Kim J.R. Rasmussen

The University of Sydney · School of Civil Engineering

This paper presents a method to perform the decomposition of the deformed shape of built-up members into the structurally meaningful "pure" modes: local, distortional and global modes. The method is based on the core concept of the authors' modal finite strip method (mFSM) for single sections, which utilizes normalized strain energies to identify d...

A new mechanical model for the full range behaviour of bolted T-stubs is proposed in this paper on the basis of a new failure mode classification system which also captures an important failure mode characterised by the rupture of the bolts combined with a moderate level of plasticity in the flange. The proposed model incorporates the abovementione...

The Generalised Component Method (GCM) has recently been formulated for analysing the full‐range nonlinear response of connections, incorporating the elastic and inelastic stiffnesses, the post‐ultimate softening as well as the ductility of each component. In this paper, the GCM is implemented in an FE analysis framework of steel structural frames....

The increasing requirements in construction for lower energy consumption have accelerated the trend towards the use of high-performance buildings. In these Nearly Zero Energy Buildings (NZEB), simple measures such as natural light control are practised to maximise the light intake and minimise the heat gain as required. These modern building envelo...

The paper presents an overview of a research project at the University of Sydney aimed at developing a general framework for the analysis and design of functional components of buildings and structures, where such components achieve large shape changes (morphing) via buckling. The shape changes are optimised, e.g. to reduce energy consumption by mi...

This study presents an experimental investigation into active nonlinear buckling control of optimally designed laminated plates via a new control method using shape memory alloy (SMA) and piezoelectric (PZT) actuators. In this control method, the SMA actuators are used to control the magnitude of plate buckling deformation whereas the PZT actuators...

Functional structures can be designed to adapt to changing external environmental conditions by suitable shape morphing. In recent years, the instability of structural components such as the buckling of thin plate elements has emerged as a viable solution for structural shape morphing, leading to increasing research attention. In this context, the...

The paper presents the development of new design guidelines for cold-rolled aluminium alloy 5052-H36 channel beams subject to global buckling. The validation data are obtained from the experimental and numerical Finite Element (FE) results as performed in previous studies by the authors. The failure modes in the experiments were observed as flexura...

This paper extends the existing Generalised Component Method (GCM) to model the full-range behaviours of connections with bolted angles, by introducing two new components, i.e., the slip component to model the slip of bolts (in shear), and the gap component to model the contact of beam bottom flange and column due to large joint rotation. The key a...

The aim of this study is to explain from a fundamental perspective, how distributing the material thickness of a metal plate in different ways can be used to control the shape of the elastic buckling mode. The Evolutionary Structural Optimisation (ESO) method is modified to control the buckled shape of plates simply supported on three sides with th...

Acknowledging the potential of system‐based design approaches, most international design standards for steel structures include preliminary versions of such alternative design methods. The Direct Design Method (DDM) is one of these approaches, which allows designing steel structures directly using advanced numerical analyses without requiring furth...

Steel structures can be consistently and efficiently designed using system-based design-by-analysis approaches such as the Direct Design Method. However, since direct design approaches lead to potentially lighter structural configurations, they can also result in larger deformations under service loads. Thus, greater attention may be required to se...

In this paper, the effect of Lode angle on the fracture strain of steels is discussed based on experimental evidence. To isolate the effect of the Lode angle, fracture strains corresponding to stress states with constant stress triaxiality but variable Lode angle parameters are obtained from both the literature and tests performed in this study of...

Data was generated using the general purpose finite element software ABAQUS and performing advanced nonlinear analyses. The database is comprised of vertical and lateral system stiffness values corresponding to different random samples of six different nominal stainless steel frames under gravity and gravity plus wind load combinations. The values...

In the process of developing the next generation of design standards for steel structures, most relevant international structural codes including AISC 360, AISC 370, AS/NZS 4100 and Eurocode 3 already incorporate preliminary versions of system-based design-by-analysis approaches that allow a direct evaluation of the strength of steel and stainless...

The paper concerns built-up cold-formed steel (CFS) structural members composed of three or four component lipped channel sections. Finite element (FE) models are calibrated against recently conducted experimental results and used to perform a parametric study of the strength and behaviour of CFS built-up section columns, considering column the len...

This paper describes a study [1] on the behaviour and design of drive-in racks with fuses installed to reduce seismically imposed internal actions. Two different cross-aisle framing systems were tested using various earthquake signals and magnitudes. The first system featured cross-aisle frames fully braced from top to bottom using diagonal braces....

