WO2014009538A1

WO2014009538A1 - Modular structural system and modular structure

Info

Publication number: WO2014009538A1
Application number: PCT/EP2013/064813
Authority: WO
Inventors: Favio Alberto ROIS; Claudio Rois KOVACEVIC
Original assignee: Ager Pharia Gmbh
Priority date: 2012-07-13
Filing date: 2013-07-12
Publication date: 2014-01-16

Abstract

The present invention relates to novel structural systems, in particular to building systems, and more particularly to unit-based housing construction systems. Further, the present invention relates to a modular and/or a portable panel. Furthermore, the present invention relates to a modular and/or portable molding matrix.

Description

MODULAR STRUCTURAL SYSTEM AND MODULAR STRUCTURE

FIELD OF THE INVENTION

The present invention relates to structural systems, in particular to building systems, and more particularly to unit-based housing construction systems. Further, the present invention relates to a modular and/or a portable panel. Furthermore, the present invention relates to a modular and/or portable molding matrix. In addition, the present invention relates to use of the said systems, modular panel, modular molding matrix.

DISCLOSURE OF THE INVENTION

DRAWINGS

Those of skill in the art will understand that the drawings, described below, are for illustrative purposes only. The drawings are not indented to limit the scope of the present teachings in any way.

Figure 1. Depicts theoretical curve calculation parameters.

Figures 2A-2E. Depict a four-point hosting model.

Figure 2A. Depicts diagram of tensions σ xx caused by the action of its own weight. Figure 2B. Depicts diagram of normal vertical tensions σ yy: All within +/-4kg/cm2. Figure 2C. Shows main tensions.

Figure 2D. Illustrates maximum moments of flexion on footing slab.

Figure 2E. Depicts diagram of displacements.

Figure 3. Depicts a modular mould.

Figure 4. Depicts basic element of the modular sheet metal form of modular mould. Figure 5. Depicts modular reinforced sheet form of modular mould.

Figure 6. Depicts modular folded mould.

Figures 7-8. Depict system of modular mould with tensioners and keys.

Figure 9. Depicts sample of system plant.

Figures 10-1 IB. Depict views of the transportation trolley for the assembly line option. Figures 12A-13. Depict a system of dual-effect hydraulic actuator for hoisting

Figure 13. Depicts jack with dual-effect hydraulic actuator and one eccentric. DETAILED DESCRIPTION OF THE INVENTION

The system, the modular and/or portable panel, and the modular and/or portable molding matrix according to the present invention provide efficiency and speed in the construction, manufacturing, and production capacity of variety of structures, including the housing units and room units. In addition, they provide high levels of intrinsic quality such as habitability, durability, strength, flexibility, and overall safety. Further, they provide a first class product with the above characteristics at a cost that is competitive with an alternative in situ approach. Furthermore, the implementation of such structure and unit is possible to be made on any type of soil, unlike the known approaches. Other features and advantages of the invention will be apparent from the following description.

The present invention relates to a panel or a modular and/or portable panel system comprising a polystyrene slab, panel, sheet, or plate or a series of polystyrene slabs, panels, sheets or plates and welded steel meshes. In another embodiment, the present invention provides a modular panel according to the preceding embodiment, wherein said polystyrene slab, panel, sheet, or plate is in the middle of, or enclosed by welded steel meshes. The steel meshes according to the present invention comprise bars that can have a variable diameter, length, and shape. The polystyrene panels, sheets, or plates according to the present invention can have variable thickness, length, and shape. In another embodiment, the present invention provides a structure comprising a modular panel comprising polystyrene slabs, panels, sheets, or plates or a series of polystyrene slabs, panels, sheets or plates and welded steel meshes. The structure according to the present invention preferably includes housing units, walls, floors, ceiling, and doors.

Further embodiment of the present invention provides a modular moulding matrix for formwork, in particular industrial modular moulding matrix for formwork for use in a construction or a structure. The modular moulding matrix according to the invention comprises the panel or series of the panels comprising the polystyrene slabs or plates and the welded steel meshes according to the preceding embodiments and modular industrial moulds for formwork, wherein said industrial moulds for formwork comprises a system that uses of plates of different materials depending on local convenience, designed as part of an integrated system including tensioners, ties, corners and finishes for optimised casting, curing and rendering of the panels which will make up the units to be manufactured. For instance: Aluminium plate system:

Plates measuring up to 0.4 m in width by 2.6 m in height, weighing 40 kg, with edge and internal reinforcements, clipped together.

