bluuebunny/crossref_metadata_2025 huggingface dataset:
Buckling analysis of tower shells under patch loading for self‐erecting wind energy plants
Authors: Nikesch Philip , Pak Daniel , Korte Sebastian
Published: September 2021

To achieve a higher performance level and lower erection costs for wind turbines in the future, a concept for the automatic erection of a wind turbine with a hybrid tower was investigated in the FOSTA research project P1392. The tubular steel tower is lifted through the lattice tower using a strand lifting system and stabilized during this lifting process with the help of hydraulic cylinders arranged in two levels in the transition piece. This stabilization results in a transverse pressure acting on the tower shell, which does not occur in the load cases during operation, but only in the construction state. In this paper, the transverse forces (patch load) acting on the tower are investigated, whereby different system states are considered.
Experiments on sheathed cold‐formed steel beam‐columns
Authors: Kyprianou Constantinos , Kyvelou Pinelopi , Gardner Leroy , Nethercot David A.
Published: September 2021

An experimental study on sheathed cold‐formed steel C‐lipped columns (studs) with service holes in the web subjected to compression and major axis bending is presented in this paper. A total of 17 experiments was performed with both oriented strand board (OSB) and plasterboard used as the sheathing material and with varying connector spacing employed between the sheathing and the steel members. Material tests and geometric imperfection measurements were also undertaken. The tested specimens comprised a single 2.4 m long cold‐formed steel member sheathed on both sides and secured at its ends to top and bottom tracks. Eight pure compression tests with plasterboard and OSB sheathing and with the spacing of the connectors varying between 75 mm and 600 mm were initially performed. Specimens with OSB were then tested under pure bending and also under combined loading, by first applying a compressive load corresponding to the 75%, 50% or 25% of the predetermined axial resistance and then laterally loaded until failure. Reducing the spacing of the connectors from 600 mm to 75 mm resulted in up to 20% and 30% increases in capacity for the studs sheathed with OSB and plasterboard respectively.
Numerical simulation of ultra‐lightweight concrete encased cold‐formed steel structures
Authors: Eid Nathalie , Joó Attila László
Published: September 2021

The use of thin‐walled structures has been increasingly spread in the last few decades due to their big advantages in both structural design and construction methods. Therefore, the recent researches have discussed a wide range of thin‐walled structures applications. However, the resistance of such structures will be decreased by buckling effect; hence, different ways of strengthening methods have been investigated. One of this method is the use of lightweight concrete as a filling of thin‐walled members. Previous experimental research at the Department of Structural Engineering at Budapest University of Technology and Economics, was carried out to investigate the axial behavior of polystyrene aggregate concrete (PAC) braced CFS elements [1]. The effect of PAC has led to increase the load‐bearing capacity and to restrain the global and distortional buckling modes of steel elements. The results revealed that the ultimate load was increased by 37‐94%. A simplified nonlinear finite element model was developed in ANSYS software to be able to predict the peak resistance of PAC filled thin‐walled members. GMNI analyses were carried out to validate the numerical model by the experimental tests. The concrete was modelled by using springs with adequate stiffness, where a parametric study was conducted to determine the proper imperfection amplitudes of different element lengths. The numerical model showed good agreement with test results.
Axial Compressive Strength of steel members made of cold formed angle sections
Authors: Aghoury Mohamed El , Hanna Maged , Ibrahim Sherif , Elhalous Rawan
Published: September 2021

Cold formed sections often fail in three basic modes which are local, distortional, and global. Local and distortional modes are characterized by entire deformations, whether translation or bending of the plates forming the section. Current design codes determine the ultimate strength of short to intermediate cold formed angle columns based on the local‐global interactive failure modes. However, these cold formed angles sections fail in flexural‐torsional mode. Thus, the predicated ultimate loads are either unsafe or excessively safe depending on boundary conditions. Therefore, in this study the ultimate axial strength of pined‐pined columns composed of cold formed angles subjected to axial compressive force are determined numerically. A nonlinear finite element model has been developed using ABAQUS software. Four nodes isoparametric shell element that allows both geometric and material non‐linarites is used. The effect of geometric imperfections is included in the model. The parameters studied include, the angle leg width‐thickness ratios, overall member slenderness ratios. Further, Lipped as well as plain angles are considered in the study. Finally, results have been compared with the predicted strengths determined by the American specifications and the newly developed direct strength method, DSM.
Application of the Saint‐Venant theory to thin‐walled sections warping
Authors: Vié Dominique
Published: September 2021

The Saint‐Venant theory proposes an exact solution to the elastic equations for beams including warping strains due to shear force and torsion. It has been at the centre of recent developments in the field of beam theory: normal stress may at first be determined as if plane sections would remain plane but under torsion and shear force, restrain warping introduces secondary normal stress.

