Pittini electrowelded steels

1

FOREWORD

Founded in the early Sixties, the Pittini Group began its activity, on an industrial scale,in the steel sector with a production that was absolutely new for the times: steel elec-trowelding, to supply the building industry with preassembled reinforcements.Since then, step by step, the whole world of construction has adopted the use of elec-trowelded reinforcement, such as flat or bent wire mesh and electrowelded latticegirders.The latter products in particular, Pittini electrowelded lattice girders – produced in awide range of types and designed for the most varied uses – have brought about sucha radical innovation in the floor slab construction techniques that today no othertechnology of the kind is used in Europe.Since nothing happens by chance it is evident that, if thousands of builders use elec-trowelded lattice girders, it is because they guarantee effective results in buildingindustrialization. This results from the flexibility of use, from the static safety (also inseismic zones), from the easy handling and positioning, and from the building speedas well as from the economic and rational working procedures on the building site.Electrowelded lattice girders, therefore, not only became by far the most suitablereinforcement for lattice girder planks or lattice girder plates, and for floors consist-ing of single large surface plates (one-room plates) but find generally favourableapplications in industrial floors and bridge decks as well as in building systemsemploying load bearing Double plate panels.This publication is intended to be a synthetic guide to the most widespread uses oflattice girders, thus maintaining a constant commitment in the research in the fieldsof technological processes and of finished products, aimed at developing a reallyindustrialized construction industry, that has always been peculiar to the PittiniFerriere Nord since their beginnings.

The electrowelding department of the Pittini Group, where electrowelded lattice girders are produced

1. LATTICE GIRDER PLANK FLOORS

Lattice girder plank floors find their best application in residential buildings, wherethey can be used both in intermediate and roof floors.Their particular characteristics allow to obtain the same – if not higher – structuralperformance and reliability as traditional floors entirely cast in place.It should be pointed out that lattice girder planks feature a good flexural rigidity evenbefore the concrete is cast; that the main bottom reinforcement is perfectly positioned andthat any additional reinforcement can be positioned correctly with a much greater accura-cy than in floors completely cast on site; that the diagonal wires (stirrups) create an effi-cient continuous connection offering great advantages with regard to shear stresses. The presence of the double stirrups, which have a 20 cm spacing, has a very positiveeffect: it guarantees an efficient connection between the prefabricated elements and thein situ concrete, absorbing any shear stresses. Stirrups, therefore, connect concrete andreinforcement in a very effective way.It should also be remarked that planks, owing to their low weight and their easyhandling, can be efficiently used also in medium and small size building sites, withclear advantages in terms of rational results and quick erection times.Pittini lattice girders are made with steel complying with European standards prEN10080-1. Therefore, they constitute a high quality reinforcement that can satisfy anyrequirement of lightweight prefabrication.

A case in which lattice girder planks are used

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Lattice girder planks are made of simple and inexpensive materials, that can be eas-ily found on the market and transported.They are: - Pittini electrowelded lattice girders;- steel bars for reinforced concrete structures; - concrete.

Where available, the bottom concrete of the planks can be cast into clay moulds.This last solution provides the lower surface of the floor with a homogeneous com-

position (a continuous clay surface); moreover, it allows to produce planks on anindustrial scale. Planks can be produced either by means of automatic prefabricationsystems or by artisan methods and even in the actual construction site on a concreteplane (see technical sheet on planks production, page 10).Transport, like all on site assembling operations, is very easy, due to the low weightof all the components (they usually have a weight which is lower than 12 kg forevery linear meter) and to their flexural rigidity, which is very high.Lattice girder planks are therefore composed of electrowelded steel lattice girders,completed with a concrete base, that can be contained in a proper clay mould.Additional reinforcement consisting of steel bars can be positioned in the thicknessof the baseboard; this is calculated according to the specific application.

