Artikeldatenbank
Autor(en) | Titel | Zeitschrift | Ausgabe | Seite | Rubrik |
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Stranghöner, Natalie; Jungbluth , Dominik; Abraham, Christoph; Söderman, Anders | Tightening behaviour of preloaded stainless steel bolting assemblies | Steel Construction | 4/2017 | 319-332 | Articles |
KurzfassungPreloaded bolting assemblies made of stainless steel are currently not permitted in steel structures due to the unknown viscoplastic deformation behaviour as well as the unknown tightening behaviour and tightening procedures for these kinds of bolting assemblies. Nonetheless, the construction industry wishes to carry out these types of connections in special cases, e.g. when special requirements exist with regard to corrosion resistance or for architectural reasons. Generally, the tightening behaviour of carbon steel HR and HV bolting assemblies according to EN 14399-3 and -4 cannot simply be transferred uncritically to stainless steel bolting assemblies due to several reasons. Within the scope of the European RFCS research project SIROCO, extensive investigations are currently being conducted on the tightening and preloading behaviour of EN ISO 4014 and EN ISO 4017 bolting assemblies made of austenitic and duplex stainless steels. First results from this project show that a targeted tightening of such assemblies is in principle possible. Specified preloading levels, e. g. Fp, C* and Fp, C, can be achieved with sufficient reliability using suitable lubricants. Herewith, it is possible to define feasible tightening procedures. Furthermore, it could be shown that these bolting assemblies show sufficient ductility and galling of the assemblies can be for sure avoided. The present paper provides an initial insight into the results of the project. x | |||||
Stranghöner, Natalie; Afzali, Nariman; de Vries, Peter; Schedin, Erik; Pilhagen, Johan; Cardwell, Simon | Slip-resistant bolted connections of stainless steel | Steel Construction | 4/2017 | 333-343 | Articles |
KurzfassungThe use of stainless steel components can lead to a significant reduction of maintenance costs compared to a structure executed in carbon steel. Because of its high material strength, ductility and corrosion resistance stainless steels are becoming more and more popular as a construction material in both building and civil engineering structures. Consequently slip-resistant bolted connections made of stainless steel are becoming more important. Slip-resistant bolted connections are used in joints where slip is not acceptable (because they are subject to reversal of shear load or any other reason) or in joints that are subject to cyclic shear load (to improve the fatigue class of the connecting plates). Existing design codes/standards do not specify slip factors for surface treatments of stainless steel grades, the minimum values of slip factors for common surface treatments/coatings that are specified in EN 1090-2 are exclusively valid for carbon steels. One of the reasons for this is that stainless steel alloys are thought to suffer more than carbon steels from time dependent behaviour (creep and relaxation) at room temperature. This could lead to higher preload losses and consequently to lower slip factors than used for carbon steels with comparable surface treatment. However, no evidence of this can be found in literature. Creep and relaxation are stress dependant phenomena and the stresses in the components of preloaded bolted connections are locally highly non-uniform. Therefore, slip factors of different stainless steel grades have to be determined by experiments to investigate the effects of time dependant material behaviour. In this paper the results of slip factor tests on four stainless steel grades are presented and the influence of surface treatments and the preload level on the slip factor of stainless steel slip-resistant connections is discussed. x | |||||
Hradil, Petr; Chen, Anqi; Baddoo, Nancy | Numerical modelling of stainless steel preloaded bolted connections | Steel Construction | 4/2017 | 344-353 | Articles |
KurzfassungThe use of stainless steel in construction has become more popular in recent years. It is used for a wide range of structural applications in aggressive environments where reliable performance over long periods with little maintenance is required. Although structural design standards are available for stainless steel, currently there are no rules covering the design of preloaded slip-resistant bolted connections because of the lack of knowledge about their long-term viscoplastic behaviour. Viscoplastic creep and stress relaxation in the preloaded bolt assemblies will lead to a certain loss of clamping force and may cause the failure of the connection if not accounted for. This paper presents the development of material models and finite element models for bolt assemblies based on an extensive experimental study of creep, relaxation and tension effects on austenitic, ferritic, duplex and lean duplex steel plates and bars for different loading rates. These models were verified against slip tests with stainless steel bolt assemblies according to EN 1090-2 and then used in a parametric study to extend the scope of the connections investigated. Both experimental programmes were carried out in the European RFCS research project SIROCO (Execution and reliability of slip-resistant connections for steel structures using Carbon Steel and Stainless Steel) as well as finite element calculations. x | |||||
