This article reviews prior research on connections between through-plates and circular hollow sections (CHS) and presents a finite element (FE) study validated against laboratory experiments. The FE analysis indicates that, for a given geometric configuration, the behaviour of through-plate-to-CHS connections closely matches the sum of branch-plate-to-CHS connection behaviour in plate tension and compression. A connection design strength, which is shown to be valid for a wide range of connection geometries and which is the sum of existing design recommendations for branch plate-to-CHS connections loaded in axial tension and compression, is hence proposed for through-plate-to-CHS T-connections. This therefore enables maximum advantage to be taken of the capacity of this type of “reinforced” tubular connection.

In many practical applications, columns are often fixed to a practically rigid concrete structure at the column base. This additional restraint should increase the real load-carrying capacity if the section is susceptible to lateral-torsional buckling. However, this effect is rarely taken into account in design, as most current design rules do not provide sufficient guidance on how to account for this additional rigidity, and so the column base fixity is often ignored. The background to the verification formulae for lateral-torsional buckling (LTB) of I-section beam-columns in Eurocode EN 1993-1-1 consists of comprehensive parametric numerical studies for members with “end fork” conditions only, i.e. for members with free rotational and warping deformations at both ends. However, these specific boundary conditions are not clearly mentioned in the code.
In the study presented in this paper, a comprehensive series of numerical FEM analyses for the realistic lateral-torsional buckling behaviour of beam-columns with one-sided rotation and warping restraints was carried out and compared with the results based on the LTB resistance of the Eurocode, calculated with increased idealized buckling loads (Ncr, Mcr) that account for the end restraints. The most important results of this study are presented in this paper and the ultimate capacity is compared for two different beam-column design methods in Eurocode 3: the interaction concept (EN 1993-1-1, 6.3.3) and the general method (EN 1993-1-1, 6.3.4).
In addition, a simplified formula is given for the additional bi-moment at the end restraint, which is to be used for designing the welded joint. Finally, an improved LTB design curve (buckling reduction factor &khgr;LT) is presented, developed at the authors' institution, which may be used for the cases studied.

Underpressure in a tank with a fixed roof may arise in the final stage of its construction as well as during its usage. After completing the construction, when the tank is empty and all manholes and valves, through which air could get into the tank, are tightly closed, underpressure may arise in the case of a sudden change in the weather (air pressure and temperature), which is particularly dangerous in spring or summer. When the tank is in use, underpressure may arise if breather valves are obstructed, e.g. covered by snow during pumping out a product stored in the tank. Underpressure may cause extensive deformations of the shell or the roof of the tank. However, the shell undergoes deformation more frequently, since the roof has a stiff supporting structure.
This article presents stages of deformations of the tank shell and their development from the occurrence of the first deformation to either removal of the causes of underpressure or cracking of the steel shell and thus automatic equalization of pressure inside the tank with atmospheric pressure.

During high wind or earthquake action, high-rise multi-storey buildings respond with relatively large storey drifts. The building envelope, in this case a curtain wall, exposed to this in-plane shear resists the action with its drift capacity. This paper describes tests on two different configurations of a newly developed unitized curtain wall, “Qbiss Air” (QAir), using three different cyclic protocols. The protocols were derived on the basis of the serviceability limit state for regions with moderate to high wind and seismicity. The details and configuration influence the response of the system significantly, so the design of the structure can provide accurate information for the design of such systems.

The applicability of extended stiffened end plate (ESEP) connections used as link-to-column connections in eccentrically braced frames (EBFs) with long (flexural yielding) links is examined in this paper. A finite element method (FEM) is used for this purpose, based on a validated parametric FE benchmark. Analysing the numerical model of an ESEP connection designed to the recent seismic design rules for special moment frames reveals that the link-to-column connections of EBFs sustain more severe conditions than the moment connections of moment-resisting systems. The design approach implemented is examined and the results are discussed. The results demonstrate that ESEP connections can be used as a successful alternative for the link-to-column connections of EBFs and the system with this type of connection can achieve the required rotations for long or flexural links.

