bluuebunny/crossref_metadata_2025 huggingface dataset:
Influencing Parameters on the Load‐bearing Capacity of Composite Dowels positioned close to the free Surface of Concrete Slabs
Authors: Broschart Yannick , Kurz Wolfgang , Wolters Kevin , Christou Georgios , Claßen Martin
Published: September 2019

Composite dowels as shear connectors between steel profiles and concrete sections have been investigated for decades. The long‐term aim is to develop consistent design approaches and implement them within Eurocode 4 covering both fields of bridge and building construction. Especially in building construction, where the concrete slabs are dimensioned increasingly slimmer in contrast to bridge construction, the composite dowels are positioned unavoidably close to free concrete surfaces (1). This causes further failure modes which have not been entirely investigated yet. At University of Kaiserslautern experimental push‐out tests were performed within a research project in cooperation with RWTH Aachen University focusing on the behaviour of these composite dowels in dependence of varying influence parameters, such as the dowel's distance to the edge, the concrete strength and the position of the reinforcement stirrups. Some results showed a significant reduction of the load‐bearing capacity and an affection of the deformability, mostly accompanied by the spalling of the concrete cover. Based on the tests, numerical simulations were calibrated and utilized to understand more about the load transfer mechanisms and to interpolate between existing experimental results. This paper will particularly show the influence of three parameters and present considerations on the load transfer model including further primary, secondary and tertiary failure mechanisms leading to the overall failure of the specimens.
Characterization of the behaviour of welded steel joints through modal components
Authors: Bayo Eduardo , Gracia Javier
Published: September 2019

The analysis and design of joints constitutes one of the most important aspects when designing steel structures. It is a common practice to model the joint behaviour by zero‐length rotational springs placed between the beam and corresponding column, or by mechanical models composed of springs and rigid bars. These models have serious limitations when considering the interactions between the shear, bending and axial forces and deformations of the panel zone.

In this research, a new approach based on the characterization of modal components is presented. First, the steel joint is modelled as a cruciform finite element of 12 degrees of freedom. Then, the stiffness matrix is decomposed in eigenvectors and eigenvalues. The eigenvectors provide information about the joint deformation modes, while the eigenvalues give information about the stiffness associated with each mode. To identify the main modes and their characteristics, a parametric study has been carried out for welded joints with and without stiffeners. For both cases, all combinations of IPE 120 to IPE 600 profiles for beams and HEA 160 to HEA 1000 profiles for columns have been studied. The only restraint imposed in the combination process is that the beam width be smaller than the column width.

First, the cruciform finite element stiffness matrices are obtained. Subsequently, a spectral decomposition is carried out using MATLAB, and then Python scripts are developed to classify the modes and eigenvalues. The statistical analysis of the results shows that after removing the three rigid solid modes the most relevant deformation modes are the shear and the two possible bending modes including their interaction. The remaining six modes correspond to deformation modes with high stiffness values that are not excited under common loading situations.
Resistance of Direct Fixings of Sandwich Panels under Cyclic Loading
Authors: Engel Alexander , Lange Jörg
Published: September 2019

Within the scope of a research project, the pull‐through resistance of direct fixings of sandwich panels under cyclic loading was determined on small‐scale sandwich specimens. The tests were carried out on wall panels with lined steel face sheets. Various core materials (PU foam, mineral wool), face sheet thicknesses, panel depths and various screw manufacturers were combined. From the test results, cyclic reduction factors for fixings on the mid and end support were determined according to prEN 14509‐2.
3‐D‐Printing with Steel: Additive Manufacturing of Connection Elements and Beam Reinforcements
Authors: Feucht Thilo , Lange Jörg , Erven Maren
Published: September 2019

Automated steel construction manufacturing with robots is becoming reality. The Institute for Steel Construction and Materials Mechanics of the Technische Universität Darmstadt has two welding robots. These robots are being used to assess various application for Additive Manufacturing. For the construction of steel, Wire + Arc Additive Manufacturing (WAAM) is suitable, which is similar to Gas‐Shielded Metal Arc Welding. The wire electrode serves as printing material. With this method we can produce components in layers and achieve deposition rates of 5 kg/h. The components studied in this research project are connection elements such as simply supported girder connections and head plates, as well as reinforcing elements such as stiffeners and beam reinforcements. In this paper topology‐optimized structures are presented, which can be printed with the WAAM directly on steel beams. First investigations on additive manufactured test specimens are shown.
Cost optimization of end‐plate connections
Authors: Mela Kristo , Hietaharju Lauri
Published: September 2019

