bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical study on bending resistance of cold‐formed steel back‐to‐back built‐up elements
Authors: Lukačević Ivan , Ungureanu Viorel , Valčić Anđelo , Ćurković Ivan
Published: September 2021

Cold‐formed steel back‐to‐back built‐up beams are efficient and very attractive structural elements which can also offer excellent efficiency in production, both in capacity and material savings. The connection between such built‐up steel components can be easily obtained by screws or bolts, but the developments in the welding processes also lead to other solutions like continuous (laser or MIG brazing) or discrete (spot welding). This paper presents a parametric numerical study on such elements where various shapes and cross‐section geometries will be analysed, using different types of connection between the built‐up steel elements. The results from the evaluation of local and global buckling behaviour of such beams will serve as a base for planning future experimental work. Based on the numerical model, the paper presents the influence of several parameters i.e., the type of the channel section (lipped or plain channels), length of the beam, continuous and discrete connections between channels, the number and the distance between discrete connections along the beam axis and along the beam height. From the parametric study, it is concluded that capacity of the cold‐formed steel back‐to‐back built‐up steel beams is highly affected by the type of connections.
Pushing the Boundaries of Accuracy: Development and Calibration of an Imperfection Measuring Rig
Authors: Meza Francisco J. , Becque Jurgen
Published: September 2021

It is well understood that the buckling response of steel members can be significantly affected by their initial geometric imperfections. Therefore, it is of paramount importance that these imperfections are accurately measured and subsequently accounted for when studying the buckling behaviour of steel members. This paper discusses the design, development and calibration of an imperfection measuring rig. The set‐up makes use of a laser displacement sensor which is moved by two electric motors along orthogonal high‐precision guiding bars and is able to record out‐of‐plane imperfections over a length of 3 m. The initial accuracy of the imperfection readings, although of very reasonable quality, was found to be limited by the out‐of‐straightness of the guiding bars along which the laser sensor is moved. However, a novel calibration technique, where the system is calibrated against a liquid surface, was found to raise the performance of the rig to unprecedented accuracy. The technique is easy to implement and inexpensive. The calibration process, as well as an analysis of the repeatability of the results and an estimate of the magnitude of the error, are presented in this paper.
Experimental investigation into the performance of cold‐formed steel walls sheathed with OSB and cement‐based panels
Authors: Iuorio Ornella , Kechidi Smail , Banks Nigel
Published: September 2021

Cold‐formed steel (CFS) structures are developing fast in both seismic and not seismic areas for their high degree of prefabrication, high structural performance and the good energy performance. In the last decades, many research groups around the world have focused on the analysis of seismic behaviour of CFS structures and the development of design procedures that still need to find their full implementation in many international codes, first of all in the Eurocode. Therefore, the development of CFS system still requires, very often, the adoption of large experimental testing, in particular, when sheathing braced design methodologies are applied. This paper presents, for the first time, the in‐plane tests of CFS walls sheathed on one side with oriented strand boards (OSB) and cement based panels (CP). In particular, a set of two full scale tests of ledger walls having 2400mm width and 2926mm height, sheathed with OSB3 and CP, and a set of two tests on ledger walls having dimensions (2400mmm x 2974mm) sheathed with OSB3 panels are presented and discussed. The tests have been carried out in accordance to the BS EN 594:1996. The results confirm in agreement with literature studies that the collapse is governed by the failure of the screws between panels and steel profiles. And, more importantly it shows that, when both OSB and CP are present the collapse is governed by the failure of the screws between cement panels and steel profiles. When comparing the two sets of walls those sheathed only with OSB panels have lateral resistance which is about 1.5 time higher than when also CP are present.
Rheological modelling of high‐temperature stationary creep tests of Grade S275JR steel
Authors: Torić Neno , Burgess Ian
Published: September 2021

The paper presents a new validation study of a unified rheological model, in reproducing creep strains from a recent experimental study performed on grade S275JR coupons. The objective of this research is to further test the modelling capabilities of the proposed rheological model and its validity for application in general structural fire engineering analysis. The rheological model is composed of two serially connected Kelvin‐Voight elements, used to represent the material's sensitivity to strain‐rate‐governed changes of yield strength, temperature and heating rate. The paper presents the performance of the model in stationary‐creep conditions.
In‐plane Seismic Performance of SC wall to foundation connections
Authors: Wang Neng , Zhou Feng , Xu Haitao , Xu Zhengyu
Published: September 2021