For thin‐walled sections, the analysis of warping due to torsion is conventional and uses the concept of sectorial area. However, the problem of shear flows due to shear force is generally solved by using an energy approach in which warping only appears indirectly. By introducing a static moment function, similar to the sectorial function used for torsion, this paper proposes to take explicit account of the warping of thin‐walled sections under the effect of shear force. In the case of sections with straight walls, it is convenient to use third degree polynomials. The proposed method can easily be calculated with a spreadsheet and may be extended to any type of arch, in particular those which consist of B‐spline functions or NURBS.

Different examples are analyzed.
Steel FRC slab in compression in composite steel‐concrete frame joints
Authors: Cervenka Petr , Dolejs Jakub
Published: September 2021

The objective of the research is a steel fiber‐reinforced concrete slab in compression in a composite frame joint. EN 1998‐1 relates only to composite joints with common concrete slab. This standard prescribes two mechanisms: mechanism 1 acts in the concrete slab with a concentrated compressive force on the column flange; mechanism 2 consists of struts and tie model, where concrete struts compress the concave parts of the column cross‐section. By these mechanisms, it is prescribed inaccurate formula for the effective width calculation of a common concrete slab in compression in the nodal zone, as the standard procedure does not consider the contribution of the confinement effect to the resistance of mechanism 1. Mechanism 1 represents a direct bearing of the concrete slab against the column flange. There is a concrete slab in compression confined by transverse reinforcement, slab continuity around the column flange and friction on the column flange. Moreover, some publications describe different inclination of the concrete struts of mechanism 2. The resistance of mechanism 2 significantly depends on this inclination. The aim of this work is to derive a more accurate formula for calculation the effective width of the steel fiber‐reinforced concrete slab in compression in the nodal zone. Experiment with real‐sized isolated composite joint, validation of ATENA numerical models and parametric study of composite joints with fiber‐reinforced concrete slab are the main steps of this research.
Development of a new design approach for composite dowels positioned close to the concrete surface
Authors: Broschart Yannick , Kurz Wolfgang , Wolters Kevin , Christou Georgios , Claßen Martin
Published: September 2021

Composite dowels as shear connectors between steel profiles and concrete sections have been investigated for decades. The long‐term aim is to implement a consistent design concept within Eurocode 4 ‐ covering both, the fields of bridge and building construction. Especially in building construction, where the concrete slabs are dimensioned increasingly slimmer in contrast to bridge construction, the composite dowels are positioned unavoidably close to free concrete surfaces. This causes additional failure modes, leading to the overall failure of the structure, which have not been entirely investigated yet. At University of Kaiserslautern more than 30 push‐out tests were performed within a joint research project in cooperation with RWTH Aachen University. These tests were focused on the resistance of composite dowels close to the concrete surface in dependence of varying influence parameters. Some results showed a significant reduction in shear strength and deformation capacity, mostly accompanied by the spalling of the concrete cover. Simultaneously, numerical simulations were calibrated and utilized to get a deeper understanding of the load transfer mechanisms and to interpolate between existing experimental results. On the basis of experimental measurements and numerical simulations a load transfer model was developed with a corresponding design approach to calculate the theoretical resistance.
A comparison between cyclic and monotonic behavior of composite diaphragm interfaces under high shear force
Authors: Rezaeian Hooman , Clifton George Charles , Lim James B.P.
Published: September 2021

Using a novel experimental test setup, the behaviour of composite floor slab interfaces having different deck rib orientation and end anchorage detail has been investigated. In the first floor slab configuration, the deck rib orientation was parallel to the supporting beam. For the second and third floor slab configurations, the deck rib orientation was perpendicular to the supporting beam. In the second floor slab, the steel deck did not continue over the top flange in order to give a solid rib of concrete surrounding the shear studs along the secondary beam. The third floor slab used the standard end anchorage detail adopted in Europe, in which the steel deck continued over the top flange and shear studs were welded to the steel beam through the steel deck. Three nominal identical specimens of each detail were constructed and tested. The first specimen of each detail was tested monotonically and the second and third ones tested cyclically.

In the elastic range, the results of reversed cyclic loading were found to be similar to those of the monotonic tests, with the backbone curves being very similar. The ultimate in‐plane shear strength of all three was lower than that of the monotonic tests by around 15%. Under cyclic loading, the envelope response of slippage was similar to the monotonic loading response. Slippage of specimens was found to be insignificant in the elastic range even after the yield point, a very small amount of slippage was observed until the specimen reached the ultimate shear strength. Then the slippage increased relatively significantly and the load dropped, with the rate of load decrease being different between configurations.
Comparison of HST and WO Shear Connector Behaviour in Composite Slim Floor
Authors: Baharom Shahrizan , Hosseinpour Emad , Majdub Mohamed S.
Published: September 2021

