bluuebunny/crossref_metadata_2025 huggingface dataset:
Compression Tests on Large Angle Columns in High Strength Steel
Authors: Bezas Marios‐Zois , Demonceau Jean‐François , Vayas Ioannis , Jaspart Jean‐Pierre
Published: September 2021

The paper discusses the stability behaviour of large angle columns in high strength steel subjected to compression loads. It presents a number of compression tests on such columns that have been performed at University of Liege with different eccentricities and slenderness and, as a result, different buckling failure modes observed. The experimental campaign is intended to widen the knowledge about the behaviour of high strength steel columns with large angle sections in compression and bending and so to complement previous experimental studies. The tests have been accompanied by numerical analyses and calculations of the load carrying capacities through present Eurocode prescribed methods. The numerical simulations have been carried out by application of the FEM software FINELG using beam elements and considering of relevant imperfections as well as geometrical and material non – linearities. The numerical and analytical results are compared and validated with the corresponding experimental ones and summarized in the present paper. The experimental campaign and the numerical simulations are part of the European‐funded RFCS project ANGELHY “Innovative solutions for design and strengthening of telecommunications and transmission lattice towers using large angles from high strength steel and hybrid techniques of angles with FRP strips”.
Favourable Steel Structures using High Strength Steels
Authors: Gong Fengyan , Dürr André , Bartenbach Jochen
Published: September 2021

As a part of the European RFCS‐project STROBE, HOCHTIEF Engineering has developed a calculation programme as the basis of a web‐tool for the design and optimization of steel beams. The programme is suitable for steel girders of normal strength and for high strength girders up to S690 including welded hybrid girders. In this paper, the developed calculation programme as well as several case studies will be presented based on an existing project which compares the design of floor systems of conventional strength steel S355 with high strength steel floor systems. The benefits of solutions using modern high strength steels for sustainable construction relative to conventional strength steel S355 in terms of saving weight and costs will be highlighted.
Determining the Yield Surface of a Metal Using Notched Strip Specimens: Geometry Optimization
Authors: Morales Mariela Mendez , Becque Jurgen
Published: September 2021

Determining the full yield surface of a metal by experimental means is a rather complex task, due to the need to subject the material to a multi‐axial stress state that includes shear. However, an interesting concept (originally credited to Hill and Bijlaard) has been proposed, whereby metal strips with oblique notches are loaded in uniaxial tension. This specific shape forces a narrow yield neck to develop between the roots of the notches, subject to multiaxial straining. The presented research aimed to further develop and optimize this concept. It was previously suspected that the geometry of the test specimens has a potentially significant effect on the results of the experiment. By means of the finite element method, a parametric study was completed to evaluate which geometric variables have the largest influence on the results and to determine the range within which these parameters yield reliable results. It was discovered that certain variables, such as the width of the neck and the radius of the notch root, had a significant impact on the results, whereas others, such as the neck angle or the opening angle of the notch, had very little or even no influence at all. Based on these results, a specific geometry was proposed for the test specimens, as a first step towards a standardized test procedure.
Lateral Cyclic Performance of Hybrid Fabricated Beam‐Columns
Authors: Javidan Fatemeh
Published: September 2021

In this paper, a high‐capacity fabricated hollow section is proposed as a lightweight replacement for concrete‐filled composite members which are commonly used as beam‐columns in seismic zones. The lateral cyclic performance of the fabricated hollow beam‐column comprising of mild steel plates (grade 250) and high strength steel (HSS) tubes (grade 750) is investigated. A finite element model is developed and validated against available experimental data. To incorporate the cyclic hardening and softening of both steel materials, a combined plasticity model obtained from low‐cycle material tests is incorporated in the finite element model. A comprehensive sensitivity analysis is undertaken to propose an optimum slenderness design for the thin‐walled steel elements with ductile failure. While the high strength steel tube elements can significantly increase the axial and lateral capacity of the hybrid section, the cyclic failure mechanism is governed by mild steel plate elements, rather than a sudden failure in the high strength steel tubes.
Pseudo‐dynamic testing of a full‐scale two‐storey steel building with FREEDAM connections
Authors: Di Benedetto Sabatino , Francavilla Antonella Bianca , Latour Massimo , Piluso Vincenzo , Rizzano Gianvittorio
Published: September 2021

The recent earthquakes have underlined the need for more advanced design philosophies able to avoid or reduce direct and indirect costs deriving from the occurrence of destructive seismic events. In fact, the traditional seismic design approach is based on performance levels implying the onset of damage which can be, in many cases, difficult to repair. In order to address social expectations and the need for resilient buildings, recently, novel low‐damage design philosophies have been proposed. These are based on the introduction, in particular points of the structure, of friction dampers able to dissipate large amounts of energy and to protect the structural members from damage. This is the case, for instance, of the Sliding Hinge Joints (SHJs), developed by the research group of the University of Auckland in 2005, or of the FREE from DAMage joints (FREEDAM), developed starting from 2009 at the University of Salerno.

