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Autor(en) Titel Zeitschrift Ausgabe Seite Rubrik
Kurrer, Karl-Eugen Die Tragwerksinnovationen Johann Wilhelm Schwedlers (1823-1894) Leicht veränderte Fassung von [1] - nachgedruckt mit freundlicher Genehmigung von Duncker & Humblot Stahlbau 5/2016 350-359 Berichte

Kurzfassung

In seiner Gedächtnisrede vom 19. November 1894 auf Johann Wilhelm Schwedler (Bild 1) verglich Otto Sarrazin (1842-1921) den am 9. Juni 1894 Verstorbenen mit Werner von Siemens (1816-1892) und Hermann von Helmholtz (1821-1894): Schwedler sei Siemens und Helmholtz geistesverwandt und ebenbürtig, stellten sie doch die Theorie in den Dienst der Praxis. “Schwedlers Schaffen hatte überall streng wissenschaftliche Anschauung zur Grundlage, und ihm in erster Linie ist es zu danken, wenn im Bau- und Ingenieurwesen, namentlich auf dem von ihm besonders gepflegten Gebiete des Eisenbaues, die mathematisch-physicalische Richtung zur vollen Geltung gebracht ist” [2, Sp. 2]. Mit der Verwissenschaftlichung der Technik durch Mathematik und Physik hebt Sarrazin den Hauptnenner im Schaffen von Siemens, Helmholtz und Schwedler hervor. Die Unterschiede liegen in ihrer jeweiligen Handlungsperspektive.
Dies kann durch das Modell der Dreiheit von Industrie, Verwaltung und Wissenschaft veranschaulicht werden (Bild 2): Setzte sich das professionelle Handeln von Siemens aus der Verwissenschaftlichung der elektroindustriellen Praxis und Konstituierung einer Verbandspolitik zusammen (s. Bild 2a), so wurde das Alterswerk von Helmholtz durch den Zug zur Industrialisierung der Wissenschaft und zur verwalteten Wissenschaft geprägt (s. Bild 2c). Hier sei nur auf die 1887 von Siemens, Helmholtz und Karl Heinz Schellbach (1805-1892) angestoßene Gründung der Physikalisch-Technischen Reichsanstalt verwiesen. Dagegen richtete sich Schwedlers Handeln aus der Perspektive eines Spitzenbeamten der preußischen Bauverwaltung in erster Linie auf die Wissenschaft und Industrie (s. Bild 2b). Wie kein anderer Baubeamter deutscher Zunge vor ihm bestimmte bei Schwedler die Wissenschaft das Verwaltungshandeln.
1851 eröffnete Schwedler durch seine - unabhängig von Karl Culmann (1821-1881) (s. [5] u. [6]), Squire Whipple (1804-1888) [4, S. 1051f.] und Dimitry Ivanovich Jouravski (1821-1891) [3, S. 1055] - entwickelte Fachwerktheorie mit einem Paukenschlag die Etablierungsphase der Baustatik (1850-1875) [7]. Kurz zuvor gewann Schwedler den Wettbewerb um den Bau der ersten Kölner Rheinbrücke [8]. In den 1860er Jahren sind es drei bahnbrechende Tragwerksinnovationen Schwedlers, die ihn mit seinen zahlreichen Eisenbauten zur höchsten Instanz des Eisenbaues in Preußen werden ließen und diesem internationales Renommee verschafften: die Schwedler-Kuppel, das Dreigelenksystem und der Schwedler-Träger. Wer war diese Ingenieurpersönlichkeit, welche mit Wissenschaft dem Eisenbau seines Landes den Weg zur Weltspitze ebnete?

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Vorstandswahlen der Bundesingenieurkammer Stahlbau 5/2016 359 Firmen und Verbäde

Kurzfassung

Keine Kurzfassung verfügbar.

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Fritzsche, P. Ersatzneubau der Schiersteiner Brücke Stahlbau 5/2016 360-362 Berichte

Kurzfassung

Keine Kurzfassung verfügbar.

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Brux, Gunther "Haus der Musik" in Regensburg - Neue stählerne Treppe Brand- und Korrosionsschutz Stahlbau 5/2016 363-364 Berichte

Kurzfassung

Keine Kurzfassung verfügbar.

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Werner, Lars Dresdner Stahlbaufachtagung 2016 - Stand und Entwicklung der Europäischen Stahlbaunormung Stahlbau 5/2016 365-367 Berichte

Kurzfassung

Keine Kurzfassung verfügbar.