Steel‐plate composite (SC) structures have been studied and used in nuclear power plants since the 1990s. However, the seismic performance of the connection between SC wall and foundation has not drawn adequate attention. In this paper, four large‐scale SC‐wall‐to‐foundation connections were designed and tested under combined constant axial‐compression and cyclic in‐plane lateral‐force. Two types of construction details were considered, namely lap‐splice and embed‐ding. Through the general observations, all the specimens failed by flexure, as the crushing of concrete, yielding of dowel rebars or steel plates occurred. The in‐plane seismic performance of the connections including the load‐carrying capacity and ductility were summarized and analyzed. The existing equations for calculating the shear and flexural strength of SC walls subjected to in‐plane loading were evaluated with test results. Since test results show that both of the connection types are feasible for practical use, further investigations on the design of lap‐splice and embedding connections were recommended.
Hysteretic Behaviour of Shear Stud Connectors in Composite Steel Moment‐Resisting Frames
Authors: Jisr Hammad El , Lignos Dimitrios G.
Published: September 2021

In steel moment resisting frames (MRFs) with composite floor slabs, seismic loads are transmitted from the slab into the beam through shear studs. Shear strength degradation of the studs due to cyclic loading results into the loss of the load transfer mechanism and composite action. To date, several low‐cyclic, high‐amplitude push‐out tests have been conducted to characterize the shear stud hysteretic behaviour. These isolated tests showed considerable degradation in the shear stud resistance; nevertheless, they do not simulate the actual hysteretic behaviour of shear studs within a composite steel beam. To elaborate, conventional cyclic push‐out tests do not replicate the actual stress state in the concrete slab, nor do they account for the force redistribution between the shear studs. This paper investigates the hysteretic behaviour of shear studs in steel MRFs with composite floor slabs. The load‐slip hysteretic behaviour of the shear studs is examined through continuum finite element (CFE) models of 2‐bay sub‐systems and their corresponding cruciform subassemblies. Moreover, shear force and interlayer slip envelopes are obtained along the composite steel beams. Results of the CFE models are used to propose new design recommendations for shear studs in composite‐steel MRFs.
Testing a Prefabricated Ultra‐Shallow Composite Flooring System with Lightweight Concrete and Shear Studs
Authors: Ahmed Inas M. , Tsavdaridis Konstantinos Daniel
Published: September 2021

This paper presents an experimental investigation on a recently developed prefabricated shallow steel‐concrete composite flooring system composed with lightweight concretes. The novel flooring system is consisted of two main structural components: two C‐channel steel beams and a partially encased concrete floor. The concrete floor, which is in the form of T‐ribbed slab sections, was constructed using three types of concrete (reinforced normal concrete, reinforced lightweight aggregate concrete, and reinforced ultra‐lightweight aggregate concrete), and the steel edge beams which partially encase the floor slab and provide clear and straight finish edges. Three full‐scale push‐out tests were conducted to investigate the effect of the lightweight concrete on the longitudinal shear behaviour of the new shear connection system, made of web‐welded shear stud connectors. It was observed that specimens with lightweight concretes demonstrated additional ductility when compared with specimen using normal concrete, and the failure mode of the shear studs alters. It is confirmed that the specimen with normal concrete has reached a higher failure shear load.
Behavior of geopolymer concrete‐filled circular steel tube members
Authors: Fang Han , Visintin Phillip
Published: September 2021

Behavior of geopolymer concrete‐filled circular steel tube members was experimentally investigated. Four column specimens and one beam specimen were prepared using fly‐ash based geopolymer concrete. The material properties for both circular steel tubes and the geopolymer concrete infill were measured. The column specimens were tested under concentric and eccentric compression while the beam specimen was tested under three‐pointing bending, aiming to investigate the behavior of the structures subject to compression or combined loading. The load‐deformation behavior, compressive and bending strengths and failure mode of the specimens observed through the experiments are also reported in this paper. The compressive load and moment interaction relationship was developed using the experimental results. The measured ultimate compressive loads and ultimate moment capacity were also compared with the predictions obtained based on European and American Standards. It shows through the comparison that the predictions based on the standards are conservative. Therefore, the European and American Standards can be applied to safely design the structures.
Structural Performance of Blind Bolt Shear Connector under Static Loading
Authors: Mirza Olivia , Hosseini Seyedeh Maryam , Mamun Mohammad Shafiqul , kuikel kiran , Mashiri Fidelis
Published: September 2021

The main goal of this research paper is to determine the shear strength of blind bolt shear connectors for composite structures under static loading. The blind bolt shear connectors are not commonly used in composite structures due to the lack of detailed research regarding the structural performance of these types of connections. Whereas, the use of blind bolt shear connectors in strengthening and retrofitting of existing composite structures can be potentially sustainable and a cost‐effective approach. Hence, in this paper, the mechanical behaviour of blind bolt shear connectors was experimentally examined using direct shear tests. In addition, a three‐dimensional finite element model was developed to evaluate the factors that influence the static strength of steel‐concrete composite beam with bolted shear connectors. Furthermore, the numerical and experimental results were plotted and compared with conventional headed stud shear connector in terms of load versus slip. Results showed that the blind bolt shear connectors had significantly higher static strength than headed stud.
Modified strut and tie model of headed stud shear connectors in open trough profiled sheeting for predicting the post‐cracking load bearing resistance
Authors: Vigneri Valentino , Odenbreit Christoph , Lam Dennis , Hanus François
Published: September 2021