The exponential function to simulate the damaging effects of void growth has been widely used in fracture initiation models to describe the effect of stress triaxiality on the fracture strain of ductile metals. Its validity has largely been demonstrated for loading conditions with high stress triaxiality, but there are comparatively fewer tests to...

First Order Reliability Methods (FORM) have been used by specification committees in the reliability analyses required for the calibration of resistance and safety factors for the past 40 years. However, these methods are iterative, require input information that may not be readily available, and make comparisons between different approaches or des...

This file includes finite element simulation data (ultimate load factors) carried out on 60 steel and stainless steel frames, including regular and irregular frame configurations with different section sizes. Ultimate load factors corresponding to different initial imperfection combinations are included.

Initial geometric imperfections are unavoidable in steel members and frames due to erection and manufacturing tolerances. These include frame out-of-plumbness, member out-of-straightness and cross-sectional imperfections, and can have a significant influence on the response and resistance of steel structures. Thus, they need to be accounted for in...

Data was generated using the general purpose finite element software ABAQUS and performing advanced nonlinear analyses. The database is comprised of ultimate load factors corresponding to different random samples of six different nominal stainless steel frames under gravity and wind load combinations. The values of the random variable assignments a...

This work studies an optimal design problem to maximize the airflow opening of a thin-walled structure for efficient ventilation. The airflow opening is defined in terms of nodal displacements as the area swept by a deformed free edge, or the volume formed between the deformed and undeformed configurations or their combination. In this study, a nov...

The design-by-analysis approach lays the foundation for the next generation of structural design standards in which the strength and structural safety check are performed in a single step at system level, without recourse to a structural standard for individual member checks. However, to date, no attempt has been made towards considering the failur...

Thin-wall structural sections and members are susceptible to three fundamental instabilities: local, distortional and lateral-torsional buckling. For cold-formed purlins or girts commonly used in roof and wall systems, distortional buckling may govern the predominant failure mode when the compression flange is not attached to sheathing or panels. T...

This paper summarises the background information and methodology used to derive a set of buckling curves proposed for cold-formed stainless steel columns and beams, incorporated in the recently revised SEI/ASCE 8-21 Specification. The study is based on experimental and numerical data collected from the literature on cold-formed stainless steel colu...

Current codes for steel structures, including AISC 360-10, AS4100 and Eurocode 3, are in the process of evolving from the current member-based design method to direct system-based approaches that allow evaluating the strength of structures directly from numerical simulations. However, these codes do not provide adequate safety factors nor reliabili...

Built-up sections are increasingly used as structural elements in the cold-formed steel (CFS) industry. They are composed of two or more component sections connected by discrete fasteners, typically spaced evenly along the length and potentially with fastener groups at the ends. Conventionally, two singly symmetric C-sections are connected to form...

Current structural codes for steel and stainless steel structures such as AISC 360-16, AISC 370-21, AS/NZS 4100 and Eurocode 3 are based on the traditional two-step member-based design approach, in which internal actions are first obtained from a structural analysis, usually elastic, and the strength of each member and connection is subsequently ch...

This file includes data on system strength of stainless steel frames under gravity loads obtained from the finite element simulations carried out on six stainless steel frames. This data was used in the analysis carried out and reported in the publication: Input and output data is provided separately for each of the six frames investigated. Frames...

The paper presents a series of four-point bending tests investigating global buckling of cold-rolled aluminium alloy channel beam members. These types of sections have been commercially fabricated in Australia using a roll-forming process as distinct from the usual extrusion process. A total of twenty specimens of three commercially available chann...

This paper presents recent research carried out at the University of Sydney on the full-range behavior of top-and-seat angle connections. A total of 18 tests were conducted, covering two connection configurations and three loading conditions, including bending, combined bending and compression, and combined bending and tension. The highlights of th...

Traditional member-based two-step design approaches included in current structural codes for steel structures, as well as more recent system-based direct-design alternatives, require building rigorous structural reliability frameworks for the calibration of partial coefficients (resistance factors) to achieve specified target reliability requiremen...

The buckling capacity of plates can be enhanced by appropriately placing discrete point-support(s) at optimal locations. However, determining the optimal locations of point-supports to achieve maximum buckling coefficients is a challenging problem, as it couples the analysis procedures for buckling and optimisation. This paper investigates the opti...

