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 -. 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 article reports on how the steel industry in Germany, as a key supplier of materials and innovations to the construction sector, is carrying out a comprehensive optimization of the management of pre-competitive cooperative research (CR) on steel applications in the construction industry. A significant aspect of this is the central use of an innovation broker (IB) role throughout the innovation process. The varying project expectations of science and industry and the related IB tasks are identified as part of an interdisciplinary research cluster on the sustainability of steel in the construction industry. A task profile is drawn up for the IB in cooperative research on the basis of various key person concepts from industrial innovation research. It is expected that the consistent implementation of this profile will increase the innovation successes from CR between the steel industry and the construction sector.

The mechanics of large deformation and failure of thin-walled structures and consequent dissipation of kinetic energy has been receiving considerable attention from several investigators, mainly motivated by the considerations of designing for structural crashworthiness and safety in the event of impact or blast loading. Analysis of such phenomena is made difficult by uncertainties in loading as well as the effects of various parameters such as strain rate, inertia, history of loading, annealing and thermal processes and geometry. In this paper I shall share some of the results of large deformation studies on various thin-walled structures of varying geometry and size or plates with various boundary conditions, subjected to the impact of drop hammer or projectiles with different features and blast loading. The resulting collapse modes and how they are influenced by various parameters such as annealing and heat treatment, geometry, discontinuities, non-uniformity in thickness and boundary conditions are discussed.

In the member states of the European Union the design of slender steel plates is covered by EN 1993-1-5:2006. One of the main application fields of EN 1993-1-5 are bridges where the design is dominated by slender plated elements. Aside of a general overview on EN 1993-1-5 this paper presents the main results of the European research project COMBRI which can be considered as stepping stone for a large number of research projects in the field of plate buckling and for a systematic development of EN 1993-1-5. The main outcomes are summarised and background information is given for a selected number of improved rules.

This paper summarizes a recently completed research programme carried out at the University of Sydney on drive-in steel storage racks subjected to horizontal impact loads. Impact loads develop frequently during the normal operation of drive-in racks when the forklift truck strikes an upright on entering or leaving a bay, and may lead to local or global collapse. The collapse follows the bowing of the upright which may cause a pallet to drop off the supporting beam rails and initiate progressive collapse down through the bay and possibly into adjacent bays as well.
The research programme comprised full-scale tests on assemblies of a four-bay-wide racking system, tests on system components, the development of finite element models capable of predicting the behaviour of the system accurately, parametric studies of the strengths and stiffnesses of steel storage racks, the development of a simple mechanical model for understanding the dynamic behaviour of the system during impact and a reliability analysis for deriving equations for the design impact loads and associated load factors.
The purpose of the paper is to give an overview of the methodology adapted for the research programme and to present the main findings and final outcome of the research.

Recent events such as natural catastrophes or terrorism attacks have highlighted the necessity to ensure the structural integrity of buildings under an exceptional event. According to the Eurocodes and some different other national design codes, the structural integrity of civil engineering structures should be ensured through appropriate measures but, in most cases, no precise practical guidelines on how to achieve this goal are provided.
At the University of Liège, the robustness of building frames is investigated following the so-called “alternative load path method”, with the final objective to propose design requirements to mitigate the risk of progressive collapse considering the conventional scenario “loss of a column” further to an unspecified event. In particular, a complete analytical procedure has been developed for the verification of the robustness of steel or composite plane frames. For sake of simplicity, these first works have been based on the assumption that the dynamic effects linked to the column loss were limited and could therefore be neglected. More recently, complementary works have been carried out with the objective to address the dynamic effects. Besides, the extension of the static procedure to actual 3D frames is under investigation in Liège. The present paper gives a global overview of the ongoing researches in the field of robustness at the University of Liège and, in particular, the global strategy aiming at deriving design requirements is detailed.

Following a period in which the governing factor was mainly functionality, bridges now seem to be returning to their role of shaping the urban landscape. In line with the change in traffic requirements and possibilities, we are experiencing a revival of the human-scale pedestrian/cyclist bridge as well. In a project supported by the European Union, the longest footbridge in Hungary - in Szolnok - was opened to traffic in January 2011. The total length of the crossing is 450 m, including a 120 m span steel arch over the River Tisza. Besides the description of the structure and its erection, this paper deals in detail with the examination of the pedestrian- and wind-induced excitations - the key issue in the design of lightweight, slender bridge structures.

The use of double split tee (DST) connections in seismic zones may represent an interesting solution from the technological point of view because of easy substitution of damaged components after destructive seismic events. But despite this significant advantage, partial-strength DST connections have found limited application so far because their use requires that tee elements are characterized by high plastic deformation capacity to assure adequate energy dissipation. Therefore, in order to overcome the limitations to the energy dissipation capacity of traditional DST connections due to significant pinching of hysteresis loops and aiming at the development of a structural solution able to withstand severe seismic events without damage to members and connecting elements, this paper proposes two different innovative dissipative solutions for DST connections and investigates their performance by means of an experimental programme whose results are presented and discussed.

