| dc.description.abstract | This master thesis examines nonlinear analysis of fibre reinforced concrete in DIANA,
what influence changes in fibre orientation and density have on the load
capacity and the load-bearing ability when the displacement grows. The most important
part of the report are the modeling and results from the analysis.
The first part of the report includes background theory for nonlinear analysis to
give a better understanding of the analysis. Additionally the report include a literature study, based on earlier research and published material about fibre reinforced concrete and its mechanical properties. Especially the residual tensile strength is interesting, since it is here the fibres become the most useful.
Both modeling and analysis have been done in the FEM-program DIANA. The
beams were modeled after the rules in NS-EN 14651. Mostly the analysis were run
with a displacement control up to a displacement of 4 mm to make it easier to see
what influence the specific types of fibre reinforced concrete had on the load-capacity
with increasing displacement. Force-controlled analysis were also tested, but most
of the analysis stopped shortly after reaching the maximum load-capacity because
of convergence.
Calculations were done to check the contribution from the fibres to the shear capacity.
The calculations were based on a set of rules suggested by COIN. Because
of the existence of the notch, the first crack will always occur in the mid-section.
The results showed that with a good consistency between the normal vector for the
crack and the orientation of the fibres, it would be considerable contributions to
the shear capacity. With higher density in the critical area, this contribution would
become larger. The results from the analysis showed that up to 45 degrees between
the normal vector and the fibre orientation, the fibres would have a positive effect
on the load-bearing capacity after larger displacements when cracks have occurred.
This thesis shows that through FEM-analysis it is possible to make good models of
fibre reinforced concrete. However, more research on strain softening and hardening
of FRC, and how to look at local changes, are necessary. In addition a set of design
rules should be developed. | |