Composite steel‐concrete slim floor construction is an economical floor system proposing minimum floor depth and fast construction besides architecture requirements. In this system, the concrete slab is supported on the lower flange of the steel beam using either in‐situ or pre‐cast technique, which eliminates the use of the down‐stand beam, hence giving a flat look. Hollow steel tube (HST) shear connector is proposed to avoid premature failure that could occur in concrete and steel beam web when the web openings (WO) connectors were used. In this paper, the comparison of push‐out test results between HST and WO to evaluate their ultimate shear load and ductility performance of these type of connectors. The varied parameters were the concrete compressive strength and shape of the HST and WO; the circular, rectangular and square. The results showed that the circular and square HST connectors achieved shear capacities 6.3 and 8.0 times higher than those with the WO type, respectively. Furthermore, the ductility of the specimens increased by 3‐4 times when the HST was used compared to WO. It shows that providing the HST significantly improved its ultimate shear load and ductility performance compared to WO.
Numerical Study of Composite Steel Cellular Beam System Using Demountable Shear Connectors
Authors: Dai Xianghe , Lam Dennis , Sheehan Therese , Yang Jie , Zhou Kan
Published: September 2021

Steel concrete composite beams have been increasingly adopted in practice due to their advantages with respect to their structural features and constructability. However, in conventional composite beam systems the composite action is applied via the shear connectors welded at the top flange of the downstand steel beam and embedded in the concrete slabs, making the disassembly of the beam system and reuse of any component impossible. This paper presents a numerical study of a new composite beam system with a steel cellular beam, metal deck flooring and using demountable shear connectors. According to the experimental study, this composite beam system made the demounting, reassembly and member reuse possible, and did not compromise the loading capacity. In the numerical study presented in the paper, the finite element model was developed and validated against the results obtained from the experimental study. The parametric study further examined the effects of concrete strength, shear connector arrangements etc. The comparison and analysis clarified the mechanism of the demountable shear connector and the effect of construction method on the load capacity of the composite beam system, and provided a deeper insight into the behavior of this type of shear connector. Through this numerical study, the structural merits of the composite beam system using demountable shear connectors were highlighted.
Experimental study of flexural behaviour of high strength steel (HSS) ‐ Engineered Cementitious Composites (ECC) composite beam with profiled steel sheeting
Authors: Nguyen Cong‐Luyen , Lee Chi‐King
Published: September 2021

Due to its high compressive strain of at least 0.5%, which is higher than both the yield strain (0.35%) of high strength steel (HSS) and the compressive strain (0.23%) of normal strength concrete (NSC), Engineered Cementitious Composites (ECC) is a material with high potential to replace NSC in HSS composite beam construction. This study reports an experimental investigation on the flexural behaviour of HSS‐ECC composite beam fabricated by using HSS I‐section in conjunction with hybrid polyethylene‐steel fibers (PE‐ST) ECC slab. Shear connection between the HSS I‐section and the top PE‐ST ECC slab was constructed by using normal profiled steel sheeting and headed shear studs. A HSS‐ECC composite beam and a HSS‐NSC composite beam were cast and tested under four‐point bending. The test results revealed that a large area of HSS I‐section in HSS‐ECC composite beam yielded compared to only a small yielded area of which in the HSS‐NSC counterpart despite the fact that both composite beams have identical configuration and silimar mechanical properties. The HSS‐NSC beam underwent longitudinal shear failure while in contrast, the HSS‐ECC beam failed by flexure and exhibited great ductility.
Experimental study on the shrinkage behaviour of steel concrete composite slab
Authors: Yamamoto Masashi , Imagawa Yusuke , Ohyama Osamu
Published: September 2021

Steel concrete composite slabs are widely adopted in civil engineering and their numbers are rapidly increasing in Japan. A steel concrete composite slab is connected between concrete and a bottom steel plate by a shear connector. FaB‐Tec Japan Corporation developed a rigid type of shear connecter with a pipe that passes through the long hole on the steel rib. The load‐carrying capacity and durability of this design have been confirmed to be equal to or more than those of the headed stud and perfobond‐rib because the long hole of the steel pipe is filled with concrete. However, the time‐dependent behaviour, especially drying shrinkage, of this type of slab remains unclear. A steel concrete composite slab contains more steel than reinforced and prestressed concrete slabs; the effect of drying shrinkage is therefore expected to be greater owing to the steel restraint. To address this question, drying shrinkage tests were performed on steel concrete composite slabs and reinforced slabs. The change of stress resultants induced on the concrete, reinforcing bar and bottom steel plate was obtained by solving the simultaneous equation derived from the equilibrium conditions for stress resultants and the compatibility condition of strain and curvature.
Curved Sandwich Panels
Authors: Lange Jörg , Groche Peter , Schäfer Stefan , Grimm Sören , Moneke Mathias , Reising Jakob , Kehl Marvin
Published: September 2021

