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Lang, Robert; Lener, GerhardSchweißnahtbewertung basierend auf 3D-Laserscanning - Praktische Anwendung eines mobilen Laserscansystems zur Oberflächenbewertung von Schweißnähten - Teil 2Stahlbau6/2016395-408Fachthemen

Kurzfassung

Die Sichtprüfung von Schweißnähten ist die einfachste und am häufigsten durchgeführte Art der Schweißnahtprüfung. Neben laufenden Soll-Kontrollen durch das Schweißpersonal während der Fertigung ist für alle Ausführungsklassen abschließend eine vollumfängliche Sichtprüfung nach EN 1990-2 [1] durchzuführen. Dabei können direkte und indirekte Prüfmethoden angewendet werden, zu denen auch die Geometrieerfassung durch Laserscanning zu zählen ist. In diesem zweiten Teil des Beitrages wird die Anwendung eines mobilen Laserscansystems für den klassifizierenden Vergleich zur rein rechnerischen Ermittlung der Ermüdungsfestigkeit erläutert (Teil 1 s. Stahlbau, H. 5, S. 336-343).

Assessment of welds based on 3D laser scanning. Practical application of a mobile laser scan system for the surface assessment of welds - Part 2.
The visual examination of welds is a simple and frequently used method for weld inspections. Besides the comparison between a target and performance state executed by the technical staff during the production process, a final visual inspection of the welds for all execution classes is demanded by EN 1990-2 [1]. According to this standard, direct or indirect methods can be applied. An example for an indirect method is the scanning of the real geometry of the weld using laser scan technology. In this second part of this article the application of a mobile laser scan system is used as a base to quantify and compare the fatigue limits of scanned specimens with numerical methods only.

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Legierungen werden fest und formbarStahlbau6/2016408Aus der Forschung

Kurzfassung

Keine Kurzfassung verfügbar.

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Saal, Helmut; Misiek, Thomas; Höglund, TorstenErmittlung der Vorkrümmungen e0 für die Berechnung von Aluminiumtragwerken nach DIN EN 1999-1-1 nach Theorie II. Ordnung Herrn o. Prof. Dr.-Ing. Dr.-Ing. E.h. Walter Wunderlich zur Vollendung seines 85. Lebensjahres gewidmetStahlbau6/2016409-417Fachthemen

Kurzfassung

Für den Tragfähigkeitsnachweis nach Theorie II. Ordnung wird der Stich e0 der Vorkrümmungen der Einzelstäbe benötigt. In dem Nationalen Anhang DIN EN 1999-1-1/NA/A1 wird als NDP zu 5.3.2(3) beschrieben, wie dieser ermittelt werden darf. Es werden die Gleichungen für die auf die Stablänge L bezogene Vorkrümmung e0/L für sechs verschiede Querschnittsformen, die ein breites Spektrum abdecken, für lineare Interaktionsbeziehungen sowie für nichtlineare Interaktionsbeziehungen hergeleitet. Die hergeleiteten Gleichungen stellen e0/L als Funktion von Faktoren dar, von denen der erste den Querschnitt, der zweite die Streckgrenze fo und der dritte die bezogene Schlankheit, Knickklasse und Interaktionsbeziehung erfasst. Die numerische Auswertung dieser Gleichungen ergibt ungünstigste Grenzwerte von e0/L, die aber angesichts des großen Spektrums der Parameter im Allgemeinen so weit auf der sicheren Seite liegen, dass die Anwendung der zugrunde liegenden Gleichungen empfohlen wird. Für Stäbe mit über den Querschnitt infolge WEZ veränderlicher Streckgrenze fo werden die Berechnungsmöglichkeiten am Beispiel eines dünnwandigen Kreisrohres dargestellt.

Determination of initial bow imperfections e0 for second-order analysis of aluminum structures according to EN 1999-1-1.
The initial bow imperfection e0 is required if structures are designed with the internal forces and moments from second-order analysis. The National Annex DIN EN 1999-1-1/NA/A1 as a NDP to 5.3.2(3) of DIN EN 1999-1-1 describes how e0 may be calculated. Based on this, formulae are derived for calculating the relative initial bow imperfections e0/L for six very different types of cross sections which cover a very wide range. Linear as well as nonlinear M-N-interaction relations are used depending on the type of cross section. These formulae describe e0/L as product of functions of which the first depends on the cross section, the second on the proof strength fo and the third on relative slenderness, buckling class and interaction relation. The numerical evaluation of these formulae gives conservative limit values for e0/L. However, due to the wide range of the parameters these values will in general be that far on the safe side that the application of the formula with the relevant parameters is recommended. For members where fo due to the HAZ is variable over the cross section a linear and alternatively a nonlinear interaction relation may be used as safe approximation. This is demonstrated with a thin-walled circular tube.