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Figure 1.1: componentsof a plank fitted with

a concrete sole

Figure 1.2: componentsof a plank utilizing concrete cast into

a clay mould

concrete

TOP Pittini lattice girder

bar4 cm

12 ÷ 14 cmLATTICE GIRDER PLANK

concrete


clay mould

bar4 cm

12 ÷ 14 cm LATTICE GIRDER PLANK

Lattice girder floors are easily assembled; planks are positioned at the design centerto center spacing (50 ÷ 60 cm) and supported by temporary props, placed at a dis-tance of 150 ÷ 200 cm. They are completed with the positioning of hollow concrete or clay blocks.

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A phase of the assembling operations

of lattice girder planks,that can also be

manually executed

Figure 1.3: Layout of lattice girder

and reinforcing bars in the plank

Lattice girder planksrequire temporary props

every 150 ÷ 200 cm


Reinforcing bars

Blocks drawn in figure 1.4 enable the construction of a lightweight floor, with T-shaped load resisting elements, as can be seen in figure 1.5. If, on the other hand, specially shaped concrete elements are placed near the planks,

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Figure 1.4: Lattice girder plank floors with

lightweight concreteand clay blocks

Figure 1.5: Load resisting element in a

lattice girder plank floor

Typical examples of plankfloors: with concrete

base (above) and withconcrete base into a clay

mould (below)

50 ÷ 60 cm

50 ÷ 60 cm

50 ÷ 60 cm

H

we obtain a monolithic reinforced concrete floor. This is statically the same as a tra-ditional cast in situ floor, requiring the use of formworks that cover the entire sur-face. It is therefore clear that this solution allows to obtain a great reduction in con-struction times and costs. If high load or span requirements have to be satisfied, there are two possible solu-

tions: to place two or more planks together, to increase the bearing reinforcement, orto increase the height of the blocks, by putting two elements one upon the other.Once planks and blocks are put in their proper place, additional reinforcement barsto absorb negative moments at the supports and distribution reinforcement are posi-tioned. Subsequently, concrete can be cast and levelled. During this phase, plankscan support all the loads developed during the casting operations.

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The perfectly homogeneous lower

surface of a plank floor,in which the concrete of

the planks is cast intoclay moulds

Figure 1.6: Section of a monolithic

lattice girder plank floor

Figure 1.7: Section offloors with double

planks; with concretehollow blocks (top) andwith clay hollow blocks

(bottom)

62 ÷ 74 cm

62 ÷ 74 cm

50 ÷ 60 cm

Another advantage resulting from the use of planks consists in the possibility ofbuilding with great ease cantilever elements, such as balconies, level and/or slantedroof overhangs. Lattice girder plank floors can be profitably used also in existingbuildings requiring static upgrading or restoration. In this case, the reconstruction of floors is made easier by the low weight of the

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Figure 1.8: Monolithicconcrete floor, entirelymade of lattice girder

planks

A phase of casting inplace concrete

Figure 1.9: Cantileversections using lattice

girder planks

balconyintermediate floor

roof overhang

roof floor

lattice girder planks

Construction details

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50 ÷ 60 cm

50 ÷ 60 cm

Clay block

Reinforcing bars for thenegative moments

Distribution reinforcement (electrowelded wire mesh) + reinforcing bars for thenegative moments Reinforcing bars for the negative moments

Reinforcing bars for the negative moments

Distribution electrowelded wire mesh

Distribution electrowelded wire meshBeam

Reinforcing bar positionedin the plank

Reinforcing bar positionedin the plank

Reinforcing bar positionedin the plankLattice girder plank

Lattice girder plank

Lintels for doors and windows

To support masonry



Distribution electrowelded wire mesh

4 cm

Floor composed of single planks completed withtwo superimposed hollow clay blocks

Section of in-plane beam Section of in-height beam

Section of the support Structural ribs obtained using double planks

Lattice girder plank floor with single clay blocks:section on the support

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Wall anchorage

Pittini electrowelded wire mesh

TOP Pittini lattice girders

4 Ø 16

Stirrups Ø 6/25

2515

B

B

~ 3 m

Figure 1.10: Details ofplan and section of a

lattice girder plankfloor that substitutes an

existing wood floor

Plank floor in therestoration of a masonrybuilding: the wood floor

is replaced, the walls arestrengthened with

electrowelded wire meshand cement mortar

components and by the effective connections that can be easily executed with theexisting load bearing structures. Fig. 1.10 shows the plan and section of a lattice girder plank floor with clay hollowblocks replacing a wood floor on stone masonry.