The new railway crossing over the River Sado at Alcacer do Sal in Portugal required a 2.7 km long bridge, comprising two approach viaducts and a main bridge. Steel-concrete composite decks were adopted, the approach viaducts having plate girder decks with 45 and 37.5 m spans, and the main bridge three spans of 160 m each with a box girder deck. The main bridge, with a continuous deck over 480 m, consists of three continuous bowstrings with a single plane of hangers on the bridge axis. The main aspects of the bridge concept design are described and the steel design in particular is discussed.

This paper introduces a simplified method for calculating the dynamic response of railway bridges under train service loads. Response spectrum analysis, which has proved itself in structural dynamics, has been adopted for the given problem. If essential parameters such as the natural frequency, mass, span and damping of a bridge are known, the maximum response quantities can be looked up in a diagram. Preparation of the response spectra diagrams is computationally intensive but they do provide an easy and quick way of obtaining accurate results. This method is exemplified for single-span bridges and the load models defined in the Eurocode. However, it is possible to expand the theory to more complex bridge systems and other load models without difficulty. With the aid of this method, the maximum dynamic response of a bridge under moving loads can be calculated in an efficient and convenient way with the accuracy required by the current design codes.

Whereas the European column buckling curves are generally well accepted, the buckling curves given in Eurocode 3-1-1 for lateral-torsional (LT) and torsional-flexural (TF) buckling are still under discussion. This situation stems from the fact that the latter have not been developed with the same broad consensus as the column buckling curves, but had to be provided for the publication of the Eurocode in a rather short time. In the meantime, further research has achieved, on the one hand, a much deeper understanding of the mechanical behaviour and, on the other, a better approach for an appropriate design formulation for member buckling cases in conformity with the code. This paper reports on current developments in new design LT and TF buckling curves that are fully consistent with the background and methodology of the European column buckling curves.

This spectacular covered market set in a beautifully landscaped hilltop of the famous Silk Road is composed of two buildings. The central open air courtyard of the greengrocer market is enclosed by oval shaped covered gallery. The fishmonger market is a smaller building set apart. The design of both markets maintains the idea of the grand bazaars, thus connecting the new buildings to the long-standing cultural traditions of Central Asia. But at the same time the steel spanned arched roof provide fully modern qualities such as space, comfort, light and ventilation.

A new underground station at Střížkov in Prague has been designed and built as a special structure with a high level of aesthetics. The hall structure is 160 m long, 42 m wide and 20 m high. Two crossing hingeless main arches spanning 160 m are fixed to concrete pylons. The roof structure is suspended from the main arches using a system of prestressed rods and supported by columns around the roof. Most of the members are curved with variable cross-sections (the majority of sections are welded boxes with a plate thickness of 10 - 35 mm except the columns, which are welded I-sections). The geometry of all parts made design, fabrication and erection very difficult. The whole structure was built under the direct supervision of the architect. The underground station was opened to the public in May 2008.

Plane grillages and finite element models are widely used for the design of bridges. In a grillage idealization the entire superstructure of the bridge is suitably represented by different sets of bar elements. On the other hand, the finite element method makes use of plane and solid elements for the three-dimensional representation of the structure. Although these models are generally accepted as sufficiently accurate, they are associated with some drawbacks. To overcome the difficulties of plane grillage and finite element analyses, a new way of modelling steel composite bridges is presented in this paper. The proposed model is based on the simulation of steel I-girders through the use of equivalent trusses. The concrete slab is represented by a set of bar elements and the bearings by the use of appropriate springs. Diaphragms and stiffeners may also be taken into account.
This new way of modelling composite bridges using a spatial system of beam-like structural elements allows deformations and internal forces to be predicted reliably, and can be used for dynamic and stability analysis. Worked examples are also provided to illus trate the setup procedure for 3D modelling and to compare the different analysis methods. The work presented in this paper is part of a research project investigating the modelling of steel and composite bridges which is being carried out at the National Technical University of Athens.

The key to harmonizing the rules for the assessment of in-plane and out-of-plane stability of structural steel members is a common definition of equivalent geometric imperfections. The nature of these is given by the elastic-critical buckling mode and their amplitudes are obtained from the evaluation of test results for member resistance according to EN 1990  -  Annex D  -  Basis of structural design.
EN 1993  -  Part 1-1  -  Design of steel structures  -  contains a set of alternative rules for stability checks. Of these, the “general method” could potentially function as a consistent and reliable set of rules for assessing both flexural and lateral-torsional buckling for any loading and support conditions, and also cover the case of combined compression, biaxial bending and torsion. This report describes the basis of the “general method” and its extension to the treatment of any stability problems in bar structures.
The reliability of the method is verified by test evaluations. This means it can be used as reference method for checking the accuracy of the other alternative stability rules in EN 1993-1-1. A comparison shows that the other alternative rules meet the requirements on the whole, with deviations of about ±10 %, which define their modelling uncertainty.