Current EN 1994‐1‐1 provides statistically calibrated equations for predicting the strength of headed stud shear connectors in profiled steel sheeting. Recent tests showed that the design resistance is overestimated for some novel open trough decks. A mechanical model was developed within the RFCS Project DISCCO [3] that considers “stud in bending” component and the elastic bending resistance of the concrete rib separately (1‐2 mm slip). However, to represent the behaviour of the connector in the post‐cracking stage (2‐6 mm), a “Modified Strut and Tie” model was developed with the support of experimental and numerical results. The concrete and the steel deck were replaced by a system of strut and tie elements whereas the stud was considered as a beam with one or two plastic hinges. In accordance with test observations, the authors assumed that the resistance of the model is limited by the capacity of the strut in front of the stud estimated through an analogy with RC corbels. The analytical resistance of the system was finally derived and compared with the results of 193 push‐out tests: the statistical evaluation delivered a correlation coefficient of 0.81 and a coefficient of variation of 0.15.
Numerical evaluation of tubular perfobond shear connectors
Authors: Souza Keila L. , da Silva André T. , Henriques José , Vellasco Pedro C. G. , Rodrigues Monique C.
Published: September 2021

Composite structures have been applied more frequently because they are an economical structural solution with excellent structural performance. The interaction is guaranteed with the use of elements that transfer the forces between these two materials. The most common mechanical connections between steel and concrete are made through shear connectors. Some of the connectors types used nowadays are stud bolt, U‐profiles, Crestbond, Perfobond and T‐Perfobond. Eurocode 4 prescribes that a connector has to possess a minimal ductility, one of the main requirements to shear connectors. The current Perfobond presents excellent resistant capacity, but low deformation capacity, contradicting what is prescribed by the code. This paper aims to study a Tubular Perforbond connector by analyzing the parameters that can influence its resistance and deformation capacity, applying FEM through Abaqus software, to simulate the composite structural, mechanical behaviour. When comparing the Tubular Perfobond connector with the Perfobond connector, it was possible to observe that the tubular connectors presented a substantial deformation capacity after peak load, while attending the connector ductility requirements. The use of Tubular connectors also decreased the concrete crushing propagation.
Non‐linear Analysis of Circular Composite Columns
Authors: Anwaar Omer , Schäfer Markus , Zhang Qingjie
Published: September 2021

Composite columns provide many advantages for the application in multi‐story and high‐rise buildings. However, EN 1994‐1‐1 does not provide rules for the design of circular concrete sections with fully encased steel profiles according to the simplified methods. Normally, the simplified method for the design of composite columns is based on a normal force‐moment interaction diagram which assumes plastic cross‐section resistance. However, the moment resistance is to be reduced by a reduction factor αM, considering among other the difference between strain‐limited and plastic moment resistance. This reduction factor is developed and calibrated for composite compression members with concrete encased sections, partially encased sections and concrete filled rectangular and circular tubes. Comparison of plastic moment resistance to results based on strain limitation show that the application for circular section with encased steel section but without a steel tube may lead to unsafe results.

The paper discusses different approaches for the determination of the N‐M Interaction curve and the design on cross‐section level. The results obtained from these methods are then compared to each other for different dimensions of cross‐sections of circular columns; and for different ratios of reinforcements, various steel grades and for normal and high strength concretes. Furthermore, the investigation focuses on the validation of the reduction factor αM and shows for which section types the values according to Eurocode 4 cannot be applied.
Experimental Assessment of Stainless and Carbon Steel Double‐Skin Tubular Stub Columns Filled with Recycled Aggregate Concrete
Authors: Castanheira Deborah S. , de Lima Luciano R. O. , Vellasco Pedro C. G. da S. , Cashell Katherine A. , Gardner Leroy
Published: September 2021