Due to their excellent combination of space enclosing, heat insulating and supporting function, steel sandwich panels – mostly flat – are used for roofs and walls of standard industrial buildings. Because freely formed structures generally are playing an increasing role in contemporary architecture, curved sandwich panels would offer a high potential to architectural design. Simultaneously, the advantageous load‐bearing capacity could further increase the benefits of their usage. The necessary design strategy, the manufacturing technology for the curved cover plates and their overall mechanical behavior – all of these 3 main keys have been investigated in an interdisciplinary research project with architects, structural‐ and mechanical engineers. It has been one of the main goals in this project to find an applicable, efficient strategy for singularly produced panels (lot size 1: serial production with quantity = 1) in favour of a maximum flexibility for individual geometries.
Applications of digital manufacturing to steel frames: The Intermeshed Steel Connection
Authors: Al‐Sabah Salam , Laefer Debra , Hong Linh Truong , Huynh Minh Phuoc , Le Jia‐Liang , Martin Tony , Matis Pantelis , McGetrick Patrick , Schultz Arturo , Shemshadian Mohammad E. , Dizon Roseanne
Published: September 2021

Despite wide use of terms such as “digital manufacturing” and “digital fabrication” in the constructional steel industry, actual use to date is mostly limited to research and development activities. In contrast, other heavy industries, such as automotive and aerospace have moved much faster and implemented many aspects of digital manufacturing and fabrication in product creation and traditional workflows. As a foil to the current state of the industry, this paper presents the erection, and disassembly of a simple, two‐storey frame that employs an alternative steel connection that can be manufactured using current plasma, laser, and water jet technologies, referred to as the intermeshed steel connection (ISC). The field demonstration described in this paper shows the connection's ability to reduce on site erection time, substantially reduce the number of site bolts, eliminate site welding, and allow for easy deconstruction. The connection has been under testing and development through a consortium of the University College Dublin, Queens University Belfast and, the University of Minnesota.
Chord failure resistance of 3D cut welded connections with CHS columns and through I‐beams
Authors: Di Benedetto Sabatino , Latour Massimo , Rizzano Gianvittorio
Published: September 2021

This paper investigates the mechanical behaviour of a novel typology of steel beam‐to‐column connection made by welding circular hollow section (CHS) columns with through‐all double‐tee beams. Such connection represents an alternative to the classical configuration with the I‐beam simply welded to the external surface of the hollow profile for which Eurocode 3 part 1.8 provides specific design rules resulting from the “ring model” theory. The main features of connections with through‐all beams derive from a change of the resisting mechanism which leads to a significant increase of stiffness and resistance. Nevertheless, such a change of the mechanical behaviour, strictly affected by the different plasticity pattern, has not been embedded in the ring model theory, yet. Instead, experiments and finite element (FE) simulations have been carried out proving that the resistance exhibited by CHS to through‐all axially loaded plates is about 2‐3 times higher than resistance referred to CHS to branch plates. The last‐mentioned connections represent the basic components in order to assess the flexural strength of connections made by CHS and I‐beams. This means that doubling the resistance of connections with beam welded to the external surface of the column, as some studies have proposed, leads to a significant underestimation of the resistance.

Within this framework, in this paper the flexural resistance of connections with CHS columns and through‐all I‐beams is assessed by developing experimental tests and analytical models aiming to propose a new design equation. Specifically, two cyclic ad two monotonic tests on real scale beam‐to‐column connections have been executed at the laboratory of the University of Salerno. Subsequently, finite element (FE) models have been calibrated and verified against the experimental results. Then, the developed FE models have been extended to perform parametric analyses to be used to verify the accuracy of a new theoretical approach able to predict the resistance of such a kind of connections. The theoretical approach has been developed basing on the upper‐bound theorem and exploiting the previous knowledge based on the so‐called ring model. The proposed formulation, when compared to the available experimental data and FE simulations, have proved to exhibit a high accuracy.
A Study on the Shear Lag Effects in Longitudinally Welded Connections Subject to Eccentricity
Authors: Orloff Kenneth L. , Rassati Gian A. , Swanson James A. , Burns Thomas M.
Published: September 2021

In United States design specifications, shear lag in longitudinally welded connections is accounted for by means of a tabulated factor, which until 2010 was only applicable to plate‐type members having equal length welds on each side, subject to the further constraint of having a minimum weld length equal to the distance between the welds. This created the paradox that connections with longitudinal welds shorter than the distance between the welds were considered by the Specification to have no capacity at all. Research in extant literature based on historical experimental data developed alternative factors that augmented and replaced the previous approaches, making them applicable to longitudinally welded plates, angles, channels, tees, and wide‐flange shapes having equal or unequal weld lengths, and without any weld length‐to‐connection width limitation. This paper presents the results of an experimental study of shear lag effects in longitudinally welded tension members under both in‐plane and out‐of‐plane eccentricity. Forty specimens were tested representing twenty configurations and the experimental results were compared to three theoretical values – (a) the shear lag factor from the 2016 American Institute of Steel Construction (AISC) Specification, (b) the shear lag factor based on a bi‐planar model found in literature, and (c) the shear lag factor from the 2010 AISC Specification. It is concluded that the shear lag factor provided in the 2016 AISC Specification offers the best prediction of the capacity of longitudinally loaded welded connections subject to both in‐plane and out‐of‐plane eccentricity.
The Behaviour of Shear Anchors with Different Grout Properties
Authors: Spremić Milan , Gluhović Nina , Jakovljević Isidora , Marković Zlatko
Published: September 2021

