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Serviceability of reinforced concrete columns strengthened by reinforced concrete jacketing

100%

Krainskyi P. , Blikharskyy Z. , Khmil R.

tom Z. 21 (171)

139--143

In this article serviceability of reinforced concrete columns, strengthened by reinforced concrete jacketing was investigated. Performance of reinforced concrete columns strengthened after initial loading was studied. Different loading levels before strengthening were considered.

W artykule zaprezentowano wyniki badań doświadczalnych dotyczących trwałości słupów żelbetowych przed i po wzmocnieniu z zastosowaniem obejm żelbetowych. Badano wzmocnienia słupów, wstępnie obciążonych do różnych poziomów wyczerpania nośności.

Theoretical and experimental in-service long-term deflection response of symmetrically and non-symmetrically reinforced concrete piles

84%

Hernández-Montes E. , Fernández-Ruiz M. A. , Carbonell-Márquez J. F. , Gil-Martín L. M.

tom Vol. 17, no. 2

433--445

Reinforced concrete piles employed in earth retaining systems are typically designed with symmetric reinforcement. The non-symmetric RC wall piles have recently been introduced by the authors, obtaining savings of up to 50% in weight in longitudinal reinforcing steel compared with the traditional solutions, leading to significant financial savings while also reducing associated environmental impacts. The structural behavior of this new RC member under long-term loading is studied, comparing it with its symmetrical counterpart. An experimental campaign has been carried out. Full scale specimens with circular cross sections symmetrically and asymmetrically reinforced were tested. Results have shown that asymmetrically RC pile developed a slightly higher deflection than its symmetrical counterpart. A new expression for the effective area of concrete in tension applicable to non-symmetrical piles is introduced. Moreover, a new stress–strain law for cracked concrete that accounts the tension stiffening effect for long-term loading is proposed. Finally, for non-symmetrical RC wall piles, the evolution of the parameter that takes into account the duration of loading in deformations is presented. Although more evidence is needed, it is shown that tension stiffening effect contribution could be overestimated by Eurocode 2 in the case of non-symmetrically or underestimated in case of symmetrically RC piles.

Pierwsze polskie kładki podwieszone i współczesne problemy ich eksploatacji

84%

Jakiel P. , Olczyk P.

2021

tom R. 77, nr 11-12

535--546

Opisano rozwiązania konstrukcyjne pierwszych w Polsce kładek podwieszonych. Nietypowe i eksperymentalne rozwiązania stosowane w tych konstrukcjach, w połączeniu z ich wieloletnią eksploatacją, nierzadko stanowią wyzwanie dla ich zarządców w zakresie bieżącego utrzymania i remontów. Zestawiając oceny stanu technicznego głównych elementów nośnych, wskazano jednocześnie na dużą wartość historyczną tych pionierskich konstrukcji w kontekście polskiego mostownictwa. Ich przebudowa lub rozbiórka powinny być ostatecznością.

The issues of early Polish cable-stayed footbridges are presented in this paper. Atypical and experimental structures of mentioned footbridges, combined with their long-time service, are quite often a challenge, regarding routine maintenance and repairs. While listing technical condition evaluation marks, great historical value of these pioneer structures considering bridge engineering in Poland was also emphasized. Finally, it was highlighted that reconstruction or demolition of the footbridges should be considered only if unavoidable.

Determination of the optimum percentage of high strength bars in RC beams with combined reinforcement using FEM

67%

Selejdak J. , Blikharskyy Y. , Bobalo T. , Kopiika N.

tom Vol. 2, nr 1

230--236

In this work on the basis of the developed and tested mathematical model, the numerical experiment is conducted in order to study in more detail the specifics of performance of concrete beams` with combined reinforcement. For this purpose nine series of reinforced concrete beams with different combination of steel bars (A400C, At800, A1000) and ribbon reinforcement (C275) were modeled. In the developed series two classes of concrete were used: C50/60, C35/45. The functions derived on the basis of mathematical modeling allow us to determine the recommended percentage of high-strength reinforcement of common reinforced concrete structures with single reinforcement. Therefore, the possibility is obtained to reduce the total structures` reinforcement percentage, increasing their deformability by the specified value without affecting the bearing capacity.