Anti-Explosion Protection System For Damping Barriers

Abstract

The present invention relates to an anti-explosion protection system based on containment barriers, which allows energy to be absorbed using a damping system formed by two walls that are connected by means of oscillators. According to the invention, the front wall (1) is supported by a system of bearings or a sliding surface (4) allowing the front wall to move relative to the second wall (2). The front wall receives the pressure wave and, owing to the movement of the mass of said front wall (1), a reduced pressure is transmitted to the rear wall (2), which is protected by the system. In said barrier, a large part of the energy from the explosion is transformed into the kinetic energy of an oscillating mass.

Claims

1. (canceled)

2. A system for blast load protection using a damping barrier, comprising: a moveable first wall (1) for receiving a pressure wave, the first wall (1) being connected to a second wall (2), the second wall forming part of a structure to be protected; and a plurality of oscillatable elastic dampers connecting the first wall (1) to the second wall (2) so that the moveable first wall is an oscillatable mass relative to the second wall; and roller bearings supporting the first wall and facilitating movement of the first wall relative to the second wall when the pressure wave is received.

3. The system of claim 2, wherein the first wall is metallic.

4. The system of claim 2, wherein the elastic dampers are oscillators.

5. The system of claim 4, wherein the oscillators have one degree of freedom.

6. The system of claim 2, wherein the elastic dampers are springs.

7. The system of claim 6, wherein the springs are metallic.

8. The system of claim 2, wherein the roller bearings are supported on a surface (4) that facilitates movement of the roller bearings.

9. The system of claim 8, wherein the surface includes rails on which the roller bearings move.

10. A system for blast load protection using a damping barrier, comprising: a moveable first wall (1) for receiving a pressure wave, the first wall (1) being connected to a second wall (2), the second wall forming part of a structure to be protected; and a plurality of oscillatable elastic dampers connecting the first wall (1) to the second wall (2) so that the moveable first wall is an oscillatable mass relative to the second wall; and rails supporting the first wall and facilitating movement of the first wall relative to the second wall when the pressure wave is received.

11. The system of claim 10, wherein the first wall is metallic.

12. The system of claim 10, wherein the elastic dampers are oscillators.

13. The system of claim 12, wherein the oscillators have one degree of freedom.

14. The system of claim 10, wherein the elastic dampers are springs.

15. The system of claim 14, wherein the springs are metallic.

Description

DESCRIPTION OF THE FIGURES

[0031] To complement the description here and in order to give a better understanding of the characteristics of the invention, in accordance with a preferred example of its practical embodiment, it is accompanied by a set of FIGURES that form an integral part of the description and represent for the purposes of illustration and without limitation the following:

[0032] FIG. 1.shows a view of the system representing the arrangement of the walls and oscillators with respect to the sliding surface.

DESCRIPTION OF THE INVENTION

[0033] The system has two walls joined together by a plurality of oscillators of a degree of freedom(m.sub.i, k.sub.i, c.sub.i). The front wall that would concentrate a certain mass (the greater the mass, the better), for which it is conceived as a metallic element, would receive the pressure wave and transmit it to the reaction wall, which would be made of concrete, with a reduced pressure thanks to the setting in motion of the mass of the front wall

[0034] The front wall, which receives the shock wave, is supported by a system of wheels or bearings or rails, or supported on a sliding surface so that it can move independently of the rear wall.

[0035] Therefore, the system is based on dissipating part of the energy generated by the explosion through setting in motion an initially static mass (the front wall). The rear wall can be part of the barrier system or directly part of the structure to be protected.

[0036] The front wall can be made of steel which provides both high mass and adequate strength. The mass can be increased by adding metal boxes to the front wall to add soil, for example.

[0037] The system can be integrated into the architecture in multiple ways that can include all types of metal surface treatments. Likewise, the system can be enhanced from an architectural point of view, leaving the oscillators visible, either from a side or through windows in the metal panel. A system of this type can be effective for protecting a control room, for example, at a reasonable cost.

PREFERRED EMBODIMENT OF THE INVENTION

[0038] The system of the present invention comprises a barrier formed by a frontal wall (1) preferably metallic, which receives the pressure wave at the time of the explosion, where the said frontal wall (1) can be considered as a metallic element of a certain mass. The front wall (1), made of metal, is supported by a sliding surface (4) that enables its displacement and where this front wall (1) is in contact with a rear wall (2) preferably of concrete by means of a plurality of oscillators (3), of a single degree of freedom, which can be springs or similar. The barrier system works in such a way that at the time of the explosion, the front wall (1) receives a pressure wave that is transmitted to the rear wall (2) by means of the plurality of oscillators (3) interspersed between both walls due to the movement of the front wall (1), resulting in a reduced pressure on the rear wall (2), since only a part of the energy of the explosion is transformed into energy of deformation of the springs, the rest of the energy being dissipated in providing movement to the front wall.