Minimum cost beam‐to‐column end‐plate joints are determined in this study. The goal is to achieve partial automation of the time‐consuming joint design. The premise is that the joint is to be designed for target bending moment and shear force resistance and initial rotational stiffness. It is assumed that the designer has prescribed the beam and column profiles and the initial rotational stiffness a priori. The joint design task is formulated as a mathematical optimization problem, where the total cost of the joint is minimized such that the resistance and stiffness requirements are satisfied. The component method described in the standard EN 1993‐1‐8 is used for evaluating the bending resistance and initial rotational stiffness of the joint. The end‐plate dimensions and bolt positions are taken as the design variables of the optimization problem. The number of bolt rows, bolt sizes and bolt strength are incorporated as parameters with fixed values during optimization. The applicability and performance of the proposed approach for joint cost minimization is demonstrated on case studies, with a comparison to an alternative procedure found in the literature. The results indicate that mathematical optimization provides a useful tool for design automation of steel joints.
Strength evaluation of bolted connections with slotted holes in non‐structural components
Authors: Kurosawa Miku , Kishiki Shoichi , Tatsumi Nobuhiko
Published: September 2019

In the bolted connections of the non‐structural exterior wall to structural frames, slotted holes are often used to improve the workability. In Japan, in case the slotted holes are used in the bolted connections of structural frame, a reduction factors according to European Recommendations for bolted connections in structural steel work(1) have to be employed to reduce the slip strength of the connections. However, the strength reduction ratio equals to 1.0 when the major axis direction and the stress direction of the slotted holes are orthogonal; thus, the strength reduction factor is not considered to be substantial in many cases. Furthermore, these provisions are not employed for connections of non‐structural components to structural frames.

In this study, a tension test of bolted connection with slotted hole was carried out to evaluate the slip coefficient and confirm the strength reduction. In order to consider influences of the surface treatment of the specimen on slip proof stress, five different types of surface treatment are considered in the test, which are hot dip galvanizing with and without antirust processing, electroplated zinc colored chromate coating with and without antirust coating, and stainless steel. From the test results, it is found that the slip strength ratio of the bolted connection with the slotted holes to that of with the conventional holes was ranging from 0.70 to 0.80. As next step, a series of slip coefficient evaluation experiments of actual non‐structural components are planned to investigate that the reduction factor obtained from the element tests could be adopted to the components. In that case, eccentricity and stress distribution in the connection should be considered.
Thor – a New Design of Overhead Transmission Line Towers
Authors: Schmidt Mark Kokborg , Nielsen Mogens G. , Endahl Brian , Steenholt‐Eliasson Karl Emil
Published: September 2019

In these years Denmark puts a significant effort into reducing the CO2‐emission. Consequently, a more flexible and strong electricity transmission grid is needed to be able to transmit the power from the offshore wind farms to the consumers. Furthermore, the grid must be able to reach the international markets.

Therefore, a new detailed design of a series of overhead line (OHL) towers have been carried out. The contemporary design has been prepared by the engineers, Ramboll, together with architects, Dissing+Weitling, for the Danish transmission system operator (TSO), Energinet, and the main purpose is to have an aesthetic OHL acceptable to the public together with a cost‐efficient series of towers.

The towers are designed as lattice structures. All the traditional lattice OHL towers are constructed using angle bars, while the new design is constructed of circular tubes for all lattice members. This design gives a more open appearance of the tower that is not as massive as the resent designed OHL towers with a shaft of monopoles. The tubes have multiple advantages compared to angle bars: smaller width, lower wind resistance, higher buckling capacity and wider profile opportunities.

The traditional angle bar towers are prepared as almost fully bolted structures with no welding. However, even though the members are bolted together welding must be done on lattice towers of circular tubes, and new connections have been developed; also, to meet the aesthetic requirements.

This paper introduces the new transmission line design with focus on the tower structure and the special aesthetic designed connections.
Research on the Semi‐rigid Joint with T‐stub in Beam‐to‐Column Connection: Suggestion for Initial Rotational Stiffness Formula
Authors: Xia Yong‐Qiang , Xiao Nan , Qian Xiao‐Qian
Published: September 2019

The stiffness of the joint has great influences on the internal force distribution in structures. Therefore the initial rotational stiffness of semi‐rigid joint with T‐stub connectors should be determined prior to internal force analysis in steel structures with T‐stub connectors in beam‐to‐column connection. According to the deformation characteristics of the joint during elastic phase, the flange of T‐stub connector bolted on the tensile side of the beam section was deemed as main research object, and was regarded as simply supported beam. Based on this calculation model, the initial rotational stiffness of the joint is determined by the flange thickness of the T‐stub connector, distance between bolts linking the flange of T‐stub connector to steel column, and lastly the height of the beam. Then the analytical formula of initial rotational stiffness was established. Numerical simulation and experimental data were employed for comparison with the results from the proposed formula, respectively, and a stiffness modified coefficient was introduced into the analytical formula, which shows that the results from proposed formula applied for case studies match well with finite element analysis data and the experimental data.
Experimental Test of Novel Honeycomb Structural Fuse
Authors: Yang T.Y. , Li Tianyi , Tobber Lisa , Pan Xiao
Published: September 2019

