African Design Magazine ADM #42 July 2018 | Page 54

TECHNOLOGY
strength of steel fibre were 13 mm,
0.2 mm, and 1800 MPa, respectively. The
compressive strength and four-point
flexural strength of UHPFRC after 90 d
standard curing were 156.1 MPa and
34.4 MPa, respectively.
Table 1: Mixture proportion of UHPC (kg/m 3 )
Lattice network construction
Due to the limitation of computing
efficiency, four-point flexural tests were
simulated on a 10 mm × 10 mm × 40 mm
prism. The fibres were considered to be
randomly distributed in the prism. The
fibre beams were generated following
the method
Figure 3: Fibre
described in [21].
distribution in the
The simulated fibre
UHPFRC prism.
distribution and
corresponding
lattice network
are shown in
Figures 3 and 4. The
lattice network was
constructed with the
method mentioned
in Section 2, and the
mesh size was 1 mm.
The matrix beam and
fibre beam are shown in blue and red,
respectively, in Figure 4.
response of UHPFRC depends on the
matrix parameters, fibre parameters,
and fibre-matrix interface parameters.
These parameters are also the inputs
for the lattice fracture model. The input
parameters for this study are shown in
Table 2. The parameters
for the matrix and steel
fibre were obtained
with experiments, and
the parameters for
the interface beams
were fitted based on
the experimental data from [26]. The
matrix and fibres were considered as
linear elastic (Figure 5(a)), while a seven
segment ductile stress-strain response
[21] (Figure 5(b)) was applied for interface
elements in order to obtain more realistic
results.
Table 2: Input parameters for the lattice fracture
model.
Figure 5: Mechanical properties of (a) matrix
beam and fibre beam and (b) interface beam.
Figure 4: Lattice network of the UHPFRC prism.
Local Mechanical Properties Assignment
From a general point of view, the flexural
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AFRICAN DESIGN MAGAZINE © | JULY 2018
Boundary condition setting
The boundary condition was set following
that happened in the experiments. A
four-point bending test was set for the