The Offered Directions in Development and Perfection of Protective Structures and Buildings

The Offered Directions in Development and Perfection of Protective Structures and Buildings

The Welded All-Metal “Sandwich Plates” as Elements of Protection Structures

By Valeriy S. Kogan, Ph .D. (Eng.)

Below are offered for elaboration and introduction the welded all-metal “sandwich plates” as enclosure elements of protection structures subjected to action of concentrated and distributed shock loads. The patentable idea of such structural elements proposed by Valeriy S. Kogan has no analogs in world practice.

1. The “sandwich plates” consist of two “facings” – flat metal sheets (outer and inner), and of joining them shear- stiff “core” – a regular cellular structure of various configuration made of special roll-formed thin-walled metal profiles produced in a waste-free technology.

There is possible, to damp out a share of dynamic loads by means of including discrete absorbing parts into the “core” system .

2. The elements of plates (sheets and profiles) are manufactured from special high-strength and heat-proof steels or titanium alloys. The “facings“ and the “core” are joined together by the electric or laser spot welding, in necessary cases – in combination with heat-resistant glues.

3. The “sandwich panels” offered may be conditionally divided into following three groups depending on expected (design) shock loads and on spaces between main load-bearing elements of the protection structure. The plates of these three groups differ by the “core” structure, manufacturing technology and economic effectiveness.

4. Group 1 – the plates of 1 15/16" - 3 7/8" (50…100 mm) overall thickness, acting under load as flexible plates or plates of finite stiffness. Their load bearing capacity is limited by their spaces and by using in the “core” structure only limited (small height) range of roll-formed profiles.

5. Group 2 – the plates of 3 7/8" - 9 11/16" (100…250 mm) overall thickness, acting under load as plates of finite stiffness, or as stiff plates. Their load bearing capacity may be sufficiently increased in comparison with the group 1, when using an extended range of roll-formed profiles for the “core” structure ensuring the increased security of their connections.

6. Group 3 – the plates of 9 11/16" - 19 5/8" (250…500 mm) and more overall thickness, acting under load as stiff plates. Under condition of using the special roll-formed profiles for the “core” structure, the stiffness and load capacity of this plates may be increased practically without limitations.

It’s especially necessary to note, that groups 2 and 3 cover also a special kind of designs under the conditional name "trampoline". These plates, due to elasticity of a "core" as though "spring" under shock loads, extinguishing thus a significant part of dynamic loadings and raising thus reliability of offered protection.

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e-mail : vskogan@yahoo.com

The Offered Directions in Development and Perfection of Protective Structures and Buildings

By Valeriy S. Kogan, Ph.D (Eng.)

All the structural solutions described below [based on the verified ideas and patents elaborated by or in partnership of Valeriy S. Kogan, Ph.D. (Eng)] may be conditionally classified as sandwich structures consisting of two load-bearing outer layers (“facings”) and of disposed between them middle layer (“core”) ensuring the joint working of the “facings” under the load, including dynamic (shock) ones, and other actions from outside.

Three principal types of structural design are offered:

1- the sandwich plates and cylindrical shells with sheet facings;

2- the “plate-latticework” systems;

3- the precast and precast-cast in place systems of modular hollow blocks with filling.

Type 1

The “facings” of the sandwich plates and cylindrical shells may be made of :

· flat or corrugated sheets of steel or titanium alloys ( Fig.1.1 );

· high-strength, heat-resistant reinforced concrete;

· “armocement” (fine-grain concrete reinforced by steel wire mesh);

· high-strength special concretes dispersedly reinforced by steel or mineral fibres ( Fig.1.2, 1.3 ) .

The “core” may be made of:

· special (including polymer-based) concretes;

· high-strength dispersedly reinforced concretes;

· aluminum alloys dispersedly reinforced by high-strength mineral fibres.

Some methods of connecting the facings with the core in above-mentioned structures are invented and patented by V.Kogan.

Type 2

The “plate-latticework” systems include:

· the “tension chord” (from inside) consisting of longitudinal and diagonal metal profiles:

· the “compression chord” (from outside) consisting of interconnected rigid plates (panels), or having the same structure as the “tension chord, when outer facing consists of flexible (membrane) metal sheets;

· the space latticework of metal profiles connecting the “chords” and ensuring their joint working under outer loads, including shock one.

This system ensures the survivalability of the enclosure structure even under considerable damages (breaches) of the outer plates (sheets), due to redistribution of internal forces among nondamaged elements of the system.

The profiles of “chords” and space latticework may be made of high-strength heat-resistant steels, or of titanium alloys.

The rigid plates (panels) of the outer “chord” may be:

· precast plates of reinforced concrete, of “armocement” (see above), or of dispersedly reinforced concrete ( Fig.2.1 );

· sandwich panels with the sheet facings of steel or titanium alloys and the core of dispersedly reinforced aluminum alloys, or lightweight concrete ( Fig.2.2 ).

The flexible (membrane) sheets of the outer facing may be made of steel (including heat-resistant), or of titanium alloys. The membranes cellwise fixed to longitudinal and lateral metal profiles of the outer “chord” are prestressed by means of adjustable ties or struts in the centres of cells.

Type 3

The structures of this type are especially intended for fast-erected field fortifications (wall fencings, breastworks, pits and manholes, blockhouses, etc.) ensuring the protection mainly from any horizontal shock loads. The basic elements of such structures are prefabricated modular box-like hollow blocks made of high-strength, fire resistant dispercedly reinforced materials ( Fig.3.1 ). After their erection, the blocks are tierwise filled by the ballast material. This system, patented by V.Kogan, was repeatedly approved in building practice of several countries ( Fig.3.2 ).

The modular blocks may be made of:

· high-strength and heat-resistant cement-based concretes dispercedly reinforcered by mineral fibres ( Fig.3.1 );

· heat-resistant polymer-based concretes dispercedly reinforcered by mineral fibres ;

· high-strength aluminum alloys dispercedly reinforcered by super-thin mineral fibres.

The ballast filling of the block structure may be of:

· sand, gravel, or fine broken stone ( Fig.3.2 );

· concretes on high-strength binders, reinforced by steel bars;

· the same, dispercedly reinforced by steel and mineral fibres.