Long-term behavior of slender long-span precast prestressed high-strength concrete girders

Paulo Fernandes, Eduardo Cavaco, Ricardo do Carmo, Paulo Maranha, Eduardo Júlio

Research output: Contribution to journalArticlepeer-review

Abstract

The long-term behavior of slender (1/40) long-span precast high-strength concrete girders was experimentally investigated regarding their use as a competitive solution in relation to steel alternatives for highway overpasses. The time-dependent effects of full-scale girders has rarely been addressed, particularly the influence of creep and shrinkage of concrete with compressive strengths around 120 MPa. Two half-scale girder specimens were produced using an economically optimized and high-strength concrete mixture, nonfiber reinforced, designed only with conventional raw materials, currently available at Portuguese precast companies, and subjected to long-term loading, with a magnitude of approximately 50% of the failure load in bending, during a period of 3.75 years. Using the same mixture, prismatic specimens were also produced and subjected to long-term loading at 24 h and 7 days of age to assess both creep and shrinkage. Results show that the age of concrete at the loading day is of paramount importance regarding the time-dependent effects. These are most relevant during the first days of loading and tend to stabilize from the 112th day of loading onward. The time-dependent girder's mid-span deflection at the end of the 3.75 years did not exceed more than 50% of the initial deformation. Comparison of results with those obtained with Model Code 2010 and the current version of Eurocode 2 shows that these underestimate strains and deflections due to creep, mostly because the short-term development of these effects, occurring during the first days of loading, are not adequately represented. On the contrary, a sound agreement between experimental and theoretical values, both in short and long term, was obtained using the Auperin et al. approach.
Original languageEnglish
Pages (from-to)1571-1589
Number of pages19
JournalStructural Concrete
Volume25
Issue number3
DOIs
Publication statusPublished - Jun 2024

Keywords

  • bridges
  • creep
  • girders
  • high-strength concrete
  • long-span
  • precast
  • prestressed
  • slender

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