11.1 Introduction
371
Generally, the existing studies have the following limitations: (i) Ultra-high performance cementitious composites (UHPCC) and UHPCC filled steel tube (UHPCCFST) have been becoming the most prospective construction materials and bearing
members for high-rise and long-span bridges. However, most of the blast tests
mentioned above are concentrated on the normal strength concrete and RC members;
(ii) Considering the accessibility of the bridge column and the threat of the terroristic car bombs, the close-range explosion (non-contact but Z ≤ 1 m/kg
1/3 ) should be
drawn much more attention. Besides, the detonation mechanism and blast loading
of close-range explosion are more complex and different from that of the far-range
explosion (Ngo et al. (2015)). However, the existing experimental studies in case
of the close-range explosion are limited; (iii) There are no consensus for the efficient analytical approach to predict the dynamic response of structural columns
subjected to the close-range explosion, although several methods have been proposed
previously.
At present, the blast performance of UHPCC-FST columns subjected to closerange explosion is studied both experimentally and numerically. The close-range
explosion test on four UHPCC-FST columns is firstly conducted with the scaled
standoff distance of 0.12 ≤ Z≤0.14 m/kg
1/3 . Then, three existing approaches are
applied to analyze the dynamic responses of CFST columns in the present and
existing close-range explosion tests, i.e., numerical simulations based on ArbitraryLagrangian-Eulerian elements method (ALE method) and velocity loading method
(velocity method), as well as the equivalent single degree of freedom method (SDOF
method). By comparisons of the experimental and predicted residual mid-span
deflections, the applicability of above three approaches are discussed.
11.2 Explosion Test on UHPCC-FST Column
11.2.1 Specimens
Four circular UHPCC-FST column specimens were prepared to investigate the
response of UHPCC-FST column under close-range explosion with different scaled
standoff distances. The geometrical and sectional details of the specimens are illustrated in Fig. 11.1. The outer steel tubes of the specimens were made from Chinese
20# steel. By conducting the direct tensile test with the MTS 810 material testing
machine at the strain rate of 2 mm/min, the true tensile stress-strain curves of five
standard tensile coupons of 20# steel are derived, as shown in Fig. 11.2. The average
yield strength, ultimate tensile strength and the elastic modulus of steel tubes can be
determined as 318.5 MPa, 507.1 MPa and 206 GPa, respectively.
UHPCC was prepared in the State Key Laboratory of High Performance Civil
Engineering Materials, Jiangsu Research Institute of Building Science in China. The
mixture proportions of UHPCC are given in Table 11.1, in which the abbreviation
HRWR denotes the high range water reducer. The detailed properties of the mixing
371
Generally, the existing studies have the following limitations: (i) Ultra-high performance cementitious composites (UHPCC) and UHPCC filled steel tube (UHPCCFST) have been becoming the most prospective construction materials and bearing
members for high-rise and long-span bridges. However, most of the blast tests
mentioned above are concentrated on the normal strength concrete and RC members;
(ii) Considering the accessibility of the bridge column and the threat of the terroristic car bombs, the close-range explosion (non-contact but Z ≤ 1 m/kg
1/3 ) should be
drawn much more attention. Besides, the detonation mechanism and blast loading
of close-range explosion are more complex and different from that of the far-range
explosion (Ngo et al. (2015)). However, the existing experimental studies in case
of the close-range explosion are limited; (iii) There are no consensus for the efficient analytical approach to predict the dynamic response of structural columns
subjected to the close-range explosion, although several methods have been proposed
previously.
At present, the blast performance of UHPCC-FST columns subjected to closerange explosion is studied both experimentally and numerically. The close-range
explosion test on four UHPCC-FST columns is firstly conducted with the scaled
standoff distance of 0.12 ≤ Z≤0.14 m/kg
1/3 . Then, three existing approaches are
applied to analyze the dynamic responses of CFST columns in the present and
existing close-range explosion tests, i.e., numerical simulations based on ArbitraryLagrangian-Eulerian elements method (ALE method) and velocity loading method
(velocity method), as well as the equivalent single degree of freedom method (SDOF
method). By comparisons of the experimental and predicted residual mid-span
deflections, the applicability of above three approaches are discussed.
11.2 Explosion Test on UHPCC-FST Column
11.2.1 Specimens
Four circular UHPCC-FST column specimens were prepared to investigate the
response of UHPCC-FST column under close-range explosion with different scaled
standoff distances. The geometrical and sectional details of the specimens are illustrated in Fig. 11.1. The outer steel tubes of the specimens were made from Chinese
20# steel. By conducting the direct tensile test with the MTS 810 material testing
machine at the strain rate of 2 mm/min, the true tensile stress-strain curves of five
standard tensile coupons of 20# steel are derived, as shown in Fig. 11.2. The average
yield strength, ultimate tensile strength and the elastic modulus of steel tubes can be
determined as 318.5 MPa, 507.1 MPa and 206 GPa, respectively.
UHPCC was prepared in the State Key Laboratory of High Performance Civil
Engineering Materials, Jiangsu Research Institute of Building Science in China. The
mixture proportions of UHPCC are given in Table 11.1, in which the abbreviation
HRWR denotes the high range water reducer. The detailed properties of the mixing