This paper presents an experimental study into the behaviour of concrete filled double skin tubular (CFDST) stub columns. A total of eight axial compression tests were carried out, half of which were filled with conventional concrete and the remainder had recycled aggregate concrete. The columns were circular in cross‐section and comprised an austenitic stainless steel outer tube and a carbon steel inner tube, of varying dimensions. Accordingly, hollow ratios of 0.67 and 0.55 were considered. The recycled coarse aggregate was made by crushing test specimens from a previous research project. A replacement ratio of 50% was adopted in these tests. Both the natural coarse aggregates and the recycled aggregates had a maximum diameter of 9.5 mm. During the tests, similar structural behaviour and failure modes were observed between the columns with conventional and recycled aggregate concrete, and the faiure modes were identical. The experimental results are compared with available design procedures and it is ultimately shown that using recycled aggregate concrete rather than regular concrete in CFDST stub columns does not have a significant effect on the performance.
Shear resistance of concrete dowels in composite slim‐floor beams
Authors: Aggelopoulos Eleftherios , Schorr Johannes , Kuhlmann Ulrike
Published: September 2021

Slim‐floor beams offer the significant advantage of shallow floor depths. When combined with deep profiled steel sheeting, for example, being able to route services in‐between the troughs provides flexibility. Despite their advantages, composite slim‐floor solutions are rarely used in buildings, partly due to the lack of codified rules and detailed design guidelines.

One of the objectives of the recently completed, European research project SlimAPP, was to investigate the structural behaviour of slim‐floor composite beams through experimental and numerical studies. Furthermore, design guidance for both the construction and the normal stage was developed. Particular focus was given to the shear connection between the steel section and the concrete slab. As an innovation compared with the conventional use of headed studs, concrete dowel type connectors were considered, where reinforcing bars are passed through openings in the web of the steel section.

The findings from push‐out tests and subsequent finite element analyses on concrete dowel connectors are presented. From these results the load resisting mechanisms have been identified. Furthermore, the effect of certain parameters such as the concrete strength, the diameter of the rebar and the size of the web opening on resistance and ductility are evaluated. Analytical models are developed to predict the shear resistance for this type of connectors considering the various load resisting mechanisms. The models are validated against numerical and experimental results from the SlimAPP project and previous research. Comparisons are also presented against results obtained from the back‐analysis of beam tests which were also performed in the SlimAPP project.
The Effect of Degree of Composite Action on Reduced Web Section (RWS) Connections
Authors: Almutairi Fahad Falah , Tsavdaridis Konstantinos Daniel
Published: September 2021

Due to the concerns regarding the effects of the composite action on the seismic performance of beam‐to‐column connections leading to premature brittle fracture of the beam bottom flange, this paper introduces a comprehensive finite element (FE) analysis studying the effect of the degree of composite action to the performance of the bolted extended end‐plate (BEEP) RWS connections subjected to cyclic loads. Circular web openings with diameter equal to 0.8 of the beam's depth and two different parameters, namely the distance from the face of the column, S, and the degree of composite action, are investigated. Based on the results, it is confirmed that the degree of composite action of RWS connections is an important factor in seismic‐resistant design. It is concluded that the low degree of composite action with the use of a structural fuse, such as an RWS connection with localised beam web opening, can potentially avoid bottom flange fracture damage. It is found that composite RWS connections can also be employed to improve the seismic performance on steel structures.
Behaviour of Smart Steel Column‐Beam Connection Under Blast Loading
Authors: Weli Sardasht S. , Gergely Vigh László
Published: September 2021

The generated damages in steel structures due to terrorist attack explosion has attracted structural engineering communities, because the effect of blast loading is extremely sever and destructive. The behavior of Superelastic Nickle Titanium Shape Memory Alloy (NiTi SMA) beam‐column connection was infrequently studied under the effect of blast loading. The present study develops smart steel beam‐column connection under the effect of blast loading. The performance of the proposed connection configuration is evaluated numerically to make better understanding of the conceptual design of NiTi SMA‐based smart bolted connections. NiTi SMA‐based smart connection stiffness and strength is determined based on Eurocode steel joint design procedures. Analytically, Simplified Kingery Airblast Calculations approach is used to generate time history blast reflected overpressure parameters. The austenite effect of NiTi‐SMA is introduced to the global 2D frame model by moment rotation capacity curves. The structural components are verified in Ultimate Limit State (ULS) by using the results of global 2D model. The outputs from the 2D global model is introduced in sub‐numerical models. The sub‐models examined by finite element software code. The result shows that the hysteresis flag‐shaped loop of NiTi‐SMA is well expressed by the sub‐models' numerical solutions. As a result, the proposed connection configuration can highlight the efficiency of NiTi‐SMA in terms of energy dissipation capacity under blast loading successfully.
Behaviour of Ferritic Stainless Steel Bolted T‐stubs Under Tension‐Part 1: Experimental Investigations
Authors: YAPICI Orhan , THEOFANOUS Marios , DIRAR Samir , YUAN Huanxin
Published: September 2021

