74
4 Triaxial Compressive Behavior of UHPCC …
range of 5–10 mm, the designed uniaxial compressive strength of ~100 MPa) for
protective structures against projectile high-speed impact was prepared under ordinary procedures. Triaxial compressive test on two batches of 50 × 100 mm cylindrical specimens with uniaxial compressive strength of 95 MPa and 129 MPa was
conducted with the confinement ratio (the ratio of confining pressure to the uniaxial
compressive strength) reached 0.84 and 0.78, respectively. The deviatoric stress–
strain curves for various confinement pressure were derived, the failure criteria and
toughness of UHPCC under triaxial compression were discussed. Finally, by using
the present and existing triaxial compression tests data (Lu and Hsu 2006; Xie et al.
1995; Sovják et al. 2013; Farnam et al. 2010; Xiong 2009) on high-strength concrete,
the dominant strength parameters of Holmquist- Johnson–Cook (HJC) constitutive
model (Holmquist et al. 1993) were confirmed. Furthermore, aiming to verify the
validity of the proposed model parameters, by utilizing the finite-element program
LS-DYNA, the predicted projectile penetration depth and residual velocity were
compared with the experimental data from eleven sets of projectile penetration or
perforation tests on concrete and rock targets with the uniaxial compressive strength
ranging from 67.5 to 157 MPa.
4.2 A Review of the Existing Works on Triaxial Behavior
of Concrete
The existing related works are mainly on normal-strength concrete (NSC) and highstrength concrete (HSC). Wang et al. (1987) performed a series of triaxial compressive test on 100 mm cubic specimen, the unconfined compressive strength was around
10 MPa and the confinement ratio reached up to 3, the nearly linear relationship of
normalized triaxial compressive strength and the confinement ratio was obtained.
Sfer et al. (2002) conducted the triaxial compressive test on 150 mm × 300 mm
cylindrical specimens with the unconfined compressive strength around 30 MPa and
the confinement ratio varing within 0 ~ 2. It is observed that the failure envelope of
which correlated well with the nonlinear Etse and Willam model (Etse and Willam
1994). Sirijaroonchai et al. (2010) experimentally studied the influences of fiber types
(high-strength hooked steel fibers, ultra high molecular weight polyethylene fibers),
fiber volumetric fraction (1 ~ 2%) and confining pressure (41 and 52 MPa) on the
passive triaxial behavior of high performance fiber reinforced cement composites
with the unconfined compressive strength of ~50 MPa. It indicated that, for relatively high confinement ratio, confining effect introduced by the fibers with various
types and fractions became minor. Chern et al. (1992) experimentally investigated
the influences of volumetric ratio of steel fibers (0 ~ 2%) and confinement pressure (0
~ 70 MPa) on the triaxial strength of the NSC with the uniaxial compressive strength
around 20 MPa. It was concluded that the addition of steel fibers has insignificant
effect on the mechanical behavior of concrete at confining pressure up to 70 MPa.
4 Triaxial Compressive Behavior of UHPCC …
range of 5–10 mm, the designed uniaxial compressive strength of ~100 MPa) for
protective structures against projectile high-speed impact was prepared under ordinary procedures. Triaxial compressive test on two batches of 50 × 100 mm cylindrical specimens with uniaxial compressive strength of 95 MPa and 129 MPa was
conducted with the confinement ratio (the ratio of confining pressure to the uniaxial
compressive strength) reached 0.84 and 0.78, respectively. The deviatoric stress–
strain curves for various confinement pressure were derived, the failure criteria and
toughness of UHPCC under triaxial compression were discussed. Finally, by using
the present and existing triaxial compression tests data (Lu and Hsu 2006; Xie et al.
1995; Sovják et al. 2013; Farnam et al. 2010; Xiong 2009) on high-strength concrete,
the dominant strength parameters of Holmquist- Johnson–Cook (HJC) constitutive
model (Holmquist et al. 1993) were confirmed. Furthermore, aiming to verify the
validity of the proposed model parameters, by utilizing the finite-element program
LS-DYNA, the predicted projectile penetration depth and residual velocity were
compared with the experimental data from eleven sets of projectile penetration or
perforation tests on concrete and rock targets with the uniaxial compressive strength
ranging from 67.5 to 157 MPa.
4.2 A Review of the Existing Works on Triaxial Behavior
of Concrete
The existing related works are mainly on normal-strength concrete (NSC) and highstrength concrete (HSC). Wang et al. (1987) performed a series of triaxial compressive test on 100 mm cubic specimen, the unconfined compressive strength was around
10 MPa and the confinement ratio reached up to 3, the nearly linear relationship of
normalized triaxial compressive strength and the confinement ratio was obtained.
Sfer et al. (2002) conducted the triaxial compressive test on 150 mm × 300 mm
cylindrical specimens with the unconfined compressive strength around 30 MPa and
the confinement ratio varing within 0 ~ 2. It is observed that the failure envelope of
which correlated well with the nonlinear Etse and Willam model (Etse and Willam
1994). Sirijaroonchai et al. (2010) experimentally studied the influences of fiber types
(high-strength hooked steel fibers, ultra high molecular weight polyethylene fibers),
fiber volumetric fraction (1 ~ 2%) and confining pressure (41 and 52 MPa) on the
passive triaxial behavior of high performance fiber reinforced cement composites
with the unconfined compressive strength of ~50 MPa. It indicated that, for relatively high confinement ratio, confining effect introduced by the fibers with various
types and fractions became minor. Chern et al. (1992) experimentally investigated
the influences of volumetric ratio of steel fibers (0 ~ 2%) and confinement pressure (0
~ 70 MPa) on the triaxial strength of the NSC with the uniaxial compressive strength
around 20 MPa. It was concluded that the addition of steel fibers has insignificant
effect on the mechanical behavior of concrete at confining pressure up to 70 MPa.