Traditional member-based two-step design approaches included in current structural codes for steel structures, as well as more recent system-based direct-design alternatives, require building rigorous structural reliability frameworks for the calibration of partial coefficients (resistance factors) to achieve specified target reliability requiremen...

The paper presents methods of analysis of built-up sections in which the discrete locations of fasteners is accounted for explicitly, rather than by smearing their effect using continuous shear flexibility as in current approaches. By considering fasteners at discrete points, it is possible to analyse the effects of placing additional fasteners at...

The safety of scaffold systems during construction is vital to prevent failures with catastrophic consequences. Engineering practice in the scaffolding industry, however, does not have a rational structural reliability basis as that used for buildings and bridges. The implementation of design clauses for scaffold systems in the current standards pa...

This paper describes the formulation of a thin-walled beam finite element for arbitrary open cross-sections, including doubly-, singly- and non-symmetric cross-sections. The formulation is developed within the co-rotational framework of OpenSees – an open source program available for the simulation of structural and geotechnical systems. The formul...

Cold-rolled aluminium alloy sections have been well known as new products of BlueScope Permalite, and have been produced by utilising the existing rolling system for cold-formed steel sections to successfully roll-form Channel and Zed sections in Australian market. The roll-forming approach is proven to be faster and more cost-effective as compared...

The paper summarises recent experimental research undertaken at the University of Sydney on determining the full-range behaviour of steel beam-to-column connections. Three series of tests were conducted on three different types of connections including bolted extended end-plate connections, top-and-seat angle connections and double web angle connec...

Available online xxxx This paper presents recent experimental and analytical investigations on the full-range flexural behaviour of double web angle connections. Experiments were carried out on bolted double web angle connections with two different configurations featuring three and five bolt rows, respectively. For each connection configuration, f...

This paper describes Finite Element (FE) analyses of cold-rolled aluminium alloy 5052-H26 columns subjected to distortional buckling using the program ABAQUS. The results of distortional buckling tests in an experimental program performed at the University of Sydney are fully described in a companion paper. The simulation results are compared and v...

This paper presents the numerical investigation of cold-rolled channel columns made of 5052 aluminium alloy subjected to member buckling. A detailed Finite Element (FE) model using software ABAQUS v 6.14 was developed to simulate an experimental program recently performed at the University of Sydney. In the FE simulations, actual measured propertie...

The behaviour and strength of cold-formed columns are mainly influenced by local, distortional and global buckling or coupled instability phenomena. Distortional buckling may govern the column strengths of open cold-formed sections with intermediate lengths. The objective of this paper is to investigate the distortional mode and ultimate capacity o...

This paper presents a series of four-point bending tests of cold-rolled aluminium alloy 5052 Zee beams subjected to lateral buckling. Six Zee beams with three different lengths were selected for testing. A dual-actuator loading system was specifically designed to keep the load always in vertical direction and through the shear centre of the cross s...

When a truss roof is subjected to sudden local damage, purlins are capable of bridging the damaged truss unit, thereby increasing the robustness of the integrated roof system. To investigate the bridging capacity purlins can provide, experiments were carried out on bolted fin plate connections that join thin-walled H-section purlins to the main tru...

Rectangular Levy-type plates restrained using point-supports have wide engineering applications. However, the analytical solutions for the buckling behaviour of such plates are not well developed. This paper presents the derivation and application of analytical solutions for the buckling analysis of Levy-type rectangular plates with arbitrarily pos...

This paper presents a series of full-scale tests on long-span cold-formed steel single C-section portal frames subjected to gravity load and combined gravity and lateral load. The tests were carried out with the objectives of observing the structural performance of an existing portal frame configuration, determining the ultimate strength of the exi...

The paper presents a study on the seismic cross-aisle behaviour of drive-in steel storage racks obtained from full-scale shake table tests. The objectives of the study are to determine the natural frequency and damping from full-scale tests as well as the inelastic response of drive-in rack frames when subjected to seismic excitation including mode...

In recent years, aluminium alloys have been paid more attention in the construction industry due to their attractive attributes such as light mass, high strength, easy recycling and high corrosion resistance. Traditionally, aluminium alloy sections used for structural applications have been formed by extrusion. Until recently, structural aluminium...

The Component Method is well established and incorporated in Part 1.8 of Eurocode3 for the design of connections of steel frameworks. It is primarily intended to provide the elastic joint stiffness, although Part 1.8 includes provisions for also determining the inelastic moment‐rotation response from the elastic limit to the ultimate moment. The la...