Many experimental and analytical research efforts have been devoted to understanding the response of such connections. Nevertheless, currently there is still a lack of knowledge dealing with their seismic response in full‐scale buildings. In order to provide a contribution to fill this knowledge gap, an experimental program is currently ongoing at the STREngTH (STRuctural Engineering Testing Hall) Laboratory of the University of Salerno dealing with the pseudo‐dynamic testing of a full‐scale two‐storey steel building equipped with FREEDAM joints. The mock‐up has been subjected to a sequence of five accelerograms and the results have confirmed that FREEDAM connections provide large energy dissipation capacity and plastic rotation supply, thanks to their regular and plumb hysteretic loops. The experimental results have been complemented with numerical models developed with the software OpenSees.
Numerical Study on An Innovative Elastomeric‐Steel Cushion Damper
Authors: Moeini Milad Ehteshami , Razavi S. Ali , Yekrangnia Mohammad , Khaloo Alireza
Published: September 2021

In this research cyclic performance of a newly developed energy dissipating device is investigated through finite element studies. The device is constructed using yielding steel Cushions and bonded rubber cubes. The Cushions dissipate the induced energy of earthquakes while the rubber cubes provide lateral constraint and post‐elastic stiffness for the bracing system due to the Hyperelastic behavior of the rubber material. The main advantage of the proposed damper is its little maintenance expense and cost efficiency since the steel Cushions can easily be replaced. In this paper, the requisite details are presented for the application of the proposed device. It can be observed from the analytical results that the proposed damper exhibits full and wide hysteresis loops resulting in excellent equivalent viscous damping while maintaining adequate lateral stiffness at various displacement levels. The dissipated energy per cycle and the respective effective stiffness and equivalent damping of the model are presented in this study.
Design Recommendations of Steel Compressed Columns of Variable Cross Sections
Authors: Marcinowski Jakub , Kołodziej Sebastian , Błażejewski Paweł
Published: September 2021

Steel columns of hollow cross‐sections being the body of revolution and simply supported at their ends are considered in the paper. Columns of such shapes are recently very frequently proposed by architects of public facilities such as airports, entertainment halls and other objects encountered in engineering practice. The provisions of the EN 1993 standard do not provide for direct procedures that can be used when designing such columns. In this paper authors present the comparatively simple procedure which can be used by designers of steel columns of such shapes. The value of critical force required in the procedure was derived for columns of variable cross section by means of Mathematica™ system. The closed formulae were obtained for a rod with a certain, predefined geometry being the surface of revolution. To this end the Rayleigh quotient in the first form resulting from the energy criterion of stability was used and the half‐wave sine function was adopted to describe the buckling form. Critical forces obtained by means of derived formulae were compared with numerical solutions. To assess the compression resistance of considered rods the general Ayrton‐Perry approach was applied and bow imperfection with assumed amplitude was used in the analysis. Amplitudes of these initial imperfections can be chosen in correspondence to fabrication quality assumed in advance. An example inserted in the paper confirms the effectiveness of the proposed procedure. Formulas for allowable compressive force derived by the authors and presented in the paper can be treated as a measure of compressive resistance and used by engineers designing columns of the considered shape.
Performance‐based assessment of seismic‐resilient steel moment resisting frames equipped with innovative column base connections
Authors: Lettieri Annarosa , Elettore Elena , Freddi Fabio , Latour Massimo , Rizzano Gianvittorio
Published: September 2021

Low‐damage and self‐centring column base connections have been proposed in the last two decades as innovative solutions able to provide the seismic resilience in Moment Resisting Frames (MRFs). Although many works have demonstrated the benefits deriving from the adoption of these systems, only a few research studies investigated the significant parameters influencing their self‐centring capability. This paper investigates the influence of the frame layout (i.e., storeys and bays number) on the seismic performance of perimeter MRFs equipped with damage‐free self‐centring column bases previously studied by the authors. Nine case‐study perimeter steel MRFs are designed and modelled in OpenSees. Incremental Dynamic Analyses are performed monitoring both global and storey‐level Engineering Demand Parameters, including peak and residual interstorey drifts. Fragility curves are subsequently used to evaluate the self‐centring capability of the structures. The present study provides insights on the use of the adopted connections for the residual drift reduction of MRFs and defines the boundaries of the investigated parameters for their application. Results highlight that the self‐centring behaviour is particularly sensitive to the number of storeys and tends to reduce with the increasing height of MRFs equipped with the proposed connections.
Trigonometric series solutions for the geometric nonlinear analysis of the compressed thin plate
Authors: Nedelcu Mihai
Published: September 2021

