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The Continuous Strength Method (CSM) provides accurate cross-section resistance predictions since allowance is made for the partial spread of plasticity and the beneficial effects of strain hardening. Although CSM design provisions for different loading conditions are available, the method was limited to the determination of cross-sectional resistance until recent research by Arrayago et al. (2020) proposed a consistent new approach to the design of stainless steel hollow section members subjected to compression. Extension of the CSM to the design of stainless steel members subjected to combined compression and bending moment is presented in this paper. The analysis is based on numerical results generated in the current study and existing results collected from the literature on stainless steel hollow section members. The results demonstrate that the adoption of the CSM design equations to predict column strength considerably improves the ac-curacy of the calculated beam-column capacities. The reliability of the proposed approach is demonstrated through statistical analyses performed in accordance with EN 1990. The authors acknowledge the funding from the MINECO (Spain) under Project BIA2016-75678-R, AEI/FEDER, UE “Comportamiento estructural de pórticos de acero inoxidable. Seguridad frente a acciones accidentales de sismo y fuego”. The first author would also like to acknowledge the financial support received from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 842395.

This paper presents a numerical modelling study investigating the response of stainless steel two-dimensional frame assemblies at elevated temperature that has not been the subject of detailed investigation to date. Finite elements models which capture the combined effects of material degradation with temperature and the interaction between the individual frame elements are developed and validated. The effect of key behavioural parameters including frame type, i.e. sway and non-sway, degree of utilisation, material grade and heating profile is investigated through an extensive parametric modelling. A new set of performance criteria in terms of limiting deflection and limiting rate of deflection for sway and non-sway frames in fire is established and verified. The first author acknowledges the support of the Secretaria d’Universitats i Recerca de la Generalitat de Catalunya (Spain) and the European Social Fund. The authors acknowledge the funding from the MINECO (Spain) under Project BIA2016-75678-R, AEI/FEDER, UE “Comportamiento estructural de pórticos de acero inoxidable. Seguridad frente a acciones accidentales de sismo y fuego”.

The Continuous Strength Method (CSM) provides accurate resistance predictions for both stocky and slender stainless steel cross-sections; in the case of the former, allowance is made for the beneficial effects of strain hardening, while for the latter, design is simplified by the avoidance of effective width calculations. Although the CSM strain limits can be used in conjunction with advanced analysis for the stability design of members, for hand calculations, the method is currently limited to the determination of cross-sectional resistance only, i.e. member buckling resistance is not covered. To address this limitation, extension of the CSM to the design of stainless steel tubular section columns is presented herein. The proposed approach is based on the traditional Ayrton-Perry formulation, but features enhanced CSM cross-section resistances and a generalized imperfection parameter that is a function of cross-section slenderness. The value of the imperfection parameter increases as the slenderness of the cross-section reduces to compensate for the detrimental effect of plasticity on member stability that is not directly captured in the elastic/first yield Ayrton-Perry approach. The accuracy of the proposed approach is assessed against numerical results generated in the current study and existing experimental results collected from the literature. The presented comparisons show that the CSM provides consistently more accurate member buckling resistance predictions than the current EN 1993-1-4 design rules for all stainless steel grades. The reliability of the proposed approach is demonstrated through statistical analyses performed in accordance with EN 1990. Finally, the paper presents a framework through which the proposed approach can be developed for other cross-section types and materials.

Stainless steel is known to have a better behaviour at elevated temperatures than carbon steel. This, combined with its aesthetic appeal and corrosion resistance, makes stainless steel structures an attractive alternative to carbon steel structures. However, EN 1993-1-4 does not establish de-sign rules associated with global analysis of stainless steel frames and EN 1993-1-2, devoted to carbon steel, provides a conservative approach for the fire design of stainless steel structures. Hence, current European codes do not provide efficient design guidelines for stainless steel frames subject to fire and therefore the response of this type of structures should be assessed by means of experimental tests and/or numerical analyses. The main objective of the paper is to assess the nonlinear structural response of stainless steel frames subjected to fire, focusing the investigation on the influence of the degree of utilization. A comprehensive numerical analysis on Class 1 and Class 3 stainless steel frames and Class 1 carbon steel frame subjected to fire is carried out varying the degree of utilization. Calibration of the FE models has been carried out as a part of a study of transient thermo-mechanical models, which are needed to assess the response of stainless steel frames subjected to fire. The authors acknowledge the funding from the MINECO (Spain) un-der Project BIA2016-75678-R, AEI/FEDER, UE “Comportamiento estructural de pórticos de acero inoxidable. Seguridad frente a ac-ciones accidentales de sismo y fuego”.

Austenitic stainless steel is an excellent construction material for structures required to withstand accidental loads such as seismic and/or fire events due to its appropriate mechanical properties, including high ductility, considerable strain hardening and good fire resistance. In recent years, a considerable amount of research has been devoted to the understanding of the structural performance of single isolated stainless steel members. However, new trends in the design philosophy moving from current member-based methods to direct system-based approaches will require more experimental evidence on more complex structural systems such as frames, which are currently scarce. With the aim of contributing to the advances in this field, one of the first known extensive experimental programmes on austenitic stainless steel frames is presented in this paper. The experimental programme comprised several sub-programmes, in which the performance of stainless steel structures at different levels was investigated. This paper describes a series of tests on austenitic stainless steel cross-sections and members, which were utilized in the planning and analysis of the subsequent frame tests. The paper also outlines the complex experimental set-up adopted for the stainless steel frame tests, including the implemented loading schemes, auxiliary elements and instrumentation, through a detailed explanation of the different issues encountered in the process of their definition. The knowledge gained and the experiences reported in this paper could assist researchers in planning similar experimental programmes. "This experimental programme was developed in the frame of the Project BIA2016-75678-R, AEI/FEDER, UE “Comportamiento estructural de pórticos de acero inoxidable. Seguridad frente a acciones accidentales de sismo y fuego”, funded from the MINECO (Spain). The financial support received from the European Commission and Spanish Ministry for Science, Innovation and Universities through the Marie Sklodowska-Curie grant agreement No. 842395 and the FPI-MINECO PhD fellowship Ref. BES-2017-082958 is also gratefully acknowledged. Authors would like to acknowledge the support, advice and suggestions from Professor K. Rasmussen (The University of Sydney), Professor B. Young (Hong Kong University) and Professor L. Gardner (Imperial College London) in the preparation of this experimental programme, and the support from Acerinox and MeKano4. The time and effort from the staff at the Laboratory of Technology of Structures and Materials and the Geotechnical Engineering and Geosciences Department from Universitat Politècnica de Catalunya are also much appreciated."

