The 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).

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The 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].

In 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.
The shear behaviour and distribution of forces within the anchor plate are crucial issues in the development of a design concept for steel-to-concrete joints with large anchor plates. The influence of different parameters, such as the dimensions of the anchor plate, the embedment depth of the headed studs or the eccentricity of the shear force, have been studied in several test series. Supplementary reinforcement was placed close to the headed studs in tension to strengthen the load-carrying capacity of the joint. The distribution of the shear forces has been assessed by means of numerical investigations together with the influence of further parameters such as concrete strength and reinforcement ratio. With regard to the load distribution within the anchor plate, elastic and plastic design approaches have been taken into account.
Based on these studies, a suitable design model has been developed for steel-to-concrete joints with large anchor plates and a higher number of fasteners than originally permitted. Owing to the consideration of supplementary reinforcement, in addition to the plastic design approach, an alternative economical solution is given which links the component method according to EN 1993-1-8 to the fastener technique according to EN 1992-4.

This paper presents the experimental and numerical investigations of an innovative composite floor system with deconstructability. In this system, a composite slab formed with metal profiled decking is connected to a steel beam using demountable shear connectors. A series of push tests was conducted to investigate the behaviour of this form of shear connector. In addition to the push tests, a full-scale composite beam was tested to failure in the laboratory under a number of cycles of monotonic loading. For direct comparison, a similar composite beam test was conducted using the same section size and concrete strength, but using conventional welded headed stud connectors. Test results showed that the behaviour of the composite beam with demountable shear connectors is comparable with that of the specimen with welded shear connectors. After the test was terminated, the demountable shear connectors were unfastened and the composite floor could be easily lifted off from the steel beam. Test results showed that these demountable shear connectors possess high ductility in comparison to the equivalent welded shear connectors. Simple design rules currently use in Eurocode 4 for welded shear connections and Eurocode 3 for bolts are proposed to predict the shear resistance of this form of demountable shear connector.

The prefabrication of concrete slabs reduces construction time and the total life cycle cost of composite steel-concrete buildings and bridge decks. Using bolts as shear connectors embedded in prefabricated concrete slabs enables reuse and easy replacement of slabs as structural members suitable for a circular economy construction concept. The results of static push-out experiments on M16 and M24 bolts, grade 8.8, are shown here. The focus is on the validation of advanced finite element (FE) modelling by experiments. Damage material models for bolt and concrete slab were used and the most realistic preloading of the bolts modelled with threads was achieved by turning the nut in the FE model. An explicit dynamic solver with mass scaling function was used for quasi-static analysis including fracture. Two failure modes obtained in experiments - bolt shear and concrete crushing - were realistically modelled by the FEA, which shows that the model is suitable for a parametric study leading to theoretical models of failure modes and slip capacity of the shear connection. Results indicate that the bolts with nuts on both sides of the steel flange can be successfully used as demountable shear connectors.

Grouped headed studs may be successfully utilized to achieve the longitudinal shear connection between prefabricated slabs and steel beams. The behaviour of the studs and the ultimate resistance of the group were analysed using the results of experimental push tests and by employing advanced FE analyses. Different arrangements of studs in the group were investigated, focusing on minimal distance between the studs. It is demonstrated that the full shear resistance of a group of headed studs is achieved even when the distances between the studs are less than the minimum requirement according to EN 1994-1-1. Concrete class C30/37 is the minimum that should be used. Furthermore, the paper presents a new model for calculating the shear resistance of grouped headed studs. The proposed design model is based on an equivalent stud diameter and can be used for various arrangements of headed studs in a group. The shear resistance formula and the requirements for ductility are consistent with the existing Eurocodes. Fatigue loading is not considered in this paper, so the proposed recommendations are valid for buildings including multi-storey car parks.

A new form of shear connection, so-called composite dowels, first appeared in Europe in last decade. It enabled economic construction of steel-concrete composite bridges without an upper steel flange, using a direct connection between steel web and concrete slab. It finally resulted in new economic structural forms and composite sections that had not been used in bridge engineering before. In 2010 the European Commission launched an international project to build three different innovative bridges in three different European countries (Germany, Poland, Romania). Each bridge project was supported by a national consortium consisting of design office, general contractor and university. This economic technology has developed fast: by the end of 2016, at least 34 bridges using composite dowels had been constructed in Europe (13 in Germany, 11 in Poland, 4 in Czech Republic, 4 in Austria, 2 in Romania). These structures use different kinds of composite section that in many cases are not covered by standard design procedures for composite structures. The need for a consistent design method was evident. This leads to a clear design concept that covers the contribution of concrete slabs in transmitting part of the vertical force in composite sections and finally breaks with the concept of a “steel skeleton” constituting the fundamental part of the composite beam. The approach proposed here needs to be as simple and clear as possible, so it assumes some simplifications at this stage. It is intended to cover many types of composite section, externally reinforced section and conventional composite section.

