Wyniki wyszukiwania - BazTech

1

Research on the design method of flexural capacity of RC beams strengthen by ultra-high performance concrete

Wang Jiawei, Ying Feifei

Archives of Civil Engineering

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2024

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Vol. 70, nr 1

487--507

EN

Due to the increase in traffic volume, load level, and service life of existing bridges, the bending bearing capacity of reinforced concrete beams (hereinafter referred to as RC beams) has decreased, leading to safety issues. In order to solve the problem of insufficient flexural bearing capacity of RC beams, this article adopts the method of ultra-high performance concrete (UHPC) flexural strengthening RC beams, establishes a finite element model of UHPC-RC reinforcement system, and conducts stress analysis with reinforcement thickness, reinforcement range, reinforcement form, and reinforcement height as parameters to determine the optimal scheme of the reinforcement system. Based on the calculation results, a theoretical formula for the maximum principal stress and maximum deflection of the reinforcement system is proposed. To verify the feasibility of the plan, a reinforcement design was carried out on an existing beam, and it was found that the bending bearing capacity of the RC beam increased by 21%; the high tensile strength of UHPC and the addition of steel fibers have a good limiting effect on cracks; The steel plate of the reinforcement system can be used as a template, reducing construction costs and having good economy.

2

Investigation on cracking performance of UHPC overlaid concrete deck at hogging moment zone of steel-concrete composite girders

Wan Zhiyong, Guo Guohe, Wang Zhiguo, He Shaohua, Tan Juliang, Hou Libo

Archives of Civil Engineering

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2023

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Vol. 69, nr 4

445--457

EN

The concrete deck at the negative bending moment region of a continuous steel-concrete composite girder bridge is the weakest part of the structure. Introducing ultra-high performance concrete (UHPC) to the hogging region may overcome the shortage and break through the bottleneck. This paper explores the cracking performance of steel-concrete composite girders with concrete slabs topped by a thin layer of UHPC subjected to a negative bending moment. A real continuous composite girder bridge is briefly introduced as the engineering background, and the cracking characteristic of the concrete deck over the middle piers of the bridge is numerically modeled. Approaches to strengthen the cracking performance of the concrete deck at the hogging region through topping UHPC overlays are proposed. The effectiveness of the approaches is examined by conducting a series of numerical and experimental tests. Numerical results indicate that the normal concrete (NC) deck near the middle forums of the bridge would crack due to the large tensile stress from negative bending moments. Replacing the top concrete with an identical-thick UHPC overlay can increase the cracking resistance of the deck under the moment. As the thickness of the UHPC overlay increased from 6.0 cm to 12.0 cm, the maximum shear stress at the UHPC overlay-to-NC substrate interface under different load combinations was decreased by 56.3%~65.3%. Experimental results show that the first-cracking load of the composite beam using an NC-UHPC overlaid slab was 2.1 times that using an NC slab. The application of a UHPC overlaid deck can significantly improve the crack performance of the steel-concrete composite girder bridge.

3

Prefabrykaty z betonów o wysokiej i ultrawysokiej wytrzymałości - teraz czy dopiero jutro?

Janczura K.

Budownictwo, Technologie, Architektura

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2017

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nr 3

58--62

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Life cycle assessment of UHPC bridge constructions: Sherbrooke footbridge, Kassel Gartnerplatz footbridge and Wapello road bridge

Stengel T., Schiebl P.

Architecture Civil Engineering Environment

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2009

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Vol. 2, no. 1

109-118

EN

The paper presents the results of life cycle assessments (LCA) performed for three bridges in which UHPC was an essential part of the structure. The bridges investigated are the Sherbrooke footbridge in Canada, the Kassel Gärtnerplatz footbridge in Germany and the Wapello road bridge in USA. The life cycle assessment was performed using the Swiss process and material database ecoinvent. The ecological effects of global warming (GWP100), depletion of the stratospheric ozone (ODP), photo-oxidant formation (POCP), acidification (AP) and eutrophication (NP) were adopted as impact category indicators according to the Dutch CML method. The results show that UHPC used in the Sherbrooke footbridge and the Gärtnerplatz footbridge causes approximately 60 to 85% of the environmental impact. In addition, appreciable contributions are made by the steel truss and the prestressing of the UHPC. In case of the Wapello road bridge, the contribution of UHPC to environmental impact was from 44 to 74% somewhat smaller. As well as UHPC, in particular normal concrete in the bridge deck, the steel reinforcement of the bridge deck and the prestressing of the UHPC contribute appreciably to the effect on the environment. The present contribution is a summary of a paper presented in 2008 AMCM conference.

PL

W artykule przedstawiono wyniki analizy całego cyklu użytkowania przeprowadzonej dla trzech mostów, w których betony ultra-wysokiej wytrzymałości (BUWW) stanowiły istotną część konstrukcji. Badane obiekty mostowe to: kładka dla pieszych w Sherbrooke w Kanadzie, kładka dla pieszych Gärtnerplatz w Kassel w Niemczech oraz most drogowy w Wapello w USA. Analiza całego cyklu użytkowania przeprowadzona została z wykorzystaniem procedury szwajcarskiej i materiałowej bazy danych ecoinvent. Ekologiczne efekty globalnego ocieplenia, zubożenie ozonu stratosferycznego, tworzenie się foto utleniacza, zakwaszanie i eutrofizacja zostały zaadaptowane jako wskaźniki kategorii wpływu zgodne z holenderską metodą CML. Wyniki analizy pokazały, że beton ultra-wysokiej wytrzymałości użyty do budowy kładki dla pieszych w Sherbrooke i kładki dla pieszych Gärtnerplatz powoduje około 60 do 85% wpływów środowiskowych. Ponadto, znaczny udział miały również stalowe kratownice i sprężanie BUWW. W przypadku mostu w Wapello, udział betonu ultra-wysokiej wytrzymałości we wpływach środowiskowych był nieznacznie mniejszy i wynosił 44 do 74%. Zarówno BUWW, a w szczególności beton zwykły w jezdni mostowej, zbrojenie jezdni mostowej i sprężanie BUWW przyczyniły się znacząco do wpływu na środowisko. Przedstawiana praca jest podsumowaniem referatu prezentowanego w 2008 roku na konferencji AMCM.