The Eurocode uses the Effective Width Method for the Cold Formed Steel design and this method is currently based on the semi‐empirical Winter formula. This formula is based on the von Karman's approach which considers that the ultimate load on a compressed thin plate with large deflections is reached when the critical stress of the plate effective width is equal with the yield stress. Winter modified the formula in order to match the experimental results but there are numerous cases in which the formula underestimates the strength capacity. Also, the formula has no input for the initial geometric imperfections. This paper presents a semi‐analytical alternative based on the trigonometric series representation of the displacement field. The procedure is applied to the uniform compressed rectangular plate with simply supported edges (internal plate of a thin‐walled member) and with one free longitudinal edge (outstand plate). This new approach considers the initial geometric imperfections with various shapes.
Printing imperfections – geometric patterns to improve resistances of 3D printed steel plates
Authors: Wang Jie , Evernden Mark , Chater Ben , Pan Jingbang
Published: September 2021

Traditional structural steel manufacturing routes typically produce prismatic members comprising of flat plate elements. Under compressive actions, the capacity of these sections is often dominated by plate instability of the lowest buckling mode. The current study proposes the use of innovative additive manufacturing to produce metallic plate elements with predefined imperfection patterns capable of postponing instability via the lowest buckling mode thus providing increased buckling resistances. To this end, a program of numerical modelling has been carried out to explore various combinations of predefined surface waves with different amplitudes in stainless steel square hollow section stub columns of varying slenderness. Their stiffness, strength, and material consumption against the typical flat sided structural steel members with the same nominal dimensions were assessed. The study identifies the possibility for ‘imperfect’ sections to achieve up to a 50% increase in strength for a minimal increase in material consumption. This innovative study highlights the significant potential of new metallic additive manufacturing technologies in achieving unprecedented material efficiency and economic design in the future steel construction industry.
Cyclic Performance of Cold‐formed Steel Moment Resisting Frames
Authors: McCrum Daniel P. , Wrzesien Andrzej M. , Simon Jordan , Grimes Michael , Broderick Brian , Lim James B.P.
Published: September 2021

This paper investigates the seismic performance of a single storey moment resisting cold‐formed steel (CFS) portal frame through cyclic testing. Six monotonic and six cyclic tests were performed on three different section sizes of CFS portal frames. The portal frames were 3.2m long x 2.2m high and the CFS sections bolted with either perfect‐fit tolerance bolt holes (PTBH) or normal tolerance bolt holes (NTBH) connections. Connections with NTBH are standard in CFS, but connections with PTBH are often only used for short‐spanning frames. Results from the tests demonstrated that both PTBH and NTBH connections had stable hysteresis and good hysteretic energy dissipation capacity and ductility. On average, the NTBH connections performed better under cyclic loading in comparison to the PTBH connections (5.4% larger ductility and 22.3% increased energy dissipation). Strain gauge results show failure due to combined bending and bi‐moment stresses, of which the bi‐moment stress component accounted for 41% of the total longitudinal stresses at the section web. It should be noted that bi‐moment stresses are often incorrectly ignored by practitioners; the experimental test results thus show that by doing so the sections would fail at 59% of the design moment.
Rapid Seismic Economic Loss Assessment for Steel Concentrically Braced Frames Designed to Eurocode 8
Authors: Hickey John , Broderick Brian
Published: September 2021

This paper presents a rapid method for calculating the expected earthquake repair costs incurred by steel concentrically braced frame structures designed to Eurocode 8. The method adopts the FEMA P‐58 performance assessment methodology which is based on the predicting Engineering Demand Parameters (EDPs), such as peak inter‐story drift and peak floor acceleration, at various seismic hazard intensity levels of interest and then using these EDPs to calculate expected damage and associated economic losses. Typically, multiple nonlinear time history analyses (NLTHA) are employed to calculate the required EDPs, however this can be computationally expensive and technically challenging. This paper proposes the use of regression equations, developed from a large number of nonlinear analyses, as an alternative to NLTHA for EDP prediction. This allows loss assessment to be carried out without the need for multiple NLTHA, a process termed rapid loss assessment. The proposed equations are applied in loss assessment for three case study CBFs. It is shown that the economic losses predicted by the rapid method compare well with results obtained from conventional NLTHA‐based assessment.
Seismic design of innovative steel frames with partially‐prefabricated infill walls
Authors: Piattoni Quintilio , Freddi Fabio , Zona Alessandro , Leoni Graziano , Dall'Asta Andrea , Argentoni Alessio
Published: September 2021

Hybrid steel and concrete seismic‐resistant systems made by steel frames with reinforced concrete infill walls (SRCWs) have potential advantages over structural solutions made only by steel or reinforced concrete (RC). In fact, the high initial stiffness of concrete is useful to minimize the damage of non‐structural elements under frequent (low to moderate) earthquakes while the ductility and dissipative capacity of the steel allow good performances under rare (high‐intensity) events. Eurocode 8 considers SRCW systems to behave essentially as RC walls. However, numerical analyses on SRCWs, designed according to the Eurocodes, pointed out an unsatisfactory seismic behaviour with discrepancies between the behaviour assumed in the design and the simulated response under seismic actions. Indeed, the idea of stiffening a steel frame with a RC infill leads complex mechanisms that are difficult to control as being affected by many variables. In this study, some of the recent developments made for innovative SRCW are transferred to hybrid steel and concrete walls with partially‐prefabricated infills. Numerical models are analysed to understand the global behaviour of the considered SRCWs and to provide a preliminary validation of the proposed structural solution.
Residual Drift Estimation for Moment Resisting Frames with Steel Degradation Properties
Authors: Petreski Borjan , Gjorgjiev Igor
Published: September 2021