This paper proposes a novel type of metallic damper, named Honeycomb Structural Fuse (HSF), a modified version of the previously developed Welded Wide Flange Fuse (WWFF). Based on the commonly available welded wide flange section, honeycomb‐shape perforations were laser cut on web. The HSF is designed to dissipate earthquake energy through plastic deformation of the web in shear, while the flanges remain elastic. To investigate the seismic behaviour of HSF, a total of 9 specimens with different honeycomb cell wall aspect ratios (cell wall thickness to cell wall centre length) and honeycomb cell combinations (number of cell rows and columns) were manufactured and tested to examine the influence of different parameters on its performance including force‐drift relationship, working mechanism and buckling modes etc., are summarized. The experiment shows that the newly proposed HSF exhibits stable energy dissipation capability, which can be used as an efficient metallic damper for seismic applications.
An Experimental Verification of Seismic Structural Control: Using In‐Plane Oval Dampers
Authors: Lee Chien‐Liang , Wang Yen‐Po , Cai Meng‐Yan , Kuan Yu‐Tung , Huang Ging‐Huei
Published: September 2019

As an effort to enhance the material utilization efficiency of metallic yielding dampers, this paper explores a new type of in‐plane oval damper fabricated to deform inelastically in an in‐plane flexural mode. Seismic performance assessment of the proposed damper was conducted via shaking table tests of a five‐story steel building frame under the Kobe earthquake with various intensities. Significant reductions of the structural acceleration and displacement responses have been achieved with the proposed device implemented, suggesting that the effectiveness and feasibility of using the in‐plane oval energy‐dissipative device for earthquake protection of building structures. Moreover, a series of nonlinear time history analysis of the five‐story model frame corresponding to the tests was further performed. The inelastic behavior of the proposed dampers was simulated by the Bouc‐Wen's model and the predicted structural vibration responses were in turn compared with the experimental results. The simulated structural responses with identified parameters of the Bouc‐Wen's model agree well with the experimental results, indicating that the proposed analytical model for nonlinear dynamic analysis of inelastic systems is adequate.
Proposal of a design curve for the overall resistance of cold formed RHS and SHS members
Authors: Toffolon Andrea , Taras Andreas
Published: September 2019

Possible inaccuracies and conservatism in the design against the local and local+global buckling of slender square (SHS) and rectangular (RHS) hollow‐sections is currently hindering the construction sector from a wider application of high‐strength steel (HSS) and slender hollow sections. Eurocode and other design provisions define class 4 at a cross‐section slenderness > 42ε (compression only) with ε2=235/fy. Thus, a significant number of SHS and RHS with fy ≥ 690 MPa – both cold formed and hot‐finished – are considered to be slender and consequently penalized. Besides that, the classification approach itself presents discontinuities in the estimation of the buckling reduction factor, whereas a design curve ranging from the plastic to the slender range would be more efficient and cost‐effective both for steel producers and designers. This paper discusses the results of an extensive numerical campaign, showing that the Eurocode 3 classification is too conservative in the case of SHS and RHS. The local buckling and local+global buckling behaviour will be analysed through an extensive parametric FEM‐model study. The gathered data are collated, and the resulting design curve is a proposal for the determination of an overall buckling reduction factor for the determination of the member resistance. The study represents one of the steps of the RFCS research project “HOLLOSSTAB”, during which new design rules for HSS hollow sections are developed on the basis of an “Overall Interaction Concept” (OIC). The paper discusses the effectiveness of this approach in the general framework of buckling design checks for hollow sections, discusses existing rules and their implications, shows the numerical campaign results and introduces overall design formulas based on the overall buckling resistance approach
A novel approach for elastic buckling loads in longitudinally stiffened webs subjected to patch loading
Authors: Graciano Carlos , Loaiza Nelson
Published: September 2019

Currently, in the EN1993‐1‐5 the ultimate strength of a longitudinally stiffened webs is calculated based on a design procedure which considers the ratio between the yield resistance and the critical buckling load. In the available formulation which is based on numerical modelling, the critical load increases with the relative position of the longitudinal stiffener. This behaviour contrasts with that observed at ultimate limit state, several experimental results have shown that the ultimate strength increases when the longitudinal stiffener is placed closer to the loaded flange. To solve this problem, new hypotheses of boundaries restrictions at the stiffener location are presented to model the elastic buckling behaviour of webs subjected to patch loading. A comprehensive finite element model is presented in this study to evaluate theses hypotheses by varying the web and longitudinal stiffener dimensions. Finally, a methodology to model the buckling behaviour of stiffened webs is presented.
Fatigue design of tension components: Revision and further development of EN 1993‐1‐11
Authors: Annan Rachid , Bechtold Martin , Friedrich Heinz , Maljaars Johan , Misiek Thomas , Paschen Michael
Published: September 2019