The Continuous Strength Method (CSM) provides accurate resistance predictions for both stocky and slender stainless steel cross-sections; in the case of the former, allowance is made for the beneficial effects of strain hardening, while for the latter, design is simplified by the avoidance of effective width calculations. Although the CSM strain limits can be used in conjunction with advanced analysis for the stability design of members, for hand calculations, the method is currently limited to the determination of cross-sectional resistance only, i.e. member buckling resistance is not covered. To address this limitation, extension of the CSM to the design of stainless steel tubular section columns is presented herein. The proposed approach is based on the traditional Ayrton-Perry formulation, but features enhanced CSM cross-section resistances and a generalized imperfection parameter that is a function of cross-section slenderness. The value of the imperfection parameter increases as the slenderness of the cross-section reduces to compensate for the detrimental effect of plasticity on member stability that is not directly captured in the elastic/first yield Ayrton-Perry approach. The accuracy of the proposed approach is assessed against numerical results generated in the current study and existing experimental results collected from the literature. The presented comparisons show that the CSM provides consistently more accurate member buckling resistance predictions than the current EN 1993-1-4 design rules for all stainless steel grades. The reliability of the proposed approach is demonstrated through statistical analyses performed in accordance with EN 1990. Finally, the paper presents a framework through which the proposed approach can be developed for other cross-section types and materials. The authors acknowledge the funding from MINECO (Spain) under Project BIA2016-75678-R, AEI/FEDER, UE “Comportamiento estructural de pórticos de acero inoxidable. Seguridad frente a acciones accidentales de sismo y fuego”. The first author would also like to acknowledge the financial support provided by the Spanish Ministerio de Educación, Cultura y Deporte through the José Castillejo-2018 scholarship.

Net section resistance in bolted cold-formed steel angles of members under tension is analyzed in this work. The efficiency reduction due to shear lag and eccentricity effects in bolted connections is studied using finite element models implemented in ABAQUS software. The nonlinearities of the steel material and the contact between elements are considered in the numerical models, and their results are in good agreement with experimental tests. A parametric study is conducted in this work using Finite Element (FE) analyses. A large number of experimental tests reported in the literature is also summarized in this work. A new expression of easy application for net section reduction coefficient is found, which allows improving the prediction of the nominal resistance of the net section.

Austenitic stainless steels offer a suitable combination of high ductility, adequate toughness, considerable strain hardening and good fire resistance, making them excellent construction materials, especially for structures subjected to accidental loading such as seismic and/or fire events. With most of the research over the recent years devoted to the behaviour of single isolated stainless steel members, advances on structural systems are scarce, yet necessary, for the further development of design codes. Hence, an extensive experimental programme on EN 1.4301 austenitic stainless steel frames including tests at different structural levels –material, cross-section, member and frame levels– has been carried out at the Laboratory of Technology of Structures and Materials at Universitat Politècnica de Catalunya. The companion paper presents the tests carried out at cross-section and member level, and the knowledge gained from the planning of the experimental set-up for frame tests, including the adopted loading schemes, auxiliary elements and instrumentation. This paper presents the results of the four tests conducted on austenitic stainless steel frames under static vertical and horizontal loading. The analysis of the test results allowed to investigate the interaction of material and geometrical nonlinearities experimentally, as well as the assessment of the EN 1993-1-4 and EN 1993-1-1 provisions for the global analysis of stainless steel frames, where the influence of material nonlinearity on second order effects is evaluated, and which is currently limited to numerical studies only. "This experimental programme was developed in the frame of the Project BIA2016-75678-R, AEI/FEDER, UE “Comportamiento estructural de pórticos de acero inoxidable. Seguridad frente a acciones accidentales de sismo y fuego”, funded from the MINECO (Spain). The financial support received from the European Commission and Spanish Ministry for Science, Innovation and Universities through the Marie Sklodowska-Curie grant agreement No. 842395 and the FPI-MINECO PhD. fellowship Ref. BES-2017-082958 is also gratefully acknowledged. Authors would like to acknowledge the support, advice and suggestions from Professor K. Rasmussen (The University of Sydney), Professor B. Young (Hong Kong University) and Professor L. Gardner (Imperial College London) in the preparation of this experimental programme, and the support from Acerinox and MeKano4. The time and effort from the staff at the Laboratory of Technology of Structures and Materials and the Geotechnical Engineering and Geosciences Department from Universitat Politècnica de Catalunya are also much appreciated."

