BRIEF SUMMARY
The anti-penetrating sandwich structure is built under the ground's surface as a protective measure for buildings underneath it, when under attack by penetrating weapons.
BACKGROUND
Important buildings that were constructed underground can survive an attack by external forces. However, the invention of penetrating weapons has increased the difficulty of solving the problem of protecting buildings from the new ordinance. In view of this, the anti-penetrating sandwich structure is built above the underground building to prevent the destruction of the buildings underneath it from attacks which employ penetrating weapons.
DETAILED DESCRIPTION
- I. Structural Materials
- 1. The anti-penetrating sandwich structure built under the ground's surface consists of “Surface soil+parallel combined steel structure (or RC structure)+energy dissipating material+parallel combined steel structure (or RC structure)+energy dissipating material+parallel combined steel structure (or RC structure)+underground seismic building” from top downwards.
- 2. The combined steel structure consists of steel plates or welded section steels. The variations of combined steel structure include the following:
- (1) Welded box beam structure
- (2) Plate girder structure
- (3) Single folded plate structure
- 3. The parallel combined steel structure is a combined steel structure arranged in parallel or piled pattern of design, and then combined through welding.
- 4. Energy dissipating materials
- (1) Engineering plastics
- A. The accurate measurement of elasticity modulus and poisson's ratio is very important in regard to the correctness of the structural analysis.
- B. During research and development of the engineering plastics, it is necessary to consider its flammability, and an experiment on energy dissipation should be performed as test reference.
- (2) Soil
- A. The accurate calculation of elasticity modulus and poisson's ratio is very important in regard to the correctness of the soil analysis.
- B. For selection of sand-gravel, the size gradation of aggregate must be executed according to the soil categorization system, and an experiment on energy dissipation should be performed as test reference.
- 5. When the engineering plastic is used as the energy dissipating material, the thermal expansion coefficient must be considered for adhesion between the engineering plastic and the parallel combined steel structure. Adhesive can be used to compensate for small difference in thermal expansion coefficient; for large difference in thermal expansion coefficient, the parallel combined steel structure can be nailed and then secured together with the engineering plastic.
- II. Structural Shape
- 1. The arch structure is a parallel combined steel structure that exhibits an upward arching pattern.
- 2. The grid beams and panel surface are the structural patterns above the RC (Reinforced Concrete), welded box or section steel grid beams, and are bonded to the parallel combined steel structure with adhesives.
- 3. The plane structure is the combined steel structure arranged in parallel pattern on a plane.
- III. Structural Design
- 1. The objective of structural design is to provide resistance to each layer against the penetrating weapons, so that the energy dissipating materials have sufficient elasticity for shape recovery.
- 2. After the penetrating weapon hits the surface soil, the penetrating force is dispersed downwards to the parallel combined steel structure on the 1st layer where the energy dissipating material on this layer can dissipate the force.
- 3. Structural Design
- (1) Stage 1
- A. Assume that the parallel combined steel structure on the 2nd layer is rigid and that the strength of the parallel combined steel structure on the 1st layer is sufficient to resist the penetration of penetrating weapons, so that the energy dissipating material on the 1st layer can disperse the force to the parallel combined steel structure on the 2nd layer and completely dissipate the penetrating force. Under such prerequisite, the required dimension derived from structural analysis can act as the design basis for the parallel combined steel structure for the 1st layer. For the structural design, please refer to the mechanics of the materials, structural mechanics, structural dynamics and the finite element method. For the soil analysis, please refer to the mechanics of materials, soil mechanics, soil dynamics and the finite element method.
- B. The parallel combined steel structure on the 2nd layer is similar to the parallel combined steel structure on the 1st layer.
- C. For the parallel combined steel structure on the 3rd layer, the energy dissipating material of the lower layers can adopt the following materials:
- i. Engineering plastics
- a. If engineering plastics are used as energy dissipating material on the 1st and 2nd layers, the engineering plastics with the same thickness can be used as the buffering energy dissipating material between the parallel combined steel structure on the 3rd layer and the underground building.
- b. If soil is used as the energy dissipating material on the 1st and 2nd layers, the energy dissipation behavior will involve both elastic and plastic deformation. Please refer to the mechanics of materials, structural mechanics, structural dynamics and the finite element method for structural analysis.
- ii. Soil
- a. If engineering plastics are used as the energy dissipating material on the 1st and 2nd layers, the energy dissipation behavior will involve the draining of the void water, and soil compressiveness. Please refer to the mechanics of materials, soil mechanics, soil dynamics and the finite element method for soil analysis.
- b. If soil is used as the energy dissipating material on the 1st and 2nd layers, soil with the same mixing ratio and thickness can be used as the buffering energy dissipating material between the parallel combined steel structure on the 3rd layer and the underground building.
- (2) Stage 2
- Execute the overall analysis on the anti-penetrating sandwich structure to confirm the force status and make further adjustments as necessary.
- (3) Stage 3
- Evaluate the probability of repetitive attack on a fixed point and carry out Stage 1 and 2 analyses, respectively, to confirm the force status and make further adjustments as necessary.
- 4. Depending on actual requirements, determine if the pile foundation shall be erected at end-points, so that the penetrating force from the penetrating weapon can be dispersed to deeper ground.
REFERENCE
Structure Systems, Heinrich Engel, 1981.