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Förderpreis der Gesellschaft für Bautechnikgeschichte ausgeschriebenStahlbau6/2016417Aktuell

Kurzfassung

Keine Kurzfassung verfügbar.

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Stranghöner, Natalie; Jungbluth, DominikVerschraubung von aufgeschweißten Gewindebolzen nach Merkblatt DVS 0904Stahlbau6/2016418-428Fachthemen

Kurzfassung

Beim Lichtbogenbolzenschweißen wird ein stiftförmiges Verbindungselement mit oder ohne Gewinde mittels eines Lichtbogens mit einem Bauteil verbunden. Verwendet werden in der Regel Verbindungsmittel wie Stifte, Buchsen und Bolzen mit Gewinde. Während des Schweißprozesses wird ein Lichtbogen an der Stirnfläche des zu verschweißenden Bolzens gezündet, wodurch sowohl die Stirnfläche des Bolzens als auch das Werkstück lokal angeschmolzen und unter einem definierten Anpressdruck zusammengefügt werden. Unterschieden wird zwischen zwei Verfahren der Schweißung, dem Lichtbogenbolzenschweißen mit Hub- oder mit Spitzenzündung.
Das Merkblatt DVS 0904 des Deutschen Verbands für Schweißen und verwandte Verfahren e.V. (DVS) gibt neben den Regelungen zum Lichtbogenschweißen von metallischen Werkstoffen der DIN EN ISO 14555 weiterführende Hinweise zum Lichtbogenbolzenschweißen für die Praxis. Für das Bolzenschweißen werden unter anderem Anweisungen für die Schweißvorbereitung, die Ausführung und die Prüfung der Bolzenschweißung gegeben. Darüber hinaus liefert das Merkblatt aber auch Angaben zur Montage und damit zur Verschraubung sowie zur Zugprüfung von aufgeschweißten Gewindebolzen. Diese Angaben betreffen das Montagedrehmoment und die resultierende Montagevorspannkraft, die auf Annahmen zu Reibbeiwerten beruhen, welche bisher nicht durch Versuche gestützt wurden. Im Zuge der Überarbeitung des Merkblatts DVS 0904 sollten diese Angaben überprüft und angepasst werden, weshalb experimentelle Untersuchungen an aufgeschweißten Gewindebolzen am Institut für Metall- und Leichtbau der Universität Duisburg-Essen durchgeführt wurden. Diese Untersuchungen und deren Ergebnisse werden im vorliegenden Beitrag als Hintergrundinformationen zu den in der überarbeiteten DVS 0904 ausgewiesenen Anziehdrehmomenten dargestellt und erörtert.

Tightening of arc welded studs according to the technical bulletin DVS 0904.
Within the process of arc stud welding, a pen-shaped threaded or non-threaded stud is connected to a steel component. During the process the two components bolt and steel component are locally melted by an arc and then plunched together. The process of arc stud welding can be divided into arc stud welding with a drawn arc or with condenser discharge. The technical bulletin DVS 0904 of the German Welding Society (DVS) gives next to the rules for arc stud welding in EN ISO 14555 further references for arc stud welding in practical use. Beside rules and references for welding preparation, execution and controlling of arc stud welding, DVS 0904 gives further information on tightening and tensile testing of the installed studs. The given tightening torque and bolt force values for different stud diameters and materials are based on assumptions for coefficients of friction, which were not determined by tightening tests. In the frame of the revision of DVS 0904 these assumptions should be checked. For this reason tightening tests were performed at the Institute for Metal and Lightweight Structures of University of Duisburg-Essen. The experimental investigations and their results are presented as background information for the revision of DVS 0904 within this contribution.

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Hörenbaum, Christoph; Laumann, Jörg; Prokop, InesZur Anwendung des Eurocode 3 Teil 1-2 für die Heißbemessung und Anregungen für dessen NovellierungStahlbau6/2016429-434Fachthemen

Kurzfassung

Die Eurocodes werden bis zum Jahr 2020 im Europäischen Komitee für Normung (CEN), Technisches Komitee TC 250, überarbeitet. In Vorbereitung auf die Eurocode-Novellierung haben engagierte Ingenieure im Rahmen der Initiative PraxisRegeln Bau (PRB) die für die praktische Anwendung häufig genutzten Teile des Eurocode 3 untersucht. Mit dem Ziel, die Praxistauglichkeit des Eurocode 3 für die Heißbemessung zu verbessern, wurden die bestehende Norm EN 1993 Teil 1-2 insbesondere in Bezug auf die Anwenderfreundlichkeit analysiert und Vorschläge für die europäische Novellierung erarbeitet. Die Analysen zeigen, dass durch Umstrukturierungen und durch die Einführung von Tabellen die Verständlichkeit und Anwenderfreundlichkeit der Regeln für die Heißbemessung bedeutend erhöht werden können.