Inter‐story drifts are the most important engineering demand parameters required for the evaluation of performance of structures subjected to lateral loading. Even though the transient inter‐story drifts are usually used for the assessment and design using the codes of practice, the residual drifts often govern the economic loss in buildings. Therefore, the residual drifts can be critical in the post‐earthquake evaluation of the structures and should be given greater consideration in the process of design of steel moment resisting frames (MRFs). This study examines an improved approach for the estimation of the residual drift demands in steel moment resisting frames subjected to realistic earthquake loading. The advancement is implemented through application of a steel degradation material model in order to capture the stiffness degradation in the inelastic range correctly. Then, this modelling is compared with simplified bilinear steel material model in order to demonstrate the advantages of the deterioration model in performance‐based assessment.
Seismic performance of MR steel frames via Incremental Dynamic Analysis
Authors: Bernuzzi Claudio , Rodigari Davide , Simoncelli Marco
Published: September 2021

The Incremental Dynamic Analysis (IDA) represents a promising design approach to assess the performance and post‐earthquake load carrying capacity of steel frames. Generally, only the maximum transient inter‐story drift is considered as damage intensity measure (DM), when IDA is carried out. In the Authors' opinion, to better appraise all the aspects characterizing the damage state of the structures, additional DMs should be considered, like residual inter‐story drift, residual load carrying capacity and low‐cycle fatigue (LCF) damage, whose quantitative evaluation is currently neglected in seismic design provisions.

The presented paper deals with Moment‐Resisting (MR) steel frames for which the structural performance is evaluated via IDA. In particular, four multi‐story frames differing for the beam‐to‐columns connections have been considered. The aforementioned DMs have been evaluated at the specific seismic intensity correspondent to the design performance level of Immediate Occupancy, Life Safety and Pre‐Collapse. Research outcomes underline how the additional information obtained from the proposed DMs provide a more accurate prediction of the damage state of MR frames, with respect to the one assessed only with the maximum transient inter‐story drift, especially when damage and residual load carrying capacity have to be quantify.
Novel adaptive steel hysteretic damper for an enhanced seismic structural performance
Authors: Gandelli Emanuele , Weber Felix , Chernyshov Sergey , Distl Johann , Taras Andreas
Published: September 2021

Traditional Hysteretic Dampers (HDs) are installed in buildings to enhance their seismic performance by increasing the effective stiffness and damping and are usually designed to guarantee the structural safety for severe Ultimate Limit State (ULS) seismic events. As a negative consequence, only minimal damping is provided during weak but more frequent Serviceability Limit State (SLS) earthquakes since HDs mainly operate in their elastic regime. This can cause high Peak Floor Accelerations (PFAs) that are detrimental for sensitive non‐structural components (NSCs), like electric network, elevators, and computers, whose integrity is crucial in high‐technological buildings (e.g. hospitals, and emergency centers). In order to improve this unacceptable situation, a novel Adaptive Hysteretic Damper (AHD) was developed by the authors. The AHD can modulate its effective damping and stiffness to its actual deformation (i.e. PGA level) leading to: (i) reduced PFAs and enhanced building response to minor SLS earthquakes; (ii) not impaired structural safety under severe ULS events. The AHD force‐displacement characteristics are experimentally assessed and nonlinear time‐history analyses are carried out on a case‐study structure to demonstrate the enhanced seismic performances compared to common HDs.
Influence of the ballasted track on the dynamic behaviour of steel railway bridges
Authors: Stollwitzer Andreas , Fink Josef , Malik Tahira
Published: September 2021

The calculated dynamic behaviour of railway bridges during high‐speed traffic differs from the actual behaviour of its bearing structure. In the case of steel railway bridges, dynamic calculations often overestimate the actual vibration responses and therefore lead to uneconomical results. This gap between calculation and measurement constitutes a complex research issue, whereas the consideration of the ballasted track in dynamic calculations has a major influence. Concerning the damping and stiffness properties of the ballasted track there is a wide range of various mechanical models. However, there is no generally applicable track‐structure model for dynamic calculations which reflects reality in a satisfactory way. In their effort to close the gap between calculation and measurement and to develop accurate track‐structure models for dynamic calculations that take into account the dynamic properties of the ballasted track, researchers at TU Wien have developed a large‐scale test facility which allows for specific research of the dynamic behaviour of the ballasted track. This paper describes the operating principle of the test facility and provides insight into the dynamic effects observed in it, in particular with regard to its vibrations and damping behaviour.
Experimental Study on Steel Slit and Shear Panel for Seismic Resistance
Authors: Gashi Ferit , Bontempi Franco , Petrini Francesco
Published: September 2021