This paper presents design approaches for cold-formed steel single C-section portal frames based on the Direct Strength Method and the Direct DesignMethod. For the Direct Strength Method, two approaches are presented, one that determines the design capacity of portal frames ignoring the effect of bimoment, as in current practice, and one that consi...

This paper presents numerical study of cold-rolled aluminium alloy channel beams subjected to member buckling. Detailed finite element (FE) models using the commercial software package ABAQUS v 6.14 are developed to simulate the tests in an experimental program fully described in a companion paper. In FE simulation, actual measured properties and g...

This paper describes Finite Element (FE) analyses of cold-rolled aluminium alloy 5052-H26 beams subjected to distortional buckling using the program ABAQUS. The results of distortional buckling tests in an experimental program performed at the University of Sydney are fully described in a companion paper. The finite element results are compared and...

This paper presents a series of four-point bending tests on cold-rolled aluminium alloy 5052 lipped channel beams subjected to member buckling. Twenty tests of three commercially available channel sections and two different thicknesses were conducted. A special designated test rig with a dual-actuator loading system was set up to allow pure bending...

Thin-wall structural members may undergo various forms of instability such as local, distortional, and lateral-torsional buckling. Each buckling mode may occur separately or interact with each other depending on the cross-section shapes and lengths. For cold-formed purlins or girts, distortional buckling may be the predominant failure mode when the...

This paper presents a comprehensive investigation of the numerical modelling of cold-formed steel single C-section portal frames using shell elements. The model accounts for the semi-rigid behaviour of connections using mesh-independent point-based fasteners at the location of physical bolts. The behaviour of deformable fasteners is ascribed though...

Cold-formed steel (CFS) built-up members are formed by connecting several single members by fasteners. This paper presents experimental, numerical and analytical studies on the effect of fastener configurations on the flexural rigidity of built-up sections. In this research, two zinc-coated steel C-sections are connected back-to-back to form a doub...

The flexural behaviour of eaves, apex and base connections for cold-formed steel single C-section portal frames is investigated through a series of connection tests and analyses of corresponding finite element models. The moment-rotation characteristics of the eaves, apex and base connections from the respective connection tests and the numerical m...

The paper summarizes experiments conducted at the University of Sydney on bolted moment end-plate connections. The overall context of this work was to obtain full-range moment-rotation curves of the connections which can be used to validate analytical and numerical models. The full-range moment-rotation curve covers not only the elastic and inelast...

This paper presents a method to identify the critical member in a single-layer latticed dome, which in the context of progressive collapse is defined as the member whose removal causes the most severe damage. The distribution of critical members in four typical types of single-layer latticed domes, including the Kiewit dome, the Ribbed dome, the Sc...

Advanced nonlinear finite element analysis (FEA) enables the Direct Design Method (DDM) of a frame by computational analysis in place of designing members and connections to codified specific equations. The Direct Design Method has become a feasible design option and attracted increasing attention from the research community, designers and code wri...

The steel industry is developing a design-by-advanced analysis specification for cold-formed steel construction. This effort provides an opportunity to utilize the latest nonlinear structural analysis (advanced analysis) to design steel structures based on their overall system behaviour. This paper concerns the system reliability calibrations of th...

This paper presents the generalisation of an energy-based method for the modal decomposition of buckled shapes of thin-walled members. This comprehensive method is derived and validated for fully decomposing the elastic buckling solution of a thin-walled member into the pure buckling mode classes of global, distortional, local, shear and transverse...

This is the second of two papers introducing the underpinning structural analyses and reliability studies that implement the system-based design-by-analysis method of steel rack frames, referred to as the Direct Design Method (DDM). The present paper presents the reliability analyses and derivation of system reliability index (β) versus system resi...

This paper concerns the underpinning system reliability calibrations that will enable the implementation of the next generation of system-based design-by-analysis method of steel rack frames, i.e., a design approach where analysis and capacity checks are carried out in a single step by using fully nonlinear analysis. The paper details the design fr...

This paper presents a generalised component model for structural steel joints that extends the Component Method to the post-ultimate and post-fracture ranges. In this approach, a tri-linear spring model was developed for each individual component to include their post-ultimate behaviour, and a new concept of the instantaneous centre of rotation was...

This paper is a companion to (Khezri and Rasmussen, 2019) [1], where the generalised strain energy-based method for the modal decomposition of buckled shapes of thin-walled members is introduced. The paper presents the application of the proposed method for full modal decomposition to various thin-walled members. A series of numerical examples are...