Current design standards for stainless steel such as ASCE 8-02 and EN 1993-1-4 prescribe provisions for the design of cross-sections and members that account for material nonlinearities and strain hardening, although these features are not considered in the global design of structures. Recent studies have highlighted the need of accounting for material nonlinearities in order to design efficient and safe stainless steel structures, and it is expected that the forthcoming versions of the standards will incorporate updated rules for the global design of these structures. To contribute to this field, this paper presents a Stiffness Reduction Method (SRM) for the in-plane design of stainless steel members and frames with stocky sections based on the prescriptions given in the next version of EN 1993-1-4. The proposed approach predicts the ultimate capacity and internal forces in stainless steel structures by performing a second-order elastic analysis in which the stiffnesses of the members are reduced by a set of factors defined in this paper to account for the effect of the spread of plasticity, residual stresses and member imperfections. The accuracy of the presented method is assessed for individual stainless steel structural members (columns, beams, and beam-columns) with different cross-sections and material properties, and for austenitic stainless steel portal frames, against numerical results obtained from nonlinear analyses conducted on finite element models. A comparison between the proposed approach and the Direct Analysis Method prescribed in the upcoming AISC 370 Specification is also provided, showing that the results are comparable in the two approaches. The research presented in this paper was developed in the frame of the Project BIA2016-75678-R, AEI/FEDER, UE “Comportamiento estructural de pórticos de acero inoxidable. Seguridad frente a acciones accidentales de sismo y fuego”, funded from the MINECO (Spain). The financial support received from the Spanish Ministry for Science, Innovation and Universities through the FPI-MINECO PhD fellowship Ref. BES-2017-082958 (I. González-de-León) and from the European Commission through the Marie Sklodowska-Curie grant agreement No. 842395 (I. Arrayago) is also gratefully acknowledged.

Resumen En la mayoria de vigas mixtas, la conexion entre el hormigon y el acero es imperfecta y, por tanto, aparece un mayor o menor deslizamiento relativo entre ambos materiales. Este deslizamiento afecta tanto a las deformaciones como a los esfuerzos de la viga. Para simular este fenomeno, en este trabajo se propone un nuevo modelo de elementos finitos bidimensional basado en elementos tipo viga, facilitando asi la interpretacion y la aplicacion practica de los resultados. Para validar la precision del modelo, se comparan los resultados obtenidos mediante el modelo con los derivados de las ecuaciones analiticas propuestas en la literatura, en dos estructuras mixtas con diferentes estados de carga.

Steel-concrete composite floors are commonly used in construction due to their favourable weightto- depth ratio and erection time. Typically, concrete is poured onto a galvanised steel deck acting as formwork. However in case of floors exposed to corrosive environments, stainless steel is likely to be chosen over galvanised steel. Besides its better corrosion resistance, stainless steel also offers desirable aesthetic appearance and good mechanical properties. Composite slabs can fail in bending, vertical shear or longitudinal shear. The latter failure mode is the most common, and its prediction depends on values obtained through full-scale tests. However, for stainless steel decks, no specific treatment exists in current design standards. This paper investigates the longitudinal shear resistance of stainless steel composite slabs through an experimental study. One short and three long span slabs, made using a Cofraplus 60 ferritic EN1.4003 stainless steel corrugated deck, are tested in accordance with Eurocode 4, annex B.3 [1]. The Partial Shear Connection (PSC) method is used to assess the longitudinal shear resistance. The experimental results together with the results provided in [2] are used to draw conclusions on the applicability of ferritic stainless steel decks in composite floors.

The use of stainless steel structures has increased during the last decade due to their durability, aesthetics and mechanical properties such as ductility, considerable strain hardening and excellent fire resistance. However, the majority of conducted research works have only focused on single isolated stainless steel members and advances in the analysis of stainless steel frames are limited. EN1993-1-4 does not provide global plastic design rules for indeterminate stainless steel structures, such as frames, despite their proved high ductility. On the other hand, the lack of guidance on plastic design is an obstacle for the optimal design of stainless steel structures, leading to uneconomical design. This paper presents a preliminary study on non-sway stainless steel frames with stocky hollow cross-sections. The study of the behaviour of stainless steel frames is based on numerical parametric studies, considering the nonlinear material behaviour and different stainless steel types (austenitic and ferritic). The paper deals with the redistribution of internal forces and assesses the existing methods based on global plastic design for frames with stocky cross-sections, where alternative design approaches accounting for moment redistribution and strain hardening effects are analysed in addition to traditional plastic design method. Preliminary results demonstrate that including bending moment redistribution and strain hardening effects in capacity predictions is essential for an efficient design of stainless steel structures.

Link elements are dissipative devices in form of beam segments that are typically included in eccentrically braced frames (EBF) subjected to lateral loads and seismic hazard. Studies related to short links, energy dissipation and plastic hinge formation have been presented for carbon steel elements with several conclusions at material, member and structural levels. Stainless steel is a nonlinear metallic material with particular appeal for its structural use due to a considerable amount of capabilities such as corrosion resistance, circular life-cycle, sustainability, strength, ductility and aesthetics. Despite the increase of the use of stainless steel for structural elements in construction, the behaviour of this material for structural purposes is not defined accurately as the carbon steel in all applications. The most important difference between these types of steel is the shape of the stress-strain curve. Whereas carbon steel typically exhibits linear elastic behaviour up to the yield stress and a plateau before strain hardening is encountered, stainless steel has a more rounded response with no well-defined yield stress, leading to a non-linear material behaviour. The elastic stiffness, maximum load, shear deformation capacity as well as the energy dissipation in short links are generally affected by the defined geometrical parameters such as link length, web stiffening and connectivity. Due to the material nonlinearity of stainless steel, this influence may be considerably affected by the stress-strain curve and its corresponding energy dissipation since a nonlinear kinematic hardening branch must be adequately provided in numerical simulations for the sake of accurately reproducing the cyclic behaviour. In this paper, a numerical model aimed at studying the cyclic behaviour of short stainless steel links subjected to seismic lateral loads is presented. The model accounts for the material and the geometrical nonlinearities. Several geometrical as well as material configurations (length, web stiffening and constitutive equations) are studied. The results and conclusions obtained in this research are used for a subsequent definition of a research program related to stainless steel frames subjected to seismic loading including several structural configurations in both concentrically (CBF) and eccentrically (EBF) braced frames assembled with plastic or slender members.

