GB2262950A

GB2262950A - Reinforced concrete structure for shelters,strong rooms,etc.

Info

Publication number: GB2262950A
Application number: GB9223305A
Authority: GB
Inventors: Jose Pedro Duarte Tavares; Peter Pearce
Original assignee: LOURDESTOUR URBANISMO E CONSTR
Current assignee: LOURDESTOUR URBANISMO E CONSTR
Priority date: 1991-11-08
Filing date: 1992-11-06
Publication date: 1993-07-07
Anticipated expiration: 2012-11-06
Also published as: PT99455B; CZ333992A3; CZ280310B6; GB9223305D0; PT99455A; GB2262950B

Abstract

A reinforced concrete structure for a shelter or strong-room comprises reinforcement in the form of parallel sheets (1) of expanded metal interconnected by bent arrays (2) comprising elements (3), which may be rods, in planes at right angles to those of the sheets (1), and elements (4) parallel to the sheets. The arrays are located relative to the sheets by further elements (6) passing through vertices of elements (3). <IMAGE>

Description

DESCRIPTIVE ACCOUNT TECHNICAL FIELD OF THE INVENTION The present invention relates to a reinforced concrete structure designed for works which demand security, such as strong-rooms, shelters and other constructions, for example, which are capable of withstanding the detonation of explosive charges and generators of high instantaneous energy levels which are propagated via shock waves.

More particularly, this invention relates to a reinforced concrete structure, the reinforcement of which essentially comprises two types of panels, one of these being formed by an expanded metal grid and the other panel by sections of reduced cross-section and high strength (rods, for example). The latter type of panel is previously manufactured from bent sections of the appropriate shapes and dimensions, disposed parallel to each other and interlocked by means of longitudinal sections arranged parallel to each other. The material of this panel may be metallic or of another appropriate nature.

The aforementioned panels are disposed with the directions of their principal axes parallel to each other, or approximately so, and are interlinked by inserting the vertexes of the bent sections into the lozenge-shaped mesh apertures of the expanded metal panels, through which portions of thin fixing section pass, which are inserted during the assembly of the reinforcement.

Concreting is only carried out once for each structural part, whether this is a slab or a wall, and is effected with highstrength concrete containing inert elements, for example gravel, crushed stone and other materials, and plasticising agents if necessary.

BACKGROUND OF THE INVENTION Experience over the years has shown that traditional reinforced concrete structures, even if further strengthened, do not provide the desired resistance to the intense force fields caused by the detonation of explosive charges. Tests which have been carried out have proved that concrete structures comprising heavy, rigid reinforcements exhibit unacceptable behaviour when subjected to the action of an explosive device.

Certain types of structures are known which, although designed with reinforcement to resist explosive detonations, have been shown not to facilitate concreting in an easy manner, since it is necessary for concreting to be carried out in various phases and because the reinforcement is installed in stages according to the progress of the concreting.

Other types of reinforced concrete structures exist which are difficult to produce, since they necessitate the fabrication of reinforcements which are complex, expensive and slow to manufacture, particularly regarding the corner structure of the panels.

Experiments performed on reinforced concrete structures expressly devised to resist the detonation of explosive charges have enabled it to be verified that sections with a cross-section larger than 15 mm transmit the kinetic energy of the explosion to an area of considerable dimensions, easily damaging the adherence between the concrete and the steel. This fact enables the wreckage of the area easily to be reduced to ruins, with all the disadvantages that this situation implies for a security building.

Other experiments performed on structures designed for security purposes, with sections of different cross-sections, have proved that the extent of the damaged area for the same weight of explosive is proportional to the cross-section of the reinforcing sections.

In certain structures, the use of U-shaped or rail-type sectional steel does not increase their strength; they can be reduced to a state of ruin even after the explosion of charges of low energy. Tests performed in areas adjacent to horizontal concreted joints have shown that not only is significant damage caused, but that the removal of wreckage comprising fractured or pulverised concrete is also facilitated.

With the types of reinforced shielding currently used, it is not uncommon for concreting to be carried out in layers which are up to 300 mm to 900 mm thick. Thicknesses such as these are due to the fact that, although reinforcement can provide adequate protection, it nevertheless does not permit concreting to be carried out easily, since its placement in the work has to be effected in stages.

CONCISE DESCRIPTION OF THE INVENTION The object of the present invention is to remedy the aforementioned disadvantages.

The invention provides for a reinforced concrete structure for works intended for security purposes, which comprises a homogeneous, continuous reinforcement consisting of two sets of panels disposed parallel to each other, or approximately so. One type of panel is obtained starting from a grid of expanded steel with mesh apertures of various configurations, normally lozengeshaped, whilst the other type of panel consists of two types of sections of reduced cross-section, of high-strength steel for example, the sections of one type being pre-bent and of suitable shape and dimensions, having vertexes with bending angles of variable size, and the sections of the other type simply being portions of sections disposed parallel to each other and interlocked with the pre-bent sections in accordance with a predefined shape.

The function of the aforementioned longitudinal sections which are interlocked with the pre-bent sections is to support the expanded metal panels.

Assembly of the panels is effected by inserting the vertexes of the panel sections fabricated in this manner into the mesh apertures of the expanded steel panel, which are maintained interlocked by means of independent sectional portions, placed in situ, on the other side of the expanded metal panel and parallel to the longitudinal axis of both types of panels.

