One concrete mixture was used for the experiment. In order to
evaluate the material models for an analysis of the experimental
columns, the following material properties were tested:
the compressive strength of the concrete and the modulus of
elasticity.
The concrete’s compressive strength was obtained from uniaxial
compression tests with cubic specimens of 150 mm at concrete ages
of 28 and 82 days. The test results are presented in Tab. 1.
The curve in Fig.4 represents the theoretical time development of
the concrete’s strength with normal hardening cement according
to EN 1992-1-1 for concrete with a cubic strength of 33 MPa at an
age of 28 days. The curve matches the results of the strength test
performed at the age of the concrete of 28 and 82 days.
The secant modulus of the elasticity of the concrete was tested on
three 100x100x400 mm prisms before the load test. The measured
value of the concrete at the age of 82 days was 33.08 GPa. The
longitudinal steel reinforcement for all the column specimens was
composed of bars of a 10 mm diameter (an actual yield strength of 514
MPa), while the stirrups had a diameter of 6 mm. The concrete cover
over the longitudinal bars was maintained at 25 mm in all the
specimens. The CFRP laminate strips used in the NSM technique,
with a designation of CFK 150/2000 were delivered in rolls, the
dimensions of which were 10x1.4 mm. The tension test revealed the
strength of the CFRP strips (2562 MPa), the modulus of elasticity (167
GPa) and the ultimate tensile strain (1.528 %). The CFRP sheet, which
was applied for wrapping the specimen columns had a fiber thickness
of 0.176 mm, a modulus of elasticity of 204 GPa, an ultimate strength
in tension of 3800 MPa and an ultimate strain of 1.55 %.