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"Das Denken in Kräften ist für gute Entwurfsarbeit - nicht nur bei Teleskopen - unerlässlich" Stahlbau 5/2016 368-372 Interview

Kurzfassung

Keine Kurzfassung verfügbar.

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Aus der Forschung: Stahlbau 5/2016 Stahlbau 5/2016 372-373 Aus der Forschung

Kurzfassung

Zukunft braucht Ingenieure und Ingenieure brauchen Zukunft
Optimierung von Jacket-Tragstrukturen für Offshore-Windenergieanlagen
Lean Construction im Rahmen der integralen modellbasierten Projektabwicklung (BIM)
Numerische Untersuchung eines Seeschleusen-Schiebetores bei Schiffsanprall
Untersuchung des aeroelastischen Verhaltens des Rotorblatts einer Windkraftanlage

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Firmen und Verbände: Stahlbau 5/2016 Stahlbau 5/2016 373 Firmen und Verbände

Kurzfassung

Entwurfshilfe zum Einsatz von feuerverzinkten Bauteilen im Stahl- und Verbundbrückenbau

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Termine: Stahlbau 5/2016 Stahlbau 5/2016 374 Termine

Kurzfassung

Keine Kurzfassung verfügbar.

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Contents: Structural Concrete 5/2016 Structural Concrete 5/2016 Contents

Kurzfassung

Keine Kurzfassung verfügbar.

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Taerwe, Luc Message from the Editor-in-Chief Structural Concrete 5/2016 697 Editorials

Kurzfassung

Keine Kurzfassung verfügbar.

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Stucchi, Fernando; Ungaretti, Marcelo Coelho; Fujii, Gilson; Peiretti, Hugo Corres; Martin, José Soriano; Doniak, Sérgio Corinthians Arena - 2014 World Cup, design and construction Structural Concrete 5/2016 698-709 Technical Papers

Kurzfassung

This paper describes the design and construction of the concrete structures of the Corinthians Arena built for the 2014 World Cup. Due to many constraints, the structure was designed, essentially, with prefabricated structural concrete members, some specific elements were designed with structural concrete cast in situ, and some areas, with special construction problems, were designed with composite steel-concrete structures.

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Godycki- wirko, Tadeusz; Nagrodzka-Godycka, Krystyna; Wojdak, Ryszard Reinforced concrete thin-wall dome after eighty years of operation in a marine climate environment Structural Concrete 5/2016 710-717 Technical Papers

Kurzfassung

The paper presents a description of the construction elements of the Gdynia Seaport main hall dome. Firstly, it provides information about the technical condition of the dome's structure. Secondly, it examines the strength analysis of the thin-walled reinforced concrete dome covering. Throughout the last 80 years the building has been exposed to an unfavourable marine climate. The analysis of the state of stress and deformations of several construction elements was carried out using a special model worked out with help of the FEM considering the combination of loads: deadweight, wind and snow, as well as the additional combination: deadweight and hurricane wind of velocity 200 km/h(55.5 m/s). The computed results of static quantities were also obtained according to F. Dischinger's method, which was used in design of the RC Gdynia Seaport dome in 1932. The computational analysis and the assessment of the technical state made it possible to make a decision concerning further safe operation of the building.
To sum up, it can be concluded that the results obtained with the FEM analysis, together with the analysis of the technical state of the 80-year-old dome, made it possible to carry out an assessment of the factor of safety of the dome's reinforced concrete elements. That in turn made it possible to come to a decision on the possibility of its further operation without causing any major local damage. What is more, it confirmed that it was permissible to construct a new dome after the tearing-down of the old one.

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von Greve-Dierfeld, Stefanie; Gehlen, Christoph Performance-based durability design, carbonation, part 3: PSF approach and a proposal for the revision of deemed-to-satisfy rules Structural Concrete 5/2016 718-728 Technical Papers

Kurzfassung

A performance-based safety factor durability design format is proposed and developed with respect to carbonation of concrete. Deemed-to-satisfy rules based on a partial safety factor design approach are developed for the carbonation of concrete. This design format follows the design procedure proposed in EN 1990 [1]. For the design format, the limit state equation for the carbonation is introduced in its probabilistic and safety factor format. The PSF approach has been used to derive design charts. Values for minimum concrete cover depending on material resistance and exposure class are proposed for critical environmental conditions and a design service life of 50 years.

