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O wzmacnianiu konstrukcji żelbetowych materiałami stalowymi i kompozytowymi

Bodzak Przemysław

Inżynieria i Budownictwo

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2020

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R. 76, nr 9

442--448

EN

Basic differences resulting from the use of two types of materials during strengthening of RC structures are described. Attention is drawn to the consequences of using steel flat bars and composite strips or mats in relation to other strain values occurring at failure depending on the material used. Their impact, especially in the case of crack width and automatically shear capacity, makes direct extension of existing models of collapse to elements strengthened with composite materials unjustified.

PL

Opisano podstawowe różnice wynikające z zastosowania dwóch rodzajów materiałów przy wzmacnianiu konstrukcji żelbetowych. Zwrócono uwagę na konsekwencje użycia płaskowników stalowych oraz taśm lub mat kompozytowych w związku z innymi wartościami odkształceń występującymi przy zniszczeniu w zależności od zastosowanego materiału. Ich wpływ, szczególnie w przypadku szerokości rys i automatycznie nośności na ścinanie powoduje, że bezpośrednie rozszerzenie dotychczasowych modeli zniszczenia na elementy wzmocnione materiałami kompozytowymi jest niemożliwe.

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Collapse mechanism analysis of a steel moment frame based on structural vulnerability theory

Jihong Y., Liqiang J.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 3

833--843

EN

This paper presents an improved method to analyze the collapse mechanism of steel moment frames based on structural vulnerability theory (SVT), in which the failure processes of the essential components are defined according to the damage characteristics of their ductile and brittle members. The improved method can accurately identify possible collapse modes of steel moment frames, because the transformation processes of such connections as beam-column joints and support joints from rigid connections to pinned ones were considered. Structural vulnerability analysis is performed on a 4-story steel frame structure by using the improved method, the results show that the collapse caused by joint failure in the first story had the maximum vulnerability index, so that the weakness of the steel frame may be located in the first story; while the collapse behaving as a “beam plastic hinge” failure, as an expected failure mode, had the minimum value. Moreover, the improved method was validated by a shaking table test due to the consistence between the experimental results and the collapse modes calculated to have the maximum vulnerability index, which demonstrates that such improved method could be effectively to predict the collapse modes of steel frame structures.

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Elastoplastic structural analysis of the Paderno d’Adda bridge (Italy, 1889) based on Limit Analysis

Rosalba F., Giuseppe C., Egidio R.

Wiadomości Konserwatorskie

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2013

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Nr 34

28--35

EN

The Paderno d’Adda bridge is a marvellous historical iron arch bridge that was built in 1889. It allows connecting the provinces of Lecco and Bergamo across the Adda river, between Paderno d’Adda and Calusco d’Adda, near Milano, northern Italy. The bridge was designed for railway needs and its use is two-fold: a railway track is located in the inner deck of the upper continuous beam; automotive traffi c runs on top of it. Today, after 123 years of continuous duty, the viaduct is still in service, with trains crossing at slow speed and alternated one-way road traffi c restricted to no heavyweight vehicles. Despite these duties, the bridge seems to have suffered from limited maintenance. With the final purpose of elaborating a safety assessment of the structure, an inelastic structural analysis of the viaduct is performed, based on a finite element model that takes into account a perfect elastoplastic behaviour of the various structural members and is apt to comply with typical principles of Limit Analysis. Specifi cally, the critical load multiplier and relevant collapse mode are investigated, for different static loading conditions on the bridge. Also, the characteristic nonlinear load/displacement response curves of the bridge are traced by incremental analyses up to the true limit load and the various critical members of the structure are identified. A further intention of this work consists in promoting interest at the international level on the Paderno d’Adda bridge, as a beautiful, living industrial monument of the scientific and technological developments of that time, by referring particularly to its present and future destinations.

PL

Most Paderno d'Adda jest niezwykłym, zabytkowym żeliwnym most łukowym , który został zbudowany w 1889 roku. Umożliwia on połączenie prowincji Lecco i Bergamo nad rzeką Adda, między Paderno d'Adda i Calusco d'Adda, niedaleko Mediolanu, w północnych Włoszech. Most został zaprojektowany dla potrzeb kolejowych, a jego zastosowanie jest dwojakie linia kolejowa znajduje się w wewnętrznym pokładzie górnej belki ciągłej, ruch motoryzacyjny powyżej. Ocena bezpieczeństwa konstrukcji: nieelastyczna analiza strukturalna wiaduktu wykonywana została na podstawie modelu skończonego elementu, który bierze pod uwagę doskonałe elastoplastyczne zachowanie poszczególnych elementów konstrukcyjnych.

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Rozrobka, doslihdzhennja ta praktichne zastosuvannja prostorovikh konstrukcihjj skladchastikh kupolihv

Klimenko F., Khramcov V., Carinnik O.

Zeszyty Naukowe Politechniki Rzeszowskiej. Budownictwo i Inżynieria Środowiska

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2000

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z. 32[180], cz.1

239-246

EN

This paper focuses on the study of the bearing capacity of reinforced concrete domes assembled from pre-cast folds with dry joint using the yield line theory of the limit load analysis. The developed equations allow determining the bearing capacity and quantitative parameters of collapse mode for this type of structures under axisymmetric loads. Based on the experiments with the 4.5 m diameter dome model under uniformly distributed load, bearing capacity and certain possible collapse modes were established. The character of crack formation, deflection, as well as lateral and longitudinal deformations of concrete folds were determined. It was established that application of the limit load analysis for determining the possible collapse modes of folded domes and for learning their bearing capacity and quantitative parameters of collapse mode, provides results that are satisfactorily close to the experimental.