Significant efforts have been made in the last decades to develop steel fibre reinforced concrete (SFRC) mixes, characterize their mechanical properties, standardize characterization tests, provide specific design rules and promote their structural
D. Daviau-Desnoyers CIMA+, Montreal, Canada
P. Rossi • J.-L. Tailhan
Universite Paris-Est, IFSTTAR, MAT, 75732 Paris, France
© RILEM 2017 223
P. Serna et al. (eds.), Creep Behaviour in Cracked Sections of Fibre Reinforced Concrete, RILEM Bookseries 14,
applications [1-4]. Despite, further research regarding the long-term behavior of SFRC under a wide range of sustained load levels encountered in various conditions needs to be done to evaluate the influence of fibers on the amplitude and kinetics of creep as well as crack propagation.
Generally, macrocracks appear in structural elements throughout their service life. Yet, it is reasonable to assume that these macrocracks do not automatically compromise the serviceability of the structural element due to the ability of SFRC to withstand stresses upon the creation of a macrocrack. In this context, crack openings under sustained loading in service conditions should be limited to the range of SFRC efficiency. Moreover, crack openings must be maintained in ultimate conditions below a critical opening upon which the bridging effect of the fibres becomes negligible, or the loads must be kept under sustained load levels leading to uncontrolled crack propagation in SFRC [5, 6]. The propagation and the widening of macrocracks in a structural element under sustained loading must be predicted adequately in order to maintain the gain in durability provided by SFRC and avoid failure.
An experimental program on SFRC notched beams was carried out to provide insights on the mechanisms leading to the propagation of cracks and ultimately to the failure under sustained loading. The objectives were to assess creep, macrocrack propagation, and the evolution of the damage under service and ultimate loads. The experimental program included flexural creep tests on pre-cracked notched beams, both in sealed and drying moisture conditions at various crack openings and sustained loading levels. This paper focuses on the results obtained on beams in sealed and drying conditions submitted to an identical loading history. The loading history was selected to simulate service conditions and ultimate conditions found in a reinforced SFRC structure.