Plank production: from the simplest systems to the prefabrication plants

By paying a little attention and by operating with accuracy, anybody can produce lat-tice girder planks. The most economical and easy way is to use a concrete plane,poured in the construction site. Wooden or square steel elements with a section of 4x 4 cm must be put on it.These elements must be fixed to the plane with a 16 cm spacing, so as to create asuitable space for the production of the plank concrete base.After the distribution on the whole surface of an ordinary demolding oil, concrete iscast in all the spaces reserved for production; it is essential that the mix be sufficient-ly fluid to ensure an even distribution. In this phase it is convenient to keep clean theupper surface of the elements, and remove any residual material.Subsequently, additional reinforcement and electrowelded lattice girders are posi-tioned.The correct positioning of the reinforcing elements in the concrete cast is obtainedby employing cast stoppers, provided with appropriate grooves that guarantee anadequate concrete cover. This function can also be performed by special spacers.

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Figure 1.11: A detail ofthe cast stoppers that

enable an easy construction of lattice

girder planks with concrete base

It is advisable to make sure that the concrete cast is adequately vibrated, since thisincreases the adherence to the reinforcement. After some days, when the concretehas matured, it is possible to strip the planks and, subsequently, to assemble them.The type of production that has been just outlined is of an artisan type, but there areindustrialized systems that use appropriate steel sheet planes or automated prefabri-cation plants enabling the production both of concrete base planks and of plankswith clay moulds.In Italy, as well as in Germany, France and other European countries, such plants

reinforcing bars

Pittini lattice girders

lattice girders planks

cast stoppers

square steel elements

have been used by groups of small-size enterprises, that have managed this way toobtain an adequate production level with low costs, while still meeting with therequirements of all partners.

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A phase of industrialproduction of latticegirder planks whose

base is cast in a clay mould

The industrial production of planks

with concrete base (onsteel sheet moulds)

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2. LATTICE GIRDER PLATE FLOORS

Pittini lattice girders, combined with electrowelded wire mesh, allow another inter-esting application in the modem industrialized construction sector: light prefabricat-ed elements for floors to be completed on site. The concept from which they derive is the same as the one of lattice girder planks;their width is considerably increased – even twenty times – owing to prefabricationby means of adequate, special moulds (see “Lattice girder plate production” on page24). This makes it possible for a floor to be made using a reduced number of prefab-ricated elements and at the same time obtaining a finish that cannot be achieved withother systems. Prefabricated plates can be used whenever a floor is to be constructed, both in civiland industrial buildings; moreover, for special requirements such as bridge deckslabs, they can be used both in connection with composite structures (steel concrete)and with main prestressed concrete beams.

The most important advantages offered by the use of prefabricated lattice girderplates for floors in a building system are:

– simple execution in the prefabrication phase, with possibility of producing plateswith particular shapes, whith holes, openings or interruptions in the slab andequipped with all accessories of technological plants;

– fast handling and installation, thanks to the large dimensions of the single ele-ments;

– easy construction of floors, since the traditional formwork carpentry operationsare eliminated and substituted by simple temporary props, disposed at a distanceof 2–2.5 m; moreover, this system allows to reduce the total quantity of steel thatremains to be arranged on site, and enables workers to operate under conditionsof maximum safety during the execution of the final concrete cast;

Lattice girder plates usedin the construction of

bridge decks (above) andfloors in a civil building

– elimination or reduction of temporary props, when adopting special lattice girderswith higher rigidity (Pittini Baustrada lattice girders);

– static flexibility; plates can be designed according to all structural needs, thanks tothe great variability of all the parameters;

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Right: a view of the installa-tion on site of a floor plate.Above: a special plate withan opening. Below: pipingfor the electric plant, posi-

tioned over the plates,before the final concrete

cast is executed

Lattice girder plate floorsusually require a small

number of temporaryprops during casting

operations

– drastic reduction of plate soffit finishing operations; thanks to the perfectly smoothsurface created by the casting plane, these operations can be limited to the sealingof the joints between the prefabricated units and to subsequent painting, or – moresimply – to the application of wallpaper.