During the ongoing revision of EN 1993‐1‐11 “Design of structures with tension components” the current fatigue design rules were subjected to a critical review. This results in modifications and amendments, including the adjustment of several parameters. The present paper gives an introduction as well as background information on those changes.
European buckling curves for aluminium compression members: A review of proposals for revision
Authors: Misiek Thomas , Norlin Bert , Höglund Torsten
Published: September 2019

As part of the ongoing revision of the Eurocodes, the regulations in EN 1999‐1‐1 on the buckling of aluminium compression members were also subjected to a critical review. This resulted in the need to revise the regulations for non‐welded compression members and for longitudinally welded compression members.

The introduction of a buckling class C for soft tempers and minor adjustments in the allocation of the individual alloys and tempers to buckling classes A and B can be understood as a fundamental change. The new allocation is presented and explained.

The required buckling curve for non‐welded columns made of materials of buckling class C was introduced in prEN 1999‐1‐1. In this context, minor improvements have also been made to buckling curves A and B. The curves are presented and compared with the results of numerical investigations. The comparison is done graphically as well as statistically (based on EN 1990, Annex D). For the design provisions of longitudinally welded aluminium compression members, a more extensive revision was necessary. The design concept was revised and switched to the use of separate buckling curves which are presented here. These curves are also compared with the results of numerical investigations.
Medium to high cycle fatigue investigation on hot dip galvanized structural steel welded joints
Authors: Viespoli Luigi Mario , Mutignani Francesco , Berto Filippo
Published: September 2019

Hot dip galvanization offers stable and lasting corrosion protection to steel structure, both acting as a barrier for external agents and inducing galvanic protection, through the deposition of a thin layer of zinc on the steel structure by submersion in a molten bath of the metal. Current standards for welded steel structures subjected to fatigue loads do not allow the use of the technique, while the cost for maintenance, repair or failure due to corrosion has an elevated worldwide impact. A series of hot dip galvanized structural steel welded specimens was tested with the aim of increasing the understanding of the damage and failure of a structure that has undergone such treatment. The goal is to define whether the use of hot dip galvanization poses a threat to structural safety and if this is eventually accountable for with the use of a certain corrective coefficient for the fatigue classes reported in the regulations. A revision of old fatigue data is here reported to critically discuss the new results presented.
Innovative composite deck slab for railway bridges: Experimental investigations on the fatigue resistance of the dowel strips
Authors: Takács Patrik , Fink Josef , Pardatscher Herbert , Petraschek Thomas
Published: September 2019

At TU Wien, Institute of Structural Engineering, Research Centre of Steel Structures, a new, extremely slender steel‐concrete‐steel composite (SCSC) plate is under investigation to meet the requirements of today's standards related to the geometric conditions and noise emission in the substitution of old railway bridges. The multi‐layer structure of the plate consists of two steel cover plates with an unreinforced concrete core, hence the name sandwich plate. Perforated shear connectors, welded alternately to only one of the outer steel plates, work together to ensure the transmission of the shear flow between the outer plates, by the activation of diagonal concrete compression struts between neighboring dowel bars. After the examination of the static load‐bearing capacity in former research programs (1), the current investigations are focussed on the fatigue behaviour of the SCSC plate, whereby the main focus lies on the investigation of the relation between the amplitude of the traffic load and the bearable number of load cycles of the SCSC plate till crack initiation in the shear connectors.

A detailed description of the numerical modelling of the SCSC plate using the Abaqus/Explicit (2) software and the calculation of the fatigue life of the dowel strips using the notch strain concept are described in (3; 4; 5). This paper gives an overview of the planning, execution and evaluation of the experimental investigations and compares the experimental and the numerical results regarding the fatigue life of the dowel strip.
Experimental study of epoxy coatings for fire protection of bridge cables
Authors: Tolstrup Jonas , Giuliani Luisa , Narasimhan Harikrishna , Jensen Jakob Laigaard , Jomaas Grunde
Published: September 2019

An experimental study on the performance of epoxy coatings exposed to different fire conditions was undertaken in order to assess if such paints could be a viable passive fire protection solution for bridge cables. Epoxy paints are of interest for this application due to their high resistance to environmental agents and the capability of resisting hydrocarbon fires. However, recent studies have shown that the performance of water‐ and solvent‐based intumescent coating are strongly affected by the fire condition, and particularly the heating rate, and it is essential to assess if these challenges are also present for epoxy paints. Therefore, two different epoxy coatings were applied to small steel plates and exposed to different constant heat fluxes ranging between 20 and 80 kW/m2 in a cone heater. The results of the experiments are presented in terms of expansion of the coating, temperatures of the substrates and efficiency of the coating, calculated as relative difference between the temperature of an uninsulated sample and a sample coated with the coating. The outcomes of the experiments indicate that there is a dependency between the incident heat flux and the char development and thus the ability to protect the substrate.
Development of fire protection for bridge cable systems
Authors: Jensen Jakob Laigaard , Narasimhan Harikrishna , Giuliani Luisa , Jomaas Grunde
Published: September 2019

Fire protection of bridge cable systems has been identified as an important mitigating action with respect to operational risk as well as the safety of existing and new bridges. In particular, cable supported bridges have been demonstrated to be vulnerable to vehicle fires.