This paper presents the basis for the design of steel and composite beams with large web openings. The main design requirements are the transfer of shear by Vierendeel bending and the control of web buckling next to and between the openings. Cellular beams with regular circular openings are a common example of highly perforated beams and their flange areas are often highly asymmetric. For these beams, web-post moments may be generated to develop the full shear resistance of the cross-section.
Tests on beams with circular, elongated circular and rectangular openings are presented which are used to verify the design methodology. In addition, the openings cause local displacements due to shear and bending, which add to the overall deflection of perforated beams. Simplified formulae are presented to determine the additional deflection relative to the equivalent solid-web beams.

The direct tension indicator (DTI) method is specified in EN 1090-2 as one of the tightening procedures for preloading bolting assemblies to a specified level of preload. As Germany so far has no experience of using the DTI method, recent experimental and theoretical investigations were carried at the Institute for Metal and Lightweight Structures, University of Duisburg-Essen, Germany, with the main focus being the loadbearing behaviour of preloaded bolting assemblies with DTIs under external axial tensile loading. Whereas tension connections employing preloaded bolting assemblies are quite common in Germany, in the UK, for example, bolted connections are preferably designed as shear connections, as far as is known. As a result of the investigations presented below, it can be summarized that, under tensile loading especially, preloaded bolting assemblies with DTIs might suffer from a severe loss of preload - something that should be considered in preloaded bolted connections in which the preload is taken into account in the design of the connections, e.g. in slip-resistant connections, to activate the slip resistance, and in tension connections subjected to fatigue. Based on these investigations, recommendations have been formulated for preloaded bolting assemblies with DTIs under external axial tensile loading.

Kienlesberg Bridge is the new link for trams, pedestrians and cyclists between the inner city and the science centre in the north-west of Ulm. 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.

Events:
worldsteel construction conference 2017
IFiress 2017
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BESTInfra 2017
3rd International Symposium on connections between Steel and Concrete
XI Conference on Steel and Composite Construction

Announcements: Dutch Steel Day
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Technical Committees (TC) activities: PMB - Promotional Management Board
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TC6 - Fatigue & Fracture
TC7 - Cold-formed Thin-walled Sheet Steel in Buildings
TWG 7.5 - Practical Improvement of Design Procedures
TWG 7.9 - Sandwich Panels & Related Subjects
TC8 - Structural Stability
TWG 8.3 - Plate Buckling
TWG 8.4 - Buckling of Shells
TC9 - Execution & Quality Management
TC10 - Structural Connections
TC11 - Composite
TC13 - Seismic Design
TC14 - Sustainability & Eco-Efficiency of Steel Construction
TC16- Wind Energy support structures

TC news: News from TC3 - Fire Safety
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News: Digital design and building: Open BIM or closed BIM?

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BVMB fordert sofortigen Stopp von ÖPP-Projekten
Deutlich mehr Wohngebäude bereits energetisch saniert
Hoher Auftragsbestand, aber weiterhin keine besseren Preise

Straßen sind Hauptbestandteil des weltweiten Verkehrswegenetzes und somit ein wesentlicher Bestandteil der Volkswirtschaften. Eine moderne und intakte Verkehrsinfrastruktur leistet einen enorm wichtigen Beitrag zur Wettbewerbsfähigkeit der einzelnen Länder. Untersuchungen zeigen jedoch deutlich: Der Zerfall des internationalen Straßennetzes schreitet voran, zuerst verfallen die Trassen und dann stockt der Verkehr. Besonders drastisch wirken sich Brückensperrungen aus, lange Umwege und Staus müssen in Kauf genommen werden. Die Öffentlichkeit und die Politik haben erkannt, dass es nicht nur um das Rückgrat des Verkehrs, sondern um viel mehr geht: Um Mobilität, Lebensqualität und wirtschaftliche Wettbewerbsfähigkeit. Eine der Kernfragen lautet daher: Wie also können Verkehrswege schneller, günstiger und haltbarer hergestellt und saniert werden? Das System “SmoothRide” der Fa. Topcon wurde speziell für diese Herausforderungen entwickelt.

