346
10 Residual Axial Capacity of UHPCC-FST Column Under …
restart and full restart. Since the new parts of bearing plate and ball joint need to be
added, the full restart method is adopted at present. As shown in Fig. 10.14a, the
simulation of UHPCC-FST column under contact detonation is firstly performed and
the corresponding restart files are generated at the terminal instant of UHPCC-FST
column under contact detonation.
In the numerical simulation, it is difficult to stop the vibration of the UHPCCFST column in a short time after the contact explosion. Considering that the present
column is basically in the elastic vibration state after 0.015 s of explosion detonates, the keyword *DAMPING_GLOBAL is adopted to stabilize the column from
vibrating quickly. The original keyword files are modified by adding the FE model,
material constitutive model and corresponding parameters of the bearing plate and
ball joint shown in Fig. 10.14b. Then, the analysis process restarts, the ALE elements
(explosive and air) are deleted immediately and the bearing plate (Fig. 10.14b) in
the modified keyword file pushes the top of the post-blast UHPCC-FST column
(Fig. 10.14a) in the restart file with a preset displacement rate. It should be noted
that, in the experiment, the axial compressive load was applied with the displacement
control manner, i.e., the displacement rate was 1 mm/min, which would consume
high computational costs in the numerical simulations. In the present numerical simulations, it is found that nearly identical results are obtained for the two displacement
rates of 2 and 10 mm/s. Hence, in order to balance the computational accuracy and
efficiency, the displacement rate of 10 mm/s is applied at the top end of the post-blast
UHPCC-FST column.
10.7 Comparisons with Test Data
In this section, the above developed numerical model is compared and validated
based on the experimental results in terms of the damage and failure modes, crater
dimensions and the residual axial capacity. The verified numerical algorithm, constitutive models and the corresponding parameters are utilized to discuss the parametric
influences on the blast resistance of UHPCC-FST column under contact detonation
in Sect. 10.8.
10.7.1 Damage and Failure Modes of Columns
Figure 10.19 illustrates the numerically simulated damage pattern of C-1 column after
1 kg TNT contact detonation. It can be found that C-1 column sufferred local crater
damage with no occurrence of overall deformation, and the steel tube in the vicinity
of the explosive is deformed without rupture, which are in good agreement with the
experiment (Fig. 10.4). Also, it can be seen that the center of the crater is 250 mm
away from the bottom of the column (Fig. 10.19a), and the crater is approximately
elliptical shape (Fig. 10.19b), which are consistent with the observations in the field
10 Residual Axial Capacity of UHPCC-FST Column Under …
restart and full restart. Since the new parts of bearing plate and ball joint need to be
added, the full restart method is adopted at present. As shown in Fig. 10.14a, the
simulation of UHPCC-FST column under contact detonation is firstly performed and
the corresponding restart files are generated at the terminal instant of UHPCC-FST
column under contact detonation.
In the numerical simulation, it is difficult to stop the vibration of the UHPCCFST column in a short time after the contact explosion. Considering that the present
column is basically in the elastic vibration state after 0.015 s of explosion detonates, the keyword *DAMPING_GLOBAL is adopted to stabilize the column from
vibrating quickly. The original keyword files are modified by adding the FE model,
material constitutive model and corresponding parameters of the bearing plate and
ball joint shown in Fig. 10.14b. Then, the analysis process restarts, the ALE elements
(explosive and air) are deleted immediately and the bearing plate (Fig. 10.14b) in
the modified keyword file pushes the top of the post-blast UHPCC-FST column
(Fig. 10.14a) in the restart file with a preset displacement rate. It should be noted
that, in the experiment, the axial compressive load was applied with the displacement
control manner, i.e., the displacement rate was 1 mm/min, which would consume
high computational costs in the numerical simulations. In the present numerical simulations, it is found that nearly identical results are obtained for the two displacement
rates of 2 and 10 mm/s. Hence, in order to balance the computational accuracy and
efficiency, the displacement rate of 10 mm/s is applied at the top end of the post-blast
UHPCC-FST column.
10.7 Comparisons with Test Data
In this section, the above developed numerical model is compared and validated
based on the experimental results in terms of the damage and failure modes, crater
dimensions and the residual axial capacity. The verified numerical algorithm, constitutive models and the corresponding parameters are utilized to discuss the parametric
influences on the blast resistance of UHPCC-FST column under contact detonation
in Sect. 10.8.
10.7.1 Damage and Failure Modes of Columns
Figure 10.19 illustrates the numerically simulated damage pattern of C-1 column after
1 kg TNT contact detonation. It can be found that C-1 column sufferred local crater
damage with no occurrence of overall deformation, and the steel tube in the vicinity
of the explosive is deformed without rupture, which are in good agreement with the
experiment (Fig. 10.4). Also, it can be seen that the center of the crater is 250 mm
away from the bottom of the column (Fig. 10.19a), and the crater is approximately
elliptical shape (Fig. 10.19b), which are consistent with the observations in the field