This paper summarizes the experimental campaign carried out for the development of new steel energy dissipative devices named Slit Dampers (SDs) designed for earthquake protection of structures. A total of eighty‐two steel shear plates with different openings and thicknesses are tested to investigate their behaviour under cyclic pseudo‐static loading. Eight types of steel shear plates are studied, including the SD with narrow slits that divide the plate into rectangular links, and the butterfly fuse with a diamond‐shaped opening that creates butterfly shape links in the plate. Other varying test parameters are loading rate, material strength, and the number of in‐parallel damper elements. It is expected that the proposed model can be successfully used to predict the behaviour of dampers in real‐world applications.
Structural member stability behaviour of steel channels
Authors: Bours Anna‐Lena , Winkler Rebekka , Knobloch Markus
Published: September 2021

In structural engineering, steel channels are often used for girders of facade constructions of steel halls, platforms, gangways and stair stringers. Since the loads are often applied to the flanges of the mono‐symmetric cross‐sections the channels are most commonly subjected to scheduled torsion. So far, a simplified design method for steel channels in bending, compression and torsion is missing.

Based on an experimental study, this paper analyses the structural behaviour of steel channel members in bending, compression and torsion. An integrated experimental and numerical study analyses the structural member stability behaviour. The study includes the analysis of the load‐rotation behaviour, of the development of internal forces and moments during load increase as well as of the residual elastic cross‐sections as a result of the development and spreading of plastic zones. Finally, the paper compares the ultimate loads of three verification methods, that are adopted and extended for steel channels, with experimental results.
Imperfection sensitivity study of hot‐rolled and laser‐welded stainless steel angle columns
Authors: Filipović Aljoša , Dobrić Jelena , Marković Zlatko , Baddoo Nancy
Published: September 2021

Stainless steel sections are used for structures in aggressive environments where the greater material cost can often be justified in return for longer maintenance‐free periods, for example in the water treatment, nuclear, petrochemical and food and beverage sectors. This paper presents a comparative imperfection sensitivity study of hot‐rolled and laser‐welded pin‐ended equal angle columns made of austenitic stainless steel grade 1.4301. Although the initial geometric imperfections in these structural elements are similar, there is a difference in the initial stress state due to the different manufacturing processes. The study includes three‐dimensional geometric imperfection measurements conducted by a laser scanner, and, in parallel residual stress measurements performed by the sectioning method using water jet cutting. The overall bow, camber, and twist imperfections are determined from the scanned specimens. In addition, the shapes of the residual stress patterns through the thickness of the angle leg are shown. Based on the findings related to imperfection distributions and amplitudes, a FE analysis is performed both on hot‐rolled and laser‐welded angles to study the influence of the variability of initial imperfections on compression resistance. The separate and combined effects of the measured residual stresses and initial out‐of‐straightness are considered and the reduction in the buckling resistances of initially straight angle columns is determined. The structural responses of hot‐rolled and laser‐welded columns are compared and discussed.
Shear Strengthening of Slender Steel Beams Using Cold‐formed Stiffeners and Adhesives
Authors: de Sousa Cardoso Hermano , Martins João Pedro , da Silva Luis Simões
Published: September 2021

This paper explores an alternative for strengthening shear‐deficient beams by fixing cold‐formed stiffeners with non‐welded joints at buckling‐prone regions. The usage of welds may not be suitable in slender beams as it introduces residual stresses and local distortion on the web. The cold‐formed stiffeners are disposed in diagonal orientation and its corrugate‐shaped geometry with high moment of inertia improves the out‐of‐plane stiffness of the beam web. The assessment of this method was performed in an experimental campaign which included three‐point bending tests of four beams. In two specimens, the cold‐formed stiffeners were fixed on the web by means of hybrid bonded‐bolted joints. Additionally, two control specimens were tested: a beam without diagonal stiffeners and a beam with diagonal welded‐steel plate.
Flexural buckling resistance of rectangular welded box section columns
Authors: Somodi Balázs , Kövesdi Balázs
Published: September 2021

Application of high strength steel (HSS – S420 and higher steel grades) is growing nowadays in the civil engineering praxis due to the numerous advantages compared to the normal strength steel (NSS – S235‐S355). The accurate consideration of the flexural buckling resistance of HSS structures is highly important in the design. Higher yield strength indicates the applicability of smaller cross‐sections, which might be more sensitive for stability problems. The purpose of the current study is (1) to investigate the flexural buckling behaviour of HSS welded rectangular box section columns and (2) to propose a reliable column buckling curve.

