1. Modeling based on the theory of plasticity
Flexural-Shear Behavior of Reinforced
UHPFRC-RC Composite Slabs /
EDCE
Candidate Talayeh Noshiravani 1 Supervisor Prof. Eugen Brühwiler 1
2011
1 Structural maintenance and safety laboratory (MCS) June 2011
Motivation
Ultra-high performance fiber-reinforced concrete (UHPFRC) has a high tensile strength and ductility that make it a suitable material for external flexural reinforcement of existing reinforced concrete (RC) slabs. An added layer of R-UHPFRC on a RC slab modifies the slab into a
R-UHPFRC-RC composite element.
Can R-UHPFRC tensile overlays contribute to the deformation capacity and shear resistance of R-UHPFRC-RC composite slabs? Can these composite members allow load redistribution after a local failure of a slab and improve the overall structural robustness?
Tensile behavior of UHPFRC
R-UHPFRC – RC element
Contribution of R-UHPFRC to shear resistance
Modeling based on the theory of plasticity
Flexure-shear rotational collapse mechanism
Adapted from Stoffel, P., Doctoral thesis, No , ETHZ, 2000
Structural Response
Experiments have shown that unlike other comparable flexural strengthening methods, tensile UHPFRC overlays contribute to
both shear strength and deformation capacity of composite slabs.
[mm]
Test specimens and experimental results
Fracture of a composite specimen
Contribution of R-UHPFRC
The R-UHPFRC elements contribute to the shear resistance of composite members by three different means:
a) The bending resistance of the R-UHPFRC elements allows the element to carry a part of the shear stresses introduced into the element by the prying action of RC segments formed by diagonal flexure-shear cracks.
b) The R-UHPFRC elements restrain the widening of a flexure-shear collapse crack in the RC element, thus improving the contribution of concrete to the shear resistance.
c) The debonding between the elements changes the stress fields in the member and reduces the intensity of the stresses that need to be carried across the flexure-shear collapse cracks.