Fish-plate tensioners between the ties to withstand the thrust of the fresh concrete(the WallTies and Forms, USA, see Figure 3).

Steel plate system:

Plates formed by welding metal "trays" with edges folded at 90° from the plane of the plate, which can be used to form large-scale panels as required in each case. The panels are connected in situ with pins and ties. The thrust of the fresh concrete is absorbed by steel fish-plate tensioners attached to the pins (see Figures 4-6).

Free dilatation system with ribbed glass fibre reinforced polymer plates and intermediate structural struts to which the tensioners which absorb the hydrostatic thrust of the concrete are anchored (Figures 7-9).

In another embodiment, the present invention relates to a hydraulic jack for hoisting the structure or the housing unit according to the present invention. Also, the present invention discloses a jack with dual-effect hydraulic actuator and one eccentric (see Figure 13). In further embodiment the present invention disclose a system of dual- effect hydraulic actuator for hoisting (see Figures 121-13)_^

In further embodiment, the present invention discloses a unit transportation trolley for the assembly line option. In the embodiment the present invention discloses a trolley preferably comprising 40 cm diameter cast wheels with a triangular tab to run on rails embedded into the floor, hot-laminated profile structure assembled in the workshop and self-propelled by electric motors (See figures 10-1 IB for Views of the transportation trolley for the Assembly Line option).

In further embodiment, the present invention relates to a modular structural system comprising a plurality of modular moulding matrix for formwork, preferably, each modular moulding matrix comprises a modular panel comprising a polystyrene slab, panel, sheet, or plate or a series of polystyrene slabs, panels, sheets or plates and a welded steel meshes enclosing the polystyrene slab. Preferably, the surface of the panel comprises concrete. More preferably, the system in addition to the moulding matrix comprises a hydraulic jack for hoisting or a jack with dual-effect hydraulic actuator and one eccentric. In another preferred embodiment, the system further to the modular panels or the moulding matrix, and the hydraulic jack according to previous embodiments comprises a trolley as set-forth above. In another embodiment, the present invention provides a system according to any of the preceding embodiment further comprising a working stage description.

In another embodiment, the present relates to production line manufacturing processes and systems that allow the units to be assembled, transported and installed for immediate use. In another embodiment, the present invention relates to a method of assembling a structure, in particular assembling a housing unit. The method of assembling of the structure according to the invention comprises any of the embodiments as set-forth above. In further embodiment, the present invention relates to the assembled structure comprising any of the preceding embodiments.

The present invention employs right techniques in each case of the process and system to apply principles of efficiency by dividing the tasks involved in the construction, manufacturing, and assembling of the structure, in particular the housing and room units offering high levels of intrinsic quality, for example, habitability, durability, strength, overall safety. It offers a first-class product at a cost that is competitive with an alternative in situ approach with speed and efficiency in the construction, manufacturing, and production capacity.

The resulting product is a home, classroom, health centre or other construction which is fully finished, ready for use simply by connecting the installations to the existing mains networks, making this the ideal technology to meet the most urgent needs for accommodation in both social and natural emergencies, using the stock available.

The technology also offers two equally efficient alternative options suitable for different applications:

a) Static or 'Airport' system: With this option the unit is assembled in a fixed location, with the various teams of workers progressively incorporating each of the stages required up to completion, in accordance with a minutely detailed schedule which includes the number of workers deployed, the times required to perform each task and the support needed from the workshop for each specialist function.

b) Dynamic or 'Assembly Line' system: With this option the unit is produced on a moving platform which progresses along a line divided into workstations, where each team progressively incorporates the results of its work, from casting the foundation slab to final quality control.

In both cases the process ends with the unit being hoisted using specially designed hydraulic jacks manufactured for this purpose, loaded onto a special trailer and then transported and delivered to its final destination, or a storage yard, where it will once again be hoisted and loaded for transportation and final installation.