In composite beam design, headed stud shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface. This paper describes the structural performance of shear connection in composite beams with profiled steel sheeting. An accurate and efficient nonlinear Finite Element (FE) model was developed to study the behavior of headed stud shear connectors welded through the deck. The concrete slab considered in this article uses profiled steel sheeting with ribs perpendicular to the longitudinal axis of the steel beam. The material nonlinearities were included in the FE model. The concrete was modeled considering a damaged plasticity model available in ABAQUS software. The results obtained from FE analysis were verified against experimental results. A parametric study was conducted to observe the effects of changing of both the stud position inside the rib of profiled steel sheeting and the concrete strength on the resistance of the stud shear connector. The shear resistance of stud connectors obtained from the FE analysis and many experimental push-out tests whose results are available in the literature were used as a database to compare with design shear resistance calculated using AISC-LRFD and Eurocode 4. It is found that the shear resistance of stud connectors, obtained from the design rules specified in these codes, in some cases is greatly underestimated, and in other cases significantly overestimated.

The use of composite floor slabs is well established and provides an opportunity to promote the use of visually exposed composite slabs. Stainless steels, with the combination of good mechanical properties and excellent corrosion resistance, are key to this strategy, specially ferritic stainless steels, whose price is lower and more stable than that corresponding to the more widely used austenitic grades, due to their low nickel content whilst still maintaining good mechanical properties and aesthetic appeal. In addition, the emissivity of these grades contributes to lowering the heating and cooling requirements of buildings, reducing the costs associated to maintenance. Generally used as cold-formed members with high resistance-to-weight ratios, stainless steel decks are slender and highly sensitive to buckling phenomena and so the study of the structural performance of composite slabs using ferritic stainless steel decking is required due to the complex nonlinear behaviour of stainless steels, which is very different from that exhibited by carbon steel. Thus, this paper presents a comprehensive experimental programme on ferritic stainless steel trapezoidal decks for composite slabs under several structural configurations occurring during construction stage: simply supported decks under positive and negative bending moment, continuous decks and internal and end support tests. All the experimental results have been compared with the predicted ultimate loads in EN 1993-1-4, which remits to EN 1993-1-3 for carbon steel, and also with some previous tests on galvanized carbon steel decks. The paper concludes that EN 1993-1-3 provisions are applicable to ferritic stainless steels.

Ferritic stainless steels, with their lower nickel content, supplement the desirable features offered by different stainless steel grades with a more controlled and lower initial investment requirements, which have encouraged the use of these materials in construction. The nonlinear behaviour of stainless steel grades is not usually considered when extending design expressions codified for carbon steel to these alloyed materials, leading to overconservative design approaches and the applicability of the different design expressions initially developed for carbon steel needs to be adjusted for every stainless steel grade. The study of stainless steel elements subjected to combined flexural buckling and bending moment loading conditions only covers the most usual austenitic, duplex and lean duplex grades, but experimental results on ferritic grades are still necessary to complete the analysis. Hence, an experimental programme on ferritic stainless steel RHS and SHS pin-ended elements has been conducted where the flexural buckling and beam-column behaviour of these elements has been investigated. Furthermore, the assessment of the different design approaches for flexural buckling and interaction expressions for combined loading has been derived from the obtained experimental results, and current specifications provided in Standards have been found to be, in general, safe but overconservative.

This work presents an FE study concerning the prediction of the shear resistance of headed stud connectors in composite beams with profiled steel sheeting subjected to static load. To confirm the FE simulation for the determination of the shear resistance of stud connectors, many experimental push-out tests whose results are available in the literature were used as a database. The FE simulations took into account the influence of many physical and mechanical parameters that affect the shear resistance of the stud connectors and such parameters are reported in the course of this paper. The prediction of the shear resistance of such studs is also calculated from currently used Standards, such as: AISC-LRFD and Eurocode-4. This research proposes new formulations for the prediction of the shear resistance and the results show that the proposed formulations significantly improve the prediction of the shear resistance of headed stud connectors subjected to static load.

This article presents some observations related to the phenomenon that occurs when a densely stiffened steel plate girder (both transversally and longitudinally) is subjected to patch loading. The failure mechanism differs considerably for the structural case of girders with unstiffened girders or the case in which the girders present largely spaced transverse stiffeners. These structural cases have been studied thoroughly in last decades. However, in steel plate girders with closely spaced stiffeners, which are occasionally found in bridge design, the current EN1993-1-5 rules underestimate the strength of the webs to transverse forces. Research work on girders with closely spaced transverse stiffeners is available but for such cases, the web plates do not include longitudinal stiffeners. Numerical simulations in previously validated models have been performed in order to gain a phenomenological insight for girders with both types of stiffeners subjected to patch loading. Preliminary results suggest that the resistance of densely stiffened steel girders (both transversally and longitudinally) must be studied and subsequently revised accordingly. In addition, it is pointed out that a certain degree of imperfection sensitivity is inferred from the results. Further studies on this topic are necessary