With the design of fire protection concepts for New Little Belt Bridge and Great Belt East Bridge, a process with development of fire protection of cable systems has been started. The project is based on the development of a fire protection concept for main cables based on insulation mats and currently a concept is being developed with use of intumescent coatings.

The R&D project and handling of the design challenges on cable systems on suspension bridges is presented, and it includes details about the main cable, cable clamps and suspenders based on numerical modelling and testing of the steel performance during fires up to 1100°C.

The fire protection relies on use of insulation mats and intumescent coatings and in developing the concept, one of the main challenges is to document the performance of the design concepts unique to each bridge. Furthermore, it is difficult to get access to information on material performance in such particular applications. Hence, in the current project, it has not been possible solely to rely on the supplier information and it has been necessary to carry out numerical modelling of performance during fire as well as use of laboratory testing.

In summary, the objective is to investigate the combined performance of the steel cable and the applied insulation concept. For solutions, design has not only to consider the fire protection of steel but also to address issues regarding cable durability and allowance for operation and maintenance.
Flexural behaviour of engineered cementitious composite encased high strength steel composite beam
Authors: Kabir Md. Imran , Lee C. K. , Rana Mohammad M. , Zhang Y. X.
Published: September 2019

In this paper, the flexural performance of a new type of composite beam comprised of High Strength Steel (HSS) section encased by polyvinyl alcohol‐engineered cementitious composite (PVA‐ECC) and lightweight concrete (LWC) is studied. An experimental investigation on the flexural performance of HSS beams encased by different thickness of ECC is conducted and their performances are compared with bare HSS beam and normal strength concrete (NSC) encased HSS beam. Four‐point bending tests are carried out on simply supported beams including one bare HSS beam, one NSC encased HSS (NSC‐HSS) beam and two ECC‐LWC encased HSS (ECC‐HSS) beams. For ECC‐HSS beams, both top and bottom flanges of the HSS sections are encased with PVA‐ECC while the web was encased by LWC. The test results showed a significant improvement in load‐carrying capacity, ductility and failure modes for ECC‐HSS beams when comparing with bare HSS and NSC‐HSS beam.
Stronger steels, higher penalties: Evaluation of flexural buckling experiments performed on welded high‐strength steel struts
Authors: Sabau Gabriel , Lagerqvist Ove , Baddoo Nancy
Published: September 2019

Stability in a structural mechanics context has posed a continuous problem throughout history for mathematicians, engineers and architects. Flexural buckling is one of the main problems steel structures are faced with in order to ensure an economic design. Different equations have been derived to estimate critical loads that could lead to collapse of compressed members. The buckling resistance of compressed struts are calculated in Europe using the European buckling curves. The method of calculating the resistance implies the use of a reduction factor based on 5 different buckling curves. These buckling curves differ based on type of cross‐section, fabrication method and steel grade. The method has been generally accepted since it proved to be reliable and versatile. The current design codes are assigning the same relevant buckling curve to the sections made of steels with yield stress of above 460 MPa. This conservative approach is one of the reasons that discourages the use of high‐strength steels in common structural applications, since the designer does not see a direct benefit from the additional steel strength. The first part of the paper briefly describes the origin of the European buckling curves. The second part presents two analytical models for calculating flexural buckling limit loads. Flexural buckling experiments performed on welded box and I‐sections made of high‐strength steel, with the yield stress in the range of 690‐960MPa. The third part analyses the existing buckling experiments and statistically evaluates the models proposed for estimating the resistance of high‐strength steel struts subjected to pure compression. The final part addresses the potential future research in the context of developing adequate flexural buckling curves for high strength steel (HSS) members.
Duplex steel segment gate Södertälje (Sweden)
Authors: Langedijk Walter , de Graaf Jan
Published: September 2019

The construction of a new lock in the Södertälje Canal (currently the largest lock in Scandinavia) is fundamental to be able to meet the continuous growth of marine traffic (both in volume and ship dimensions). The renewal project will ultimately result in an extension of the lock chamber (170 metres in length and 25.3 metres in width), the construction of two new sluice heads including stainless steel lock gates and a new bascule bridge.