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Figure 2.1 Section of PittiniTOP and HD Baustrada

lattice girders (dimensions are expressed in mm)

Floor construction utilizing self-supporting

plates, that eliminate thenecessity of temporary

propping

Plates ensure a perfectlower finish of the floors;before painting the soffit,

it is sufficient to seal the joints between the

prefabricated units


Ø 8 ÷ 16

h = 95 ÷ 400

h = 70 ÷ 205

Ø 6 ÷ 10Ø 7 ÷ 8

Ø 5 ÷ 6 Ø 6 ÷ 12

Ø 5

Lattice girder plates consist of a concrete slab, with a thickness of 40 to 70 mm(weighing about 100 kg/m2) stiffened for transporting, lifting and installation opera-tions by a system of electrowelded reinforcements, which consist of an embeddedelectrowelded wire mesh reinforcement and one or more lattice girders, only partial-ly embedded. Reinforcing bars can be added, according to the steel section requiredto absorb the positive moments. Also the longitudinal wires of the mesh and thelower wires of the lattice girders concur to the realization of this steel area.Lattice girder plate dimensions can feature the most varied dimensions to suit par-ticular applications:

– 120 – 250 cm width (the length is equal to the dimensions of the rooms present inthe building plan) in ordinary applications, where their dimensions are limited bythose of the prefabrication plants and of the transport vehicles;

– dimensions and shapes to completely cover the rooms, if the prefabricated elementcan be produced on site.

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Figure 2.2: Components of a lattice

girder plank

A special plate, produced on site,

covers a room completely

concrete TOP Pittini lattice girder


bar

4 cm

120 ÷ 240 cm

LATTICE GIRDER PLATE

The floor slab is obtained by placing the prefabricated plates one beside the otherand is completed by the positioning of the additional reinforcement bars (distribu-tion and for the negative moment) and with a concrete cast, having an adequatethickness. In this case a monolithic floor slab is obtained.

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completing concrete cast

prefabricated plate


Pittini 520 L electrowelded wire mesh



block of lightweight concrete polystyrene block

clay block

prefabricated plate

For lightweight floor slabs, plates are supplied from the prefabrication plant withpolystyrene void formers which are positioned between the lattice girders.Slabs can be lightened also with other elements, such as blocks using either light-weight concrete or clay.

Generally, plate floor slabs feature many advantages with respect to traditionalfloors cast on site. This is mainly due to the following reasons:

– availability of a light and flexurally rigid structure before completing the concretecast on site;

– elimination of the operations connected with positive moment reinforcement (it isalready accurately placed in the plate in the prefabrication plant) and easy posi-tioning of the additional negative moment reinforcement;

– for two–way floor slabs, a part of the positive moment reinforcement is alreadypositioned in the plate during the prefabrication phase, while the remaining one iseasily placed in the construction site; it is inserted in an orthogonal position withrespect to the reinforcement in the plate, passing trough the electrowelded latticegirders and on the prefabricated plate;

Figure 2.3: Section of a monolithicfloor employing lattice

girder plates

Figure 2.4: Section of alightweight lattice girder

plate floor showing various types of blocks

– effective continuous connection between the prefabricated element and the con-crete on site (to absorb shear stresses) guaranteed by the very close double stir-rups of the electrowelded lattice girders.