During the assembling of a steel structure with anchors, grout should be used in connections between steel elements and a reinforced concrete support element. In horizontal and vertical joints, grout is used as a good construction practice for solving geometric tolerance problems. Grout can be used with cast‐in anchors or post‐installed anchors. However, the relation between anchor shear resistance and characteristic grout compressive strength is not described in detail in technical regulations. The behaviour of a connection considering achieved slip tolerances should match the boundary conditions set in the global analysis. In the support joint, grout properties could influence the value of the slip between a steel part and a concrete part of the joint. Slip value could be significant for the relevant design cases featuring the interaction of shear force and tension force. In this paper, results of the push‐out test conducted on anchors are presented. Based on the experimental test, the finite element analysis was performed to investigate the shear connection behaviour. According to the preliminary results, it can be concluded that a grout strength and a grout thickness influence the connection response when serviceability loads are applied, although they do not influence the ultimate load bearing capacity of anchors. In some cases, using the contemporary solutions of high strength grout materials, the slip between steel and concrete parts in the connection could be reduced.
Intelligent Steel Structures – Measurement‐Based Model Updating Concepts for Innovative Design Strategies
Authors: Kraus Matthias , Chowdhury Sharmistha , Wudtke Idna
Published: September 2021

Structural systems are in general quite sophisticated in terms of interactions between individual members with respect to their stressing and resistance. In addition, the stochastic nature of different loads and resistances, respectively, is quite different. A consistent statistical representation of the random variables for a structural component/member is therefore quite complex. In this context, the implementation of intelligent structures and the incorporation of the measuring data can help to improve the prediction of random variables for a certain member and therefore to update models in the design process. Depending on the obtained measurement data, the updating can either refer to the statistical representation quality of different values, but also to the quantity of random variables or even to the update of the mechanical model and its boundary conditions. For that reason, a classification of updating possibilities in the context of the design process described by different hierarchical levels is useful. The aim of this article is to give an overview and insight on corresponding concepts of sensor‐based design strategies for steel structures. In addition, first research results regarding the effect of measurement‐based updating on the quality improvement of the design process is presented.
A proposal for the local stresses in retrofitted crane runway girders due to eccentric wheel loading
Authors: Kettler Markus , Unterweger Harald , Derler Christoph
Published: September 2021

Generally, the local stresses near the web‐flange connection represent one of the most decisive criteria for the fatigue design of steel crane runway girders, particularly because every crane wheel induces an individual stress cycle and fatigue failure can potentially occur at any position of the girder's length. This paper presents a crane runway girder made of steel that has been retrofitted in the past to reduce the local bending stresses in the web, because of the installation of a new, heavier crane. This was done by additional longitudinal stiffeners to form a boxed upper flange. The local vertical stresses in the girder's web are investigated numerically and experimentally and the influence of the subsequently attached reinforcement plates, forming a boxed upper flange, is studied. Traditionally, it is state of the art to neglect any local bending stresses in the web after retrofitting the upper flange area to get a local box section. The results presented in this paper indicate that the additional local bending stresses within the upper flange box section can be significant and should not be neglected for fatigue design. Therefore, a new design concept for the calculation of the local bending stresses in webs of retrofitted crane runway girders with new boxed upper flange is proposed.
Assessment of the Interaction Conditions of I‐shaped Cross‐Sections
Authors: Ludwig Christian
Published: September 2021

In this research, the interaction conditions for double‐symmetric I‐sections without fillets are analysed. Interaction conditions are necessary for the determination of plastic load‐bearing capacity, which is preferred over elastic load‐bearing capacity for economic reasons. In literature, standards and current research projects, different interaction conditions for My, Mz and Mω are available. However, analyses of their accuracy are missing. This research intends to determine the deviations of each interaction condition using numerical approaches. The interaction conditions are verified on the basis of extensive parameter studies. This study shows that the solutions available in EN 1993‐1‐1 and prEN 1993‐1‐1 lead to uneconomical results. Furthermore, for the application of the interaction condition according to EN 1993‐6 certain limits have to be considered to avoid a non‐conservative design. In this paper, the new extended exponent method is presented. This method is a simple, economical and conservative solution.
Large‐scale fatigue tests on thick walled circular hollow sections
Authors: Dürr André , Roth Jakob
Published: September 2021