As required by the client, a special type of lock gate is adopted in the design: a segment gate made of duplex steel (a specific type of stainless steel). Another unique feature of this project is that the bearings and hydraulic cylinders are integrated on a steel skid structure. This complete structure can easily be adjusted in the future to align the main axles in the desired position and direction. This is an important mitigation measure in the design to guarantee the fatigue strength of the steel structures in the event of settlements of the sluice head abutments in long term.

This paper aims to give insight into the design challenges and elaborates on the chosen solutions of these innovative duplex segment gates.
Guyed Wind Turbine Towers: Developments and outlook
Authors: Jespersen Martin , Støttrup‐Andersen Ulrik
Published: September 2019

In the quest of reducing carbon emissions, sources of renewable energy, such as wind, are in high demand. Developers of onshore wind farms are increasingly faced with site conditions which are not ideal in terms of harvesting wind energy, such as forest, mountain areas or wind availability.

This has several root causes such as: site scarcity, political instruments to ensure energy mix and lack of transmission. Some of the potential challenges for such sites are 1) larger hub height is required to maintain energy yield and reduce the turbulence intensity, 2) installation is costly, 3) road transport is costly from increased diameters of conventional towers, and 4) increased foundation cost for tall towers.

Guyed masts have been applied within the field of telecommunications for many years. Previous comparisons of the advantages of guyed masts over self‐supporting towers highlights that positive properties of the guyed mast include: lower cost with height, less erection time and cost‐effective foundations.

In order to reduce the cost of tall wind turbine towers a guyed wind turbine (GWT) tower concept, where the conventional steel tubular tower is supported by guy ropes (cable stays) just below the tip of the blade, has been proposed by Ramboll dating back to 2003. It is only in recent years that the hub heights relevant for application of this concept is coming into market. In 2013 Ramboll participated in a research project disclosing the use of guyed towers for constructing tall wind turbine towers, which demonstrated a significant positive cost impact and documented the technical feasibility of the concept.

For the concept cost reductions are obtained through the entire supply‐chain of the wind turbine tower: steel consumption, foundations, transport and installation.

The paper will give a general introduction to the guyed wind turbine tower concept and update with developments.
Automatically Welded Tubular X‐Joints for Jacket Substructures: Prediction of the Technical Fatigue Crack Location
Authors: Schaumann Peter , Schürmann Karsten , Pittner Andreas , Rethmeier Michael
Published: September 2019

To increase the competitiveness of jacket substructures compared to monopiles a changeover from an individual towards a serial jacket production based on automated manufactured tubular joints combined with standardized pipes has to be achieved. Therefore, this paper addresses fatigue tests of automatically welded tubular X‐joints focusing on the location of the technical fatigue crack. The detected location of the technical crack is compared to numerical investigations predicting the most fatigue prone notch considering the structural stress approach as well as the notch stress approach. Besides, the welding process of the automated manufactured tubular X‐joints is presented.
Local Buckling Coefficient Calculation Method of Thin Plates with Round Holes
Authors: Kelpša Šarūnas , Peltonen Simo
Published: September 2019

When slender parts of plated structural members are under compression the local buckling may govern resistance of the whole structure. In addition to that, holes in those slender parts may reduce the resistance even more. Knowing that holes in different positions of steel structural members are very common, a simple but as precise as possible calculation method of critical buckling force would be beneficial for engineers. In order to create such a method, which would take the influence of the holes into account, an extensive analysis campaign of elastic buckling of thin plates with holes has been carried out. The finite element method was used for the calculations, and analysis of the obtained results derived to a simple calculation expression.

The influence of different positioning and diameters of holes on elastic local buckling force is analyzed in the paper, and the developed calculation equation is presented. The proposed calculation method/ equation can be used by engineers in order to easily predict the elastic buckling coefficients and the critical forces of plates with round holes under compression. In order to add more value for engineers, the factors which have influence on the critical buckling force are commented. Also, recommendations for further development and possible extensions of the method are given in the paper.
Influence of Structural Detailing on the Stability Behaviour of Truss Girders
Authors: Mämpel Silvio , Kraus Matthias
Published: September 2019

In the design of truss structures, stability verifications are often decisive. Especially flexural buckling is of relevant issue. Structural systems are therefore usually stabilised by means of constructional members and components. Depending on the stiffening system and loading, the torsional behaviour and lateral torsional buckling of members can be of importance as well. However, all conventional structures for stabilisation have in common that they in general provide a shear stiffness (by bracings or sheeting) as well as an elastic rotational support.