In the case of lightweight floors, the resisting element is composed of a series ofT–shaped resisting structures, both for positive and negative moments (in this casethe lower slab, that is the plate, contributes to the compressive strength).As stated above, the use of prefabricated plates in the floor construction guarantees

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prefabricated plate



bearing reinforcement


lattice girder plates

lattice girder plate beam plate

distribution electrowelded wire mesh reinforcement for negative moments

reinforcement for negative moments

connecting reinforcement


Figure 2.5: Two-waymonolithic floor slab

with plates

Figure 2.6: Load resistingelements for negative and

positive moments in a light-weight floor (above).

Figure 2.7: Sections ofbeams contained in the

floor thickness, executed with the plate asformwork (above) or with

a prefabricated beam

a smooth soffit finish, with a homogeneous surface; in fact, it is possible to obtainbeams within the overall thickness of the finished floor. Two techniques can be usedfor this purpose: prefabricated beam-plates (where the traditional reinforcement ispartially embedded in the concrete cast) and beams placed over the plates, with thetraditional reinforcement positioned over the prefabricated elements.

Under certain construction site conditions (bridge or viaduct structures, that must bebuilt without interrupting the traffic or flows underneath; considerable height of thefloor; slabs on canals or culverts) it may be necessary to completely eliminate tem-porary propping. In these cases, in addition to the use of Baustrada HD Pittini latticegirders, it can be useful to execute the casting of the central ribs. This way it is pos-sible to obtain a self-supporting capacity of up to 6 to 7 m and to reduce, at the sametime, the strain stresses during the final concrete cast.

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Lattice girder plate floorwith a beam, having the

same slab thickness,made with a

prefabricated plate

Figure 2.8: Section of a self-supporting plate

having a width of 250 cm,whose central ribs are

stiffened both by PittiniBaustrada lattice girders and

by a concrete cast executedin the prefabrication phase

Lattice girder plate withconcrete cast ribs, self-

supporting on a 6 m span

HD Baustrada Pittini lattice girders

Lattice girder plates are the most suitable prefabricated elements for the execution ofbridge decks, when pre-stressed concrete beams or steel beams are used. This allows toobtain immediately a basic element on which it is possible to carry out – under maxi-mum security conditions – all the subsequent operations, while avoiding the need forcostly formwork.Considering the application to bridge decks, another advantage must also be taken intoaccount: with an adequate interruption of the concrete casting, corresponding to theconnections with the beams, they can cover the whole width of the deck, including thelateral cantilever parts. The slab casting, in these cases, can be performed either in asingle or in two distinct phases: the latter solution requires a lower number of latticegirders to be positioned in the cantilever section. If the final concrete cast is performedin two phases, in the first one the inner spans and a little part of the overhangs are cast;in the second one – executed after some days – the remaining parts of the cantileversections are cast, after the positioning of the prefabricated vertical elements on theedges of the slab, that constitute a finished container of the concrete cast. In such a waythe execution of the deck is carried out without any difficult formwork installation andalso without the expensive special equipment usually required.

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An example of steel structure with

self-supporting platefloors in a civil building

(offices)

Figure 2.9: Section of a caissonsteel-concrete bridge.

Figure 2.10: A slab executedwith self-supporting plates both in

the span and in the cantilever

section b-b section a-a

lattice girder plate1st phase

2nd phaseb

b

a

a

Pittini 520 B wire meshPittini 520 B wire mesh

5 HD Baustrada Pittini lattice girders 9 HD Baustrada Pittini lattice girders

Particularly important from a technical point of view is the mutual cooperation thatis generated – once the concrete cast is fully matured – between the slab (deck) andthe main beams to which the slab is rigidly connected (anchored) so as to create onlyone resisting section.

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A viaduct executed with acomposite steel-concrete

structure. The slab is builtusing self-supporting lattice girder plates.