This paper looks at the problem of connection flexibility in steel-concrete bridge girders under moving loads. The static action of the load changing location on the structure is considered. An analytical model of the girder is used assuming strain discontinuity at the steel-concrete interface as a result of beam-plate partial interaction. The effects of a flexible connection are characterized by the proposed index defined on the basis of the internal forces in the girder. This index can be calculated during loading tests on the basis of the neutral axis position at the section of the girder considered. Numerical analyses show that values of the index characterizing beam-plate interaction depend on the position of the load on the structure and the function describing connection stiffness.

Woven coated fabrics commonly used for tensile membrane structures are PVC-coated polyester fabrics and PTFE-coated glass-fibre fabrics. Regarding the stiffness of these materials, membrane structure experts frequently point out that glass/PTFE fabrics are “stiffer” than PES/PVC fabrics. However, this statement cannot be verified by existing literature, although numerous publications deal with the stress-strain behaviour of coated woven fabrics. Available stress-strain test data are almost impossible to compare, mainly because published stress-strain data for glass/PTFE refer to materials with higher strengths than the published test data for PES/PVC materials. The aim of the present paper is to compare the stiffness properties of PES/PVC and glass/PTFE fabrics with identical tensile strength properties by means of theoretical investigations and uniaxial tensile tests. The results demonstrate that glass-fibre fabric indeed exhibits a higher tensile stiffness than comparable polyester fabric for typical working stress ranges between the prestress level and the maximum design strength. However, for lower stress ranges up to approximately three-quarters of the design strength, the tensile stiffness of glass-fibre fabrics is identical with or even lower than that of comparable polyester fabric. The transverse strain is considerably higher for the glass-fibre fabric throughout.

In the EUR district, in the city of Rome, a complex membrane project is built, different from known tensile projects. In more than 10 years the idea of a light floating cloud inside the glazed congress centre has been developed, and is now going to be realized. This article describes the design process of shape and detail, different trial assemblies and it shows the final layout and the details.

Modern materials are used throughout large building envelopes of today’s and tomorrow’s architecture. Freedom in form combined with the growing selection of materials make this application very popular. Material properties are presented and discussed to allow the specialist engineer to make the right decision when consulting owners and architects. Basic considerations and requirements can take the form of a checklist to make sure that all involved in the design process have the full background and understanding of this process. The presented case studies show a variety of solutions, including some typical material combinations. Clients will be convinced by what they see, and the examples provide an opportunity to further develop the subject, starting from a good base and understanding. The examples cover all common materials and methods, including ETFE, glass-PTFE, PVC polyester, glass-PTFE mesh as well as multi-layer insulated systems.

This paper highlights the processes that are required to take a membrane structure from the design stage to final fabrication. Those processes involve determining the final geometry, developing an approved seam layout, undertaking material tests to determine stretch characteristics and issuing a final set of fabrication documents. The importance of each step is highlighted and the particular issues as they relate to membrane structures are presented. Particular note is made of the benefit that previous experience in this unique form of construction has in bringing a membrane structure to a successful completion. The paper concludes with a few examples of just what can be achieved when all the final stages of fabrication are carefully followed.

This paper summarizes the differences in the design approaches for tensile surface structures between the earliest structures in the 1950s and today’s practice. Current software tools allow more refined and advanced calculations. Nevertheless, a basic hand calculation can clarify the process in a few pages and provide the appropriate key data. A transparent setup allows the form-finding and structural analysis to be redone. The calculation of the cable net for the bandstand by André Paduart (1958) is analysed in this paper as a case study. Both the hand calculation (19 pages) and the numerical simulation are summarized and the design context of the initial and current calculations are described. The approximations made by Paduart resulted in a remarkably intelligible and coherent evaluation of the cable net structure. The historical approach can still be applied for a first verification of a pretensioned cable net or for a membrane structure as the simplified calculation method is similar.

This paper provides a detailed overview of the design and construction of a series of temporary pavilions based on the Tensairity® principle. The pavilions are currently used in the Superbike racing category (Ducati Superbike Team), for the Audi tron Sailing Series, the ISAF Sailing World Cup and for other temporary events (3KIT pavilion). The paper describes the Tensairity® principle, the architectural and structural design of the pavilions, the manufacturing of the components and the assembly of the Tensairity® roofs.