The influence of different structural truss details are analysed with regard to the girder stability. In this context, the stiffness of bracing systems and its position as well as the influence of rotational stiffness provided by purlins are investigated. In doing so, individual truss girders are analysed as well as systems of several girders based on full three‐dimensional beam models. The investigations provide information on the global stability behaviour with respect to different girder quantities stabilized by one bracing system. Additionally, a subset of structural systems are modelled in more detail using shell elements in regions of connections/joints to account for structural detailing influences. Overall, the aim is to identify and focus different effects of structural details on the stability behaviour of lattice girders to promote an economic and safe design.
Out‐of‐Plane Buckling Assessment of Frames through Overall Stability Design Method
Authors: Papp Ferenc , Szalai József , Majid Movahedi R.
Published: September 2019

This article extends the innovative Overall Stability Design Method (OSDM) for steel portal frames with double symmetric I and H cross‐sections. The OSDM utilizes linear buckling analysis and equivalent initial geometrical imperfection in the shape of buckling mode for the assessment of out‐of‐plane buckling resistance. The method was developed for single structural members with two alternative procedures. One of them is the overall imperfection method which uses equivalent amplitude and the other is the overall strength reduction method which follows the classic reduction factor based procedure. Both methods have been validated for fundamental cases of lateral‐torsional buckling and coupled flexural and lateral‐torsional buckling of individual members published recently. In this article these methods are extended for portal frames. The method may be adapted by any commercial design software which is able to execute a relevant transmission of the displacements (namely the warping) through the applied frame corner joints. The overall validation of the method for portal frames needs considerable investigations. This article aims to do the first step by the presentation of the procedure through benchmark examples.
Experimental and numerical analysis of the local and interactive buckling behaviour of hollow sections
Authors: Toffolon Andreas , Müller Andreas , Niko Igor , Taras Andreas
Published: September 2019

Inadequate knowledge regarding specific local and interactive behavior of slender high‐strength steel (HSS) hollow sections presents an obstacle in implementing these sections in the construction practice. The current approach in the standard is simplified and offers overly conservative results. Dealing with non‐standard cross‐sections only expands on these difficulties. This paper contributes to the on‐going RFCS project “HOLLOSSTAB”, which has been dealing with the aforementioned issues. The project design proposal is based on the “Overall interaction concept” (OIC), and a new set of design rules for hollow sections is currently being developed. In this concept, linear buckling analysis (LBA) is used to obtain the slenderness of the member, and Geometrically and Materially Non‐linear Imperfection Analysis (GMNIA) is used to determine an “overall” buckling reduction factor. Extensive experimental tests are used to validate the method, by correlating the experimental results with numerical test results (GMNIA‐real) and statistically analyzing them. The focus of the tests in this paper is the use of high‐strength steel, ranging from S500 to S890, used for rectangular hollow‐sections and hexagonal‐hollow sections. The state‐of‐the‐art measuring tools available, offer the possibility of precise reverse‐engineering process, creating numerical models based on experimental test, which allows an accurate prediction of the ultimate load capacity of the specimens. Digital image correlation (DIC) allows a review of the buckling shape, comparing numerical model with real shape of tested specimen. The paper aims to validate the numerical models, as well as validity of assumptions on imperfection amplitude.
The Validity of the Universal Transformation Method in Global Buckling Design
Authors: Hajdú Gábor
Published: September 2019

In this paper, the limit and validity of the universal transformation method in global buckling design are examined. To calculate the stability resistance of compressed steel members an alternative approach, so‐called equivalent imperfection method, was applied into Eurocode 1993‐1‐1:2005 (1). Later, Papp showed that the equivalent unique global and local imperfection concept is valid for lateral‐torsional buckling and coupled buckling too (2). This method is based on the equivalent reference member method, where the buckling resistance of the irregular member should be equal to the buckling resistance of the reference member. The reference member has pinned ends, its cross‐section, axial force and bending moments are the same as in the equivalent cross‐section of the original member. Between the real member and the reference member forward and backward transformation are needed. In order to investigate the consistency of the above‐mentioned transformation technique on prismatic and tapered beam‐columns several geometrically and materially nonlinear analysis with imperfection were executed. The (semi‐) probabilistic safety level assessment of the universal transformation method performed according to (3), where the difference between the theoretical and experimental resistance is being used to measure the accuracy.
Numerical analysis of the behaviour of stainless steel cellular beam in fire
Authors: Cashell K.A. , Malaska M. , Khan M. , Alanen M. , Mela K.
Published: September 2019

This paper is concerned with the behaviour of stainless steel cellular beams during a fire. Stainless steel has become increasingly popular in recent years for structural applications, mainly due to its excellent corrosion resistance, as well as its other attractive physical and mechanical attributes. During a fire, stainless steel generally retains a higher proportion of their room temperature strength (above temperatures of 550°C) and stiffness (all temperatures) compared with carbon steel. In the current paper, the focus is on the fire behaviour of stainless steel cellular beams. There are no specific design rules available for these members and the carbon steel design rules for cellular beams are typically used with the stainless steel material properties. This work aims to investigate the validity of this approach by analysing the behaviour of stainless steel cellular beams with stiffened webs under fire conditions. A nonlinear finite element (FE) model is developed using the ABAQUS software, and is validated using fire test data. Then, the model is employed to conduct parametric studies in order to determine the most salient factors. Finally, design guidance is provided for stainless steel cellular beams in fire conditions, which consider the most influential geometric and material characteristics.
Application of the Master Curve concept on the choice of duplex stainless steel to avoid brittle fracture
Authors: Langenberg Peter , Kucharczyk Pawel , Pilhagen Johan , Stranghöner Natalie , Schedin Erik
Published: September 2019

