Impact relaxation member and building

Abstract

To provide a novel impact relaxation member that can relax an impact at the time of entry by causing an inrushing flying object, such as an aircraft, to slide.SOLUTION: An impact relaxation member to be fitted to an outside surface of a structure 1 includes at least a sacrifice layer 2. When a flying object collides with an outside surface to be protected to which the impact relaxation member is fitted at an acute angle, the sacrifice layer 2 causes the flying object to slide along the outside surface to be protected while a raw material constituting the sacrifice layer 2 is broken, deformed or moved by the flying object to prevent the flying object from penetrating the outside surface to be protected.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an impact absorbing member and a building. [Background technology]

[0002] One method being considered as a countermeasure against aircraft collisions (counter-terrorism measures) at nuclear power plants is to protect them by increasing the thickness of the building's walls. However, to reliably protect the interior of the building from aircraft collisions, reinforced concrete walls 2 to 3 meters thick would be required.

[0003] However, if the ceiling of the building were to be made of 2-3m thick reinforced concrete walls, regardless of the sides, it would be unrealistic to make the upper part heavier in order to ensure earthquake resistance, as this would require enormous costs.

[0004] In view of this, as a countermeasure against aircraft collisions that does not increase wall thickness, a configuration has been proposed in which the building is surrounded by a separate protective structure, as disclosed in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-252800 A Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, large aircraft such as passenger planes normally land on a runway while slowing down at a descent angle of about 3° (if the descent angle is made larger, the aircraft will lose control and stall). However, the ceiling of a building is only a few dozen meters square, making it difficult to accurately crash an aircraft that has lost control into the target building. Therefore, if an aircraft is to be intentionally crashed into the ceiling of a building, it is not realistic to have a large descent angle. Therefore, when a large aircraft collides with the ceiling, it is expected that the collision will be at an oblique angle with a descent angle of approximately several degrees.

[0007] The present invention has been made based on the above-mentioned findings, and aims to provide an unprecedented shock-absorbing member and building that can mitigate the impact of an incoming object such as an aircraft by allowing the object to slide and preventing the transmission of kinetic energy to a building, even if the object approaches at a descent angle of several degrees (10 degrees or less); for example, by installing the member on the ceiling of a building, it is possible to make the reinforced concrete wall in that part of the ceiling thinner. [Means for solving the problem]

[0008] The gist of the present invention will now be described with reference to the accompanying drawings.

[0009] A shock absorbing member attached to the outer surface of the structure 1, The impact absorbing member includes at least a sacrificial layer 2, The sacrificial layer 2 is an impact mitigation member characterized in that, when a flying object collides at an acute angle with the protected outer surface to which the impact mitigation member is attached, the material constituting the sacrificial layer 2 is destroyed, deformed or displaced by the flying object, causing the flying object to slide along the protected outer surface, thereby preventing the flying object from penetrating the protected outer surface.

[0010] The present invention also relates to an impact mitigation member as described in claim 1, characterized in that when a flying object collides with the protected outer surface to which the impact mitigation member is attached at an angle of 10° or less, the material constituting the sacrificial layer 2 is destroyed, deformed or moved by the flying object, causing the flying object to slide along the protected outer surface, thereby preventing the flying object from penetrating the protected outer surface.

[0011] The present invention also relates to an impact mitigation member as described in claim 2, characterized in that it has a sliding layer 3 that supports the sacrificial layer 2 and slides along with the flying object against the protected outer surface when the flying object collides with the sacrificial layer 2.

[0012] The present invention also relates to an impact absorbing member as described in claim 3, characterized in that a friction reducing layer made of a material having a smaller dynamic friction coefficient than the sacrificial layer 2 and the sliding layer 3 is provided between the sacrificial layer 2 and the sliding layer 3 or between the sliding layer 3 and the protected outer surface.

[0013] The present invention also relates to a shock absorbing member according to claim 1, characterized in that the sacrificial layer 2 includes a metal plate having a thickness of 10 mm to 50 mm.

[0014] The present invention also relates to a shock absorbing member according to claim 1, characterized in that the sacrificial layer 2 is configured to include a large number of spherical bodies.

[0015] The present invention also relates to a building equipped with the shock absorbing member according to any one of claims 1 to 6, characterized in that the shock absorbing member is provided on at least the outer surface of the ceiling portion 1a.