Feldmann, Markus; Schaffrath, Simon | Assessing the net section resistance and ductility requirements of EN 1993-1-1 and EN 1993-1-12 | Steel Construction | 4/2017 | 354-364 | Articles |
KurzfassungIn Eurocode 3 the strength functions are derived from simple engineering models, which always require a certain degree of material ductility. With regard to high-strength steels and the accuracy of the design models themselves, several problems are involved due to a lack of sound consideration of the plastification and damage process. Additionally, the current ductility requirements of EC3 obstruct the use of high-strength steels with fy > 500 MPa. Within the current revision of EC3, comprehensive investigations have been conducted to overcome these obstacles. To complement extensive experimental tests, improved numerical methods considering damage mechanics have been used to predict the real plastification and damage process for relevant details. The numerical models were validated by comparing them with experimental results. Subsequently, a parametric study was conducted to investigate the influence of strength and toughness properties separately. It could be shown that the reduction factor of 0.9 to account for the net section resistance can be omitted if cracks can be excluded. Furthermore, it became clear that a strain requirement based on the uniform elongation &egr;u is not appropriate. Moreover, it was revealed that the yield ratio fu/fy has a significant impact on the toughness requirements necessary to reach the full net section resistance. Owing to a lack of minimum upper-shelf toughness requirements in delivery standards, which would secure an appropriate inner damage resistance of the material, a substitution criterion is proposed. x | |||||
News: Steel Construction 4/2017 | Steel Construction | 4/2017 | 366 | ECCS news | |
KurzfassungThe Interactive Blue Book's Back x | |||||
ECCS news: Steel Construction 4/2017 | Steel Construction | 4/2017 | 367-369 | ECCS news | |
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Content: Steel Construction 3/2017 | Steel Construction | 3/2017 | Contents | ||
Jönsson, Jeppe | Eurosteel 2017 Copenhagen - The 8th European Conference on Steel and Composite Structures 13-15 September 2017 | Steel Construction | 3/2017 | 199 | Editorials |
Jensen, Jakob Laigaard; Lambertsen, Jens; Zinck, Morten; Stefansson, Einar | Challenges of water ingress into bridge cable systems | Steel Construction | 3/2017 | 200-206 | Articles |
KurzfassungExperience with the operation and maintenance of cable-borne bridges of various ages over the last 20 years shows that water ingress into steel cable systems often occurs and causes a high risk of serious corrosion that may lead to traffic restrictions, extraordinary inspection and maintenance costs and, in the worst case, bridge closures. Examples of such experience cover suspension bridges as well as cable-stayed bridges in the USA, UK, Germany, France, Argentina, Sweden, Norway, Denmark and many other countries. The problem of water ingress is particularly critical as inspections for corrosion in cable systems are difficult to carry out and early warnings difficult to obtain. x | |||||
Ichinose, Luiza Hiroko; Koyama, Masahiro; Sakano, Masahiro | Effectiveness of fatigue retrofits to transverse beam and sway bracing connections in steel bridges | Steel Construction | 3/2017 | 207-215 | Articles |
KurzfassungA great number of fatigue cracks have been found in the welded joints at the top end of web gap plates in the transverse beam connection, at the top end of vertical stiffeners in the sway bracing connection, and at the web penetrations with the transverse beam bottom flange. x | |||||
Fajuyitan, O. Kunle; Sadowski, Adam J.; Wadee, M. Ahmer | Buckling of very short elastic cylinders with weld imperfections under uniform bending | Steel Construction | 3/2017 | 216-221 | Articles |
KurzfassungThe length-dependent behaviour domains of thin elastic cylindrical shells under uniform bending have recently received significant research attention. Ovalization is known to affect very long cylinders that undergo significant cross-sectional flattening before failing by local buckling. This effect is restrained by the end boundary conditions in shorter cylinders, which instead fail by local buckling at moments close to the classical analytical prediction. In very short cylinders, however, even this local buckling is restrained by the end boundary, and failure occurs instead through the development of a destabilizing meridional fold on the compressed side. Although this is a limit point instability under bending, ovalization does not play any role at all. This 'very short' length domain has only recently been explored for the first time with the aid of finite element modelling. x | |||||
Bräutigam, Katharina; Knoedel, Peter; Ummenhofer, Thomas | Plastic behaviour of polygonal hollow sections in bending | Steel Construction | 3/2017 | 222-226 | Articles |
