Numerical study on the dynamic response of a massive liquefied natural gas outer tank under impact loading

In this paper, the dynamic response of a typical 160 000 m(3) liquefied natural gas (LNG) prestressed concrete outer tank under impact loading is investigated. The applicability of the Holmquist-Johnson-Cook (HJC) material model of concrete and numerical simulation method on impact that is proposed in this paper is verified by the test results of concrete slabs under projectile impact cited from the reference. A detailed finite element (FE) model of the LNG outer tank, including walls, buttresses, domes, beams, and bottom plates, under the impact of a Tomahawk cruise missile is established. In addition, pre-stress on the wall, impact angles, locations, and velocities are considered and their influence on dynamic response studied. The impact damage types for the LNG outer tank are concluded according to dynamic response results including stress, displacement, stress sweep range, and energy, and critical impact velocities to distinguish these damage types are also determined. In addition, the damage types and their failure mechanism are analyzed by the damage factor proposed in this paper, which is based on energy propagation. Finally, four empirical formulas of impact loading recommended by the standard "accident analysis for aircraft crash into hazardous facilities" are used for checking the impact resistance performance of the LNG outer tank and compared with FE numerical simulation results. It is demonstrated, by using empirical formulas, that the common 160 000 m(3) LNG outer concrete tank could suffer flange impact loading. However, all the four empirical results were more conservative compared to numerical results under the same missile perforation velocity.