In recent years, BlueScope Permalite in Australia has used the existing rolling system for cold-formed steel sections to successfully roll-form aluminium alloy sections. In comparison with the conventional extrusion method, the roll-forming process is faster, more cost-effective and may enhance the strength of the aluminium alloy. This paper presen...

Extrusion is the most common method to produce aluminium structural members. In Australia, aluminium structural solutions recently introduced by BlueScope Permalite consist of aluminium structural Channel (C-) and Zed (Z-) section members produced by using the existing rolling system for cold-formed steel sections. Compared to extrusion, the roll-f...

The paper summarises recent research programs undertaken at the University of Sydney on determining the full-range behaviour of steel connections including post-peak softening and fracture. The overall context of this work is to produce models based on the Component Method for the moment-rotation behaviour of joints that are sufficiently simple and...

The paper provides an overview of the behaviour, analysis and design of cold-formed steel portal frames. It describes a recent research program involving full-scale testing of large-span portal frames composed of singly symmetric C-section uprights and rafters as well as built-up doubly symmetric I-section uprights and rafters. For both types of fr...

This paper presents the generalisation of an energy-based method for the modal decomposition of buckled shapes of thin-walled members. This comprehensive method is derived and validated for complete decomposition of the elastic buckling solution of a thin-walled member into the pure buckling mode classes of global, distortional, local, shear and tr...

This paper reports on experiments addressing the buckling and collapse behavior of back-to-back lipped channel built-up cold-formed steel (CFS) columns assembled using 16 different CFS lipped channel sizes. The lipped channel sections are connected at the web using a pair of self-drilling screw fasteners at a specified spacing along the column leng...

Steel storage pallet racks are slender structures sensitive to the second-order effects. Therefore, the stability and seismic response of unbraced pallet racks are greatly influenced by the behaviour of the connections between pallet beams and uprights. In recent applications, a bolt has been installed in the otherwise boltless connections broadly...

The conventional numerical approximation of Mindlin plate equations can lead to erroneous solutions for thin plates. The so-called shear-locking problem has been well studied in the context of the finite element method (FEM) whereas the development of numerical formulations for its successful elimination in meshfree methods is still a subject of in...

In this paper, the compound strip method is applied to the stability analysis of cold-formed steel built-up sections. A beam element with adjustable stiffness properties is adopted to represent the utilised fastener and the associated stiffnesses of the connection elements are incorporated in the global stiffness matrix of the built-up sections. Th...

Current methods for designing steel structures, such as load and resistance factor design (LRFD) are based on safety checks of individual members derived from elastic analysis. The next generation of steel design methods will move from member-based to system-based design. Recent advances in nonlinear structural analysis make it possible to design a...

This paper reports on experiments addressing the buckling and collapse behavior of common built-up cold-formed steel (CFS) columns. The built-up column consists of two individual CFS lipped channels placed back-to-back and connected at the web using two self-drilling screw fasteners at specified spacing along the column length. The experiments aim...

Geometric imperfections have a significant effect on both buckling and strength capacities of structural members. It is essential to accurately measure the geometric imperfections for finite element simulation especially for thin-walled sections. This paper presents the procedure to measure and incorporate geometric imperfections into finite elemen...

The paper describes finite element analyses using the program ABAQUS 6.14 of cold-rolled alluminium alloy 5052 channel sections in stub column tests. Aluminium structural members have been used considerably in not only roof systems but also primary load-bearing components due to such advantages as superior corrosion resistance, light weight, ease o...

Cold-formed Hollow Steel Sections (HSS) are widely used in the construction industry. The distribution of residual stress in non-stress-relieved cold-formed HSS is complex due to the highly non-uniform variation around the cross-section and through the plate thickness. Modeling residual stress in frame analysis is therefore a difficult task. This p...

The European racking federation design guidelines FEM10.2.07 (2012) contains provisions for the analysis and design of drive-in and drive-through racks. It specifies different methods for carrying out the design, and the design verifications differ depending on the method chosen. However, there appears to be no published studies that compare the an...

This paper presents a numerical investigation of the effects of discrete fasteners on the buckling behaviour of cold-formed steel (CFS) built-up columns and concludes with the assessment of the applicability of the current direct strength method (DSM) to the design of these members. To this end, the compound strip method is first utilised to accura...