Steel-concrete composite floors are commonly used in construction due to their favourable weight-to-depth ratio and erection time. Typically, concrete is poured onto a galvanised steel deck acting as formwork. However in case of floors exposed to corrosive environments, stainless steel is likely to be chosen over galvanised steel. Besides its better corrosion resistance, stainless steel also offers desirable aesthetic appearance and good mechanical properties. Composite slabs can fail in bending, vertical shear or longitudinal shear. The latter failure mode is the most common, and its prediction depends on values obtained through full-scale tests. However, for stainless steel decks, no specific treatment exists in current design standards. This paper investigates the longitudinal shear resistance of stainless steel composite slabs through an experimental study. One short and three long span slabs, made using a Cofraplus 60 ferritic EN1.4003 stainless steel corrugated deck, are tested in accordance with Eurocode 4, annex B.3 [1]. The Partial Shear Connection (PSC) method is used to assess the longitudinal shear resistance. The experimental results, together with the results provided in Task 3.3 of the “Structural Applications of Ferritic Stainless Steels (SAFSS, RFSR-CT-2010-00026)” project [2], are used to draw conclusions on the applicability of ferritic stainless steel decks in composite floors. ispartof: Construction and Building Materials vol:189 pages:728-735 status: published

This paper presents a finite element model for the analysis of composite beams with partial interaction. In this model, the elements of the composite beams are modeled by six different types of frame elements. Compared with other methods presented in the literature, the main advantages of the proposed method are as follows: (1) intuitiveness, as the different elements of the model present a close and easy to understand relation with the structural behavior of the composite beam; (2) applicability as the method directly provides useful information for the design work; (3) versatility and generalization in dealing with any combination of loading and boundary conditions (Furthermore, the proposed model enables the analysis of statically indeterminate structures, tapered beams as well as structures with non-uniform shear connector distributions.); (4) easy elaboration of models; and (5) possible widespread use of the model, as the proposed method can be implemented in any structural software. To validate the accuracy and the efficiency of the proposed model, a set of FEMs are verified against those results obtained by analytical equations available in the literature for different boundary and loading conditions. Furthermore, a set of parametric studies are performed to investigate the effects of the size of the FEMs along with the influence of the connection stiffness on the behavior of composite beams with different I beams.

If steel structures are subjected to the combination of bending, shear and patch loading, the interacting stability behaviour in the design should be taken into consideration. The combined loading situation can often occur in case of bridge girders during launching, therefore the determination of the load carrying capacity under the combined loading situation is an important aspect of the bridge design. In the current version of EN1993-1-5 [1] there is no standard design method to take the interaction of these three effects into account and there are a very small number of previous investigations in the literature about this topic. The current paper focuses on the investigation of the interaction behaviour of longitudinally unstiffened steel I-girders under the combination of bending, shear and patch loading. The companion paper (Part II) Kovesdi et al., 2014 [25] deals with the M–V–F interaction behaviour of girders with longitudinal stiffeners. Based on a verified numerical model, the load carrying capacities are determined on various girder geometries for various loading situations, and the applicable interaction equation is investigated in the current paper.

In this paper, the flexural response of extruded wrought aluminium girders is presented. This structural element is intended for usage in marine structures such as light docks, marinas and yacht ports. Ease of use, durability, reduced weight, manoeuvrability and the potential development of bespoke sections are appealing properties in such structures that are fulfilled satisfactorily by this type of aluminium elements. Both experimental and numerical analyses are presented. Experimentally, modules of the girders are tested with loading about both minor and major axes. Numerically, the tests are satisfactorily reproduced for the sake of validation and a subsequent exploitation of the model is addressed for further study of the structural response of the girders. A discussion of the results is presented with some design recommendations of these particular structural elements.

During the last decades, various material models have been proposed describing stainless steel nonlinear behaviour through different parameters. The differences among these models are analysed herein using experimental data of different stainless steel types. An interactive computer programme, usable for any series of experimental data, is developed and presented: the procedure for the determination of Young׳s modulus (E0) is pointed out and the least-square adjustment to optimize the strain-hardening exponents of different material models is described. Different expressions for the calculation of the parameters, proposed by several authors and used in a variety of codes, are analysed and new ones are proposed.

This paper presents a new proposal for estimation of critical load for non-prismatic, thin plates simply supported on four edges subjected to shear. The research included wide parametric studies using more than 500 samples. The parameters taken into account were the web thickness, the panel aspect ratio and the inclination angle. The influence of each was analysed separately and then some simplifications were made in order to find coherent expressions to describe the behaviour of the studied panels. The numerical results were then used to validate the solution proposed in EN 1993-1-5. As a result of this comparison, it is concluded that new design formulations are needed for tapered plates with a considerable slope. Based on previous research by the authors concerning four various geometrical typologies of tapered panels, four expressions for the shear buckling coefficient kφ are proposed.

Cold-formed stainless steel members are widely used due to their high corrosion resistance and high resistance-to-weight ratio but their susceptibility to buckle implies that instability phenomena such as web crippling, where the web locally buckles due to concentrated transverse forces, must be considered. On the other hand, the emergent ferritic stainless steel has very low nickel content and therefore, they are cheaper and relatively price stable compared to austenitics and duplex. Their promising future has aimed to develop efficient design guidance and as a result, a new unified web crippling resistance expression based on numerical simulations and thereafter validated with experimental results has been proposed.

