10.8 Parametric Study
359
Figure 10.29 further shows the blast induced crater depth, the residual axial load
bearing capacity, as well as the corresponding damage index of present UHPCCFST column with varied core concrete strength. It indicates that, (i) with the increase
of core concrete strength, the crater depth of the column reduces gradually, the
corresponding reducing trend within the concrete strength range of 30–75 MPa is
more prominent compared to that within the concrete strength range of 75–170 MPa;
(ii) higher compressive strength of core concrete exhibits higher original and residual
axial capacity of the column, the curve of residual axial capacity of the column
exhibits linearly increasing trend, while the curve of the original axial capacity of
the column shows firstly linearly increasing trend (below 75 MPa) and then enters
into the plateau. It is probably attributed to the influence of the structural stability of
the column under compression. When the core concrete strength exceeds a certain
range, further increasing the core concrete strength do not have much contribution to
the axial capacity of the column; (iii) the damage index of the post-blast column first
increases for the concrete strength ranging from 30 to 75 MPa and then reduces within
the concrete strength range of 75–170 MPa. The corresponding variation range of
the damage index is from 0.3 to 0.4, which indicates that the damage index is not
sensitive to the compressive strength of core concrete.
10.8.2.2 Cross-Sectional Diameter
The cross-sectional diameters of core concrete are selected as 88, 288, 388 and
488 mm. Considering the steel tube thickness of 6 mm, the corresponding crosssectional diameter of column are determined as 100 mm, 300 mm, 400 mm and
500 mm, respectively. The other parameters, i.e., steel tube thickness, steel tube
strength and compressive strength of core concrete, are kept identical with those of
column C-2. Figure 10.30 further shows the blast induced crater depth, the residual
axial load bearing capacity, as well as the corresponding damage index of present
UHPCC-FST column under contact detonation with different cross-sectional diameters of core concrete. It should be noted that, the column with a diameter of
100 mm is breached in the vicinity of the detonation point and the crater depth
was set as 100 mm. It indicates that, (i) the crater depth decreases with increasing
the cross-sectional diameter of core concrete, e.g., the crater depth reduced by
61.8% when the core concrete diameter increases from 88 to 191 mm, while beyond
191 mm, further increasing the core concrete diameter has little effect on the crater
depth; (ii) increasing the core concrete diameter can effectively improve the original
and residual axial capacity of the column; (iii) the damage index reduces rapidly
when the core concrete diameter increases from 88 to 191 mm, however, further
increasing the core concrete diameter cannot significantly reduce the damage degree
of UHPCC-FST column.
359
Figure 10.29 further shows the blast induced crater depth, the residual axial load
bearing capacity, as well as the corresponding damage index of present UHPCCFST column with varied core concrete strength. It indicates that, (i) with the increase
of core concrete strength, the crater depth of the column reduces gradually, the
corresponding reducing trend within the concrete strength range of 30–75 MPa is
more prominent compared to that within the concrete strength range of 75–170 MPa;
(ii) higher compressive strength of core concrete exhibits higher original and residual
axial capacity of the column, the curve of residual axial capacity of the column
exhibits linearly increasing trend, while the curve of the original axial capacity of
the column shows firstly linearly increasing trend (below 75 MPa) and then enters
into the plateau. It is probably attributed to the influence of the structural stability of
the column under compression. When the core concrete strength exceeds a certain
range, further increasing the core concrete strength do not have much contribution to
the axial capacity of the column; (iii) the damage index of the post-blast column first
increases for the concrete strength ranging from 30 to 75 MPa and then reduces within
the concrete strength range of 75–170 MPa. The corresponding variation range of
the damage index is from 0.3 to 0.4, which indicates that the damage index is not
sensitive to the compressive strength of core concrete.
10.8.2.2 Cross-Sectional Diameter
The cross-sectional diameters of core concrete are selected as 88, 288, 388 and
488 mm. Considering the steel tube thickness of 6 mm, the corresponding crosssectional diameter of column are determined as 100 mm, 300 mm, 400 mm and
500 mm, respectively. The other parameters, i.e., steel tube thickness, steel tube
strength and compressive strength of core concrete, are kept identical with those of
column C-2. Figure 10.30 further shows the blast induced crater depth, the residual
axial load bearing capacity, as well as the corresponding damage index of present
UHPCC-FST column under contact detonation with different cross-sectional diameters of core concrete. It should be noted that, the column with a diameter of
100 mm is breached in the vicinity of the detonation point and the crater depth
was set as 100 mm. It indicates that, (i) the crater depth decreases with increasing
the cross-sectional diameter of core concrete, e.g., the crater depth reduced by
61.8% when the core concrete diameter increases from 88 to 191 mm, while beyond
191 mm, further increasing the core concrete diameter has little effect on the crater
depth; (ii) increasing the core concrete diameter can effectively improve the original
and residual axial capacity of the column; (iii) the damage index reduces rapidly
when the core concrete diameter increases from 88 to 191 mm, however, further
increasing the core concrete diameter cannot significantly reduce the damage degree
of UHPCC-FST column.