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Kennedy, Stephen J.; Martino, Aldo E.SPS bridge decks for new bridges and strengthening of existing bridge decksSteel Construction1/201521-27Articles

Kurzfassung

The sandwich plate system (SPS) is a structural composite material made up of two metal plates bonded to a polyurethane elastomer core. SPS delivers high strength and stiffness, making it an excellent alternative to conventional stiffened steel and reinforced concrete. For strengthening of orthotropic bridge decks, SPS Overlay can be used to create a stiff bridge deck without removing the original plates. The renewed deck improves the distribution of wheel loads across the longitudinal stiffening elements, decreases deck curvatures associated with large concentrated wheel loads, extends the fatigue life of fatigue-critical welds and increases the life of the wearing surface and the whole bridge. For new bridge applications, prefabricated SPS bridge deck plates reduce the dead load by up to 70 % compared with concrete bridge decks, thus allowing bridges to carry significantly greater live load without the need for girder or pier strengthening. Deck replacement can be completed while leaving the steel or concrete girders in place or, where speed of erection is critical, pre-assembled longitudinal deck-girder units can be used.

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Lener, GerhardSteel bridges - numerical simulation of total service life including fracture mechanic conceptsSteel Construction1/201528-32Articles

Kurzfassung

The assessment of the total service life of a steel structure should gain importance in the near future due to the increasing significance of building preservation and building modernization. The main cause of the failure of existing structural steelwork under cyclic loading effects is material fatigue. Most steel structures are, however, failure-tolerant. For economic reasons, this behaviour can be considered by including the crack propagation phase in the assessment. This contribution presents newly developed software tools and the results of some simulations of the total lifetimes of existing structures.

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Mano, Toshihisa; Mangerig, IngbertTensile load-carrying behaviour of elastomeric bearingsSteel Construction1/201533-41Articles

Kurzfassung

Elastomeric bearings for seismic isolation applications can be subjected to tensile loads depending on the geometrical configuration, high vertical seismic motion or excessive horizontal deformation due to the elongated-period horizontal motion. It is a known fact that cavities develop within elastomeric material when it undergoes a certain amount of tensile force in a very constrained condition since a high hydrostatic tensile stress builds up. Once these cavities have developed, the tensile stiffness of the bearing drops dramatically. This paper contributes to understanding this phenomenon itself and its influence on the basic properties of elastomeric bearings. For this purpose, two types of elastomeric bearing were tested and the cavitation phenomenon observed. Moreover, those test results are compared with the FE simulation results from the modified hyperelastic material model with the cavity damage criterion. The two-phase softening model presented here can simulate the real softening behaviour of elastomeric bearings well, and it may even help us grasp a better insight into the cavitation phenomenon.

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Prof. Udo Peil awarded honorary doctorateSteel Construction1/201541People

Kurzfassung

Keine Kurzfassung verfügbar.

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Höglund, TorstenCold-formed members - comparison between tests and a unified design method for beam-columnsSteel Construction1/201542-52Articles

Kurzfassung

In [1] a unified method for the design of steel beam-columns is presented. The method has been checked for rolled steel beam-columns and extruded aluminium beam-columns. It is included in Eurocode 9 [19] for aluminium members and it is proposed to be included also in Eurocode 3 Part 1-3 [16] as well, but then it needs to be checked for typical cold-formed sections.
Cold-formed sections are usually un-symmetric and thin-walled, for instance channel sections or C-shaped sections (lipped channels). When used as compression members, local buckling causes a redistribution of the longitudinal stress which leads to a shift of the effective centroid. The shift causes overall bending and reduces the column strength when the member is compressed between pinned ends. In fixed-ended columns, however, the shift of the effective centroid is balanced by a shift of the applied force and bending is not introduced [6]. As a result, the strength of fixed-ended channel column exceeds that of a pin-ended column of the same effective length [7].
Using effective width for the flanges of channels e.g. according to EN 1993-1-5 [17] gives conservative result as the centroid of the effective section is too close to the web. The mixed effective width/effective thickness method for outstand elements given in Annex D of EN 1993-1-3 [16] is the basis in the following interpretations.

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Enercon wind turbine erected by Liebherr craneSteel Construction1/201552News

Kurzfassung

Keine Kurzfassung verfügbar.

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Bedair, OsamaAn analytical expression to determine "realistic" shear buckling stress in cold-formed lipped channelsSteel Construction1/201553-58Articles

Kurzfassung

Current North American and European design provisions ignore the rotational restraint when evaluating local web shear buckling stresses in cold-formed steel channels. This paper offers a new analytical expression for computing local buckling shear stresses in cold-formed channel members taking into account the rotational restraints imposed by the flanges and the lips. The expression derived is suitable for hand calculations and can replace current code expressions in order to achieve economical steel designs. Comparisons with existing design formulas currently used in practice for the limiting conditions show a difference within 5 %.

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Phänomenta Science Center in Lüdenscheid, GermanySteel Construction1/201558News

Kurzfassung

Keine Kurzfassung verfügbar.