KurzfassungSteel poles made from polygonal sections are an economic alternative to circular hollow sections for use as lighting towers or transmission line pylons. For transmission lines especially, the intention behind the design of the poles is to make them more compact in order to avoid land usage and achieve an inconspicuous appearance. If the pole diameter is reduced, the slenderness of the sections needs to be reduced as well in order to achieve the desired resistance, but increasing the wall thickness disproportionately reduces the cost-effectiveness of the structure. The European design rules for overhead electrical lines [1] do not allow plastic behaviour of stocky sections to be used, which reduces the advantages of compact sections. x | |||||
Announcements: Steel Construction 3/2017 | Steel Construction | 3/2017 | 226 | Announcements | |
Nguyen, Van Vinh; Hancock, Gregory J.; Pham, Cao Hung | New developments in the direct strength method (DSM) for the design of cold-formed steel sections under localised loading | Steel Construction | 3/2017 | 227-233 | Articles |
KurzfassungA consistent and simplified direct strength method (DSM) is proposed for the design of cold-formed (or thin-walled) sections under localized loading, which is called web crippling. The development of this method proposes generalized equations for the design of thin-walled sections under the four different localized load cases: interior one-flange (IOF), end one-flange (EOF), interior two-flange (ITF) and end two-flange (ETF). The same parameters are used in the DSM equations for both the IOF and the EOF load cases. However, the ITF and ETF load cases require different parameters in the DSM equations to predict the capacities of structural members. The equations contain both an inelastic reserve component and a yield load component which are different from those proposed previously in this regard. x | |||||
Christensen, Rasmus Magdal; Nielsen, Mogens Gunhard; Støttrup-Andersen, Ulrik | Effective vibration dampers for masts, towers and chimneys | Steel Construction | 3/2017 | 234-240 | Articles |
KurzfassungSlender steel structures such as masts and towers consisting of or supporting cylindrical elements or chimneys can be susceptible to vortex shedding. Vortex-induced vibrations (VIV) can occur in slender structures because a fluctuating cross-wind force is generated from vortices shed alternately from opposite sides of the structure. Significant VIV occur when the frequency of the vortex shedding is the same as the natural frequency of the structure. If the critical wind speed for VIV often occurs for a structure and the vibration amplitudes caused by the VIV are critical with respect to fatigue, the result can be failure of the structure. An effective method of damping the vibrations can be to install a tuned liquid sloshing damper (TLSD). This paper focuses on the design of a TLSD and compares this with the tuned mass damper (TMD) solution. x | |||||
Grimsmo, Erik L.; Aalberg, Arne; Langseth, Magnus; Clausen, Arild H. | How placement of nut determines failure mode of bolt-and-nut assemblies | Steel Construction | 3/2017 | 241-247 | Articles |
KurzfassungBolt-and-nut assemblies under tension loading can either fail by bolt fracture or thread failure. The latter failure mode is arguably undesirable because it leads to failure at a comparatively low deformation level. Moreover, incipient thread failure is challenging to detect in the case of over-tightening since the bolt remains in the bolt hole after this type of failure occurs. The failure mode of bolt-and-nut assemblies is determined by several well-known factors such as the thread engagement length and the relative strength of bolt and nut. However, one factor that has received limited attention in the literature is the placement of the nut along the threaded portion of the bolt. We have performed a series of direct tension tests on various single M16 bolt-and-nut assemblies where the placement of the nut was varied. Some of the assemblies experienced that placing the nut close to the thread run-out, i.e. near the unthreaded portion of the bolt (the shank), led to thread failure, whereas placing the nut sufficiently far from the thread run-out led to bolt fracture. We carried out finite element simulations of the tests in order to investigate further the mechanisms occurring during failure. In the case where the nut was located close to the thread run-out, the simulations revealed that necking of the bolt affected the effective overlap of the internal and external threads. This effect seemed to contribute to thread failure in both tests and simulations. x | |||||
Odenbreit, Christoph; Nellinger, Sebastian | Mechanical model to predict the resistance of the shear connection in composite beams with deep steel decking | Steel Construction | 3/2017 | 248-253 | Articles |
KurzfassungThe resistance of a typical shear connection with headed shear studs in a composite beam is analysed for the normal case in accordance with EN 1994-1-1. The reducing effect of a trapezoidal metal decking to the ultimate loadbearing capacity is considered with empirically derived reduction factors and equations that were developed between the late 1970s and early 1980s. The RFCS research project “DISCCO” [1] investigated the shear stud resistance with novel types of steel decking. In many cases, the shear resistance predicted by EN 1994-1-1 [2] was not reached in tests. x | |||||
The open-air theatre in Tecklenburg has been refurbished | Steel Construction | 3/2017 | 253 | News | |