The fatigue strength according to EN 1993‐1‐9 and other recommendations for the design of steel structures are generally determined by fatigue tests. Because of cost and time reasons fatigue tests are usually performed on small‐scale specimens. However, test results gained on these specimens with smaller dimensions cannot cover the influence of a possible size‐effect on the fatigue strength. For the transfer of the fatigue strength to real structures with larger dimensions and larger wall thicknesses additional large‐scale fatigue tests are required. At the University of Applied Sciences Munich, several large‐scale fatigue tests on thick walled circular hollow sections with welded K‐joints were performed in recent years. The large‐scale fatigue tests had dimensions similar real structures with lengths up to 18 m, weights up to overall 17 tons and wall thicknesses up to 60 mm. Within this paper, the used test bench for the large‐scale fatigue tests is described and the results are discussed regarding the influence of the size effect.
Fatigue durability of large‐sized trough rib ortho‐tropic steel deck for deck crack
Authors: Hirai Takahide , Saito Shiro , Sakano Masahiro
Published: September 2021

A lot of fatigue cracks were reported in orthotropic steel deck (OSD) because the structure of OSD supported wheel load directly. Among them, many fatigue cracks at the intersections between trough rib and transverse rib were reported. Improved structures of the the intersections between trough rib and transverse rib were reported by many researchers. The purpose of this paper is to propose new structure of OSD that using Thread Rolling Screw at joint of trough rib and transverse rib instead of welding and confirming its fatigue durability by fatigue test. Two specimens were prepared. These differences are thickness of deck plate. After fatigue test, we drilled 40 mm diameter hole at upper deck surface and conducted magnetic particle testing to confirm development of deck crack. As a result, fatigue cracks developed at the connection between transverse rib and deck plate in existing structure while no fatigue cracks were detected in proposed structure.
Selecting Suitable Bolt Parameters to Achieve Ductility at Elevated Temperatures
Authors: Shaheen Mohamed A. , Foster Andrew S. J. , Cunningham Lee S. , Afshan Sheida
Published: September 2021

A detailed FE study is presented investigating the factors affecting failure modes of bolt assemblies under tensile force at ambient and elevated temperatures. Axisymmetric FE models incorporating important behavioural aspects including surface interaction and damage modelling were developed. Stripping failure is generally undesirable because it results in premature failure of the bolt, which can deteriorate the rotational capacity of connections and robustness of steel frames. The paper discusses how the thread length in the grip Lt can affect the failure mode of bolt assemblies at elevated temperatures. This paper concludes that at ambient temperature, stripping can occur at certain Lt length dependent upon the nut dimension deviation from the basic profile; this length reduces with temperature.
DSM Design of Cold‐Formed Steel Columns Failing in Flexural‐Torsional Modes at Elevated Temperatures
Authors: Bicelli Antonio , Landesmann Alexandre , Camotim Dinar , Dinis Pedro
Published: September 2021

The purpose of this work is to extend the scope of the previous studies, by considering fixed‐ended columns under elevated temperatures (up to 800° C) with three cross‐section shapes (lipped channels, racks and stiffened lipped channels), various cross‐section dimensions (five per shape) and different lengths. The results presented and discussed consist of column FT post‐buckling equilibrium paths and failure loads, which are obtained through geometrically and materially non‐linear Ansys SFEA. In order to cover a wide FT slenderness range, several room‐temperature yield stresses are considered. The model prescribed in EC3‐1.2, for cold‐formed steel, is adopted to describe the temperature‐dependence of the steel material properties. Finally, the numerical failure loads obtained by the authors, together with numerical and experimental ones collected from the literature are used to propose a modification of the DSM‐based FT strength curves developed previously by authors and assess the merits of the new design curves. It is shown that the proposed modification improves visibly the failure load prediction quality, thus providing encouragement to continue the search for an efficient and reliable DSM‐based design approach for columns failing in FT modes at elevated temperatures.
Experimental study on rotational restraint provided by sandwich panels at elevated temperature
Authors: Horváth László , Joó Attila László , Lendvai Anita
Published: September 2021

By the wider spread of sandwich panels as a cladding system on industrial steel buildings, the research on various design aspects is evolving as well. The principal aim of the research introduced in this paper is to study the rotational restraint provided by sandwich panels at both ambient and elevated temperatures, and derive the temperature dependent rotational spring stiffnesses. In the frame of an ongoing international RFCS research program named STABFI, several experimental test series were carried out. This paper has a main focus on the part of the small scale tests, in which the rotational behavior of the screwed connection between sandwich panels with mineral wool core and H‐beam was investigated. The panel‐substructure connections were tested to define rotational stiffness at different inner panel sheet temperatures (20, 200, 250, 300, 450 and 600 C°). During testing the temperature of the inner sheet, the outer sheet, and the core of the sandwich panel were recorded. The applied torsional load at the axis of the connection and the rotation was measured and recorded, from which the moment‐rotation diagrams of the joints were derived. Based on these curves the temperature dependent rotational spring stiffnesses were also determined.
Experimental analysis of steel beams with fire resistant properties subjected to the ISO 834 Fire
Authors: Jordão Alexandre Magnus , Scabbia André Luiz Gonçalves , e Silva Valdir Pignatta
Published: September 2021