Arbeitnehmer wollen mehr von ihrem Bruttogehalt haben, Arbeitgeber brauchen motivierte Mitarbeiter. Eine win-win-Situation, wenn Arbeitnehmer und Arbeitgeber eine steueroptimierte Gehaltsumwandlung im neuen Jahr vereinbaren. Die komplizierten Spielregeln wurden nun von der Oberfinanzdirektion Nordrhein-Westfalen konkretisiert.

Die Oberfinanzdirektion Frankfurt am Main weist auf eine brisante Fallgestaltung hin, die in der Praxis vielfach zu erheblichen Steuernachteilen führt. Gemeint sind Abfindungszahlungen an den Kommanditisten einer GmbH & Co. KG, der gleichzeitig Geschäftsführer der Komplementär-GmbH ist und eine Abfindung erhält. Diese Abfindung kann nicht begünstigt besteuert werden.

Die Bundesvereinigung Mittelständischer Bauunternehmen (BVMB) hatte gerufen und erneut waren über 600 Vertreter der mittelständischen Bauwirtschaft nach Bonn gekommen. Beim traditionellen Neujahrsempfang unterstrich BVMB-Präsident Thorsten Bode die Position der Mittelständler am Bau. “Die Auftragsbücher sind voll, aber die Herausforderungen groß”, betonte Bode. Er zeigte sich “enttäuscht” darüber, dass die Politik nach wie vor an mittelstandsfeindlichen ÖPP-Projekten festhält, begrüßte die Gründung der bundeseigenen Infrastrukturgesellschaft Verkehr und übte heftige Kritik am geplanten neuen Bauvertragsrecht. Der Parlamentarische Staatssekretär Norbert Barthle konnte in seiner Festrede aber nur bedingt die Wünsche der BVMB erfüllen.

Auftraggeber schweigt zu Bedenken - was tun?
Muss Baufirma für Mehrvergütung Angebote fingieren?
Bau teurer als Budget des Bauherrn: Architekt haftet
UBB-Ticker: Künftige Baustelle vor Angebot zu besichtigen?

Dass sich steuerlich Jahr für Jahr vieles ändert, ist nichts Neues. Doch 2017 toppt alle bisherigen Steuerjahre. Einer Sonderausgabe des Informationsdienstes “Steuern sparen professionell” zufolge standen mit dem Jahresanfang 2017 sage und schreibe 125 steuerliche Änderungen an. Manche Steueränderungen - meist für Steuerzahler positive - treten sogar rückwirkend in Kraft. Die für die Praxis interessantesten Steueränderungen stellen wir Ihnen in diesem UBB-Überblick vor.

Der Nachtragsbearbeitungsprozess der Deutschen Bahn AG ist ein Dauerbrenner bei den Kritikpunkten der im Bahnbaubereich tätigen Unternehmen. Mit verschiedenen Maßnahmen, die unter den Projektnamen “Nachtragsmanagement 4.0” zusammengefasst sind, beabsichtigt die DB AG in Kooperation mit der Bauwirtschaft, die Nachtragsquote und die Durchlaufzeiten der Nachträge zu reduzieren. Der UBB stellt diese vor.

Wer bauen will, freut sich ungebrochen: Immer noch ist Kapital für Projekte so günstig zu bekommen wie Jahre zuvor nicht. Die Niedrigzinsphase hält weiter an, auch wenn die Zinsen bisweilen dezent wieder anziehen. Für mittelständische Bauunternehmen bedeutet das aber nicht nur eitel Sonnenschein: Die kleinen und mittleren Unternehmen (KMU) haben ihre Finanzierungs- und Banken-Situation 2016 zum zweiten Mal in Folge schlechter als im Vorjahr eingeschätzt. Dies gilt ganz besonders für die kleinen Unternehmen mit bis zu 40 Mitarbeitern und Mitarbeiterinnen. Das zeigen die Ergebnisse des “KMU-Banken-Barometer 2016”. Der Verband “Die KMU-Berater - Bundesverband freier Berater e. V.” hat diese Umfrage unter Unternehmen jetzt zum dritten Mal durchgeführt.

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