[0016] The present invention also relates to a building according to claim 7, characterized in that the ceiling portion 1a is a reinforced concrete wall having a thickness of 1.5 m or less. Effect of the Invention

[0017] Since the present invention is configured as described above, it provides an unprecedented shock absorbing member and building that can mitigate the impact of an incoming flying object such as an aircraft by sliding it. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic explanatory diagram of the present embodiment. [Diagram 2] FIG. 1 is a schematic explanatory diagram of a first modified example. [Diagram 3] FIG. 11 is a schematic explanatory diagram of a second modified example. [Figure 4] FIG. 1 is a schematic explanatory diagram of the basic form of a mock ceiling used in impact analysis. [Diagram 5]FIG. 11 is an explanatory diagram showing analysis results of a comparative model and an analytical model. [Figure 6] FIG. 11 is an explanatory diagram showing analysis results of a comparative model and an analytical model. [Figure 7] FIG. 11 is an explanatory diagram showing analysis results of a comparative model and an analytical model. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] A preferred embodiment of the present invention will be briefly described below with reference to the drawings to illustrate the operation of the present invention.

[0020] The impact absorbing member according to the present invention is attached to an outer surface to be protected, such as the ceiling 1a of a reactor building of a nuclear power plant.

[0021] When a flying object such as an aircraft crashes into the protected outer surface to which this impact mitigation member is attached at an angle of several degrees, the flying object that collides with the sacrificial layer 2 slides along the protected outer surface while destroying, deforming or moving the sacrificial layer 2 (the material that constitutes it), and the flying object maintains almost its speed and bounces slightly before flying away, so that the kinetic energy of the flying object is consumed by the destruction of the sacrificial layer 2, while most of the kinetic energy remains in the flying object. Therefore, the transmission of the kinetic energy of the flying object to the structure 1 such as a building is suppressed as much as possible, and the penetration of the flying object and the transmission of impact to the inside of the structure 1 are prevented. EXAMPLES

[0022] A specific embodiment of the present invention will now be described with reference to the drawings.

[0023] This embodiment is an example in which the present invention is applied to a nuclear reactor building as a structure 1.

[0024] Specifically, an impact mitigation member is provided on the outer surface of the ceiling 1a of the building, and this impact mitigation member includes at least a sacrificial layer 2. When a flying object collides with the protected outer surface (the outer surface of the ceiling 1a of the building) to which the impact mitigation member is attached at an acute angle (for example, an angle of 10° or less), the material constituting the sacrificial layer 2 is destroyed, deformed or displaced by the flying object, allowing the flying object to slide along the protected outer surface, thereby preventing the flying object from penetrating the protected outer surface.

[0025] The side walls 1b of the building are reinforced concrete walls having a thickness of about 2 to 3 m (enough to withstand the impact of a large aircraft), and the ceiling 1a is a reinforced concrete wall having a thickness thinner than the side walls 1b, for example, 1.5 m or less.

[0026] In this embodiment, by configuring the ceiling portion 1a to have an impact absorbing member as described later, it is possible to make the ceiling portion 1a a reinforced concrete wall having a thickness of 1.5 m or less, specifically, less than half that of the side wall portion 1b (for example, approximately 1.0 m to 1.2 m).

[0027] In this embodiment, as shown in FIG. 1, a single metal plate (iron plate 4) with a thickness of about 20 mm is used as the sacrificial layer 2. The metal plate is laid on the upper surface (flat concrete surface) of the ceiling portion 1a so as to cover almost the entire upper surface. The area of ​​the ceiling portion 1a is several tens of meters square, and it is preferable to lay a metal plate that is originally a single piece and has an area equivalent to the area of ​​the ceiling portion 1a. In addition, after laying the divided body on the upper surface of the ceiling portion 1a, it may be welded to form a single metal plate. The thickness of the metal plate is set appropriately in the range of about 10 mm to 50 mm depending on the material of the metal plate. In addition, the sacrificial layer 2 may be configured by stacking multiple metal plates in the vertical direction.

[0028] In this embodiment, the metal plate is allowed to move relative to the outer surface (upper surface of the ceiling; the outer surface to be protected) of the ceiling 1a when a flying object hits it, and is locked (loosely fixed) to the ceiling 1a with a wire, net, or the like (not shown) to an extent that prevents it from falling due to an earthquake. Note that, for example, a configuration may be adopted in which the metal plate is locked by a locking mechanism provided on the ceiling 1a during normal times, and an automatic lock-release mechanism may be provided that automatically releases the locking by the locking mechanism when the approach of a flying object is detected by the detection means.

