Ein Beitrag zur Ertüchtigung bestehender Stahltragwerke unter besonderer Berücksichtigung des Fügeverfahrens Schweißen

Lüddecke, Falk

doi:10.1002/stab.200790010

Cited by 18 publications

(15 citation statements)

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“…Also, welding should be carried out only during periods of reduced traffic (Hanswille & Piel, 2007), because a relative displacement of the components to be welded can significantly affect the quality of the welds and render the repair obsolete. In addition, repair welding is not possible for some historic steels, such as puddle steel, which was mainly used until 1900, due to the irregularly distributed lamellar slag inclusions (Lüddecke, 2018).…”

Section: Crack Repair and Retrofitting -State Of The Artmentioning

confidence: 99%

Strengthening of steel structures with fatigue cracks using adhesively bonded non-prestressed and prestressed CFRP lamellas

Ciupack

Ledecký

Kasper

et al. 2019

Modern Building Materials, Structures and Techniques (MBMST)

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In comparison to classic strengthening methods of fatigue-damaged steel structures, adhesively bonded CFRP lamellas show several advantages. Compared to bolted reinforcement measures and the drilling of the crack tip, crosssectional weakening is avoided. Heat-induced, negatively acting residual stresses and distortions, usually occurring during repair welding, can also be excluded. Therefore, the effectiveness of adhesively bonded CFRP lamellas to enhance the remaining lifetime of fatigue damaged steel structures is examined in a German research project. Selected results are presented in this paper. To characterize the steel, CFRP and adhesive materials, different tests on small scale specimens are carried out. With the help of fatigue tests on CT-samples the remaining fatigue lifetimes of specimens strengthened with adhesively bonded CFRP lamellas is compared to the remaining lifetimes of specimens strengthened by established methods such as drilling the crack tip and repair welding. Based on the evaluation of the crack propagation after the rehabilitation measures, the great potential of adhesively bonded CFRP reinforcements can be deduced. By prestressing the lamellas, the remaining lifetime can generally be increased further. The combination of adhesively bonded CFRP lamellas together with established rehabilitation methods shows a particularly high positive influence on the remaining lifetime of the CT-specimens.

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Section: Crack Repair and Retrofitting -State Of The Artmentioning

confidence: 99%

Strengthening of steel structures with fatigue cracks using adhesively bonded non-prestressed and prestressed CFRP lamellas

Ciupack

Ledecký

Kasper

et al. 2019

Modern Building Materials, Structures and Techniques (MBMST)

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“…These include the mentioned concentrations of impurities in the zones of segregation and the tendency to embrittlement by nitrogen-induced aging of steel material refined by air (Thomas and Bessemer steel). Systematic investigations on the weldability of old mild steel, the selection and adjustment of the welding processes have been carried out in [4]. The investigations focused on welding on the surface of the components.…”

Section: State Of the Artmentioning

confidence: 99%

“…While the inner high impurity content is generally considered a show stopper for welding, only few practical welding result surveys are known that rely on actual parts of old structures using usual connection types. While the investigations in [4] are restricted to weld seams on the component surface using the rim layer, it was verified in [3] and [5] that also butt welding of old mild steels is possible despite the melting of the segregation. However, the weldability of the components had to be verified by means of extensive material investigations of all components to be welded, by means of process tests and welding tests on the structure.…”

Section: State Of the Artmentioning

confidence: 99%

“…To evaluate the weldability of the selected mild steels, welding tests were carried out. Contrary to the investigations in [4], butt welds were welded between plates of old mild steels and a new structural steel S235. For the material sample of I-beams (HDD, TFT and TFS) the required plates were extracted of the web to consider the influence of segregation.…”