[0039] The sliding surface (4) can be replaced by a system of roller bearings or a system of sliding rails.

[0040] To analyze the response of the oscillator system, the explosion can be treated as an impulse on the outer wall, i.e. the frontal wall (1) of metal. If the duration of the law of triangular pressures is short with respect to the period of the oscillators (3), as is the case, the impulse is equivalent to imposing an initial velocity on the plurality of oscillators (3) of a value equal to the value of the impulse divided by the mass. Under these conditions, assuming, in a simplified way and as an initial approximation, that the shock absorbers move synchronously, the equation of motion of the wall as a whole can be written as indicated in the following equation

[00001]$\begin{array}{cc}x\left(t\right)=e^{-{}_n.Math.t}.Math.\frac{{\stackrel{.}{x}}_0}{{}_d}.Math..Math.\sin .Math..Math.{}_d.Math.t=e^{-{}_n.Math.t}.Math.\frac{{\mathrm{iA}}_{\mathrm{wall}}}{{}_d.Math..Math.m_i}.Math..Math.\sin .Math..Math.{}_d.Math.t=e^{-{}_n.Math.t}.Math.\frac{\frac{1}{2}.Math.p_r.Math.t_{\mathrm{rf}}.Math.A_{\mathrm{wall}}}{{}_d.Math..Math.m_i}.Math..Math.\sin .Math..Math.{}_d.Math.t& \\ {}_n=\sqrt{\frac{K}{M}}& \\ {}_d={}_n.Math.\sqrt{1-{}^2}& \end{array}$

is the damping index
i is the impulse to the wall due to the explosion
p.sub.r is the reflected pressure due to the explosion that is imposed on the barrier
t.sub.rf is the duration of the equivalent triangular wave
A.sub.wall is the area of the wall affected by the pressure of the explosion
.sub.n is the natural frequency of the system of 1 gdl
.sub.d is the natural damped frequency of the system of 1 gdl
m.sub.i mass of each of the harmonic oscillators M=m.sub.i

[0041] The system can be appreciated in a simpler way by means of a numerical example

Example 1

[0042] Assuming a detonation, an explosive equivalent to 20 kg TNT located 3.00 meters from the wall, the reflected pressure, p.sub.r, would be 3952 kPa, and the duration of the equivalent triangular law of pressures, t.sub.rf would be 0.68 ms. Admitting that there are 4 steel springs per square metre of wall, that the springs have an average diameter of 25 cm(D), 20 mm bar diameter, d, and 9 coils(/V), the stiffness of the 4 springs would be:

[00002]$K=n_{\mathrm{springs}}.Math.\frac{{\mathrm{Gd}}^4}{8.Math.D^3.Math.N}=4.Math.\frac{200{10}^6}{2.Math.\left(1+0.3\right)}.Math.\frac{{0.02}^4}{8{0.25}^{3}9}=43.8.Math..Math.\mathrm{kN}.Math.\text{/}.Math.m^3$

[0043] Regarding the mass of the system, it would be necessary to have the mass of the panel (MP) plus the mass of the 4 springs, so that per square meter, if it is assumed that the front panel is a steel plate of 40 mm thickness, the mass would be:

[00003]$M=M_p+4M_{\mathrm{spring}}=7.85\left(0.0411+490.25\frac{{0.02}^2}{4}\right)==7.85\left(0.04+0.0088\right)=0.384.Math..Math.t.Math.\text{/}.Math.m^2$

[0044] Therefore, the angular frequency of the system and the damped angular frequency (assuming damping, consistent with a metallic structure of 1%) would be:

[00004]${}_n=\sqrt{\frac{K}{M}}.Math.\sqrt{\frac{43.8}{0.384}}=10.67.Math..Math.\mathrm{rad}.Math.\text{/}.Math.s.fwdarw.T=\frac{2.Math.}{{}_n}=\frac{2.Math.}{10.67}=0.59.Math..Math.s$${}_d={}_n.Math.\sqrt{1-{}^2}=10.67.Math.\sqrt{1-{0.01}^2}=10.67.Math..Math.\mathrm{rad}.Math.\text{/}.Math.s$

[0045] By applying the expression of x(t), the displacement due to the explosion and the corresponding reaction in the concrete wall can be determined.