The photograph aboveshows the bearing caissonstructure carried out with

Cor-Ten steel

Viaduct deck on pre-stressed concretebeams, executed withself-supporting plates

stiffened by Pittini“Baustrada” HD lattice

girders

Adopting the same technique in civil buildings, roof overhangs and balconies arevery easy to build. A peculiar application of plates with cantilever sections consist in increasing theroad width in existing masonry bridges. The tecnique is very easy: after the road surface has been removed, the new deck isexecuted by employing special plates (without the concrete casting in the central area,

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Figure 2.11: Section of overhanging

floor parts, for roof overhangs and

balconies, constructedwith lattice girder plates

A phase of placing on site special lattice

girder plates for wideningthe road in an existing

masonry bridge

balconyintermediate floor

roof overhang

interruption of the concrete cast of plates

interruption of the concrete cast of plates

corresponding to the former road pavement) whose concrete prefabricated slab iscast only near lateral cantilevers.Also in this case, on site construction operations are reduced, both with regard to thereinforcement placement (supplied almost completely embedded in the slab) and tothe elimination of temporary props and formwork.As shown by the descriptions and examples reported the laying operations of theprefabricated elements are very easy, and therefore do not require special hoistingdevices or skilled workers.Finishing operations are executed with extreme ease, both with regard to the instal-lation of additional reinforcement bars and to the execution of the concrete casting.Furthermore the class of concrete for the final concrete cast has the same character-istics as those of the structures usually installed on site.

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The bridge during the widening operations

Below: a phase of thefinal concrete cast


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distribution electrowelded wire mesh




plate reinforcement anchoring



lattice girder plate

lattice girder plate

Section on a support

Section on a in-height beam

Section on a masonry support

Section in midspan

TOP Pittini lattice girderspolystyrene bloks



bars for positive moments

bars for negative moments



Plate production: a highly tested system of lightweight prefabrication

Lattice girder plate production does not feature any difficulty; for a limited quantityor special production all that is required is to have a concrete track available, on whichsuitably shaped moulds, made of 4 ÷ 5 mm thick steel sheet, can be installed. In thismould, once the transversal cast stoppers are fixed, according to the design length ofthe plate, the casting and levelling of the concrete are performed, on which preassem-bled reinforcement elements (lattice girders, wire mesh and bars) are installed.Concrete vibration allows to obtain a higher compressive strength, a good adherenceto the reinforcement elements and a better lower surface of the plates.The same prefabrication track can also be installed on site.

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On site production of lattice girder plates: concrete spreading,

reinforcement installationand subsequent vibration

In general, these phases are similar also for an industrialized plate production, thattakes place in special plants such as tracks fitted with vibration and, possibly, accel-erated curing systems.An industrial prefabrication building yard offers the notable advantage of rational-ized production phases, which guarantee a continuous production. Moreover, ration-alization allows to limit the production costs while assuring productions with a con-stant quality level.The best solution consists in the installation of the prefabrication plant inside a cov-ered area, equipped with an overhead travelling crane – with a capacity not lowerthan 5 tonnes – and a concrete mixing plant.In the production plant, through appropriately arranged attachments, various tracksare assembled (width 120 – 250 cm, length 8 m) and are placed on adequate supportsso that workers can operate under optimum conditions.Such elements constitute the prefabrication tracks, i.e. the plants that allow to obtainhigh production yields at extremely high finishing standards.

Tracks allows the production of plates having a width from 50 to 250 cm, a thick-ness from 4 to 7 cm and variable lengths, according to design requirements. Tracksfor the production of 250 cm wide plates can be equipped with longitudinal caststoppers that allow the simultaneous production of two 120 cm wide plates.The plate reinforcement (Pittini electrowelded lattice girders, mesh and reinforcingbars) which has been preassembled in an appropriate area, is then istalled on thetrack previously sprayed with a demoulding compound.The length of the plates is determined by the distance between the transversal caststoppers. It is important that the reinforcement is kept at an adequate height from thetrack – by means of normal spacers – in compliance with the concrete cover design.

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On site prefabrication of large plates for a multistorey building

for dwellings

An element of the trackfor the prefabrication of

lattice girder plates with amaximum width of 250 cm,

equipped also with a self-advancing vibrating trolley.

