Damage of Reinforced Concrete Walls from Shock and Impact

Transcription

1 Damage of Reinforced Concrete Walls from Shock and Impact Coupled Multi-Solver Approach X. Quan Development Engineer Century Dynamics, ANSYS, Inc.

2 Overview Introduction Methods of Space Discretization (MSD) Coupled Multi-Solver Approach Interaction/coupling among MSD Numerical Simulations Truck bomb explodes near a physical barrier Boeing 747 jet impacts physical barriers Conclusions

3 Physical Barriers Built around nuclear power plants May consist of multiple barriers Usually made of steel-reinforced concretes Must provide adequate structural strength to prevent failure under terrorist attacks complete demolition projectile/fragment penetration spalling of barrier materials

4 Numerical Simulations Can supply detailed and accurate stress/strain fields than simplified analytical approaches Use nonlinear dynamic analysis computer program ANSYS AUTODYN Investigate damage initiation and development in a steel reinforced concrete wall under shock and impact loadings

5 Space Discretization Lagrange numerical grid moves with material Euler material moves through fixed numerical grids ALE (Arbitrary Lagrange Euler) rezoning the interior continuously Meshfree: Smooth Particles Hydrodynamics each particle is an interacting mass and interpolation point

6 Space Discretization Use Single Space Discretization Method Advantage easy setup of computational models Disadvantages not appropriate to all the regimes of the problem response of structures to an explosion: detonation and blast are best modeled by Euler while structural response is best modeled by Lagrange Need Coupled Space Discretization Methods-Coupled Multi-Solver Approach

7 Coupled Multi-Solver Lagrange/Lagrange interactions between Lagrangian grids contact/slide surfaces best to simulate impact problems Euler/Lagrange coupling between Eulerian/Lagrangian grids best to simulate structural response to explosive loadings

8 Concrete Wall

9 Concrete Wall

10 Material Modeling Concrete: RHT Strength and Failure pressure hardening strain hardening strain rate hardening damage (strain softening) Reinforced Steel Bars von Mises strength ultimate strain failure reinforced ratio: 0.8%

11 Numerical Modeling Concrete is represented by 36,000 Lagrange solid elements Steel rebars are represented by 6,000 beam elements Explosive detonation and expansion of gas products are modeled by Euler solvers from 1,000,000 to 2,000,000 Euler-Ideal gas elements in 3D simulations Euler/Lagrange coupling is applied

12 Location of Bomb

13 1D to 3D Remap 1D Euler simulation on explosive detonation and its spherical expansion Before it reaches the wall, 1D blast field is remapped onto a 3D Euler-Ideal gas grid Advantages of remapping unique feature of ANSYS AUTODYN save a lot of computing time in 3D calculation accurate modeling early stages of the blast

14 1D to 3D Remap

15 Damage: Contact Front View Back View

16 Damage: Contact

17 Damage: 5m Front View Back View

18 Damage: 10m/20m 10m, front 20m, front

19 Total Energy 5 m Detonation Total Energy (µj) 10 m Detonation 20 m Detonation Time (ms)

20 Summary 60m wide, 30m high, and 1m thick steelreinforced concrete wall is considered Truck bomb contains 5000Kg TNT The wall stands when the bomb explodes at 10m 20m The wall fails when the bomb explodes at 0m, contact detonation 5m

21 Jet Impact

22 Material Modeling Airplane is made of aluminum with linear equation of state piecewise linear strain hardening strength ultimate strain failure erosion Thickness is adjusted so the overall weight of the entire airplane and weight distribution among fuselage, engines, and fuel are correctly represented.

23 Numerical Modeling Concrete is represented by 56,000 solid elements for 1m thick wall 186,000 solid elements for 3m thick wall Steel rebars are represented by 16,000 beam elements Airplane is represented by 15,000 shell elements Lagrange/Lagrange interaction is applied

24 1m Thick Wall

25 3m Thick Wall

26 Damage: 1m Thick Front View Back View

27 Damage: 3m Thick Front View Back View

28 Summary 1m & 3m thick, 150m wide, 60m high steelreinforced concrete walls are considered Walls are impacted by a Boeing 747 passenger jet Impact velocity: 83.3m/s (300km/s) 1m thick wall fails under the impact 3m thick wall withstands the impact

29 Conclusions The shock and impact simulations demonstrate the successful use of the coupled multi-solver approach. ANSYS AUTODYN has the capability to simulate various terrorist threats against physical barriers of nuclear power plants. ANSYS AUTODYN can be the most cost effective numerical tool for physical barrier designers

30 References X. Quan, et al, Applications of a coupled multisolver approach in evaluating damage of reinforced concrete walls from shock and impact, 18th international conference on structural mechanics in reactor technology, Beijing, China, August 7-12, 2005 M. Katayama et al, Numerical simulation of jumbo jet impacting on thick - concrete wall effects of reinforcement and wall thickness, 2nd Asian conference on high pressure research, Nara, Japan, November 1-5, 2004