All buildings with human occupation need to be designed to withstand a certain standardized fire time related to the safety of their occupants. Within this context, the structure plays an extremely important role as passive fire protection element. As a result, the use of fire‐resistant steel has been produced and used to decrease the volume of passive protective material and sometimes eliminate it due to the presence of alloying elements such as niobium and molybdenum on its composition whose chemical synergy, coupled with carefully metallurgical processes, can maintain the material's mechanical properties above that those associated with the conventional steel. This paper is part of an extent research and aim to present initial experimental results of the behavior of no protected three side exposed beams under 60 minutes ISO 834 Fire curve with and without fire‐resistant properties. The tests were carried out into a horizontal furnace and the vertical deflection at the thirds of span was measured while the central was calculated based on these measurements. The experiment did not have the intention of investigate the connections, because of that, were stiffened for supporting the large plastic deformations of the specimen
Fire Testing of Grade 304 Stainless Steel Plate Material Under Transient‐state Conditions
Authors: Farmani Mohammad Amin , Du Xingchen , Heidarpour Amin , Zhao Xiao‐Ling
Published: September 2021

Owing to its superior performance at high temperatures, stainless steel is usually considered as a potential replacement for mild steel in a wide range of structural fire engineering applications. When it comes to the fire design of steel structures, time‐dependent deformations occurring in the adequately‐heated steel material, called “thermal creep” need to be somehow considered in the design calculations. In EUROCODE 3‐1‐2, for example, the thermal creep strains are implicitly included in the transiently‐determined stress‐strain curves for steel at elevated temperatures. Using the same approach, this paper investigates the fire‐temperature mechanical properties of Grade 304 stainless steel by conducting transient tensile tests at temperatures of up to 900°C on standard coupons taken from a 3.0 mm thick plates. To simulate structural fire conditions in the transient tests, the temperature of the sample is steadily increased when a constant tensile load is applied. From these tests, strain‐temperature curves are obtained, wherein the strain contains both mechanical and thermal components. The strain‐temperature curves with the same heating rate of 10°C/min are then converted to elevated‐temperature stress‐strain curves suitable for fire design applications.
Fire design of composite beams and slabs: practical design considerations according to Eurocode 4
Authors: Pimentel Ricardo , Craveiro Helder , Simões Rui
Published: September 2021

Composite slabs and beams are widely used in the construction market. The fire design is often required, which demands an assessment of materials' resistances at elevated temperature. The main topic of this article is to evaluate the impact of the temperature distribution in the concrete flange for the fire design of composite beams and slabs. The analytical design methodology proposed by Eurocode 4 will be implemented to a comprehensive number of examples, where different methods to address the slab temperature profile in the concrete flange are used. Practical advice for fire design and protection coating definition will be presented. Numerical Finite Element Model (FEM) analyses were used to support some of the conclusions.
Mechanical Properties and Resistance Coefficient of Carbon Steel during Fire
Authors: Murakawa Tomonori , Takahashi Yusuke , Imagawa Yusuke , Ohyama Osamu
Published: September 2021

Recently, serious fire accidents have occurred on bridges. For example, the 9‐Mile Overpass located near Detroit, MI, USA, experienced serious damage, where the steel‐concrete composite girder bridge fell down. To avoid future instances of such events, we need to understand the effect of the decrease in hardness of carbon steel during fire on structural characteristics, and to clarify the collapse mechanism of a bridge. Fifty years ago, the Japan Society of Steel Construction (JSSC) defined the mechanical properties of carbon steel up to 900 °C. However, recently, there have been bridge fire incidents where the heat has exceeded an estimated 1000 °C. Therefore, it is necessary to conduct the high temperature tensile test above 900 °C. In Japan, the design method has changed from the allowable design method to the limited design method, and a fire design method for the safety, serviceability and restorability of bridges has not been established. In near future, we seek to clarify the resistance coefficient for fire design. Herein, we carry out the high temperature tensile test to determine the relationship between strength and temperature, and propose a resistance coefficient for fire design based on these results. The 1 % yield strength of SM400 (minimum tensile stress: 400 N/mm2) decreased on average by 26 % at 500 °C, and on average by 94 % at 1100 °C. It was found that the elongation of carbon steel is greatest at 800 °C.
Post‐fire behaviour of structural stainless steel
Authors: Molkens Tom , Cashell Katherine A. , Malaska Mikko , Alanen Mika , Rossi Barbara
Published: September 2021