Residual stress in steel structural elements have significant influence on the flexural buckling behaviour of welded box section columns. This phenomenon causes that hot‐rolled, cold‐formed and welded sections have different flexural buckling behaviour and resistance. Previous research results of the authors proved that different buckling curves can be used for HSS or NSS welded square box section columns. Research is continued and extended to the investigation of rectangular box sections, which significantly increase the applicability of the design proposals. The buckling resistances for NSS and HSS rectangular welded box section columns are determined by using deterministic numerical simulation technique for a wide range of relative slenderness and steel grades. Based on the simulation results buckling curves are proposed for all the analysed steel grades and aspect ratios.
Experimental study of welded austenitic stainless steel I‐section beam‐columns
Authors: Feber Nina , Jandera Michal , Rossi Barbara , Kremen Tomas
Published: September 2021

Stainless steel beam‐columns were experimentally and numerically investigated in this study. All members were subjected to compression and major axis bending induced by an eccentricity of the compressive load. The loading eccentricities for the tests varied to provide a wide range of bending moment‐to‐axial load ratios. The experimental program covers 10 welded I‐section specimens made of austenitic stainless steel grade EN 1.4301 (AISI 304L). Material tensile coupon tests and initial geometric imperfection measurements are also described in detail. Measurements of initial imperfections were performed using two different methods, using a mechanical dial and laser scanning. The test results were subsequently used for a validation of a finite element (FE) model, developed in ABAQUS software to replicate the beam‐column behavior. The accuracy of the models with the two combinations of local and global imperfections were evaluated by comparison with the test results.
Pseudo‐dynamic testing of a full‐scale two‐storey steel building with RBS connections
Authors: Di Benedetto Sabatino , Francavilla Antonella Bianca , Latour Massimo , Cavallaro Giovanni Ferrante , Piluso Vincenzo , Rizzano Gianvittorio
Published: September 2021

After the earthquakes of Kobe (1995) and Northridge (1994) many research efforts have focused the attention on the seismic behaviour of partial strength beam‐to‐column joints because, in these seismic events, brittle fractures of welds of full‐strength joints belonging to MRFs have been observed. One of the most popular solutions developed in the aftermath to overcome the drawbacks of the typical welding joint details consisted in the adoption of the so‐called Reduced Beam Section (RBS) strategy. With this strategy beam ends are weakened into areas located sufficiently far from the column in order to reduce the stress concentration in the welds. Nevertheless, while many experimental efforts have been devoted to this connection typology, the available experimental results on full‐scale structures are still quite limited.

Within this framework, aiming to provide a contribution to fill this knowledge gap, an experimental program concerning the pseudo‐dynamic testing of a full‐scale two‐storey steel building equipped with five different connection typologies is currently undergoing at the University of Salerno. In this paper the results of the first experimental campaign, dealing with MRFs with RBS connections, are presented. The mock‐up has been subjected to a sequence of seven accelerograms and the results have confirmed that, if properly designed, RBS connections provide large energy dissipation capacity and plastic rotation supply. Nevertheless, the failure of welds due to damage accumulation can be still possible, even adopting full penetration butt joint welding details conforming to Eurocode 3 and Eurocode 8 provisions.

The experimental results have been complemented with numerical analyses developed with the software SeismoStruct. The comparisons between the numerical simulations and the experimental results show that the applied mixed distributed and concentrated plasticity approach, based on the adoption of phenomenological spring models, can capture accurately the global response of the structure, but it predicts with lower accuracy the local response parameters.
Weight optimization of stainless‐steel built‐up structural elements
Authors: Venslavavičiūtė Raminta , Daniūnas Alfonsas
Published: September 2021

This paper describes the use of stainless‐steel as a structural material, discusses current structural design considerations, reviews recent research work, and highlights important findings and developments.

Over the past 25 years, structural design codes for stainless‐steel have been introduced or substantially altered or are still being modified, while at the same time there is a growing interest in the use of stainless‐steel in construction. Realistic modeling of structural elements of stainless‐steel plays an important role in the analysis and design of steel framed structures. Structural element modeling and optimization using stainless‐steel, in case a built‐up column, can contribute to existing research on stainless‐steel. The object under consideration is a stainless‐steel built‐up column, which is classified as atypical structural elements. The purpose of this optimization problem is to perform the minimization of the weight of the selected built‐up column, when the height of the column and the load acting on it are known. The built‐up column is considered with two different types of cross‐sectional chords: at first with circular (CHS) cross‐sectional chords and then with elliptical (EHS) cross‐sectional chords.

A genetic algorithm based optimum design is presented for such a built‐up column. The design algorithm obtains a built‐up column with the least weight by selecting appropriate sections from standard set of duplex stainless‐steel hollow elliptical cross‐sections. The optimization model accounts for the strength and stability constraints. The built‐up column is under action of compressive axial force, bending moment and combination compressive axial force and bending moment. The parameters under consideration include the height and width of the outer cross‐section of the column's chords, the ratio of the outer cross‐sectional dimensions to the thickness and the initial eccentricity of the load. The computation results showed that the chosen optimization model and genetic algorithm allow efficiently obtaining the column of minimum weight, where the variables are column chord cross‐section and diagonals cross‐section. The design algorithm used to solve the problem is described in detail in this work.