Expressways are typically constructed on high embankments to accommodate transverse box culverts. If the embankment height could be reduced while still accommodating culverts, then the road construction costs could be lowered by reducing the required volume of embankment soil. The authors achieved this by devising a transverse box culvert whose steel-concrete composite sandwich deck slab resembles the composite slabs used for road bridges.
The slab was tested indoors for bending failure, punching shear failure and fatigue strength under cyclic wheel loading. It was tested in an expressway for loading by heavy vehicles. The experiments demonstrated the soundness of the design method.
This paper describes the design and construction of this structure, and the results of the indoor and outdoor experiments.

Vibration due to traffic and wind causes fatigue damage to overhead sign structures mounted on highway bridges. Fatigue damage due to traffic vibration depends on the type and dimensions of the bridge, type of bearings, volume of traffic, location of overhead sign structures, etc. Factors influencing vibration are investigated in this study by carrying out frequency response analyses, with the parameters being the bridge, bridge pier and bearing types, the location of the sign structures and the weight of the electronic information panels. It can be seen that the damage increased after replacing the steel bearings by elastomeric bearings. These factors were verified through frequency response analyses. The results obtained in this study can be applied to the development of measures to prevent fatigue damage in overhead sign structures due to traffic vibration.

The deck plate of steel orthotropic bridges is loaded in fatigue by traffic. Increases in both the traffic intensity and the magnitude of the wheel loads have caused premature fatigue cracking of steel bridges in the Netherlands, mostly on very busy motorways. Overlaying the steel orthotropic bridges with 50 mm of heavily reinforced concrete has proved to be a suitable way of reducing the steel stresses at critical locations in the steel deck plate of fixed bridges. This repair method adds no weight to the bridge because the asphalt is simply replaced by a concrete layer.
The self-weight of the overlay has to meet strict demands in the case of movable bridges because the wearing surface is only a few millimetres thick. Reducing the depth of the overlay might be effective provided the reinforcement is not susceptible to corrosion. Suitable types of reinforcement were researched in an earlier study in which the bending stiffness of the composite structure, the strength of the steel-concrete interface layer and the bond between the reinforcement and the concrete were investigated in static experiments. The study of the fatigue behaviour of the composite section (concrete layer + steel deck plate) will be discussed in this article.

The ability of thermally sprayed zinc and aluminium to protect steel against corrosion has been exploited for almost 90 years. By further protecting the zinc and the aluminium with paint, some corrosion engineers have expected a service life of at least the sum of the life of the metal plus the life of the paint. Experiences and recent results from research activities have shown that aluminium further coated with thick paint can have a very short life when used in seawater or marine atmospheres.

Steel trusses and other structures with angle section members are usually designed by elastic methods. This may lead to uneconomical designs when these sections are subjected - besides the axial force - to biaxial bending arising not only from eccentric connections, but also from direct transverse loading. This paper provides a simple inelastic interaction formula, Eq. (14), as well as an enhanced inelastic formula, Eq. (27), for the combination of axial force and bending moments about the principal axes which may be used for angle cross-sections of classes 1 or 2. The formulae do not always exhaust the full plastic cross-sectional resistance but do lead to a more economical design of the section, especially when bending is dominant. The formulae cover only the design of the cross-section and do not address stability considerations.

The motorway viaduct over the Nalón River is 1100 m long and 27 m wide. The longitudinal structural system consists of a single strict composite box that takes advantage of the different properties of structural steel and concrete, going beyond the double composite action systems already in use for a long time. The box girder is enlarged by means of composite trusses connected to the upper slab at both sides of the deck. Longitudinally, the structure can be divided into two sections:
- a 660 m long curving approach section over the river plain
- a 440 m long straight section crossing the riverbed. The central part of this section is a 124 m span rigid frame composed of a box girder with varying depth and two elegant piers, one on each side of the river.
The bridge was constructed by launching from both abutments. The launching of the main section, due to the varying depth of the box girder in the main span, required longitudinal auxiliary elements in order to launch it in the same way as the spans of constant depth. A temporary pier was built in the middle of the river in order to reduce the cantilever in the main span to a moderate length. The viaduct construction was completed in May 2007.

This article describes an experimental programme aimed at studying the effect of cover, ratio between diameter and effective reinforcement ratio (&phgr;/&rgr;s, ef) and the influence of stirrup spacing on the cracking behaviour of reinforced concrete elements. The experimental programme was conceived in order to contribute to the debate - fuelled by the publication in recent years of Eurocode 2 EN1992-1-1 and the revision of the Model Code under way when the tests were carried out (and now published as a finalized document) - regarding the influence of these parameters on cracking. Important theoretical aspects are discussed, including where the crack width is estimated by current code formulations and what relevance this may have on the correlation between crack opening and durability of RC structures, especially with regard to structures with large covers. The effect of stirrup spacing, a variable absent from current codes, is also discussed.

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