Bearing failure is a form of localized failure that occurs when thin-walled cold-formed steel sections are subjected to concentrated loads or support reactions. To determine the bearing capacity of cold-formed channel sections, a unified design equation with different bearing coefficients is given in the current North American specification AISI S100 and the Australian/New Zealand standard AS/NZS 4600. However, coefficients are not available for unlipped channel sections that are normally fastened to supports through their flanges. Eurocode 3 Part 1.3 includes bearing capacity equations for different load cases, but does not distinguish between fastened and unfastened support conditions. Therefore, an experimental study was conducted to determine the bearing capacities of these sections as used in floor systems. Twenty-eight web bearing tests on unlipped channel sections with restrained flanges were conducted under End One Flange (EOF) and Interior One Flange (IOF) load cases. Using the results from this study, a new equation was proposed within the AISI S100 and AS/NZS 4600 guidelines to determine the bearing capacities of cold-formed unlipped channels with flanges fastened to supports. A new design rule was also proposed based on the direct strength method.

Slotted cold-formed steel studs are used in loadbearing external plasterboard walls. The cold-formed steel studs in these walls are supported by and joined to track sections at the top and the bottom. This paper describes the compression testing of the loadbearing studs in order to observe the behaviour of the studs and the track joints. The experiments included a joint design with a special web stiffener used in practice. The studs were C-sections and the tracks were U-sections. Eight different test series were performed. Each test series had different column lengths and thicknesses, both with and without web stiffeners, in order to establish the influence of these on the joint behaviour and loadbearing capacity of the slotted cold-formed steel studs.

This paper describes a parametric study of the dynamic behaviour of steel pipe rack structures subjected to explosion loading. The pipe rack design is assumed to be a multi-planar lattice girder consisting of rectangular or square hollow sections. Numerical analysis with the finite element method was performed on a series of 54 pipe racks in total, varying parameters such as mass distribution and aspect ratio. The study provides a deeper understanding - and forms the basis for a more accurate prediction - of the dynamic response of multi-planar lattice girder structures such as steel pipe racks.

The development of the “CoSFB-Betondübel” is presented in this paper. The “CoSFB-Betondübel” is a deep-embedded concrete dowel connecting in situ concrete with a steel section to assure composite action and thus allow for composite beam design. The loadbearing behaviour and parameters influencing this behaviour were determined through experimental tests. Special focus was given to the influence of the ratio of the resistance of the concrete dowel to the concrete compression class. The evaluation of the results concluded in a National Technical Approval [1]. Further investigations were performed via FE analysis in ABAQUS. Further, 3D models with non-linear material and geometry were prepared and validation undertaken. In addition, a real application example of CoSFB is shown.

Fretting fatigue is a major obstacle for bolted joints used as an alternative to welding. Several studies of the subject so far have concerned aluminium or titanium joints, but due to the recently developed high-strength steels that can be challenging to weld, the steel industry would also like to explore this field. This paper presents the experimental fatigue test results of double-lap joints in S355 and S960QC steels. The results are compared and analysed using the SWT parameter and an FE model of the test specimen. The noticeable difference in fretting fatigue behaviour of these materials will be explained and the controversial crack initiation issue addressed.

One aim within the RFCS-funded RUOSTE research project was to study the effects of high-strength steel properties on local buckling. The respective parameters were investigated on 34 stub column specimens. The specimens were made of S500MC, S700MC and S960MC, with a non-dimensional local slenderness varying between 0.64 and 1.55. Extensive imperfection measurements were undertaken and analysed. The specimens were then used in stub column tests to investigate the local buckling behaviour. The results were first compared with the resistance curve of the current Eurocode (EC), which was shown to be rather optimistic, especially towards the slender end of the range. Secondly, the results were compared with the general method, which uses an equivalent imperfection approach.

This paper presents a design approach for calculating rectangular hollow section (RHS) splices (bolted end plate connections) under tension forces or bending moments in accordance with EN 1993-1-8. Based on models available in the literature, a Eurocode-conform model is presented using the component method. The original model, based on experimental and numerical investigations, uses a three-dimensional yield line method to predict the tension resistance of bolted splices with hollow sections considering the joint as a whole. The adapted model is fully compatible with EN 1993-1-8. Moreover, the original model has been extended to predict also the design moment resistance of such RHS splices.