Description of working stages:

1) Preparation for casting: Installation of forms for the reinforced concrete slab and a polyethylene film

2) Installation of the lower reinforcement mesh work previously cut to size in the workshop and fitted with plastic separators to ensure correct covering at the base

3) Installation of the sewerage and water installation elements, pre-assembled in the workshop in their correct position

4) Installation of the separators between the meshes

5) Installation of the anchoring combs, produced in the workshop

6) Installation of the upper reinforcement meshwork

7) Plant-produced concrete cast by pump

8) Vibrating-screeding-smoothing of the surface

9) Curing in steam tent

10) Layout of walls

11) Assembly of panels and modular forms, with the installation sections fitted to each wall, with the joints in place and the cables installed. Suitable carpentry elements will be installed with the forms (frames or base frames). At this point the required structural reinforcements to absorb the hoisting and transportation stresses are installed.

12) Assembly of modular slab formwork and resistant reinforcement

13) Casting of concrete walls and slab.

14) Pre-curing in steam chamber

15) Stripping of walls

16) Steam curing

17) Stripping of slab

18) Hot air drying

19) Final coating of walls

20) Application of floors

21) Installation of plumbing elements

22) Installation of kitchen equipment, work surface and lower units 23) Installation of doors and windows

24) Exterior rendering

25) Interior rendering

26) Installation of electrical elements

27) Quality control

28) Hoisting

In another embodiment, the present invention discloses a house manufacturing plan methods and times study according to Table 1.

Experiments and unexpected results

Technical details of the panel construction system according to the present invention:

CENTRED AND ECCENTRIC COMPRESSION

A vast quantity of tests was performed on panels of different thicknesses and heights, the results representing all of these being as set out below:

Centered Compression

4 cm panel - Height 020 cm - Maximum linear load = 760 kN/m

6 cm panel - Height 400 cm - Maximum linear load = 590 kN/m

6 cm panel - Height 300 cm - Maximum linear load = 1130 kN/m

4 cm panel - Height 270 cm - Maximum linear load = 1340 kN/m

Eccentric Compression

4 cm panel - Height 240 cm - Maximum linear load = 566 kN/m

6 cm panel - Height 300 cm - Maximum linear load = 707 kN/m

6 cm panel - Height 400 cm - Maximum linear load = 360 kN/m

4 cm panel - Height 270 cm - Maximum linear load = 680 kN/m

SIMPLE FLEXION

The flexion tests were in general performed with various configurations, and the ultimate moments representing the panels tested are therefore set out below. 4 cm panel: Compression layer 3 cm - Ultimate moment = 8.1 kNm/m

7 cm panel: Compression layer 3 cm - Ultimate moment = 12.2 kNm/m

With ultimate shearing stress recorded = 13.6 kN/m

8 cm panel: Compression layer 3 cm - Ultimate moment = 12 kNm/m

Bow on breakage = span/100 (*)

(*)The sample is supported only at the ends, and transversal deformation is therefore not restricted, while the deflection is not that inherent in the performance of the panels under flexion.

SHEARING TEST (SHEARING FORCE)

The shearing tension revealed by the tests is, with regard to the overall thickness of the panel:

4 cm panel (10 cm total) = 1.5 MPa

8 cm panel (15 cm total) = 1.3 MPa

TEST OF HORIZONTAL LOAD CONTAINED ON THE PLANE

The capacity of the panels is such in response to these demands that the tests in all cases come to an end because the anchoring elements have failed, although these values are sufficiently high to define more than satisfactory performance (50/100 kN at a height of 2.4 m - 4 cm panel)

For alternated cyclical horizontal load tests, values of 350 kN have been achieved (4 cm panel).

SOFT IMPACT TEST

4 cm thick panels received 540 J impacts (drop height = 1.80 m), with the

instantaneous bowing being recovered well within the regulatory requirements.

HARD IMPACT TEST

A 3.5 kg steel sphere dropped from a height of 2 m leaves an imperceptible imprint on the concrete surfaces. ECCENTRIC VERTICAL LOAD TEST

4 cm thick panels of polystyrene withstood, in accordance with the standards, moments of 300 Nm for 24 hours without any type of consequence.

SEISMIC TESTS

A prototype residential home built entirely from panels (walls, slabs, stairs and roof) was subjected to horizontal accelerations of 10 m/s2, with variable frequencies, including that of the structure itself, with absolutely no type of damage or cracking being recorded.

By way of example it should be pointed out that a standard seismic event in a high-risk region would involve horizontal design accelerations in the order of 3.5 m/s2.