[0029] The sacrificial layer 2 is not limited to the iron plate 4, and may be made of other materials such as an aluminum plate or a rubber plate, or may be made of a large number of metallic spheres (steel balls 5). When spheres are used, it is preferable to provide a rising peripheral wall 6 on the outer periphery of the ceiling portion 1a, as in the modified example 1 shown in FIG. 2, and to make the inner surface of the rising peripheral wall 6 a mortar-shaped one. When the spheres are arranged in a manner to be spread inside the rising peripheral wall 6, even if the spheres are moved by the impact of a flying object, they can be automatically returned to the laid state (self-repairing action). In addition, a magnetic field generating device may be further provided to apply a magnetic field to align the spheres and enhance the self-repairing action.

[0030] Due to the above-mentioned sacrificial layer 2, even if a flying object (for example, a large airplane) hits the building, the sacrificial layer 2 breaks, deforms, and moves while sliding on the ceiling, and does not penetrate the ceiling of the building. Only a small part of the kinetic energy of the flying object is transmitted to the building. (For example, if the flying object slides with an impact angle of 10° and a friction coefficient of 0, the cosine of the kinetic energy is 2 (10° = 97% of the impact does not reach the ceiling.) If the impact angle of the flying object is acute (less than 90°), the sacrificial layer 2 acts to slide the flying object. The angle at which the sliding effect occurs most effectively is 45° or less, and particularly preferably 10° or less.

[0031] The impact absorbing member may also be configured to have a sliding layer 3 that supports the sacrificial layer 2 and slides along with the flying object against the protected outer surface when the flying object collides with the sacrificial layer 2.

[0032] The sliding layer 3 may be configured to have a large number of spherical bodies (steel balls 5) spread between the outer surface to be protected and the sacrificial layer 2, as in the modified example 2 shown in Fig. 3, or to have one or more metal plates (e.g., an aluminum plate with a thickness of about 3 mm to 10 mm, made of a material different from the sacrificial layer 2) laminated thereon. The presence of the sliding layer 3 allows the sacrificial layer 2 to slide more smoothly when hit by a flying object.

[0033] In addition, the impact mitigation member may have a friction reduction layer made of a material having a smaller dynamic friction coefficient than the sacrificial layer 2 and the sliding layer 3 between the sacrificial layer 2 and the sliding layer 3, or between the sliding layer 3 and the protected outer surface, or between both.

[0034] As the friction reducing layer, a sheet material such as a Teflon (registered trademark) sheet can be appropriately used.

[0035] In this embodiment, the impact absorbing member is provided on the outer surface of the ceiling 1a of the building, but the impact absorbing member may be provided on the ceiling of other buildings or structures, not limited to buildings.

[0036] Since this embodiment is configured as described above, when a flying object such as an aircraft crashes into the protected outer surface to which the impact mitigation member is attached at an angle of several degrees, the flying object that collides with the sacrificial layer 2 slides along the protected outer surface while destroying, deforming or moving the sacrificial layer 2 (the material that constitutes it), and the flying object maintains almost its speed and bounces a little before flying away, so that the kinetic energy of the flying object is consumed by the destruction of the sacrificial layer 2, while most of the kinetic energy remains in the flying object. Therefore, the transmission of the kinetic energy of the flying object to the structure 1 such as a building is suppressed as much as possible, and the penetration of the flying object and the transmission of the impact to the inside of the structure 1 are prevented.

[0037] Therefore, in this embodiment, the impact absorbing member can cushion the impact of incoming flying objects such as aircraft by allowing them to slide, making it possible to provide protection from flying objects while making the reinforced concrete walls of the ceiling thinner, thereby achieving both earthquake resistance and cost-effectiveness.

[0038] In order to confirm the effect of the shock absorbing member of this embodiment, a shock analysis was performed using the shock analysis software Ls-DYNA. The analysis results are shown in Figs.

[0039] Since an aircraft is generally made of relatively soft materials, if it collides with a building, for example, the impacted part will gradually collapse, shaking the entire building (global damage). However, some parts of the aircraft, such as the engine or wheels, which are relatively hard, may in some cases penetrate the wall of the building (localized damage). In order to analyze localized damage in this impact analysis, a large aircraft jet engine (Rolls-Royce Trent XWB, weight 7,267 kg) was modeled as the flying object, and the ceiling structure of a nuclear power plant (prestressed concrete at Hamaoka Nuclear Power Plant, 2m thick concrete with D51 rebars arranged vertically and horizontally at 300mm pitch, with 5 layers of rebar) was modeled as the structure (ceiling of the building), and the analysis was performed under the following conditions.