The European Directive on the Energy Performance of Buildings (EPBD) obliges the member states to ensure that, by 31 December 2020, all new buildings are nearly zero-energy buildings (nZEB). This paper presents solutions for steel-intensive commercial buildings that achieve this requirement. Several key components such as façades, floor systems and steel piles for ground energy storage were investigated in detail using numerous numerical simulations and practical tests of selected options. Furthermore, options for a whole building which fulfil the zero-energy building approach were identified for different European climates by performing a parametric study using a thermal building simulation tool.

According to EN 1090-2, steel components have to be identifiable and traceable throughout the whole production chain. The choice of identification method is not specified consistently in international rules and standards. In terms of durability and liability, markings should be resistant to particular fabrication processes such as sandblasting, hot-dip galvanizing or coating. The methods are hard stamping, scribing, plasma marking and needling. The effect of the notch caused by the marking process on the fatigue strength of the components has not yet been investigated in detail. As a result, a classification of the notch details in the European detail categories of EN 1993-1-9 is, in principle, impossible. For these reasons, the influence of durable marking methods on the fatigue strength of steel components needs to be clarified by experimental fatigue tests currently being performed at the Institute for Metal and Lightweight Structures, University of Duisburg-Essen. Part of this investigation involves examining the different surface conditions of hard-stamped, scribed, plasma-marked and needled specimens. The experimental investigations are being carried out considering two different steel grades, S355J2 and S460N, and three different steel plate thicknesses, 15, 25 and 40 mm.

This paper presents the design method for slim-floor construction that comprises a steel beam and a concrete or composite floor slab in which the beam is integrated within the depth of the slab. The slabs are either supported on a plate attached to the bottom flange or the bottom flange of the beam itself. The main design parameters and load transfer mechanisms are discussed. Plastic analysis has been adopted for the design of the bending capacity at the ultimate load condition and the design procedures described are in accordance with the principles given in Eurocode 4. Attention is paid to the type of shear connection between steel and concrete.

This article reviews the performance characteristics of and some recent developments in slim-floor and integrated beam construction. This form of construction provides a flat floor using precast concrete slabs or deep composite decking and offers advantages over other forms of construction in many sectors. Composite slim-floor beams have superior stiffness and can achieve longer spans.

Shallow floor beams, abbreviated to SF beams and also known as slim floor beams, are beams where most of the beam member is embedded in the concrete decking of the floor, which is supported on the lower flange or outward ledge of the beam. SF beams are composite members in which composite action can be utilized in both the serviceability and ultimate limit state conditions or only at the serviceability limit state, depending on the decking type. This paper discusses the composite action in SF beams when the decking is of a solid type, i.e. consists of a reinforced concrete slab or composite slab with profiled sheeting, making it possible to benefit from the composite behaviour at all important limit states. Hollow-core decking supported on SF beams is a special case in which the composite action can only be employed in the design for serviceability conditions. Another paper covers the special issues regarding the design of such shallow floors.

Slim-floor structures combine the advantages of prefabricated slab elements with steel-frame construction and lead to economic building solutions fulfilling the demands of modern architecture in combination with transparent structural envelopes without intervening columns as well as implicit flexibility for sustainable construction. Over past years, new slim-floor solutions have been developed to broaden the market for composite structures when compared with conventional concrete flat slabs. However, due to the shallow depth of composite slim-floor girders, their structural response, especially their deflection behaviour, differs from normal composite girders. The concrete is already in the cracked condition under service loads in regions of sagging bending moments. The contribution of the concrete chord to the effective moment of inertia Ii,0 of the composite cross-section and the bending moment Mc in the concrete chord are not negligible for the total loadbearing capacity of the composite section. These two effects are not normally considered when calculating the deflections of composite girders based on the effective width given in codes such as EN 1994-1-1 [1]. Therefore, the following paper will show different methods for calculating the deflection of these shallow types of composite girder.