The present invention has advantages which are relevant for security purposes in relation to the existing types of structures, amongst which the following can be emphasised: - the reduced cross-sections of the high-strength sections which form one of the panels (diameters of the order of 8 to 12 mm in the case of rods), their positioning, and their high density in the structure make it impracticable to create openings for the possible accommodation of explosive charges; - the different assemblies of the various panels and their positioning in relation to the length of the wall of the structure maintain the concrete and the reinforcement in position and thus impede their removal after the detonation of an explosive;; - the reinforcement is directly installed in situ and comprises neither weak points nor horizontal joints in the walls, the panels continuing over the entire height of the wall; the vertical joints of the panels have overlaps and do not meet one another, whilst the junctions between the different elements of the reinforcement are not rigid, which prevents cleavage and stratification of the structure, thus limiting the transmission of shock waves produced at the time of detonation of an explosive device; - the reinforcement described may be inspected in its entirety before concreting is carried out; - the structure is designed so that concreting of its walls is only carried out once, over the entire height, with the object of permitting a uniform flow of concrete and ease of access for the rod vibrator; ; - during concreting, the components of the reinforcement cannot become displaced, and the existence of barbs on the elements which constitute it enables excellent adhesion of the concrete to be obtained; - the difficulty of inspecting the configuration of the reinforcement after concreting using non-destructive means of testing.

DESCRIPTION OF THE DRAWINGS The characteristics and advantages of the present invention will become evident from their description with reference to the accompanying drawings, where: Figure 1 is a transverse sectional view of the reinforcement of the reinforced concrete structure, according to a preferred embodiment of the invention; and Figure 2 is a transverse sectional view of the reinforcement of the reinforced concrete structure according to an alternative embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION The proposed reinforced concrete structure for works intended for security purposes in accordance with the present invention is explained below, by way of example, by means of the embodiments illustrated in the drawings. According to a preferred embodiment of the invention, illustrated in Figure 1, the reinforcement of the reinforced concrete structure consists of two sets of panels 1 and 2, panel 1 being formed by an expanded steel grid with mesh apertures which may have a lozenge-shaped configuration, which is placed in the structure in a suitable position, i.e.

approximately vertically in walls or horizontally in slabs. The panel 2 is placed in relation to the panel 1 in a position which is preferably parallel to the latter's principal axes, and comprises two types of high-strength steel sections of reduced cross-section (the diameters varying between 8 and 12 mm in the case of rods). The sections 3 of the panel 2 are pre-bent, and have bends with suitable geometric configurations, such as a continuous W-shape, for example. The sections 4 which are interlocked with the pre-bent sections 3 are disposed in a direction which is perpendicular to the plane of the sections 3, and their function is to support the panels 2.

Interlinking of the panels 1 and 2 is effected by inserting the vertexes 5 of the pre-bent section 3 into the mesh apertures of the panel 1, the two panels being fixed by inserting various sectional portions 6 of reduced cross-section through the vertexes 5.

The operation of interlinking the panels is carried out in situ over the entire longitudinal extent of the panels, and is repeated transversely for the number of times which are necessary so as to obtain the required number of assemblies, with the reinforcement ultimately acquiring the form of a homogeneous, continuous, elastic array.

According to an alternative embodiment of the present invention illustrated in Figure 2, the continuous reinforcement is formed by the set of two panels 1 and 2, wherein these panels are as described previously for the first, preferred, embodiment of the invention. However, interlinking of the panels 1 and 2 according to this alternative embodiment is carried out in situ, and is effected by positioning two pre-bent panels 2, one on each side of an expanded steel panel 1, in such a way that the vertexes of both sections 3 of the panels 2 pass through a mesh aperture of the panel 1, remaining superimposed and finally being interlinked by means of sectional fixing portions 6.

Concreting of the reinforcement as in the examples described is carried out using high-strength concrete containing suitable inert elements and also plasticisers if necessary.

Claims

CLAINS

1. A reinforced concrete structure for works intended for security purposes, characterised in that the reinforcement is essentially formed by two sets of panels (1 and 2) disposed parallel to each other or approximately so, the panels (1) of one set being of expanded metal formed as a mesh of suitable geometric shape, lozenge-shaped for example, and disposed in parallel planes, the panels (2) of the other set being previously manufactured from pre-bent sections (3) of shapes and dimensions appropriate for the said mesh which are disposed in parallel planes, the panels (1 and 2) being interlinked so as to constitute a homogeneous, continuous, flexible reinforcement.

2. A reinforced concrete structure according to Claim 1, characterised in that the panels (2) are formed by sections (4) and by pre-bent sections (3), the said sections (4) being disposed approximately perpendicular to the planes of the prebent sections (3), the sections (4) being interlocked with the pre-bent sections (3) and serving to support the panels (1).

3. A reinforced concrete structure according to the preceding Claims, characterised in that the sets of panels (1 and 2) are interlinked on both sides by inserting the vertexes (5) of the pre-bent sections (3) into the mesh apertures of the panels (1) of expanded metal in such a way that these sections form overlaps approximately in the same plane, fixing being effected by means of independent sections (6) adjacent to the panels (1), the latter sections passing through the vertexes of the pre-bent sections (3) which are situated on both sides of the panels (2).

4. A reinforced concrete structure according to the preceding Claims, characterised in that interlinking of the panels (1 and 2) is effected by positioning two panels (2), one on each side of a panel (1), in such a way that the vertexes of both the prebent sections (3) of the panels (2) pass through a mesh aperture of the panel (1) lying superimposed, finally being fixed by means of independent sections (6).

5. A reinforced concrete structure as hereinbefore described with reference to and as shown in the accompanying drawings.