Section: Welding Tests With Currently Available Filler Materialsmentioning

confidence: 99%

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02.06: Weldability of old mild steels within the rehabilitation of historical steel structures

et al. 2017

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Welding process causes notch effects and residual stresses. Accordingly, the risk of brittle fracture grows. In comparison with currently used steels, old mild steels have a lower toughness. The weldability of mild steel is limited and only feasible under specific conditions. If for structural reasons welding is preferred instead of the use of bolts, the metallurgical characteristics of the steels have to be considered. These include the concentrations of impurities in the zones of segregation and the tendency to embrittlement by nitrogen-induced ageing.In the corresponding paper, experimental and analytical studies of the weldability of old mild steels are presented. Extensive material analyses to determine the mechanical and the technological properties of the material will be an essential part of the investigations. Particularly, the increased impurities of phosphorus, sulfur, nitrogen and also oxygen in the segregation zones as well as the distinctive non-metallic inclusions complicate to produce load-bearing butt welds. Welding materials currently available are not designed for welding such materials. Nevertheless, in the context of a research project welding tests on old mild steels has been carried out using current welding electrodes. Supported by involved industrial partners, a stick electrode adapted to the characteristics of old steels will be developed.

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“…Zusätzlich sind die sich aus den Einzelversuchen ergebenen Regressionsgeraden der Versuchsreihen dargestellt. Exemplarisch sind in Bild 8 für die Vorbelastung 10 7 -mal Ds = 160 N/mm 2 und in Bild 9 für die Vorbelastung 10 7 -mal Ds = 250 N/mm 2 Bei der Durchführung von Betriebsfestigkeitsnachweisen für neu eingebrachte Schweißkerbdetails kann somit die Vorgeschichte des Bauteils an der neuen Verbindungsstelle vernachlässigt werden.…”

Section: Versuchsergebnisseunclassified

Schweißen ermüdungsbeanspruchter Altstahlkonstruktionen – Untersuchungen zum Einfluss der Vorbelastung auf die Lebensdauer der Schweißkerbdetails

2007

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Für die Sanierung und Ertüchtigung bestehender, vorwiegend nicht ruhend beanspruchter Stahltragwerke mittels Schweißen ist bei der ingenieurmäßigen Bemessung neu eingebrachter Schweißverbindungen der Nachweis der Betriebsfestigkeit zu führen. Um für die Restlebensdauerermittlung den Anteil der vergangenen ermüdungsrelevanten Belastung abschätzen zu können, wurden experimentelle Untersuchungen durchgeführt. Hierbei erfolgte u.a. die Einprägung einer definierten Vorbelastung in einen äußerlich ungekerbten Grundwerkstoff, anschließend die Kerbung und die Ermüdungsbeanspruchung der Probe bis zum Bruch. Dieses Vorgehen repräsentiert einen bereits vorbelasteten Altstahl, an dem nachträglich eine Reparatur durchgeführt wurde. Aus den Ergebnissen lässt sich ableiten, dass die aufgebrachten Vorbelastungen in der Regel keinen signifikanten Einfluss auf die erreichbare Lebensdauer ausüben, wenn eine Oberflächenbearbeitung durchgeführt und ein ausreichender Einbrand gewährleistet wird. Dies bedeutet, dass die eingeprägte Vorgeschichte bestehender Konstruktionen beim Nachweis der Betriebsfestigkeit von neu eingebrachten Schweißkerbdetails vernachlässigt werden kann.

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Ein Beitrag zur Ertüchtigung bestehender Stahltragwerke unter besonderer Berücksichtigung des Fügeverfahrens Schweißen

Cited by 18 publications

References 0 publications

Strengthening of steel structures with fatigue cracks using adhesively bonded non-prestressed and prestressed CFRP lamellas

Strengthening of steel structures with fatigue cracks using adhesively bonded non-prestressed and prestressed CFRP lamellas

02.06: Weldability of old mild steels within the rehabilitation of historical steel structures

Schweißen ermüdungsbeanspruchter Altstahlkonstruktionen – Untersuchungen zum Einfluss der Vorbelastung auf die Lebensdauer der Schweißkerbdetails

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