[00005]$x\left(t=T.Math.\text{/}.Math.4\right)=e^{-{}_n.Math.\frac{T}{4}}.Math.\frac{\frac{1}{2}.Math.p_r.Math.t_{\mathrm{rf}}.Math.A_{\mathrm{wall}}}{{}_d.Math..Math.m_i}.Math..Math.\sin .Math..Math.{}_d.Math.\frac{T}{4}=e^{-0.0110.67\frac{0.59}{4}}.Math.\frac{\frac{1}{2}.Math.39520.68{10}^{-3}1}{10.670.384}1.0=0.9840.328=0.32.Math..Math.m$$q_{\mathrm{wall}}=43.80.32=14.02.Math..Math.\mathrm{kPa}$

[0046] It is observed that a high load is obtained, but is compatible with the size of a conventional wall. For a wall height of 3.00 m, and assuming that the wall is simply supported and that the depth of the wall is 25 cm (a minimum value), the required reinforcement would correspond to a minimum amount, as can be seen in the following equation and it would not be necessary to have shear reinforcement:

[00006]$M_{\mathrm{Ed}}=14.02\frac{3^2}{8}=15.77.Math..Math.\mathrm{kNm}.Math.\text{/}.Math.m.fwdarw.A_s=\frac{M_{\mathrm{Ed}}}{z.Math..Math.f_{\mathrm{yd}}}\frac{15.77}{0.90.2}.Math.\frac{1.0}{50}=1.75.Math..Math.{\mathrm{cm}}^2.Math.\text{/}.Math.m$$V_{\mathrm{Ed}}=14.02\frac{3}{2}=\frac{21.03.Math..Math.\mathrm{kN}}{m}.fwdarw.=\frac{V_{\mathrm{Ed}}}{\mathrm{bd}}=\frac{21.03}{0.2}=0.1.Math..Math.\mathrm{MPa}.fwdarw.\mathrm{Does}.Math..Math.\mathrm{not}.Math..Math.\mathrm{require}.Math..Math.\mathrm{shear}.Math..Math.\mathrm{reinforcement}$

[0047] In order to evaluate what would be the difference compared to the unprotected wall, in the same case, one would have:

[00007]$K_E=.Math.\frac{P_E}{{}_{\max }}=.Math.\frac{P_E}{\frac{5.Math..Math.{\mathrm{pL}}^4}{384.Math..Math.\mathrm{EI}}}=.Math.\frac{K_L}{\frac{5.Math..Math.L^3}{384.Math..Math.\mathrm{EI}}}=.Math.\frac{384}{5}.Math..Math.\frac{0.643{10}^7.Math.\frac{1}{12}.Math.{0.25}^3}{3^3}=.Math..Math.71111.Math..Math.\mathrm{kN}.Math.\text{/}.Math.m^2$$M_E=K_M.Math.M=0.50\underset{P_E=K_L.Math.\mathrm{pL}}{0.252.5}3=0.94.Math..Math.t.Math.\text{/}.Math.m$$T=2.Math..Math.\sqrt{\frac{M_E}{K_E}}=2.Math..Math.\sqrt{\frac{0.94}{71111}}=0.023.Math..Math.s.fwdarw.\frac{T}{t_{\mathrm{rf}}}=\frac{0.023}{0.68{10}^{-3}}=33.82.fwdarw.\mathrm{DFL}=0.142.fwdarw.q_{\mathrm{eq}}=0.1423952=561.Math..Math.\mathrm{kN}.Math.\text{/}.Math.m^2$

[0048] The above expressions are obtained by means of an equivalent static analysis, simulating the wall, which is treated as a doubly embedded beam, as a system of one degree of freedom.

[0049] It is observed that, without the protective barrier, the load acting on the wall is 40 times greater than for the scenario studied. It therefore follows that the proposed system is highly effective. In order to be able to support this level of load with a conventional solution, it would be necessary to have a wall of great thickness with buttresses, etc., giving rise to a very significant occupation of space.

[0050] The system is, therefore, a barrier based on damping, in which much of the energy of the explosion is transformed into the kinetic energy of an oscillating mass. From the example given above, it can be deduced that damping barriers are a very effective and promising alternative, which are also made up of elements that are easy to manufacture and install. It is of a type that enables adequate integration into architecture and can be combined with windows that allow visualization of the damping system. A clear application of this can be the protection of control rooms.