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Qian, Chunxiang; Zhang, Yi; Huang, Haoliang; Qu, Jun; Guo, Jinqiang Influences of superplasticizers on the basic and drying creep of concrete Structural Concrete 5/2016 729-735 Technical Papers

Kurzfassung

The influences of naphthalene-based plasticizers and polycarboxylate acid/salt superplasticizers on the creep of concrete, including basic creep and drying creep, were investigated. The internal relative humidity and pore structure of concrete and the surface tension of the pore solution were tested. The results show that polycarboxylate acid/salt superplasticizers refine capillary pores in concrete and reduce the surface tension of the pore solution, and also restrain internal moisture transmission and redistribution. As a result, creep of the concrete is reduced. Compared with naphthalene-based plasticizer, polycarboxylate acid/salt superplasticizer causes a greater reduction of drying creep, but a smaller reduction of basic creep. This is because the moisture redistribution is quite feeble and quickly balanced in a sealed condition. Concrete with polycarboxylate acid/salt superplasticizer has the lowest creep value because polycarboxylate acid/salt superplasticizer improves the degree of hydration and reduces the porosity of macro pores.

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Daviau-Desnoyers, Dominic; Charron, Jean-Philippe; Massicotte, Bruno; Rossi, Pierre; Tailhan, Jean-Louis Influence of reinforcement type on macrocrack propagation under sustained loading in steel fibre-reinforced concrete Structural Concrete 5/2016 736-746 Technical Papers

Kurzfassung

To meet the growing challenges of sustainability, it is necessary to control and anticipate the cracking problems of structures under sustained loadings. At the structural level, very little information is available regarding the combined effect of SFRC and reinforcement under sustained flexural loading. This paper presents the results of four flexural creep tests on large steel fibre-reinforced concrete beams reinforced with fibres only or in combination with unbonded/bonded prestressing strands or traditional reinforcing bars. The main objective was to assess the influence of the reinforcement type on crack propagation, crack openings and compliance evolution in SFRC under sustained loading. The results show that the driving mechanism behind crack propagation is the same for all beams, regardless of reinforcement type, and is therefore governed by type of fibre concrete.

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Di Carlo, Fabio; Meda, Alberto; Rinaldi, Zila Design procedure for precast fibre-reinforced concrete segments in tunnel lining construction Structural Concrete 5/2016 747-759 Technical Papers

Kurzfassung

This paper presents a procedure for designing precast tunnel segments for mechanically excavated tunnel linings in fibre-reinforced concrete, without any traditional steel reinforcement. Both ultimate and serviceability limit states are considered as well as structural checks at different construction stages of the segment, including demoulding, positioning on floor, storage, transportation, handling and the final stage concerning the loads due to the ground pressure.
The structural checks are performed by means of bending moment-axial force interaction envelopes for both the considered limit states, once the constitutive relationship of the material is defined for each stage. Traditional interaction envelopes are drawn for the ultimate limit state check, whereas for the serviceability limit state check, envelopes obtained by limiting the maximum crack opening and maximum concrete compressive stress are proposed. The shear action is also accounted for by reducing the bending moment-axial force envelope. The possibility of having the assistance of a test procedure for particular loading situations is also proposed. Finally, a case study related to a precast steel fibre-reinforced concrete segment is analysed in order to clarify the procedure and show, practically, how to define the actions and evaluate the interaction envelopes.

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Nguyen, Viet Anh; Jesse, Frank; Curbach, Manfred Experiments to establish the loadbearing behaviour of lightweight sandwich beams using textile-reinforced and expanded polystyrene concrete Structural Concrete 5/2016 760-767 Technical Papers

Kurzfassung

Textile-reinforced concrete (TRC) is a combination of small-grain high-performance concrete (HPC) and high-strength textile reinforcement. TRC enables thin layers and has high tensile and compressive strengths. In this paper, TRC was used for the face layers and combined with a core of lightweight expanded polystyrene concrete (EPC) to create lightweight sandwich beams without special joint reinforcement to connect the layers. The experimental testing of the loadbearing behaviour of this kind of sandwich beam, along with the influence of the shear span-to-depth ratio (a/d) as observed during three- and four-point bending tests, will be summarized. The failure behaviour of the sandwich beams is influenced by the shear span-to-depth ratio, the type of bending test and the tensile capacity of the TRC layer. A diagonal tension failure occurred in experimental beams with 2.6 ≤ a/d ≤ 5.2 in three-point bending tests and 3.1 ≤ a/d ≤ 4.1 in four-point tests. The shear strength of the beams could be conservatively estimated according to the current European standards.