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Nützel, Oswald; Saul, ReinerLong-term corrosion protection for bridge cables with butyl rubber tapes using the ATIS Cableskin® systemSteel Construction1/201559-64Reports

Kurzfassung

ATIS Cableskin® is a corrosion protection system for bridge cables which uses proven materials to strike out in a new direction. These innovative ideas mean that, for the first time, corrosion protection work on scaffolds and in enclosures will be a thing of the past, and the costs and traffic restrictions are massively reduced. It is worth highlighting the extremely long lifetime of this corrosion protection.

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Winterstetter, Thomas; Alkan, Mustafa; Berger, Radu; Watanabe, Maiko; Toth, Agatha; Sobek, WernerEngineering complex geometries - the Heydar Aliyev Centre in BakuSteel Construction1/201565-71Reports

Kurzfassung

The present paper describes the engineering design by Werner Sobek for the new Heydar Aliyev Centre in Baku, a masterpiece of 3D freeform architecture by Zaa Hadid.

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EUROFER: Chinese steel imports confuse buyers in Europe as Chinese steel producers exploit the export tax regimeSteel Construction1/201571News

Kurzfassung

Keine Kurzfassung verfügbar.

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ECCS News: Steel Construction 1/2015Steel Construction1/201572-74ECCS News

Kurzfassung

Events
Announcements
Technical Committees (TC) activities
TC News

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Call for entries: European Steel Design Awards 2015Steel Construction1/201574-76News

Kurzfassung

Keine Kurzfassung verfügbar.

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Announcement: Steel Construction 1/2015Steel Construction1/201576Announcement

Kurzfassung

Keine Kurzfassung verfügbar.

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ECCS individual membershipSteel Construction1/201576News

Kurzfassung

Keine Kurzfassung verfügbar.

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Contents: Structural Concrete 1/2015Structural Concrete1/2015Contents

Kurzfassung

Keine Kurzfassung verfügbar.

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Annual table of contents 2014Structural Concrete1/2015Annual table of contents

Kurzfassung

Keine Kurzfassung verfügbar.

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Müller, Harald S.From accomplishments to challengesStructural Concrete1/20151Message from the fib President

Kurzfassung

Keine Kurzfassung verfügbar.

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Ignatiadis, Anett; Fingerloos, Frank; Hegger, Josef; Teworte, FrederikEurocode 2 - analysis of National AnnexesStructural Concrete1/20153-16Technical Papers

Kurzfassung

Eurocode 2 consists of four parts that have to be applied in conjunction with the respective National Annexes of the CEN member states. The National Annexes were introduced, in particular, to maintain national safety levels and to account for regional aspects in the different states.
The CEN (European Committee for Standardization) will revise and extend all structural Eurocodes by 2018. As part of that process, two main objectives for revising Eurocodes have been formulated: a reduction in the number of Nationally Determined Parameters (NDP) and improving the “ease of use”.
In order to reduce the number of NDP, improve the ease of use and allow for further harmonization without changing the main structure and the design models of Eurocode 2, the National Annexes of EN 1992-1-1 for the different CEN member states have been compared and analysed. Furthermore, the analysis of the National Annexes may help to identify some main aspects for the revision of Eurocode 2.
This paper summarizes the analysis of the National annexes of EN 1992-1-1 and makes first proposals for further harmonization.

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Wang, Lijie; Caspeele, Robby; Van Coile, Ruben; Taerwe, LucExtension of tabulated design parameters for rectangular columns exposed to fire taking into account second-order effects and various fire modelsStructural Concrete1/201517-35Technical Papers

Kurzfassung

Fire, as one of the most severe load conditions, has an important impact on concrete structures. Not only does a fire affect the material strength, it affects structural stiffness and stability as well. A concrete column, compared with other structural members, in most cases has to cope with both vertical forces and bending moments transferred by slabs and beams. Consequently, it is essential to find a reliable and practical way of establishing interaction curves for the overall structural behaviour of concrete columns subjected to fire. In this paper, a cross-sectional calculation method based on the material models of Eurocode 2 is explained and adopted in order to calculate interaction curves for a typical rectangular column exposed to the ISO 834 standard fire. Subsequently, an iterative approach is introduced to develop interaction curves taking into account second-order effects in the case of all the four faces of a column exposed to fire. The maximum permissible slenderness ratios for columns in different fire durations are obtained and compared with Eurocode 2 provisions. Finally, this method is used to calculate the maximum permissible slenderness ratios for columns exposed to hydrocarbon and natural fires.