On the application of Eurocode 3 Part 1-2 for structural fire design and suggestions for amendment.
The Eurocodes will be revised in the European Committee for Standardization (CEN), Technical Committee (TC) 250, up to 2020. In preparation on the Eurocode amendment engaged engineers have examined the most frequently used parts of Eurocode 3 within the Initiative PraxisRegeln Bau (Practice-oriented Rules in Building Construction - PRB). With the aim to improve the user-friendliness and ease of use of EN 1993-1-2 for structural fire design the existing norm was analysed and proposals were compiled for the European amendment. The analyses show that restructuring and new tables can enhance comprehensibility and ease of use of the rules for structural fire design of steel structures considerably.

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Sicherheit durch unabhängige PrüfungStahlbau6/2016434Aktuell

Kurzfassung

Keine Kurzfassung verfügbar.

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Biogas-Rohrleitungstrasse - Zeit- und Kostenersparnis durch maßgeschneidertes modulares HalterungssystemStahlbau6/2016435-436Berichte

Kurzfassung

Keine Kurzfassung verfügbar.

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Dissertationen: Stahlbau 6/2016Stahlbau6/2016437-438Dissertationen

Kurzfassung

Elastic constants of architectural fabrics for design purposes
Beitrag zur Analyse von Sandwichelementen als tragende Bauteile
Probabilistische Betrachtung der Schadensakkumulation für stählerne Schweißverbindungen

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Kurrer, Karl-EugenHartmann, F., Jahn, P.: Statik und Einflussfunktionen - vom modernen Standpunkt aus.Stahlbau6/2016438-439Rezensionen

Kurzfassung

Keine Kurzfassung verfügbar.

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Möller, EberhardHänsel, J., Haspel, J., Salge, Chr., Wittmann-Englert, K. (Hrsg.): Baumeister - Ingenieure - Gartenarchitekten.Stahlbau6/2016438Rezensionen

Kurzfassung

Keine Kurzfassung verfügbar.

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Wenzel, FritzZum Tod des Bauforschers Hartwig SchmidtStahlbau6/2016439-440Persönliches

Kurzfassung

Keine Kurzfassung verfügbar.

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Aktuell: Stahlbau 6/2015Stahlbau6/2016440-442Aktuell

Kurzfassung

20. DASt-Forschungskolloquium 2016 (Christoph Lorenz, Essen) / Lebensraum schaffen mit leichten Systemen aus Stahl / Innovations-Hub “Prävention im Bauwesen”

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Termine: Stahlbau 6/2016Stahlbau6/2016442Termine

Kurzfassung

Keine Kurzfassung verfügbar.

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Contents: Structural Concrete 6/2016Structural Concrete6/2016Contents

Kurzfassung

Keine Kurzfassung verfügbar.

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Hawkins, Will J.; Herrmann, Michael; Ibell, Tim J.; Kromoser, Benjamin; Michaelski, Alexander; Orr, John J.; Pedreschi, Remo; Pronk, Arno; Schipper, H. Roel; Shepherd, Paul; Veenendaal, Diederik; Wansdronk, René; West, MarkFlexible formwork technologies - a state of the art reviewStructural Concrete6/2016911-935Technical Papers

Kurzfassung

Concrete is the most widely used construction material. Worldwide consumption of cement, the strength-giving component in concrete, is now estimated to be 4.10 Gt per year, having risen from 2.22 Gt just 10 years ago. This rate of consumption means that cement manufacture alone is estimated to account for 5.2 % of global carbon dioxide emissions.
Concrete offers the opportunity to create structures with almost any geometry economically. Yet its unique fluidity is seldom capitalized upon, with concrete instead being cast in rigid, flat moulds to create non-optimized geometries that result in structures with a high material usage and large carbon footprints. This paper will explore flexible formwork construction technologies that embrace the fluidity of concrete to facilitate the practical construction of concrete structures with complex and efficient geometries.
This paper presents the current state of the art in flexible formwork technology, highlighting practical uses, research challenges and new opportunities.