WELDING SEPARATION TEST

Compliance with the terms of UNI ISO 10-297 and concordant standards was verified for the resistance of the welding points. It was in all cases found that this resistance was at least 2.26 times the comparative force required by the standard (0.3 of the breakage resistance of the smallest diameter bar).

Minimum separation load for the series of tests = 1.66 kN

Comparative load = 0.74 kN

WEATHERPROOFING TEST

The panels have been classified as E (the highest category) having been exposed to 140 mm/h rain with winds of 106 km/h for 24 + drying + 72 hours.

FUNGAL GROWTH RESISTANCE TEST

The results of these tests reveal performance by the Cassaforma surfaces which surpasses traditional methods, with level 0 being verified (substrates free of the growth of microorganisms) on the surfaces described, as opposed to level 1 (dispersed microorganisms) in the samples of traditional masonry.

FIRE RESISTANCE

Various tests have produced consistent results in terms of the fire-resistant capacity of the technology described, the significant data being as follows: - 60 min at 2500° C without release of vapours or production of flame

(6 cm panel with 35mm of concrete).

- 4 cm panel with 25 min of concrete

Fire Resistance Level:

Structural Adequacy = 241 min

Integrity = 241 min.

EXAMPLE CALCULATION

It is included by way of example a part of the analysis performed by the finite element method for the load state corresponding to the hoisting of a prototype bedroom at four points, with a surface of 40 m2 to illustrate a particular case of the evaluation of forces and determination of structural reinforcements (see Figure 1)

Figures 2A-2E depict a four-point hosting model:

Figure 2A shows diagram of tensions σ xx caused by the action of its own weight. Distance from support to edges 2.40, Normal horizontal tensions: Most below 2.5 kg/cm2, At aperture angles, local maximums from -10 to +16 kg/cm2

Figure 2B shows diagram of normal vertical tensions σ yy: All within +/-4kg/cm2

Figure 2C shows main tensions σΐ greater (traction where applicable)

At most challenging angles, maximums of 10 kg/cm2 (15 maxlocal), Main tension o2 less, At the same angles sigma2 around 3, Absolute maximum tension σ2=30 kg/cm2

Figure 2D shows maximum moments of flexion on footing slab, Reinforcement =

1.88cm2/m meshwork, Moments of flexion on slab (7 cm thickness)

Reinforcement xx : Less than 200 kgm/m.

Reinforcement yy: On the 140 kgm/m supports

In the 210 kgm/m section

Reinforcement 1.88 cm2/m meshwork

Figure 2E shows diagram of displacements (not to scale)

RESIDENTIAL HOME SPECIFICATIONS General description

Three-bedroom homes with living-dining room/kitchen and 2 bathrooms with an area of 53 m².

Individual specifications: Foundation:

The homes are constructed using a semi-elastic reinforced concrete footing slab, calculated for the extreme cases of possible ground conditions, and making rational use of the structural functionality of the superstructure materials. These slabs are 15 cm thick, with a quantity of metal meshwork determined in accordance with the demands, the characteristics of the supporting terrain question, in other words the acceptable resistance levels and ballast moduli and the conditions required in accordance with hoisting and transportation stresses.

Structure and walls: The walls of the home themselves provide the load-bearing structure, which comprises all the walls acting as component elements of the construction system, or otherwise as reinforced concrete partitions.

SMS System outer walls: comprising reinforced micro-concrete partitions with 10 kg/m3 expanded polystyrene sheets inside, with an appropriate thickness in order to meet interior comfort demands (e = 4 cm), plus a double high-resistance electro- welded steel meshwork (proportional yield stress > 550 MPa), 2.5 mm in diameter, tied using 3 mm diameter connectors of the same material. The heat transfer coefficient k is calculated in accordance with the terms of IRAM 11601 and concordant standards. Roof: Constructed using a traditional 6 cm thick reinforced concrete slab, as the base payer for the heat insulation, which comprises 3 cm thick expanded polystyrene sheets to which is attached a roof made of pre-painted trapezoidal sheeting or imitation tiling, using screws with plastic plugs and elastomer washers.

The side and ridge boards are pre-painted and bolted to the roof structure.