Research on stainless steel structures has primarily focused on the structural response and design of individual members, whilst the response of joints has received far less attention to date. Recently, a series of experimental tests has been conducted on austenitic and duplex stainless steel moment resisting connections which highlighted both the excellent ductility and significant overstrength exhibited by such connections as well as the severe conservatism of current design rules specified in EN 1993‐1‐8 when applied to stainless steel joints. A comprehensive experimental study on the structural behaviour of stainless steel T‐stubs fabricated from EN 1.4003 ferritic stainless steel grade is reported in this paper. The tested configurations included both single and double bolt rows and have been assembled with A4‐80 stainless steel bolts. In order to determine the material characteristics of the T‐stubs and the connecting bolts, tensile coupon tests were performed and the material anisotropy exhibited by ferritic stainless steel has been quantified. The ultimate resistance, plastic deformation capacity and failure mode of each T‐stub were obtained and are reported herein. The obtained results are utilised to assess the accuracy of existing design rules and to validate the numerical model discussed in the companion paper.
Advanced Design of Steel to Timber Bolted Joints
Authors: Vopatová Kristýna , Cábová Kamila , Židlický Břetislav , Kuříková Marta , Wald František
Published: September 2021

The paper is focused on the topic of steel to timber joints with inserted steel sheet. These joints have significantly higher load‐bearing capacity compared to the classic timber joints with timber parts only. In order to study the mechanical behaviour of these joints with inserted steel sheet in tension, experiments were prepared at Czech Technical University in Prague, and the numerical model was created using the ABAQUS code. The test specimens were designed for the most accurate approximation of realistically designed structures based on the recommendation given in the standard. The eight different specimens varied in the diameter of the fastener, the size of the steel washers, the number of rows of fasteners, their spacing and the strength class of the timber. For this experimental study, a set of timber of the C24 strength class and glue‐laminated timber of GL24h strength class was prepared. Results of experimental work cover failure modes of timber and diagrams of displacement in control points. In the model, timber was described as an orthotropic elastic material with defined nine independent elastic constants. Contact bonds were defined between the bolts and the timber member as well as between the bolts and the steel based on experiments. Part of the work is dedicated to the verification and validation of the numerical model. The verification of the numerical model was based on the results of the analytical model given in the current design standard. The validation approved the good agreement of the numerical model with results of tension tests, with maximal deviation up to 19 %.
Flexural Strength of I‐Beams with Holes in the Tension Flange
Authors: Carlson Ryne B. , Swanson James A. , Rassati Gian A. , Burns Thomas M.
Published: September 2021

This paper focuses on the flexural strength of steel wide‐flange members that have holes in the tension flange. A comparison of the scant experimental data in literature with the strength predicted using the 2016 American Institute of Steel Construction (AISC) Specification shows that the predictions are not very accurate and most of the time are quite conservative. The research presented in this paper discusses a parametric analysis performed numerically in an effort to develop a design equation that better fits experimental data, without compromising the safety of flexural members. Extant literature already attempted proposing replacement design equations to address this issue. This paper proposes new design equations and compares all proposed replacements against experimental data augmented by the results of a series of numerical analyses aimed at filling the gaps in the available experimental datasets. These analyses were performed accounting for damage initiation in the finite element models, in an attempt to establish the bending moment at which fracture initiates and were calibrated against known experimental results. It is concluded that the introduction of the concept of a net plastic section modulus, calculated across the cross‐section containing the tension flange holes, provides the best practical approach to attain an accurate, yet conservative, estimate of the effective flexural capacity of a beam with holes in the tension flange.
Experimental investigations on the design and execution of shear loaded blind rivet joints in steel lightweight construction
Authors: Kalkowsky Florian , Glienke Ralf , Blunk Christoph , Dörre Maik , Henkel Knuth‐Michael
Published: September 2021

There is a barely manageable variety of blind rivets available on the market. This is because there is no universal product standard, which establishes the mechanical properties of blind rivets in a suitable manner. Whenever structural engineers dimension joints with blind rivets, they face a major challenge due to the lack of design values for the blind rivets themselves and the impractical application limits according to EN 1993‐1‐3. It is therefore necessary to determinate the design values of the blind rivets itself and for their applications in the field of steel lightweight construction in time and cost‐intensive experimental investigation. Furthermore, the regulations according to the ECCS, which allow the experimental‐based determination of design values for such applications, are insufficient, as they do not consider alternating stresses as well as compact joint dimensions.