Dehan, Véronique; Bourgeat-Lami, Elodie; D'Agosto, Franck; Duffy, Brendan; Fortini, Andrea; Hilton, Sharon; Krassa, Kalliopi; Keddie, Joseph L.; Koh, Ming L.; Lansalot, Muriel; Lee, Michelle; Lesage de la Haye, Jennifer; Martin-Fabiani, Ignacio; Mantzaridis, Christos; Mazeffa, Douglas P.; Sear, Richard P.; Schulz, Malin; Sibbald, Morgan; Skerry, Brian; Thomas, Brett | High-performance water-based barrier coatings for the corrosion protection of structural steel | Steel Construction | 3/2017 | 254-259 | Articles |
KurzfassungThis article provides an overview of the outcomes of a European-funded project called BarrierPlus. A new type of water-based barrier coating was developed for structural steel applications. The advantages of this coating include enhanced moisture resistance, low volatile organic compounds (VOCs) and one-component self-crosslinking free of isocyanates. To enable this performance, a latex polymer binder was uniquely designed without using soap-like molecules, known as surfactants, to form the dispersion. By minimizing surfactants in the coating, the barrier properties were significantly enhanced. The latex was successfully scaled up to 15 kg quantities by an SME, coating formulations were scaled to pilot quantities and a variety of characterization and coating performance tests were completed. A life cycle assessment found that the BarrierPlus coating has a better environmental profile than an industry benchmark solvent-borne coating and showed promising results relative to commercial waterborne benchmarks. x | |||||
ECCS news: Steel Construction 3/2017 | Steel Construction | 3/2017 | 261-264 | ECCS news | |
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Cover Picture: Steel Construction 2/2017 | Steel Construction | 2/2017 | Cover Pictures | ||
KurzfassungThe Kienlesberg Bridge is the new link for trams, pedestrians and cyclists between the inner city and the science centre in the northwest of Ulm, Germany. The bridge crosses a railway junction near the main station and a new high-speed rail link. The geometric boundary conditions lead to unequal spans and complex alignments. Therefore, the scheme that won the design competition, which is now under construction, proposed a bridge made of steel. The superstructure was designed as a semi-integral continuous beam with main girders of varying depth. Owing to the pedestrian and cyclists'path on one side, the orthotropic plate cross-section is asymmetric and the main girders have varying depths. Special calculations and details were necessary for dynamic and noise control reasons. The bridge is being built using incremental launching See article on pages 189-195 (photo: W. Dechau). x | |||||
Content: Steel Construction 2/2017 | Steel Construction | 2/2017 | Contents | ||
Demonceau, Jean-François; Leoni, Graziano; Couchman, Graham; Veljkovic, Milan | Latest developments in research, standardization and practice - A workshop on composite structures, TUD, Delft, 20 October 2017, in honour of Prof. Riccardo Zandonini, chairman of TC11 | Steel Construction | 2/2017 | 91-92 | Editorials |
da Costa, Job Duarte; Braun, Matthias; Obiala, Renata; Odenbreit, Christoph | Design of single-span beams for SLS and ULS using semi-continuous beam-to-column joints - Part 2: Composite beams with variable bending stiffness and joints according to EN 1993-1-8 | Steel Construction | 2/2017 | 93-114 | Articles |
KurzfassungThe objective of this article is to facilitate the use of semi-continuous joints by providing ready-to-use tables and charts for design, which also permit the benefits accruing from the use of semi-continuous composite beams to be directly identified. The relevant features for the design of composite beams, such as bending moment distribution, maximum deflection and natural frequency, are derived analytically. The influence of semi-continuous steel joints on the performance of single-span composite beams is analysed. The article concludes with an example of the use of a new slim-floor beam type - the composite slim-floor beam (CoSFB). The tables and charts derived are applied in this example with the intention of demonstrating the advantages of using semi-continuous joints in combination with composite beams. The present article extends the design of semi-continuous steel beams presented in the previous article on this subject [1]. x | |||||
Ruopp, Jakob; Kuhlmann, Ulrike | Steel-to-concrete joints with large anchor plates under shear loading | Steel Construction | 2/2017 | 115-124 | Articles |
KurzfassungIn industry and plant engineering especially, high flexibility is required at joints between steel and concrete. According to current standards, the maximum number of fasteners is limited to an arrangement of 3 × 3 anchors on an anchor plate. The load-carrying behaviour of large anchor plates under tension, shear and restraining forces was investigated within the scope of the research project “Large Anchor Plates with Headed Studs for Highly Stressed Constructions in Industry and Plant Engineering”. This paper describes the research results obtained at the University of Stuttgart for large anchor plates under shear loading. Findings for large anchor plates under tension and restraining forces are given in [20], which were mainly investigated at the University of Kaiserslautern. x |