Stainless steel offers excellent mechanical properties as well as corrosion resistance and performs better in a fire compared to carbon steel in that it retains its strength and stiffness for a longer duration. The current paper is focussed on the post‐fire condition, which has only received limited attention to date from the research community. The motivation for the work is to show that stainless steel elements which have been exposed to fire can be re‐instated with minimal additional costs in a short time frame. The paper proceeds with a description of recent material tests into the residual properties of grade 1.4301 austenitic stainless steel, following exposure to elevated temperature. Two different types of test are added to this available data. Firstly, a series of tensile tests are completed on coupons taken from a loaded stainless steel beam previously examined under fire conditions. Secondly, a set of virgin coupons (i.e. which have not been previously heated or tested) are exposed to different levels of elevated temperature and cooling procedures. This is with a view to understanding the ability of structural elements made from this material to survive a fire and continue in service. The results are then employed along with other data obtained from the literature to conduct a detailed study into the design considerations.
Numerical simulation of damage patterns in the plastic hinge area of fire protected (SFRM) steel beams and its effect on their fire resistance
Authors: Zografopoulou Kalliopi , Mistakidis Euripidis
Published: September 2021

Sprayed Fire‐Resistive Materials (SFRMs) are low strength, brittle materials used as passive fire protection on steel structural members. Their main drawback is that they can develop significant damage when the underlying steel member is subjected to mechanical deformations. The current study addresses numerically the damage patterns of the passive fire protection that could arise at the plastic hinge area of IPE steel beams and their effect on the fire resistance of the member. Initially, a numerical method that combines the smeared crack model and the discrete crack concept is implemented for the simulation of the mechanical behavior of the fire protective material and the prediction of the damage it sustains. The results of the mechanical analysis, considering the parameters of cross‐section height, SFRM thickness, monotonic or cyclic loading and presence of geometric initial imperfections, suggest that the damage pattern, which is a result of the combination of interface delamination and crack formation in the body of the material, can be categorized in two basic forms. In the sequel, a heat transfer analysis is conducted on the steel beams, under standard ISO‐834 thermal load, taking into account the damage derived by the mechanical analysis, in order to assess the reduction in the fire resistance of the beams, compared to the corresponding beams with an intact fire protection layer or without any fire protection.
The Role of Tendons for Fire Safety Design of Pre‐tensioned Steel Structures
Authors: Du Yong , Li Guo‐Qiang
Published: September 2021

Pre‐tensioned steel strands as basic elements have been widely used in hybrid string structures, suspended roofs and cable‐stayed bridges. When subjected to localised fire, the steel cables relaxes due to thermal expansion, reduction of mechanical properties as well as creep strain at elevated temperature. Meanwhile, the bond strength of anchors at each end of a steel cable decreases due to adhesive properties of filling material decreasing at elevated temperature. In this paper, a set of new formula was regressed to determine the full range of stress‐strain relationship, reduction factors of mechanical properties and creep strain of steel cables at elevated temperature. A special thermal transfer path considering of the cavity radiation among wires has been developed to determine the transient temperature distribution in the cross section of steel strands. Analytic method was developed to predict the temperature in the centre of hot‐cast anchors and temperature history of cold‐cast anchors at ISO834 fire was also investigated by ANSYS software. Thermo‐mechanical action of global pre‐tensioned steel structures was investigated by analytic and numerical simulation methods. The expertise and knowledge also provides insights to the fire safety design of pre‐tensioned steel structures.
An Experimental Study of the Effects of Crack and Detachment on Insulation Properties of Intumescent Coating
Authors: Wang Lingling , Wang Yongchang , Li Guoqiang
Published: September 2021

This paper presents the results of an experimental study to investigate the failure modes of intumescent coatings and their effects on temperatures attained in steel sections and load carrying capacities of steel columns. Primer and intumescent coatings were applied to unloaded steel plates, unloaded I‐shaped short sections and axially loaded I‐shaped long columns. For the axially loaded columns, three different surface treatments were considered. The failure modes of intumescent coatings include distributed fine cracking, discrete wide and deep cracking, and detachment. Distributed fine cracks appeared on the unloaded plate specimens. Discrete crack was the main failure mode on the unloaded steel sections. For the loaded long columns, the intumescent coating failure modes included both discrete crack and detachment. Intumescent coating failure affected the average temperatures attained, with average temperatures of the plate specimens, unloaded steel sections and loaded steel columns being 411°C, 472°C and 543°C respectively after 30 minutes of standard fire exposure. Different surface treatment does not seem to have much effect on fire resistance of the carbon steel columns, the two columns reaching fire resistance times of 38 and 39.5 minutes respectively.