To close the gap of knowledge this paper presents results from systematic investigations on the shear and load‐bearing behavior of blind rivets and joints with blind rivets. Based on the investigations the authors suggest the extension of the current design and execution rules in order to allow a safe design by separate verification of the components and blind rivet.
Extension of the application limits of blind fasteners for joining high‐strength steels in metal lightweight construction
Authors: Kalkowsky Florian , Glienke Ralf , Blunk Christoph , Dörre Maik , Henkel Knuth‐Michael
Published: September 2021

Wherever joints in metal lightweight construction are only accessible from one side, joining techniques such as screwing or welding are uneconomic or inapplicable, blind fasteners and especially blind rivets as the most common type are the means of choice. Nevertheless, with the use of blind rivets, problems arise for the structural engineer, because of the lack of proper design rules according to the Eurocode 3. With the research affords of the authors this deficiency was eliminated for the field of normal strength steel in the past.

However, with the increasing usage of high‐strength steels in such constructions, new problems emerge and the developed design rules are not valid yet. This paper presents results from quasi‐static tests on blind rivet joints with different steel grades of the components to extend the proposed design rules. Different effects were identified, which lead to a reduced shear resistance of the blind rivets. At the same time the results point out the benefits of high‐strength steels on the load‐bearing behaviour. Furthermore, results from fatigue tests on blind rivet joints are presented. These show a notable influence of the steel grade on the fatigue resistance of the joint as well as the potential for the design of such joints.
Experimental Evaluation of Ductility of Bracing Members
Authors: Patra Pratik , Sahoo Dipti Ranjan , Jain Arvind Kumar
Published: September 2021

In earthquake‐prone region, concentrically braced frames (CBFs) are used as lateral load resistance systems and prevents damage in structures. Special concentrically braced frames (SCBFs) are special type of CBFs system which is designed for higher level of displacement ductility and energy dissipation. In case of SCBF system, the connections are designed to undergo inelasticity which helps in dissipating the energy of the system. Two types of the connections that are used in the SCBF system are out‐of‐plane buckling (OOPB) connection and in‐plane buckling (IPB) connection. The latter is a newly developed connection for the SCBF system to prevent out‐of‐plane buckling of the braces which minimizes the damage of the non‐structural components of the building. In the present study, a state‐of‐the‐art comparison of the IPB and OOPB brace system were done keeping slenderness ratio and compactness ratio constant. Large‐scale tests were conducted on the two type of connections. Elliptical clearance of eight‐time the thickness of the gusset plate was used for the OOPB braced system. Linear clearance of three times the thickness of the knife plate was used for the IPB braced system. The parameters that were compared to measure the efficiency of the connections were displacement ductility, cumulative energy ductility and failure mechanism. It is found that the OOPB brace system performs better as compared to the IPB brace system keeping all other parameters constant. The reasons for the poor performance of the IPB brace system were discussed.
Analytical model for the prediction of the plastic shear resistance of the panel zone in welded joints
Authors: Corman Adrien , Demonceau Jean‐François , Jaspart Jean‐Pierre
Published: September 2021

This article addresses the problem of prediction of the plastic shear resistance of the panel zone (PZ) in welded steel beam‐to‐column joints under monotonic loading. Existing analytical models are first critically reviewed through comparisons with available experimental data. These comparisons reveal that none of them is able to accurately capture all the complex phenomena governing the plastic shear resistance of the PZ. Therefore, a new analytical model is developed based on the extensive use of finite element (FE) analysis. This approach includes the development and validation of a FE model within the Abaqus environment and the use of the so‐validated model in order to perform a parametric study on (non‐)axially loaded (un‐)stiffened interior and exterior joint configurations. This parametric study helps to gain a better understanding of the actual distributions of stresses within the PZ. Based on these observations, a new analytical model is proposed and validated against the numerical results. This model proves to work well and to outperform existing analytical models by providing a more coherent estimation of the plastic shear resistance of the PZ.
European traffic on road bridges and recalibration of damage equivalence factor for fatigue verification
Authors: Bianchi Gianluca , Nussbaumer Alain , Pedro José J. Oliveira
Published: September 2021

The evolution of European traffic, combined with the current revision works of the Eurocodes (CEN250 project 2nd Eurocode generation), represents an opportunity to improve the simplified method for fatigue checks (also known as the lambda method) for road bridges. The works reported herein focus on the reassessment of the λ1 factor curves for the damage effect of highway traffic on road bridges, using the existing Eurocode FLM3 model. The aim of the research is to model the traffic and resulting stress ranges at details on bridges with different static systems. The simulation results shall be as similar as possible to reality by introducing different parameters that were not taken into account in the EN 1993‐2 background simulations [1, 2], including the passage of multiple vehicles at the same time in the flowing and congested traffic conditions. The development of new λ1 factor curves lead to a different classification into midspan bending moment, shear force, and support midspan and shear force. Within this study, the validity of the formulas for λ2 and λ3 were also checked. The new curves have less dispersion and may be taken into consideration to update the current curves from EN 1993‐2.
Deep Learning based method for the prediction of the buckling resistance of SHS and RHS
Authors: Toffolon Andrea , Kraus Michael A. , Taras Andreas
Published: September 2021