Metallic alloys have a significant role in thin-walled engineering structures due to their unique properties such as corrosion resistance, low density or durability. Their mechanical behaviour is usually nonlinear, and this nonlinearity can be further increased during the work-hardening process. In such cases, designers have to take the proper stress–strain relationship into account to obtain reliable prediction of deformations or internal forces. In this paper, a theoretical model is proposed to match different kinds of measured data or already existing stress–strain models. It is flexible to accommodate any number of measured or recommended material parameters, and therefore makes design rules independent on testing standards. It is particularly suitable for computer code implementation. The approximate inversion of the multistage model is also included in the presented study. The general formula is applied on the set of parameters typically available for structural stainless steels in Europe (0.2% and 1.0% proof strength and ultimate strength) and compared to the existing models by curve-fitting of analytical equations to measured stresses and strains of austenitic, duplex and ferritic stainless steels. The comparisons clearly showed that this three-stage application of the generalized multistage model yields more accurate results compared to the existing material models both in its direct and inverse form.

In this paper, an experimental programme of six steel plate girders subjected to patch loading as well as results of forty eight numerically-tested prototypes are presented. Results of ultimate load capacity as well as structural responses from these girders are provided. In addition, experimental and numerical values of ultimate load capacity are compared with those predicted by EN1993-1–5. With such results, the response of transversally stiffened steel plate girders is discussed throughout the paper. Particular emphasis is given to the influence of the transverse stiffening on the ultimate load capacity of the girders. It is observed that girders with largely spaced transverse stiffeners present a considerably different response from girders with closely spaced transverse stiffeners. The structural response for the former case has been thoroughly studied in the last decades whereas little attention has been paid for the latter. Further analysis of this particular topic is provided in a companion paper.

This paper presents an experimental and numerical research on tapered steel plate girders subjected to shear. Experimental tests included four small-scale tapered steel plate girders. Research was focused on both, critical shear load and ultimate shear resistance. Moreover, the post-buckling behaviour of tapered plates was studied. Further, some parametric studies with various geometries of tapered panels were done in order to find the most favourable design situations. The analysed parameters were: the panel aspect ratio, the inclined flange angle, the web and the flange slenderness. Numerical simulations allowed distinguishing four different typologies of tapered plate girders which should be considered separately in design because of their different behaviour. Verification of the simplified procedure for tapered plates proposed in Eurocode EN 1993-1-5 allowed concluding that for some cases the estimation of the ultimate shear resistance is situated on the unsafe side and need to be revised.

In this paper, an analysis of the structural response of concrete-filled tubular columns (CFT) when subjected to combined bending and compression is presented. The reference frame of the study is the usage of such members as piers of integral bridges. The main objective of the study is to assess both the resistance and the ductility of these structural elements when subjected to lateral displacements. These displacements, together with the corresponding axial forces, represent actions to which the integral bridges piers might be subjected to. For the sake of studying this response, a numerical model is used as a simulation tool over a hypothetical matrix of CFT with realistic proportions. A parametric study is undertaken to monitor the influence of the steel contribution- and the length-to-diameter ratios on the strength and ductility of the CFT. These numerical studies together with a wide experimental database found in the literature have been useful for drawing conclusions concerning these topics. A design proposal concerning the cross-sectional capacity of the CFT, based on the studies performed by other researchers which accounts for confinement, is provided. This proposal has been compared with the present EN1994 formulation. In addition, design formulae which might characterize the ductility of the CFT in terms of the maximum allowable lateral displacements are provided for non-slender CFT piers of integral bridges.

In this paper, a mechanism solution aimed at reproducing the ultimate load capacity of steel plate girders subjected to patch loading is provided. This mechanism is particularly useful for the cases in which the steel plate girders present closely spaced transverse stiffeners. A thorough description of the influence of the transverse stiffening on the ultimate load capacity of girders subjected to patch loading is given partly herein and in a companion paper. Presently, the formulation provided in EN1993-1-5 underestimates the ultimate load capacity of girders presenting such geometrical proportion. Comparisons between numerical and theoretical results show the accuracy of the proposed model. The results obtained with such prediction prove structurally sound and enhance satisfactorily the current formulation of EN1993-1-5.

Because of public construction budgets were cut over the last few years, new bridge girders with corrugated webs to reduce the construction costs have become more widely studied and used. In spite that tapered bridge girders with corrugated webs (BGCWs) are used in modern bridges, their shear strength and behaviour rarely exists in literature. Based on available literature, the web of the linearly tapered BGCWs may be divided into three typologies with different structural response to shear force. This paper presents a study into the shear strength and behaviour of the different web panels of the tapered BGCWs near the end and intermediate supports of continuous bridges using the dimensions of constructed bridges. Accordingly, parametric studies are conducted with variations in the aspect ratio of the web panel, different inclination angles of the tapered web panel and the flange slenderness ratio. After that, the paper checks the available design model under these additional parametric study models. The paper is extended to check corrugation dimensions for the use in conventional structures. It is noticed that as the corrugation angle (a) between longitudinal and inclined sub-panels decreases, the ultimate shear of the girders decreases because the rigidity of the web decreases. The available design model is compared to the FE results and it is found to yield suitable results for girders used in bridges as well as conventional structures. Overall, new conclusions on the shear strength and behaviour of tapered BGCWs are presented.

The structural case of hybrid girders subjected to patch loading is treated identically than the one for homogenous specimens in EN1993-1-5. The EN1993-1-5 formulation is based upon a theoretical model which consists of a plastic resistance Fy partly reduced by a resistance function χF, this latter accounting for instability. The EN1993-1-5 formulation predicts that the ultimate load capacity of steel plate girders subjected to patch loading increases, among others, with the hybrid grade fyf/fyw. In this work, an appraisal of the theoretical and numerical responses of hybrid and homogenous specimens subjected to patch loading is presented. Some peculiarities concerning the treatment of hybrid girders are pinpointed though. It is numerically demonstrated that the moment capacity of the flanges (and thus, fyf/fyw) does not play any role in the resistance of girders predicted in EN1993-1-5. Accordingly, a design proposal which enhances the current formulation is provided.

