Theoretical model for size and shape effect of UHPFRC in flexural tension considering tensile behaviour influenced by fibre orientation

Author(s): B. Frettlöhr
Paper category: Symposium
Book title: RILEM-fib-AFGC International Symposium on Ultra-High Performance Fibre-Reinforced Concrete
Editor(s): F. Toutlemonde, J. Resplendino
Print ISBN: 978-2-35158-130-8
e-ISBN: 978-2-35158-131-5
Publisher: RILEM Publications S.A.R.L
Pages: 689 – 698
Total Pages: 10
Language: English

Abstract: 
The fibre orientation in UHPFRC members influences significantly the structural behaviour and strength and needs to be considered in design. The stress – crack opening law could be described by a fibre model and this corresponded well to own tensile tests.
Between the fibre orientation and the tensile strength a nonlinear function was derived. The stress – crack opening law based on the fibre model for a one dimensional fibre orientation was approximated by a piece-wise function, and this was used to describe the constitutive law in tension of UHPFRC considering the fibre orientation.
To explain the experimentally verified size and shape effect of the flexural tensile strength, an original fracture mechanics model was developed following the "fictitious crack model" of Hillerborg et al. (1976) and compared to other models. It was found that fracture mechanics alone cannot explain the size and shape effect of the flexural strength of UHPFRC but a theoretical explanation is only possible by additionally considering the fibre orientation.

Online publication: 2014
Publication Type: full_text
Public price (Euros): 0.00