This paper proposes a data‐driven and deep learning based model for the prediction of the buckling load of square and rectangular hollow sections (SHS and RHS) based on Finite Element Method (FEM) results of the local buckling effects. The data was elaborated during the EU‐funded research project – HOLLOSSTAB (2016‐2019), where a new design method – termed the “Generalized Slenderness‐based Resistance Method” (GSRM) ‐ was developed, aiming to simplify through a unified analytical approach time consuming computational analyses for the prediction of the local resistance of SHS and RHS. This method further generalizes the concepts of established design methods such as the Direct Strength Method. This paper investigates an alternative approach to the development of design rules for this same mechanical problem: the application of deep learning models for the prediction of the buckling load through simple input parameters, such as geometric quantities, material values and applied load to circumvent the application of the analytical formulae. Thereby, a Deep Neural Network (DNN) model is created and calibrated for the prediction of the buckling loads of SHS and RHS based on the training data given by the extensive FEM parametric study. A statistical evaluation in accordance with EN1990 elaborates a partial safety factor for the proposed DNN. The predictions from the DNN are then compared to the numerical results from FEM analyses and to the predictions of the GSRM and EC3. Since the numerical results were originally validated against large scale experimental tests, this newly developed DNN makes use of a very large set of very representative (numerical) tests. A further comparison assesses the computed partial safety factor and the related quantities of interest for the DNN to the respective counterparts of the GSRM method. This work represents one of the first steps for the development of design methods in the field structural design adopting the most recent advances in computer sciences, and future enhancements of the currently developed models are discussed and proposed as a conclusion.
FE Model Validation and Advanced Analyses of Steel Members with Steel Claddings at Elevated Temperatures
Authors: Ma Zhongcheng , Havula Jarmo , Joo Attila , Lendvai Anita
Published: September 2021

In order to investigate the stabilization effect of distinct steel members by steel cladding system including trapezoidal sheeting and sandwich panels in fire using advanced analysis techniques, the computer models and modeling techniques must be validated by available experiment tests. However, the fire tests in this area are scarce. As part of a wider validation scheme, this paper presents the modeling method using Ls Dyna explicit solver and the comparison of FE analysis results with four experimental tests at elevated low to medium temperatures (150‐300 °C) in RFCS STABFI project. After the model validation, the advanced fire analyses of steel columns with two types of steel claddings such as trapezoidal sheeting and sandwich panel are carried out to investigate the stabilization effect. The analyses show that for the studied I‐section column under both axial compression and bending moment, the position of steel claddings, either connecting with the tension flange or the compression flange, has significant influence on the fire resistance of the steel columns. When the trapezoidal sheet is connected with the compression flange, the fire resistance of steel column is 17 % more than that without cladding. Sandwich panel cladding has influences on the deformational behavior of column during the fire exposure. However, the contribution of sandwich panels to the fire resistance of steel columns is negligible due to the delamination of inner panel sheet.
Structural Fire Analysis of One‐storey Steel‐framed Buildings with Steel Claddings
Authors: Ma Zhongcheng , Havula Jarmo , Mela Kristo , Kesti Jyrki
Published: September 2021

Traditionally the structural stability of steel building frames is ensured by frame action or bracing elements. Recent European research projects have demonstrated that significant cost savings can be achieved, if cladding panels forming the building envelope are used to provide stability. The purpose of the paper is to investigate the possible stabilization effect of steel structures by steel claddings in fire, without additional wind bracings using Finite Element Method. The Finite Element analyses for full‐scale steel‐framed buildings with steel claddings under fires are still challenging due to large number of elements in the steel claddings. In this paper, the equivalent orthotropic shell element is used to model the trapezoidal roof sheeting, and composite shell element with soft core is used to model the sandwich panel in the cool compartment. Due to the delamination of inner steel face in fire, the sandwich panels in the fire compartment can be either neglected or modeled with two‐layer composite shell ignoring the inner steel sheet. The comparative study is performed, and the results suggest that the difference is small and the sandwich panels in the fire compartment can be neglected. The stabilization effect of steel claddings in fire is studied by the comparison of deformation and force responses between buildings with traditional steel bracings and with steel cladding only. In case of ISO fire, the fire resistance of entire one‐storey building with steel claddings only is 22% longer than the one with traditional steel bracings.
Deformations of steel end‐plate beam‐to‐column joint when subject to simulated steady‐state and transient‐state fire heating regimes
Authors: Maslak Mariusz , Pazdanowski Michal
Published: September 2021