Installation of drains: Polypropylene piping and accessories are used, with rubber ring seals of the AWADUCT make, feeding into a collector pipe inserted into the footing slab, 0.110 m in diameter, which can be extended as far as the connection to the inspection box or septic tank. Mains water installation: Saladillo H3 homopolymer polypropylene piping and accessories are used, with heat-fusion joints, for both cold and hot water. Water heating system using a high-recovery electric storage heater with a 60 litre capacity.

Electrical Installation: Calculations in accordance with the applicable electrical regulations, with approved, first-rate materials. The piping is corrugated and fire- resistant. The conductors are single-pole, insulated with PVC, earth wiring with terminal for spike connection. The house is fitted with three circuits with the corresponding breakers and a primary circuit-breaker for the whole system.

Heating: Electric heating panels, one per room, powered by a special electrical circuit. Windows and doors:

Windows with folded sheet metal frames and natural aluminium sliding panels.

Exterior doors with sheet metal frames and injected double sheeting door panels with a double pallet lock and peephole. Interior doors with sheet metal frame and solid synthetic enamel painted door panels. Double rocker brass door handle, 'Ministry'- type.

Exterior and interior plastering: Walls with textured acrylic rendering, of the Revear type. Waterproof. Drop ceiling with mould-resistant latex paint.

Cladding: Bathrooms: Ceramic tiling to a height of 1.80 m throughout the perimeter. Kitchen: 30x30 cm ceramic tiling.

Floors: Wooden flooring with wooden skirting boards in all rooms, except bathrooms. In the bathrooms the floors are tiled, with pointed joints.

Kitchen fittings and furniture: Both bathrooms are equipped with a tiled bathtub, toilet with cistern and lid, washbasin unit, Florencia series by Ferrum. FV Allegro taps.

Complete set of accessories (towel rail, soapdish, hooks, liquid soap dispenser and towels). 3 mm mirror. In the kitchen, the units below the work surface are fitted with drawers, cupboard, boiler enclosure and dresser in melamine-clad MDF. 18 mm thick grey granite work surface with edging, cut with stainless steel sink with FV mixer tap.

Cooker with oven and four rings, fully electric.

Light fittings: Light fittings with energy-saving bulbs in all rooms.

Furnishing: Roller blinds fitted to all windows (except in bathrooms).

Main bedroom: Double bed with mattress, pillows and bedspread. Two bedside tables with lamps. Wardrobe and decorative picture. Baby room: Complete baby's cot with blanket. Bedside table with lamp and decorations, rocker and rag. Selection of toys.

Teenage bedroom: Complete bed with mattress, pillows and bedspreads. Complete wardrobe. Bedside table with lamp and decorations. Decorative picture.

Living-dining room: Refrigerator. Washing machine. Microwaves. Coffee maker. Wooden table with four wooden chairs. 2-seater sofa. 1-seater armchair. Rug. Standard lamp. Doormats.

MODULAR CLASSROOM SPECIFICATIONS

General description

50 m2 modular classrooms with capacity for 28 students. Space for teacher. Fully equipped, with teacher's desk, blackboard, students' desks, light fittings and plumbing.

Individual specifications

Foundation

Structure and walls

The walls of the classroom themselves provide the load-bearing structure, which comprises all the walls acting as component elements of the M2 construction system, or otherwise as reinforced concrete partitions.

SMS System walls: comprising reinforced micro-concrete partitions with 10 kg/m3 expanded polystyrene sheets inside, with an appropriate thickness in order to meet interior comfort demands (e = 6 cm), plus a double high-resistance electro- welded steel meshwork (proportional yield stress > 550 MPa), 2.5 mm in diameter, tied using 3 mm diameter connectors of the same material. The heat transfer coefficient k is calculated in accordance with the terms of IRAM 11601 and concordant standards. Roof

Constructed using a traditional 6 cm thick reinforced concrete slab, as the base payer for the heat insulation, which comprises 3 cm thick expanded polystyrene sheets to which is attached a roof made of pre-painted trapezoidal sheeting or imitation tiling, using screws with plastic plugs and elastomer washers.

The side and ridge boards are pre-painted and bolted to the roof structure.

Installation of drains

Polypropylene piping and accessories are used, with rubber ring seals of the AWADUCT make, feeding into a collector pipe inserted into the footing slab, 0.110 m in diameter, which can be extended as far as the connection to the inspection box or septic tank.