Until today, there is known that the lack of information prevented the recommended methodology from being properly established. Because of this, the obtained results confirmed that these types of structural elements of the steel in question are needed to develop a more efficient design of stainless‐steel structures in the design method and thus contribute to its wider use in construction.
Examination of Structural System of Hales Turgus Vilnius Shopping Center, Constructed with Iron and Steel in 1906
Authors: Aktuglu Yesim Kamile
Published: September 2021

Hales Turgus, Vilnius Shopping Hall, was built in 1906, in construction with iron‐and‐steel. It has a very special structure, constructed with iron‐and‐steel, inside the building. It has a perimeter wall, built with brick. All these main details are similar with the structural details of Budapest Central Market Hall (Nagy Vasarcsarnok), built in 1897 and also of Central Sofia Market Hall (Tsentralni Hali), built in 1909. All of these landmarks are having the similar architectural plan and similar iron‐and‐steel construction solution. And also the architectural planning of all three shopping halls will be examined, by comparing altogether. The connection of the structural system with the architectural planning will be defined to lead the way about how a new shopping hall, constructed with structural steel, can be designed in future. The reasons why they all are still in servive with their original function will be given through the meeting of architecture and structure of the building. In the paper, all these main similarities will be examined, through the structural details of iron‐and‐steel construction, through their sustainability features, which keep them still in service with their original function.
A Simplified Approach for Seismic Performances Estimation for Steel Moment Resisting Frames
Authors: Nastri Elide , Montuori Rosario , Piluso Vincenzo , Todisco Paolo
Published: September 2021

Seismic events in recent years have underlined the need to quickly classify the built heritage in terms of seismic performances. The capacity of a structure can be assessed by means of inelastic analyses, requiring sophisticated numerical procedures. The simplified method herein proposed only requires use of common analyses such as the elastic structural analysis and the rigid‐plastic analysis. For this reason, it lends itself well to be used in the immediate aftermath of an earthquake, not requiring any static or dynamic non‐linear analyses. The proposed methodology has been set up by means of a large parametric analysis, carried out on 420 frames designed according to 3 different approaches: the first one is the Theory of Plastic Mechanism Control (TPMC), ensuring the design of structures showing global collapse mechanism (GMRFs), the second one is based on the Eurocode 8 design requirements (SMRFs) while the third is a non‐seismic design, based on design for vertical loads (OMRFs).
Structural performance evaluation of square hollow section column under compressive axial force with bending moment having different width‐thickness ratio
Authors: Hayashi Takuro , Sato Atsushi , Yoshioka Shimpei
Published: September 2021

The square hollow section (SHS) is commonly used for the column of the steel building structures in Japan. The moment‐resisting frame will resist the lateral force with the flexural manner of the columns. Under the seismic event, the bending moment will be significant, and the plastic hinge may be formed in the columns. It is crucial to understand the structural behavior at the component level to capture the structure system's ultimate limit state by computational simulation. Understanding the strength and the ductility is one of the essential aspects, but it is also crucial to know the structural elasto‐plastic behavior until the ultimate limit state. It is worthwhile to conduct the testing of the members under combined loading conditions. In this paper, the test results obtained from the different width‐thickness ratio SHS were reported. The forces subjected to the specimen were axial force and cyclic bending moment; therefore, the member was under combined loading condition. Collapse mode, maximum bending moment, and plastic deformation capacity were evaluated in consideration of the effect of the width‐thickness ratio; comparison study between the current design recommendation was also shown.
Steel Structure Prediction Model for Fixed Roof Oil Tanks
Authors: Denic Uros , Spremic Milan
Published: September 2021

This paper will focus on fixed roof storage tanks and its sub‐category cone roof tanks. Paper presents major factors and outputs of tank design process. Theoretical analysis is done for a cone roof tank model and correlation between tank surface, shell thickness and total steel weight used. Detailed algorithm for tank design was realized using MathCAD software using Eurocode standards. Using this algorithm, 432 hypothetical tanks were designed. Data analysis of the collected output data was analysed using R statistics programming language. Using regression models and testing them led to the optimum statistical model.

For the purpose of this work, data for 21 real world tanks including fixed roof and floating roof tanks were collected. The data was collected with help of MOL, INA and few other EPC contractors. Paper compares real world data with outputs of the model.

Model can be used for quick estimates and control of material consumptions. Taking few input parameters and applying minimal effort can lead to a very accurate steel consumption prediction. With additional real‐world data, acceptable ranges of deviation from the mean could be set‐up. Thus, allowing for better control on Client part or EPC companies.
Design and Construction of the Lille Langebro, Copenhagen
Authors: Fryer Simon , Eckhart Thomas , Nugent Peter
Published: September 2021

The Lille Langebro is the latest movable bridge to be built across the harbour in Copenhagen. Its design was the subject of an international competition commissioned in 2014 by the client, Realdania, and won by a collaboration of Buro Happold, Wilkinson Eyre and Eadon Consulting. The bridge has an overall length of 160m and carries pedestrians and cyclists over a 7m wide deck. The superstructure is steel comprising main longitudinal members that are triangular in cross section along each edge. The geometry is complex with plan curvature and an undulating profile, resulting in an interesting form that results in double curvature of the steel plates.