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Duplan, François; Abou-Chakra, Ariane; Turatsinze, Anaclet; Escadeillas, Gilles; Brûlé, Stéphane; Javelaud, Emmanuel; Massé, FrédéricOn the use of European and American building codes with low-strength mortarsStructural Concrete1/201536-44Technical Papers

Kurzfassung

The standard European building specifications, grouped in a nine-volume Eurocode, describe different approaches for determining the properties of commonly used building materials such as steel, aluminium, concrete, etc.
The American Concrete Institute (ACI) also offers different reports concerning concrete structures (ACI 318R), lightweight concrete (ACI 213R) and the long-term mechanical behaviour (ACI 209R) of concrete. Those reports, used as building codes, are applicable when the properties and composition of the material respect various criteria.
All those materials that do not meet the scope criteria of Eurocode 2 or ACI reports because of their composition, property values or application cannot be used in the design of structures with those building codes. Regarding cement-based materials, concretes and mortars whose compressive strength is lower than the minima might not be useful for structures; however, they present an interesting potential for applications such as infrastructure materials, slabs-on-ground, etc. When designing structures and infrastructures in those materials, the accuracy of any formula offered by those building codes should be checked before being used.
This article compares experimental measurements and predictive formulas for the engineering properties (compressive and tensile strengths, modulus of elasticity). The results show that the addition of specific aggregates with low stiffness and strength modifies the relation between those engineering properties, thus reducing the accuracy of some of the predictive formulas suggested in ACI reports or Eurocodes.

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Cairns, JohnBond and anchorage of embedded steel reinforcement in fib Model Code 2010Structural Concrete1/201545-55Technical Papers

Kurzfassung

This paper describes the changes to design provisions for embedded steel reinforcement in the fib Model Code for Concrete Structures 2010. The changes introduce new coefficients for steel grade and clear spacing between bars, and extend the range of concrete strengths covered. The way in which the contribution of hooks or anchorages is calculated has been revised and the contribution of end bearing to laps and anchorages of compression bars is recognized. The revised rules represent a move away from a distinction between laps and anchorages per se towards a distinction based on the presence or absence of transverse pressure perpendicular to the bar axis within the bond length. The benefits of staggering laps with only a proportion of bars lapped at a section are also reviewed. Finally, the potential impact of lap and anchorage performance on structural robustness is discussed, and it is concluded that this can only be achieved if bar yield precedes splitting mode bond failures.

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Prince, M. John Robert; Singh, BhupinderBond behaviour of normal- and high-strength recycled aggregate concreteStructural Concrete1/201556-70Technical Papers

Kurzfassung

The effect of concrete grade on the bond between 12 mm diameter deformed steel bars and recycled aggregate concrete (RAC) has been investigated with the help of 45 pullout tests with concentric rebar placement for coarse recycled concrete aggregate (RCA) replacement levels of 25, 50, 75 and 100%. For all the three concrete grades, the measured bond-slip relationships indicate similar mechanisms of bond resistance in the RAC and the natural aggregate (NA) concrete. The most accurate and least conservative predictions of the measured bond strengths were obtained from the local bond-slip model in the fib Model Code for Concrete Structures 2010. Bond strength normalized to fc(3/4) resulted in an improved match with test data and increased with an increase in the RCA replacement levels and decreased with an increase in compressive strength. An attempt to explain this behaviour has been sought in terms of brittleness index, an analogous parameter from rock mechanics. An empirical bond stress versus slip relationship has been proposed for the 12 mm diameter bar and it is conservatively suggested that similar anchorage lengths for this bar in all three concrete grades can be adopted for the RAC and the NA concretes.

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Mihaylov, BoyanFive-spring model for complete shear behaviour of deep beamsStructural Concrete1/201571-83Technical Papers

Kurzfassung

This paper presents a five-spring model capable of predicting the complete pre- and post-peak shear behaviour of deep beams. The model stems from a two-parameter kinematic theory (2PKT) for the shear strength and displacement capacity of deep beams under single curvature. Four of the springs of the model represent the shear resistance mechanisms of the beam, while the fifth spring models the flexural behaviour. The model predicts not only the load-displacement response, but also the deformation patterns of the beam and how these patterns change with increasing load. Validation studies are performed by using 28 tests from the literature, showing excellent results. The model is used to interpret the tests and to draw conclusions about the behaviour of deep beams. It is shown that shear strength variations of up to 60 % between nominally identical specimens can be caused by variations in the path of the critical shear cracks. It is also demonstrated that loss of bond of large reinforcing bars increases the shear capacity of deep beams. Finally, the five-spring model is shown to predict the post-peak shear behaviour effectively, which is important for the analysis of structures under extreme loading.

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Zhou, Lin-Yun; Liu, Zhao; He, Zhi-QiFurther investigation of transverse stresses and bursting forces in post-tensioned anchorage zonesStructural Concrete1/201584-92Technical Papers

Kurzfassung

In the post-tensioned anchorage zone, the load transfer path of an anchor force can be visualized by an infinite number of isostatic lines of compression (ILCs). The method was initially proposed by Guyon and recently attracted significant interest from a number of researchers. Based on the work of these predecessors, an updated mathematical model has been proposed in order to analyse the bursting forces and the distribution of transverse stresses in the anchorage zone. Compared with the results of a finite element analysis, the updated equations are more accurate than the previous ones. Based on the observation that the sixth-order polynomial expression is better than the fourth-order one, as far as the solution of bursting stresses is concerned, it can be reasonably postulated that a de facto function of the ILCs must exist. Additionally, it is equally interesting that the bursting forces derived with the updated analytical model are the same as those obtained with the formula in the current AASHTO-LRFD Bridge Design Specifications based on numerical stress analyses.

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