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Ji í ek, Pavel; Foglar, MarekNumerical analysis of a bridge pier subjected to truck impactStructural Concrete6/2016936-946Technical Papers

Kurzfassung

The impact of heavy trucks on a bridge substructure can lead to progressive collapse of the bridge superstructure, and to disastrous accidents. This type of load should therefore be taken into consideration, especially in the design of motorway bridges. For some structural arrangements, vehicle impact is the decisive loading for the design of the bridge substructure. This paper presents verification of the detailed procedures given by European standard EN 1991-1-7 for bridge pier impact load - dynamic analysis, which is compared with the outcomes from a detailed finite-element model (FEM) of a truck impact prepared using AUTODYN software. A nonlinear material model of concrete with damage and strain-rate effect is used to assess the impact performance of a bridge pier. The paper further presents the results of a numerical study focused on the influence of different types of bridge pier reinforcement arrangement on their resistance to vehicle impact. The performance of various types of reinforcement is analysed and compared. Practical recommendations are drawn for the design of bridge piers which can be subjected to vehicle impacts in an urban environment.

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Jing, Yuan; Ma, Zhongguo John; Clarke, David B.Full-scale lateral impact testing of prestressed concrete girderStructural Concrete6/2016947-958Technical Papers

Kurzfassung

Lateral impact damage from over-height vehicle collisions with bridge superstructures is of increasing concern in the United States. However this issue is not fully addressed in current bridge specifications. Previous researchers have conducted a number of small-scale tests to study the impact process. Also, the finite element method has largely been used to analyze the complicated collision mechanism. This paper provides an opportunity for full-scale lateral impact testing of a prestressed concrete girder, which leads to a realistic level of damage and mechanism analysis. A full-scale lateral impact testing facility was designed and built on a construction site in Knoxville, Tennessee. The over-height vehicle impact was simulated by impacting the bottom of an AASHTO Type I prestressed concrete girder with an impact cart. This paper describes the details of the impact testing facility as well as the response of the prestressed concrete girder during lateral impact. The collected test data were calibrated by using finite element software ABAQUS.

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Yekrangnia, Mohammad; Taheri, Amir; Zahrai, Seyed MehdiExperimental and numerical evaluation of proposed precast concrete connectionsStructural Concrete6/2016959-971Technical Papers

Kurzfassung

In this article, the cyclic performance of an innovative precast beam-to-column connection is evaluated experimentally and numerically. Two full-scale beam-column cross-shape interior connection specimens named PF-1 and PF-2 are tested. By adding extra nuts to the connecting bolts, specimen PF-2 behaves in a more shear-dominant pattern and shows less pinching. Comparison of performance of these specimens with the numerical monolithic model in terms of stiffness, strength, ductility and energy dissipation capacity indicates the proposed system can provide conditions close to the monolithic connection. However, to reduce the pinching drawback, a minor modification was made leading to performance improvements in strength and equivalent viscous damping ratio up to 51 % and 29 % respectively. The results of this study have direct industrial relevance and may be used for the development of reliable seismic guidelines for precast concrete structures.

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Lu, Xilin; Wang, Lu; Wang, Dun; Jiang, HuanjunAn innovative joint connecting beam for precast concrete shear wall structuresStructural Concrete6/2016972-986Technical Papers

Kurzfassung

The precast shear wall structure has outstanding features for green buildings due to its construction convenience, safety, high quality and low pollution. In general, precast concrete shear walls are connected by multiple joints. The joint between precast walls has very strong influence on the whole structure, which calls for more detailed investigation. A new kind of connection - the joint connecting beam - was developed to connect the vertical reinforcement in precast concrete shear wall structures. This innovative connecting method has the advantages of convenient operation and saving steel. To evaluate the performance and for better application of the joint connecting beam, an experiment on seven full-scale specimens was conducted under cyclic loading, including two cast-in-situ walls and five precast walls with varying reinforcement and sectional heights of the joint connecting beam. A comparison was performed between cast-in-situ walls and precast walls with joint connecting beam, focusing on failure mode, hysteretic curve, skeleton curve, bearing capacity, ductility and energy-dissipating capacity. The results show that the joint connecting beam can effectively transfer the load of precast walls, especially for squat precast walls. Moreover, finite element models were developed to simulate the performance of the specimens. The simulation results agree well with experimental results.

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Marchetto, Francesco; Caldentey, Alejandro Pérez; Corres-Peiretti, HugoStructural performance of corner joints subjected to a closing moment using mechanical anchorages: an experimental studyStructural Concrete6/2016987-1002Technical Papers

Kurzfassung

Keine Kurzfassung verfügbar.