Mains water installation

Saladillo H3 homopolymer polypropylene piping and accessories are used, with heat- fusion joints.

Electrical installation

Calculations in accordance with the applicable electrical regulations, with approved, first-rate materials. Corrugated, fire-resistant pipes. The conductors are single-pole, insulated with PVC, earth wiring with terminal for spike connection. Three circuits with the corresponding breakers and a primary circuit-breaker for the whole system. Heating

Three electric heating panels powered by a special electrical circuit.

Windows and doors

Folded sheet metal window frames and prepainted aluminium-edge casement windows of the Modena series.

Exterior doors with sheet metal frames and injected double sheeting door panels with a double pallet lock and peephole.

Double rocker brass door handle, 'Ministry'-type.

Exterior and interior plastering

Walls with textured acrylic rendering, of the Revear type. Waterproof and elastic. Drop ceiling with mould-resistant latex paint.

Cladding

Bathrooms: 30x30 cm ceramic tiling to a height of 1.80 m throughout the perimeter. Floors

In the study area, vinyl flooring. Painted wooden skirting boards. In the bathrooms, 30x30 cm tiled flooring.

Fittings

Washrooms with compartments with toilets with cistern and lid, Capea series by Ferrum. 18 mm grey marble surfaces with two washbasins with automatic press-button taps.

Light fittings

Two energy-saving light fittings in each washroom. Eight light fittings with 2 x 36W fluorescent tubes with protection for the study sector. Three exterior light fittings. Furnishing

Teacher's desk, chair and blackboard. Fourteen double desks and 28 chairs for the students.

OTHER EMBODIMENTS

The detailed description set-forth above is provided to aid those skilled in the art in practicing the present invention. However, the invention described and claimed herein is not to be limited in scope by the specific embodiments herein disclosed because these embodiments are intended as illustration of several aspects of the invention. The embodiments set-forth above can be performed and combined with other disclosed embodiments according to the invention. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description which do not depart from the spirit or scope of the present inventive discovery.

Such modifications are also intended to fall within the scope of the appended claims.

Claims

1. A modular structural system comprising a plurality of modular moulding matrix for

formwork of said structure, wherein each modular molding matrix comprises a panel or series of panels and a modular industrial mould, each said panel comprises welded steel meshes enclosing a polystyrene slab and concrete on its surface, said modular industrial mold are connected with pins and ties and comprises a system of plates and tensioners for casting and curing the structure.

2. A modular structural system according to claim 1 , wherein said system further comprises a plurality of hydraulic jacks with dual-effect hydraulic actuator and eccentric for hoisting the structure.

3. A modular structural system according to claim 1 or 2, wherein said system further

comprises a trolley for transporting the structure which runs on rails embedded into the floor.

4. A modular structural system according to any of claims 1-3 , wherein said system further comprises a steam chamber for curing and drying the structure.

5. A modular structural system according to any of claim 1-4, wherein the polystyrene slab has a thickness of 3-15cm and height of 020cm-400cm.

6. A modular structural system according to claim 5, wherein the polystyrene slab has

thickness of 4cm and height of 020cm, thickness of 4cm and height of

240cm, thickness of 4cm and height of 270cm, thickness of 6cm and height of 400cm, thickness of 6cm and height of 300cm, thickness of 6cm and height of 300cm, or thickness of 6cm and height of 400cm.

7. A modular structural system according to any of claims 1-6, wherein the welded steel meshes have a diameter of 2.5mm with yield stress of above 550 MPa.

8. A modular structural system according to any of claims 1-7, wherein the plates of said modular industrial mould has a thickness of up to 0.4m and height of up to 2.6m.

9. A modular structure comprising a panel or series of panels wherein the panel comprises welded steel meshes enclosing a polystyrene slab, wherein the polystyrene slab has a thickness of 3-15cm and height of 20cm-400cm.

10. A modular structure according to claim 9, wherein the polystyrene slab has a thickness of

4cm and height of 020cm, thickness of 4cm and height of 240cm,thickness of 4cm and height of 270cm, thickness of 6cm and height of 400cm, thickness of 6cm and height of 300cm, thickness of 6cm and height of 300cm, or thickness of 6cm and height of 400cm.

11. A modular structure according to any of claims 9-10, wherein welded steel meshes have a diameter of 2.5mm with yield stress of above 550 MPa.