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Ma, Chau-Khun; Awang, Abdullah Zawawi; Garcia, Reyes; Omar, Wahid; Pilakoutas, Kypros Behaviour of over-reinforced high-strength concrete beams confined with post-tensioned steel straps - an experimental investigation Structural Concrete 5/2016 768-777 Technical Papers

Kurzfassung

This study examines the flexural behaviour of high-strength concrete (HSC) beams confined using an innovative steel strapping tensioning technique (SSTT) able to provide active confinement. Twelve over-reinforced HSC beams (fc &equals: 50 or 80 MPa) were designed to fail prematurely by concrete crushing at mid-span. The mid-span region of eight such beams was confined externally using the SSTT with different steel strap confinement ratios, the aim of which was to delay concrete crushing. The test results are discussed in terms of the failure modes, load-deflection response and the concrete and tensile reinforcement strains observed. Although the unconfined beams failed in a brittle manner with no post-peak deflection, the steel straps were very effective at enhancing the post-peak deformation of the SSTT-confined beams by up to 126 %. Moreover, for the beams tested in this study, the use of the SSTT led to failures after yielding of the tensile reinforcement. The proposed SSTT can be used to confine HSC elements where ductility is required.

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Yu, Qiang; Le, Jia-Liang; Hubler, Mija H.; Wendner, Roman; Cusatis, Gianluca; Ba ant, Zden k P. Comparison of main models for size effect on shear strength of reinforced and prestressed concrete beams Structural Concrete 5/2016 778-789 Technical Papers

Kurzfassung

This paper presents a critical comparison of the existing code provisions for the shear strength of concrete beams. The comparison is based on the computerized filtering-out of the inevitable statistical bias from the available multivariate database on shear strength, on an examination of the predicted size effects on shear strength and their underlying hypotheses and on the results of recent high-fidelity numerical simulations of shear failure. In addition to examining the existing models, the present comparison also provides several key considerations for testing the scientific soundness of any model of shear failure in concrete beams, which is necessary for future revisions to the design code provisions.

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Yang, Yuguang; den Uijl, Joop; Walraven, Joost Critical shear displacement theory: on the way to extending the scope of shear design and assessment for members without shear reinforcement Structural Concrete 5/2016 790-798 Technical Papers

Kurzfassung

This paper presents a new theory for the shear capacity of reinforced concrete members without shear reinforcement. While recognizing that there are multiple failure mechanisms, the theory attributes the opening of a critical flexural shear crack as the lower bound of the shear capacity. It proposes that the shear displacement of an existing flexural crack can be used as the criterion for the unstable opening of the critical flexural shear crack. Based on the theory, the paper presents a simplified shear evaluation model. Compared with the current shear provisions in the design codes, the model is characterized by good accuracy and a solid physical background. It demonstrates a great flexibility for dealing with complex design conditions. As an example, the paper discusses the possibility of extending the theory to the shear resistance of higher-strength concrete. The suggested method provides a more logical and fluent transition from normal- to high-strength concrete and shows good agreement with experimental observations.

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Brantschen, Fabio; Faria, Duarte M.V.; Ruiz, Miguel Fernández; Muttoni, Aurelio Bond behaviour of straight, hooked, U-shaped and headed bars in cracked concrete Structural Concrete 5/2016 799-810 Technical Papers