[0040] ·Analysis conditions Simulated projectile: radius 350mm, length 2600mm, weight approx. 7.8t, flight speed 150m / s (cruising speed 549km / h), descent angle 10 degrees Mock ceiling: A 30m x 30m ceiling was modeled with a structure supported by side walls and beams (2 x 2), and a size of 10m x 10m was modeled. The basic form was a 300mm thick concrete slab with 50mm diameter rebars arranged vertically and horizontally at 300mm intervals (see Figure 4. Figure 4 shows an example where the horizontal bars are arranged on the upper side and the vertical bars on the lower side). Comparison model (conventional example): The ceiling structure is six times thicker than the basic type (1,800 mm) and has six layers of reinforcement. Analytical model (this embodiment): The ceiling structure is four times thicker than the basic type (1200 mm) with four layers of reinforcement, and a single 20 mm thick steel plate (not fixed) is laid on top of that.

[0041] The analysis results show that in the comparison model, the flying object penetrates the ceiling immediately after impact (0.01 seconds later), and as it penetrates deeper, eventually (0.09 seconds later) the inner surface (underside) of the ceiling will peel off, meaning that concrete will fall into the building. In order to prevent this, it is clear that the reinforced concrete needs to be made thicker (however, making it any thicker could make it difficult to ensure earthquake resistance).

[0042] In contrast, in the analysis model, the flying object slid over the steel plate while bending (undulating) it (the steel plate also moved slightly relative to the ceiling surface), preventing the flying object from penetrating the ceiling, and although the inner surface (bottom surface) of the ceiling was slightly deformed, it did not peel off, and it was confirmed that the concrete was prevented from falling. It was also confirmed that there were no breaks in the steel plate.

[0043] From the above, it was confirmed that by laminating the steel plate (sacrificial layer 2) on the outer surface of the ceiling of the building, it is possible to realize a configuration that can prevent flying objects from penetrating into the ceiling without making the concrete wall of the ceiling as thick as the sides. In other words, according to the configuration of this embodiment, the thickness of the reinforced concrete of the ceiling can be reduced to at least 2 / 3 of the conventional example, and it is thought that it is also possible to reduce it to about 1 / 2. The weight of a 20 mm thick steel plate is roughly equivalent to the weight of a 70 mm thick concrete. [Explanation of symbols]

[0044] 1 structure 1a Ceiling 2 Sacrificial Layer 3. Slip layer

Claims

1. A shock absorbing member attached to an outer surface of a structure, The impact absorbing member includes at least a sacrificial layer, An impact-absorbing member characterized in that, when a flying object collides at an acute angle with the protected outer surface to which the impact-absorbing member is attached, the material constituting the sacrificial layer is destroyed, deformed or displaced by the flying object, causing the flying object to slide along the protected outer surface, thereby preventing the flying object from penetrating the protected outer surface.

2. 2. An impact mitigation member as described in claim 1, characterized in that when a flying object collides with the protected outer surface to which the impact mitigation member is attached at an angle of 10° or less, the material constituting the sacrificial layer is destroyed, deformed or displaced by the flying object, causing the flying object to slide along the protected outer surface, thereby preventing the flying object from penetrating the protected outer surface.

3. 3. The impact absorbing member according to claim 2, further comprising a sliding layer that supports the sacrificial layer and slides along with the flying object against the protected outer surface when the flying object collides with the sacrificial layer.

4. 4. The impact absorbing member according to claim 3, wherein a friction reducing layer made of a material having a smaller dynamic friction coefficient than the sacrificial layer and the sliding layer is provided between the sacrificial layer and the sliding layer or between the sliding layer and the protected outer surface.

5. 2. The shock absorbing member according to claim 1, wherein the sacrificial layer is configured to include a metal plate having a thickness of 10 mm to 50 mm.

6. 2. The shock absorbing member according to claim 1, wherein the sacrificial layer is configured to include a large number of spherical bodies.

7. A building comprising the shock absorbing member according to any one of claims 1 to 6, characterized in that the shock absorbing member is provided on at least the outer surface of the ceiling.

8. 8. The building according to claim 7, wherein the ceiling portion is a reinforced concrete wall having a thickness of 1.5 m or less.

Images