Duplex stainless steel gets more and more common in structural applications even in steel bridges. For these cases, the choice of duplex stainless steel material to avoid brittle fracture is of great importance as e.g. steel bridges are exposed to low temperatures, generally down to −30 °C or even lower, and fatigue loads. EN 1993‐1‐4 also covers duplex stainless steel, but the given toughness requirements for duplex stainless steel are insufficient. Due to this fact, first investigations have been carried out on various duplex stainless steel base materials and welded specimens based on the fracture mechanic based concept of EN 1993‐1‐10 including the Wallin Master Curve concept. The objective was to achieve a first insight in the applicability of EN 1993‐1‐10 for structural applications with different types of duplex stainless steels in principle. In this frame, Charpy and fracture mechanics tests have been evaluated for 1.4462, 1.4362 and 1.4162 duplex stainless steels of 30 mm and 50 mm thick base materials and weldments. The results have been transformed into the general approach used in EN 1993‐1‐10 originally developed for ferritic structural steel considering the structural detail of a welded longitudinal attachment with a semi elliptical surface crack at the weld toe. The results demonstrate that the investigated duplex stainless steels and their weldments show a very good toughness behaviour and that the EN 1993‐1‐10 model can be transformed for application of duplex stainless steel. The paper presents these first results.
AMAGER BAKKE: A steel building with the design challenge of creating a world famous recreational roof
Authors: Nordestgaard Peter Madsen , Arndt Casper Højgaard
Published: September 2019

Amager Bakke is a spectacular construction. The 43,000 m2 combined waste to energy plant and artificial ski slope has a full height of 85 m. The roof provides public access for a park with the size of 2½ soccer fields. The park includes hiking, climbing, skiing area, viewing platform, café and trees.

The building has a high complexity due to the exterior architectural expressions require the correct shape for a double curved skiing slope, which was merged with the interior demands for machinery. The result is a complex geometrical structure for which steel was the only feasible material to apply when forming the superstructure. Furthermore, the fire compartmentation of the plant and the park gave special design issues concerning structural robustness and municipality's approval of the regulatory fire safety strategy.

Early in the engineering process it was decided that an innovative approach was required. Therefore, the limits of BIM tools were challenged and widened. The 3D‐model was used for design layout, collision check, quantity surveyor and illustrating the erection timeline. Additionally, the model was continuously operated for interchanges with the client, the architect, and the contractor.

The steel superstructure was executed in S235, S355, and S460 steel. A total of approximately 7,500 tons of weight was applied to the building parts. Various forms of large span roof steel girders were used with different static systems, to carry ∼1,000 concrete slab elements on the roof. The facade is covered with ∼1,000 aluminum bricks on steel sandwich panels and the cantilevered chimney hangs on the gable side starting more than 50 m up and reaching 124 m above ground level. This required a tuned mass damper in the top. The building complex also includes an 11‐storey office building, which caused additional demands regarding acoustical vibrational damping through the structures and floors.
Optimum Design of Cold‐formed Steel Beams: Particle Swarm Optimisation and Numerical Analysis
Authors: Perampalam Gatheeshgar , Poologanathan Keerthan , Gunalan Shanmuganathan , Ye Jun , Nagaratnam Brabha
Published: September 2019

Cold‐formed steel (CFS) members, when subjected to optimisation, can significantly increase their ultimate load carrying capacity leading to a more economical and efficient structural system. This paper presents the details of an investigation on optimisation of CFS beams subjected to bending capacity and an investigation of shear and web crippling capacities of optimised sections. The optimisation was aimed to meet construction constraints reported in Eurocode 3 (EC3). In this research, 4 different CFS sections were considered including the introduction of 2 novel sections (Super Sigma and Smart Beam) which has closer shear center to the web and less susceptible to web buckling. The bending capacity of the available sections were obtained based on the effective width method reported in EC3, while the optimisation procedure was performed using particle swarm optimisation (PSO). The capacities of the optimised CFS beams were also obtained using the nonlinear finite element (FE) analysis and the FE results were compared with EC3. The FE results showed that the Smart beam and Super Sigma claim dual advantage of increase in section moment capacity and restrain against torsional effect than the conventional CFS channel sections with the same amount of material. These optimised cold formed steel beams can be employed in light gauge steel building constructions.