotation at the connections. The proposed model yields a conservative prediction for the tested connections with a mean test-to-prediction ratio of 1.05 and the coefficient of variation of 6% or 9%, depending on the limit state. A design example is provided to illustrate the implementation of the proposed model in practice.

Static Bearing Capacity Investigation of a Novel Prefabricated Light-Steel Beam–Column Connection

In this study, a novel prefabricated light-steel beam–column connection consisting of a thin-walled rectangular hollow section column and two cold-formed steel truss beams is proposed and investigated by carrying out experimental tests. Eight cruciform beam–column connection specimens with different configurations are fabricated and tested to failure under monotonic static loading. First, failure mode and the loading–displacement curve of each specimen are investigated. Consequently, the effect of three variables, including truss-beam configuration, truss-beam type, and with or without sleeve tube reinforcing the column, on the static bearing capacity of the proposed connection and the deflection of the truss beams are investigated. It is found that plug welding the sleeve to the column can significantly increase the static bearing capacity of the proposed connection. In addition, fillet welding connecting the column and the channel connectors to accommodate the end of the truss beams is crucial to the static bearing capacity of the proposed beam–column connection. Because beam–column connections with single-truss beams have a higher load-bearing capacity and require less material and assembly work, it is recommended to adopt this type of configuration for the proposed connection.

Cold-formed stainless steel SHS and RHS columns subjected to local-flexural interactive buckling

Design of cold-formed stainless steel tubular columns undergoing local-overall flexural interactive buckling is investigated in this paper. A numerical study has been carried out to study the interactive buckling behavior of square hollow section (SHS) and rectangular hollow section (RHS) columns of various stainless steel grades that are employed in structural applications. A finite element model was developed and verified against available experimental cold-formed stainless steel SHS/RHS column data. Extensive parametric studies, with cross-section aspect ratio, plate slenderness, overall slenderness and stainless steel grade selected as key variable parameters, were carried out thereafter to generate further numerical data featuring the tubular columns undergoing local-flexural interactive buckling. The obtained interactive buckling strengths were used to assess the design provisions in current European, American, Australian/New Zealand and Chinese design standards for stainless steel structures as well as available Direct Strength Method (DSM) design rules in the literature. It is shown that better predictions can be achieved when material nonlinearities of different material grades are accounted for. A modified DSM, which relies on simple hand calculations, is developed in this paper. It is demonstrated that the modified DSM is a suitable and efficient design alternative for cold-formed stainless steel SHS/RHS columns subjected to local-flexural interactive buckling.

Development of Flexural Buckling Rules for the New AISC Stainless Steel Design Specification

AbstractThis paper presents the development of flexural buckling curves for austenitic and duplex stainless steel welded I‐sections and structural hollow sections, which are proposed for implementation in the new AISC stainless steel specification. The proposed buckling curves were developed following the same type of reliability analysis employed to develop the flexural buckling curve included in AISC 360 Specification for Structural Steel Buildings for carbon steel, considering all the experimental data available in the literature and a large number of numerical results. In order to facilitate their implementation, the proposed curves follow a similar form as the AISC‐type of curve included in AISC 360, with the only differences being the addition of a yield plateau and the values of selected coefficients used to adjust the shape of the curves.Three different buckling curves are proposed: one buckling curve for circular hollow section (CHS) columns and I‐section columns buckling about the major axis; one for rectangular hollow section (RHS) columns; and one for I‐section columns buckling about the minor axis. The proposed curves represent a significant improvement with respect to the currently available stainless steel flexural buckling curve included in AISC Design Guide 27, providing an increase in strength predictions of up to 55%.

Macro‐modelling of 3D tubular column‐to‐truss beam joints

AbstractThe European Research Project “Innovative 3D joints for robust and economic hybrid tubular construction” aims at developing innovative plug‐and‐play joints for hybrid tubular construction where square (or rectangular) tubular columns are combined with truss‐beams composed of cold‐formed lightweight steel beams. This kind of joints provides a highly efficient structural system for modular solutions that are essential for fast‐track construction. An important task of this project is to develop a 3D joint model that takes into account 3D behavior of joints. The 1D component method presented in the Eurocode 3 part 1‐8 is extended to a 3D level by considering all relevant components and interactions between them.In the literature, some studies showed that the out‐of‐plane deformation of the tubular column faces depends on the loading and boundary conditions of the other faces. The first objective of this article is thus to propose a new 2D springs model taking into account the correlation between out‐of‐plane deformations of the faces of rectangular hollow section (RHS) columns. Then, a formulation of a 3D macro‐element of the joint is presented. Finally, the model is validated using two distinct procedures: 1) an analytical procedure implemented in a symbolic calculation software; 2) a modelling by finite elements.