Kurzfassung

Most classic investigations on bonding properties in reinforced concrete have been performed on the basis of pull-out tests, where a reinforcement bar is pulled out from an uncracked concrete cylinder, prism or cube. In these tests, the bond is governed by the concrete strength and bar surface properties of the reinforcement (bond index, rib geometry) or by the splitting strength of the concrete (concrete cover). In the latter case, bond failure occurs due to uncontrolled cracking of the concrete specimen. In contrast to these fundamental tests, bond in many structural members is activated within already cracked concrete. This is particularly relevant for the reinforcement in beams and slabs (both for flexural and transverse reinforcement), as the reinforcing bars might be located at planes where flexural cracks develop. The opening of these cracks along the reinforcement is nevertheless not uncontrolled (as opposed to splitting failures), but it is governed by the bending deformations. The bond properties and strength of the reinforcement in actual members are therefore influenced by the opening of these cracks and are potentially different from those observed in classic pull-out tests.
The present paper aims to address this topic by presenting the results of an experimental investigation with 89 monotonic pull-out tests performed on cracked ties. The opening of the cracks was controlled while transverse bars - located in the plane of these cracks - were pulled out from the specimens. The tests were performed for crack openings ranging from 0.2 mm to 2.0 mm in order to cover conditions both at the serviceability and ultimate limit states. The results show a very significant influence of in-plane cracking on both strength and bond-slip stiffness, with decreasing mechanical performance for increasing crack openings. The performance of different actual anchorage types (straight, hooked, U-shaped and headed bars) - generally characterized through force-slip relationships - is finally analytically investigated and compared to the test results.

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Figueira, Diogo; Sousa, Carlos; Calçada, Rui; Neves, Afonso Serra Design recommendations for reinforced concrete interfaces based on statistical and probabilistic methods Structural Concrete 5/2016 811-823 Technical Papers

Kurzfassung

A concrete interface is a material discontinuity that requires special care with respect to structural design and assessment. Therefore, the definition of design expressions based on experimental testing data must ensure the necessary reliability depending on the type of structure and its use. The present work describes a new proposal for the design of concrete interfaces subjected to shear loading for different roughness profile types. The proposal is characterized by three linear branches (for monotonic loading) and an S-N curve (for cyclic loading) and is the result of a parametric analysis of existing experimental data (obtained by the authors and also from an extensive literature search) based on statistical and probabilistic methods. Design expressions were defined in order to minimize the dispersion and variability of the safety factor values for each experimental test considered and also to assure that those values are within a target range (defined according to reliability considerations). These improvements became clearer when the new proposal was compared with the most common design code recommendations.

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Villalba-Herrero, Sergi; Casas, Joan R. New structural joint by rebar looping applied to staged box girder bridge construction. Static tests Structural Concrete 5/2016 824-835 Technical Papers

Kurzfassung

The paper describes the design, development and experimental checking of a modified type of structural joint with limited length between concrete segments cast in-situ. The design concept is based on the developed length of an anchorage hook stiffened by transverse reinforcement bars and is particularly suited for the case of in-situ construction of staged box girder bridges, with the intention of possibly using lighter scaffolding.
The studies concentrated on the strength, stiffness and serviceability of the proposed joint are presented. The research work comprises the bending behaviour of reinforced concrete slabs with loop joints with regard to the diameter of the loop bar, loop joint width and ultimate and fatigue load. The results are compared to the behaviour of reinforced concrete slabs without joints. A total of 16 slabs were tested with static and fatigue loading tests. The present paper evaluates the flexural behaviour in static loading tests. The results of fatigue tests have also shown excellent performance.
In the static tests, crack widths and cracking pattern were observed at service load levels, and the ultimate behaviour was evaluated by means of tests to failure.
From the test results, the service performance of the loop joints was confirmed to be similar to slabs without joints. The static loading tests confirm the good performance and effectiveness of this loop joint type under static loading. Details of the loop joint design criteria are also proposed.

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Yanaka, Makoto; Ghasemi, Seyed Hooman; Nowak, Andrzej S. Reliability-based and life-cycle cost-oriented design recommendations for prestressed concrete bridge girders Structural Concrete 5/2016 836-847 Technical Papers

Kurzfassung

There are several methods available to decide appropriate design recommendations to prevent corrosion of reinforcing steel in prestressed concrete bridge girders. With respect to chloride-induced corrosion, in the present study two methods are considered. The first one is based on the target probability of corrosion initiation and the initial cost. The other method is based on the life-cycle cost that includes the initial cost, maintenance cost, and expected failure cost. This paper deals with the development of recommendations for durability design of structures in marine environments from the reliability point of view, taking into consideration the life-cycle cost of a structure. In order to address the problem, the chloride diffusion coefficient of a cracked area under service load is obtained considering opening and closing motion of cracks. Utilizing the diffusion coefficient of a cracked area, the development over time of the chloride concentration at the surface of reinforcement can be predicted. This information is used to quantify the probability of initiation of corrosion of prestressing steel as well as the distribution of life-cycle cost. Based on the findings, recommendations for durability design in various exposure environments are developed.

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