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Belletti, Beatrice; Damoni, Cecilia; Cervenka, Vladimir; Hendriks, Max A.N.Catenary action effects on the structural robustness assessment of RC slab strips subjected to shear and tensile forcesStructural Concrete6/20161003-1016Technical Papers

Kurzfassung

In this paper, the behaviour of RC slab strips subjected to transverse loads and axial tensile forces is investigated by means of analytical and numerical simulations. The results obtained are compared to the experimental results from tests performed at the Swiss Federal Institute of Technology (ETH). The prediction of the structural response was part of an international benchmark study [1]. The aim of the paper is to investigate the capability of the adopted models and their main influencing parameters, especially from the perspective of a reliable structural robustness assessment. It is known that in some cases axial tensile forces have a beneficial effect on the bearing capacity of slab strips, thanks to the development of catenary actions. Such hidden strength resources are usually not taken into account in the current design process. For this reason, validation of suitable numerical tools, able to properly predict the structural response, is useful for a reliable structural robustness assessment. The paper underlines the importance of benchmark development, especially for specimens, in which both mechanical and geometrical nonlinearities play an important role.

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Cladera, Antoni; Marí, Antonio; Bairán, Jesús Miguel; Ribas, Carlos; Oller, Eva; Duarte, NoemíThe compression chord capacity model for the shear design and assessment of reinforced and prestressed concrete beamsStructural Concrete6/20161017-1032Technical Papers

Kurzfassung

A simplified mechanical model is presented for the shear strength prediction of reinforced and prestressed concrete members with and without transverse reinforcement, with I, T or rectangular cross-section. The model, derived with further simplifications from a previous one developed by the authors, incorporates the contributions of the concrete compression chord, the cracked web, the dowel action and the shear reinforcement in a compact formulation. The mechanical character of the model provides valuable information about the physics of the problem and incorporates the most relevant parameters governing the shear strength of structural concrete members. The predictions of the model fit very well the experimental results collected in the ACI-DAfStb databases of shear tests on slender reinforced and prestressed concrete beams with and without stirrups. Due to this fact and the simplicity of the derived equations it may become a very useful tool for structural design and assessment in engineering practice.

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Qi, Jia-Nan; Ma, Zhongguo John; Wang, Jing-Quan; Liu, Tong-XuPost-cracking shear strength and deformability of HSS-UHPFRC beamsStructural Concrete6/20161033-1046Technical Papers

Kurzfassung

Eleven T-beams, reinforced with high strength steel, were tested to failure to investigate the effect of shear span to depth ratio, fibre ratio, fibre type, concrete strength and stirrup ratio on the shear behaviour, especially post-cracking shear strength and deformability, of ultra-high performance fibre reinforced concrete (UHPFRC) beams. Test results indicated that fibres were efficient not only in enhancing the post-cracking shear strength, but also in improving the post-cracking deformability of UHPFRC beams. In addition, fibres could bridge the cracks and help in redistributing and homogenizing the concrete stress beside the cracks, allowing more short fine diagonal shear cracks with small spacing to develop around the existing cracks. A moderate amount of stirrups can effectively restrain shear cracks and allow more parallel diagonal shear cracks to develop and propagate thoroughly within the shear span. The stiffness of the UHPFRC beams at ultimate state was about 50 % of initial beam stiffness, which was considerable in strength calculations and ductility analysis, especially in seismic performance evaluation. Lastly, the current shear provisions were evaluated using the experimental results.

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Wieneke, Katrin; Kueres, Dominik; Siburg, Carsten; Hegger, JosefInvestigations of the punching shear behaviour of eccentrically loaded footingsStructural Concrete6/20161047-1058Technical Papers

Kurzfassung

The punching shear design provisions according to various codes have been derived from the results of tests conducted on centrically loaded flat slabs. The application of these provisions for footings and ground slabs might lead to inconsistent results since more compact dimensions and soil-structure interaction lead to higher punching shear capacities. In this context, Eurocode 2 introduced a new design equation for column bases, which was derived from the evaluation of test results from centrically loaded footings.
Since centrically loaded footings represent an exception in practice, Eurocode 2 and ACI 318-14 consider load eccentricities by increasing the applied load, while the fib Model Code 2010 proposes a reduced length of the control perimeter to determine the punching shear resistance. The different approaches were derived from the evaluation of tests on eccentrically loaded flat slabs and have not been verified for footings yet.
Theoretical and experimental investigations on the punching shear behaviour of eccentrically loaded footings indicate a reduction of the multi-axial stress state along the column face with increasing load eccentricity. Based on punching tests on eccentrically loaded footings described in literature, non-linear finite-element simulations were performed and subsequently the influence of load eccentricities on the punching shear behaviour was examined in parametric studies. In this article, the results of the numerical simulations are presented and compared to experimental results and various code provisions.

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