The bridge has two sections that swing to allow shipping through a 35m wide navigation channel. In order to maintain a slender profile in elevation, an innovative moment connection has been designed to connect the moving parts together at midspan. This connection clamps the sections together but is released to allow longitudinal movements arising from temperature.

The four bridge sections were entirely prefabricated, being assembled upside down in the workshop and then turned over. They were then delivered to site by sea for erection on site using a large capacity shear leg crane.
Ultimate Strength of K‐joints in Lattice Structures Composed of Circular Hollow Sections (CHS)
Authors: Đuričić Đorđe , Marković Zlatko , Janković Milena , Lučić Duško
Published: September 2021

This paper deals with the analysis of the design resistance of joints in lattice structures composed of welded circular hollow sections (CHS). The analysis was carried out on a K‐joint. Determination of the design resistance of lattice structures is based on the calculation of design resistance of compression members in uniform compression, taking buckling into account, in accordance with EN1993‐1‐1 and the calculation of design resistance of joints in lattice structures in accordance with EN1993‐1‐8.

The value of the design resistance of compression members in uniform compression is obtained through new diagrams for the resistance of members used for determining the value of compression members' design buckling resistance for a given buckling length of a member.

Calculation of resistance of brace members in K‐joints of a welded lattice structure composed of circular hollow sections (CHS) in accordance with EN1993‐1‐8 is analysed both according to the equations given in the adopted standard and according to the equations given in the new proposal for EN 1993‐1‐8.

Through a comparative analysis of these two criteria, using appropriate diagrams, a simple procedure was given in order to calculate and determine whether the ultimate strength of the brace member was achieved by its buckling or by plastification of the chord member of the joint. The suggested diagrams give an evaluation of the utilization ratios of the adopted members of lattice structures. Provided the sections were properly chosen, it is possible to rationalize the structure.
Fire design proposal for members with cold‐formed lipped channel and sigma sections under compression
Authors: Arrais Flávio , Lopes Nuno , Real Paulo Vila
Published: September 2021

Steel structural elements with cold‐formed thin‐walled sections are becoming increasingly common in buildings due to their lightness and ability to support large spans. In these members, local, distortional and global instabilities are important common failure modes. At high temperatures, these instability phenomena are intensified. This paper presents a numerical study on the behaviour of columns with lipped channel and sigma sections in case of fire when subjected to compression. A parametric study, considering different steel grades, temperatures and different cross‐sections with different slendernesses, is presented. Comparisons are also made between the numerical results and analytical design rules, such as the Part 1‐2 of Eurocode 3, using its Annex E or its French National Annex, where a different constitutive law is recommended for cold‐formed profiles. It is possible to conclude that the simple calculation rules are on the safe side but sometimes too conservative. Therefore, new proposals with adjustments to the current design rules are presented for these particular cases that are very common in cold‐formed steel constructions, in order to keep the results on the safe side becoming the design rules less conservative.
Construction of CoS2/Zn0.5Cd0.5S S‐Scheme Heterojunction for Enhancing H2 Evolution Activity Under Visible Light
Authors: Ma Lijun , Xu Jing , Zhao Sheng , Li Lingjiao , Liu Ye
Published: August 2021

In the field of photocatalysis, building a heterojunction is an effective way to promote electron transfer and enhance the reducibility of electrons. Herein, the S‐scheme heterojunction photocatalyst (CoS2/Zn0.5Cd0.5S) of CoS2 nanospheres modified Zn0.5Cd0.5S solid solution was synthesized and studied. The H2 evolution rate of the composite catalyst reached 25.15 mmol g−1 h−1, which was 3.26 times that of single Zn0.5Cd0.5S, whereas pure CoS2 showed almost no hydrogen production activity. Moreover, CoS2/Zn0.5Cd0.5S had excellent stability and the hydrogen production rate after six cycles of experiments only dropped by 6.19 %. In addition, photoluminescence spectroscopy and photoelectrochemical experiments had effectively proved that the photogenerated carrier transfer rate of CoS2/Zn0.5Cd0.5S was better than CoS2 or Zn0.5Cd0.5S single catalyst. In this study, the synthesized CoS2 and Zn0.5Cd0.5S were both n‐type semiconductors. After close contact, they followed an S‐scheme heterojunction electron transfer mechanism, which not only promoted the separation of their respective holes and electrons, but also retained a stronger reduction potential, thus promoting the reduction of H+ protons in photocatalytic experiments. In short, this work provided a new basis for the construction of S‐scheme heterojunction in addition to being used for photocatalytic hydrogen production.