The bearing capacity and rigidity of selected steel end‐plate beam‐to‐column joint are analysed in the paper. Those properties are determined numerically, based on the fire conditions simulated for this node. For comparison, two alternative heating regimes, typical for steady‐state and transient‐state scenarios, are considered. In the first case, an initially statically preloaded joint is evenly heated up to a predetermined temperature and subsequently, in this temperature, subjected to monotonously increasing static load until reaching the ultimate bearing capacity. In the second scenario, the same joint, subjected to the same preliminary static load, is subsequently statically loaded to reach a predetermined ratio of its ultimate bearing capacity and then, during the time of simulated fire, monotonously heated until failure. During the analysis it is assumed, that the steel is heated at a low rate, not affecting its material properties at given temperature. A cluster of curves depicted in the bending moment vs. effective rotation angle system of coordinates is a result of the first analysis. Each of these curves corresponds to a selected steel temperature. In the second case, the deformability of the joint, increasing with temperature, is expressed by a set of relationships between joint rotation and the corresponding temperature of steel. Thus a single relationship of this type corresponds to a selected level of external load applied at the node.
Numerical investigation of instabilities of steel members restrained by sandwich panels at elevated temperature
Authors: Lendvai Anita , Joó Attila László
Published: September 2021

Sandwich panel constructions are getting popular from the second half of the 20th century however, the restraint provided by sandwich panels in regards to the instability of structural members was not investigated at elevated temperature, which became the scope of the research introduced in this paper. An experimental test series was conducted at the Department of Structural Engineering at the Budapest University of Technology and Economics in order to study the stability behavior of structural members restrained by sandwich panels at ambient and elevated temperature. In this paper 18 tests are introduced, in which centrally located HEA120 sections of a 3.00 m x 3.00 m sized supporting sandwich panel diaphragm were tested for axial compression. The results indicate, that the decrease in load bearing capacity of PIR panels is higher, that in the case of mineral wool panels. The data derived from experimental tests were used for developing a complex numerical model. The primary objective of this paper is the comparison of numerical results with the results derived from experimental testing. This research has been financially supported by the European Union, in the frame of the Research Fund of Coal and Steel (RFCS) program. The authors gratefully acknowledge the support.
Numerical analysis of the torsional and flexural‐torsional buckling behaviour of compressed steel members at elevated temperature
Authors: Possidente Luca , Tondini Nicola , Battini Jean‐Marc
Published: September 2021

Steel angle sections are frequently employed in bracing systems or in truss structures as single members or as built‐up members. Angles may be coupled back‐to‐back to create Tee or cruciform cross‐sections. These sections may be sensitive to torsional and flexural‐torsional buckling due to the cross‐section shape and the fact that the axial force may not be applied at the shear centre. In this work, a comprehensive numerical investigation of the behaviour of compressed angles, T and cruciform steel cross‐sections at elevated temperature was performed. A parametric study was carried out on Class 1 to 3 profiles subjected to uniform temperature distribution. Several numerical finite element analyses were carried out by varying the slenderness, the cross section, the steel grade and steel temperature employing beam and shell finite elements. It was found that the buckling curve given in the European structural code for steel structures in fire, i.e. EN 1993‐1‐2, provided results, that may not be conservative for a large slenderness range of practical interest, 0.4 ≤ λθ ≤ 1.5. Based on the results, adapted buckling curves were proposed to better predict the behaviour of angles, T and cruciform compressed cross‐sections at elevated temperature.
Fire performance of connections between high‐strength steel tubular members
Authors: McCann Finian , Wang Di
Published: September 2021

An investigation is conducted into the behaviour of bolted endplate connections between high‐strength steel tubular members at elevated temperatures. Experiments are described where assemblies comprising Grade S460 steel square hollow sections connected via bolted endplates are heated to a target temperature between 150°C and 750°C using ceramic heating pads. The assembly, which is inclined at 45° to the horizontal, is then loaded vertically, thus generating combined bending and axial thrust in the members. The in‐plane vertical deflection, the applied load and temperatures at various points were measured. Results for the ultimate loads, equilibrium paths and the observed failure modes are discussed along with the influence of temperature on these features. A complementary nonlinear finite element analysis of the experimental assemblies is also described. Material models incorporating temperature‐dependent strengths, stiffnesses and strain hardening relationships available from the literature are employed, with temperature fields calibrated using steel temperatures recorded during the experiments applied to the models. It is shown that good agreement exists between the ultimate loads, equilibrium paths and failure modes predicted by the numerical models and those observed in the experiments, thus validating the modelling approach. It is found that, at lower temperatures, buckling of the endplate was the governing mode of failure. With increasing temperature, the mode of failure transitions to flexure in the beam and column stubs, thus suggesting that a relative degree of fixity is offered by the connections at the higher temperatures.