This paper presents a new resistance model for steel plate girders subjected to patch loading. The model aims to correct the EN 1993-1-5 formulation concerning the resistance to transverse forces with the help of findings presented in several doctoral studies on this topic. In addition, a statistical calibration of the new model is addressed. This calibration includes a new proposal for the resistance function χ-λ. The proposal is conceived for fulfilling safety levels of the partial safety factor that match the current values included in EN 1993 for instability-related problems. These new proposals are in accordance with the design philosophy found in EN 1993-1-5 for the design of plated structures.

The resistance of plate girders subjected to patch loading has been studied thoroughly for the case of homogenous girders. The particular case of hybrid girders has been generally treated identically than for homogenous specimens. In this paper, the current EN1993-1-5 formulation is evaluated and some peculiarities concerning the treatment of hybrid girders subjected to patch loading are pinpointed. It is numerically demonstrated that the moment capacity of the flanges does not play any role in the resistance of plate girders to patch loading as predicted in EN1993-1-5. Accordingly, a design proposal which corrects the current EN1993-1-5 formulation is presented at the end of the paper.

Extensive research focused on the structural behavior of hybrid steel plate girders is nowadays available in the literature. Furthermore, extensive research devoted to the resistance of homogeneous girders to patch loading has been performed in the last decades. Investigations dealing simultaneously with both fields are, however, rather scarce. The driving force behind developing the present research work has been the aim of completing the knowledge of the patch loading field for the particular structural alternative of hybrid steel plate girder. In the current paper, experimental results found in the literature as well as additional numerical simulations developed by the authors are summarized. The results presented can be used for assessing the resistance of hybrid steel plate girders subjected to patch loading. An in-depth exploit of such results is presented in a companion paper.

In this paper, an experimental test performed on a hybrid steel plate girder was subjected to concentrated loads at the end of an unstiffened panel is presented. This load was intended to produce a typical reaction of the piers while launching steel girders in bridges. In this test, strain measurements were taken with conventional pre-wired gauges as well as with newly developed wirelessly connected strain-measuring system. Both measurements were carefully compared and the accuracy of the developed system was demonstrated. Results were also compared with numerical simulations deployed with FE models and on such a basis; the reliability of the developed wireless system was proven. Finally, suggestions of potential research trends in this area are provided.

European design rules EN1993-1-5 allows the usage of FE-Analyses as reliable tools in the verification of limit states of plated structures. Throughout the modelling of these structures, certain initial conditions must be assumed. Consequently, engineering judgment is needed to some degree. This paper presents an assessment of the influence of these conditions on the ultimate load capacity of steel plate girders when subjected to patch loading. The basis of the research is a thorough comparison between theory and design rules by means of experimental and numerical results. The results obtained prove usefulness for practical and academic purposes alike.

This paper summarizes and presents main results of the investigation conducted in the Department of Construction Engineering of the UPC dealing with shear behaviour of stainless steel plate girders. Initial shear buckling stress together with ultimate shear capacity of these structural elements have been evaluated with special attention paid to the effect of including stiffeners, both transverse and longitudinal. The studies conducted, both numerical and experimental tests, have permitted the development of new and simple design expressions to determine more accurately the initial shear buckling stress in stainless steel web panels and the ultimate capacity of plate girders considering the presence of a rigid or non-rigid end post.

This paper summarises and presents main results of an in-depth numerical analysis dealing with the shear buckling resistance of stainless steel plate girders. The studies conducted have permitted the development of a simple design expression to determine the critical shear buckling stress in steel web panels. This expression takes into account the effects of the material nonlinearity together with the actual boundary conditions of the web panel given by the geometry of the plate girder by two defined parameters: η and k rss , which is the shear buckling coefficient. Expressions given to obtain η will quantify mainly the effect of the material nonlinearity whereas the proposed analytical expression of k rss will reproduce principally the influence of the real boundary conditions in a web panel.

During the last few decades, owing to their several advantages, composite columns have gained acceptance for high-rise buildings as an alternative to steel or reinforced concrete columns. When a composite column is subjected to an eccentrically applied sustained axial load, its structural response must undergo both a short-term and long-term analysis. The study presented in the current paper aims to evaluate the short- and long-term response of concrete-encased composite columns. A numerical model previously developed and experimentally verified is systematically used within this work. This model is capable of developing non-linear and time-dependent analyses on reinforced concrete frame structures. In order to verify the obtained numerical results for this particular case, a series of experimental results on concrete-encased composite columns are compared with those derived numerically. Once verified, the model is used as a simulation tool to analyse in depth the structural short- and long-term response of composite columns. Finally, based on the present study, conclusions about design criteria for concrete-encased composite columns are drawn.

To better understand the response of stainless steel plate girders loaded in shear, an experimental campaign was carried out at UPC as a part of extensive research on shear behaviour of stainless steel girders. A total of 8 stainless steel plate girders were tested. The primary design variables were, apart from the aspect ratio and slenderness of the web panel, the rigid or non-rigid condition of the end post. In parallel, a numerical model was developed in code ABAQUS [Hibbit, Karlsson and Sorensen Inc., ABAQUS/Standard, Version 6.3. User’s manual. Rhode Island (USA); 2002]. The tests results served as a basis for calibration of numerical models and furthermore for the development and verification of a new approach to structural stainless steel design. Different responses and modes of failure in shear were observed and special attention was taken of the effect of the rigidity of the end post during the analysis of results. The comparative analysis of the experimental results with current codes’ approaches clearly shows that shear design procedures included in Eurocode 3 Part 1.4 [European Committee for Standardisation. ENV 1993-1-4. Eurocode 3: Design of steel structures. Part 1.4: General rules—supplementary rules for stainless steel. Brussels; 1996], which specifically deals with stainless steel structures, are overly conservative.