An experimental study of I beam-RHS column demountable joints with welded studs

This paper presents the results of an extensive experimental investigation on the behaviour of a new type of joint between open structural steel beam and rectangular hollow section (RHS) column. The proposed joint is demountable: threaded studs are welded to the front face of the hollow section column and angle cleat legs are then bolted to the column by means of the welded studs and to the beam flanges by ordinary bolts. Twenty-one full-scale single side or double side bolted beam-column joints combining different sections have been tested under monotonic and cyclic loads. The test results confirm that these joints behave as semi rigid and partial strength ones which possess sufficient stiffness and moment resistance for use in the construction of low to medium-rise steel buildings as an alternative to other traditional solutions. The proposed joints also exhibit a moderate energy dissipation capacity under cyclic loads, suitable for construction in moderate seismic regions. This research work demonstrates that the proposed joint is easy to execute on site without specialized manpower or expensive facilities.

Behavior and Design of Normal- and High-Strength Steel SHS and RHS Columns

AbstractThe behavior and design of hot-rolled and cold-formed steel square and rectangular hollow section (SHS and RHS) columns, made of both normal- and high-strength material, are addressed in th...

A Generalized Analytical Method to Evaluate the Post-limit Properties of Joints in Bending Moment According to Eurocode3

On the structural analysis, connection effects should be evaluated in terms of rotational stiffness and ultimate strength; this makes it possible to obtain realistic behavior of the structure. In this research, a simple analytical evaluation is carried out to predict the behaviors of the connections as a bi-linear curve. Mechanical properties of the initial and the second parts of this curve are obtained by component-based method and a suggested classification method, respectively. The component-based method represents a joint by using a combination of rigid and flexible components. Each of the components is modeled by means of specific stiffness and strength values and they are assembled together to obtain the initial mechanical properties of the joint. The suggested classification method classifies all the components in a connection into three groups based on comparing the ultimate and the design moment strength of each component with those of the connection. By considering this procedure, a new equation is proposed to determine joint post-limit rotational stiffness. This simple and fast method is applicable to any type of joints regardless of profile type and applied loading. The proposed method is applied to a bolted angle, an end-plate to rectangular hollow section column and two bolted end-plate beam-to-column connections. The results are compared with those obtained from some other analytical, numerical and experimental methods. The outputs confirm that the proposed method is simpler, more accurate and less time consume than the other methods.

Superior design solutions of section sizes in steel buildings for different lateral frame systems and column shapes

Superior design solutions of section sizes in steel buildings for different lateral frame systems and column shapes

Design of cold-rolled stainless steel rectangular hollow section columns

Considering the effects of cold-forming and strain hardening in the design of cold-formed stainless steel columns is an effective way to reduce construction costs. This approach has become a common trend in the revision of relevant design codes. A few studies were conducted in the past on two key aspects: (i) predicting the enhanced material properties in cold-formed stainless steel cross-sections and (ii) modifying the design methods to adapt to stainless steel material characteristics. However, in the existing literature, they had been separately studied, and integration of these two aspects to form a complete design method was rarely reported. In this study, a series of column tests were conducted on 19 stub and 32 long columns in rectangular hollow sections. The measured imperfections, material properties, load-displacement curves, and failure modes were reported. A new design method for columns was developed, which could clearly and accurately determine the column capacity over the space encompassed by member slenderness and cross-sectional slenderness values. The proposed design method and the method laid out in the Design Manual for Structural Stainless Steel were evaluated against the test data. It was demonstrated that the two design methods were both very conservative in predicting the column capacity when material properties in the annealed condition were used. However, their performances improved when the predicted enhanced material properties were used. Generally, the predictions of the proposed design method matched the test data better. Furthermore, a reliability analysis was conducted, and resistance factors were recommended for the corresponding design methods.