Resistance to shear is one of the most important load cases to be considered when designing slender steel plated structures, but this issue has not been widely studied in stainless steel structures due to its recent introduction into construction as structural material. This paper presents an experimental and numerical investigation to study the response of stainless steel plated girders subjected to shear load near service conditions and their evolution up to failure developed in the Laboratory of Structural Technology of the Department of Construction Engineering in the Universitat Politecnica de Catalunya (UPC). Experimental results have been compared with those derived from the application of ENV 1993-1-4 and with the results derived from the numerical model. Some conclusions can be reached from the investigation on shear strength of stainless steel plated girders. Moreover, a new expression for the critical shear buckling stress in simply supported stainless steel plates is presented and a comparative analysis among different design methods to determine shear resistance has been performed.

After the deep analysis and evaluation of the experimental and numerical results obtained during the described experimental campaign [Estrada I, Real E, Mirambell E. General behaviour and effect of rigid and non-rigid end post in stainless steel plate girders loaded in shear. Part I: Experimental study. Journal of Constructional Steel Research 2005 [submitted for publication]], an extended numerical analysis in code ABAQUS [Hibbit, Karlsson and Sorensen Inc., ABAQUS/Standard, Version 6.3. User’s manual. Rhode Island (USA); 2002] has been carried out dealing with the evaluation of the postbuckling strength in stainless steel plate girders. Finally, a proposal of design expressions for predicting their ultimate shear capacity is made since current design specifications dealing with shear resistance included in Eurocode 3, Part 1–4 [European Committee for Standardisation. ENV 1993-1–4. Eurocode 3: Design of steel structures. Part 1.4: General rules—supplementary rules for stainless steel. Brussels; 1996] have been demonstrated to be overly conservative. Taking special attention of the material non-linearity and the rigid or non-rigid condition of the end post, specimens covering a wide range of slenderness and aspect ratios ( a / d from 0.5 to 3.0) have been numerically tested. Austenitic and Duplex stainless steel grades, which are the most commonly used in construction, have been evaluated during the whole analysis development. Finally, a new design proposal based on the Rotated Stress Field model developed by Hoglund [Hoglund T. Shear buckling resistance of steel and aluminium plate girders. Thin-Walled Structures 1998;29(1–4):13–30], adequately adapted to the particular features of stainless steel is presented in order to reach a more optimum use of this relatively modern resistant material in construction.

En este trabajo se realiza un estudio del comportamiento de conectores tipo perno de estructuras compuestas de hormigon y acero mediante la simulacion numerica del ensayo push out en seccion viga-losa maciza de hormigon. Se analiza el comportamiento de los materiales en regimen no lineal, empleandose en un primer caso un modelo bilineal con criterio de rotura de Von Mises para el acero y el hormigon, y en un segundo caso un Modelo de Dano Plastico para el hormigon. Como herramienta para la modelacion numerica se emplea el programa computacional ABAQUS. Se aborda el procedimiento metodologico de modelacion numerica del ensayo de conectores. Se observa una buena correspondencia existente entre los resultados numericos y experimentales, evidenciandose la efectividad del uso del Metodo de Elementos Finitos para el estudio del comportamiento de conectores. Finalmente, respaldado por los estudios numericos y experimentales, se realiza unavaloracion de precision en la estimacion de la capacidad resistente de los conectores obtenida a partir de las normativas: AISC-LRFD (2005), Eurocodigo 4 (2004) y la Normativa Ramal Cubana NR-080-2004, observando que dichas normativas sobreestiman este valor en muchos casos. Rev. ing. constr. [online]. 2015, vol.30, n.1, pp. 53-68. ISSN 0718-5073. http://dx.doi.org/10.4067/S0718-50732015000100005

Stainless steels are ideal for sustainable structural performances due to their excellent corrosion resistance, appropriate mechanical properties, aesthetic appearance and easy maintenance. However, the nonlinear behaviour and strain-hardening effects characterizing these materials make them different from carbon steel and some specific guidance is necessary. Although some investigations regarding the behaviour of stainless steel beam-columns subjected to combined compression and bending moment have already been published, most of them are based on the most commonly used austenitic and duplex grades. Hence, the work presented in this paper deals with the flexural buckling resistance of ferritic stainless steel RHS and SHS columns subjected to combined loading. The assessment of several design approaches codified in EN1993-1-4 and proposed in the literature has been conducted by comparing numerical results with the predicted ultimate capacities. The partial safety factor gamma(M1) currently coded in EN1993-1-4 has been found to provide unsafe ultimate flexural buckling resistance predictions and new coefficients for the k interaction factor for ferritic RHS and SHS elements are proposed.

The present investigation studies the effect of the material non-linearity on the deflection calculation of stainless steel beams. A comparative analysis of experimental results and those obtained by means of different analytical methods is presented. This comparative analysis includes experimental results on deflection obtained from several tested stainless steel beams. The methods studied are the simplified method proposed in Eurocode 3, Part 1-4, ENV-1993-1-4: Design of Steel Structures. General Rules–Supplementary Rules for Stainless Steel, and different methods based on a numerical model that takes into account the material non-linearity. Finally, a new method for calculation of deflections considering the material non-linearity is proposed. It is based on an analytical expression of the moment–curvature relationship for stainless steel cross-sections.