Lattice girder plate casting on a

prefabrication track

Then concrete is cast and, after a first spreading and levelling, it is compacted by thevibrations of the self-advancing vibrating trolley.In the case of plates designed for the production of lightweight floors with poly-styrene blocks, they must be positioned on the concrete after the vibration, thus guar-anteeing an adequate bond between the concrete and the block.

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Installation of the lightening polystyrene

elements

Plate dismantling usinga special lifting device

Should an accelerated production process be desired, tracks can be provided with aplant for artificial concrete curing, consisting in a heat exchanger positioned belowthe track – composed of a coil where diathermic oil is circulated, under pressure andappropriately reheated – or in a tunnel, made with polythene sheets, placed over thetracks after vibration has taken place, in which steam is blown.

When concrete has reached a minimum strength of 120 kg/cm2 – the following day,under normal conditions – it is possible to remove the plates from the tracks. In orderto avoid any cracking of the prefabricated slab as far as possible, it is necessary toevenly distribute the vertical tension, using a lifting device connected to an adequatehoisting unit.Lattice girder plates are then transported to the storage area and then shipped to thevarious building yards. In these phases, the rigidity of the partially embedded latticegirder gives the plates a great ease of handling; using simple fork lift trucks it is pos-sible to perform transport and loading operations of 7-8 elements at a time.In the construction yard handling is performed by lifting the plates one by one fromthe truck, and positioning them directly on the area to be covered. If in the buildingyard there is not a crane with a 1 ton lifting capacity the operation can be performedby the truck mounted hoist.

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Transport of latticegirder plates

Lattice girder platesbeing unloaded from thetruck and positioned onthe span to be covered

by the truck hoist

3. DOUBLE PLATE PANELS

The idea of employing prefabricated plates, not only for floors but also for theconstruction of walls, allowed the development of a new building system withpartially prefabricated wall elements. At first, the system was built with twoseries of floor plates installed in a vertical position, mutually positioned and con-nected on site. Afterwards the system was made of two-plate modular elements –the so called Double plate panel – connected in parallel already in the prefabrica-tion cycle by a system of special electrowelded lattice girders: the “Double PlateHD Pittini”.The Double-plate building system is therefore based on a prefabricated panel,

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composed of parallel plates that – once installed on site, one beside the other andcompleted by an adequate connecting reinforcement and a concrete cast – make upa load bearing wall. The height of this wall is equal to the height between floors, and both surfaces areperfectly finished.The Double-plate building system can be employed in all constructions, both forcivil and industrial use, allowing to obtain advantages that are very similar to theones obtained using lattice girder plates for floor slabs.

The main advantages are:– simple execution in the prefabrication yard, thanks to the use of the same plants

as those used for lattice girder plates (see the technical sheet “Production ofDouble-plate panel”);

– maximum geometric flexibility (thickness – width – height);– possibility of executing plates with particular shapes, or fitted with openings for

Right: an apartmentbuilding, produced with

the Double-plate building system.

Above: a prefabricatedDouble-plate panel

during the assemblingoperations

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Right: special Double-plate panels for bearing

walls with openings. Above: special panel

equipped with fittings forthe electrical system

Panel installation by theuse of adjustable props

fixed both on the supportand on prefabricated ele-

ment (equipped with ananchorage system)

doors, windows or connections between orthogonal walls, to be carried out onsite. The two plates can also have different dimensions: this solution is adoptedfor the construction of corner joints and for the connection between wall andfloor;

– possibility of containing parts of the technological plants (electrical pipes, boxesand connections), that are inserted during the prefabrication phase;

– quick installation on site, thanks to the low weight (200 kg/m2), to the modular dimen-sions of the single elements and to the simple propping operations required to main-

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tain a correct alignment and the necessary stability before the final concrete cast;

– simple construction of walls, since the carpentry operations required for the tradi-tional formwork are completely eliminated by the simple use of the temporaryprops;

– reduction of the total quantity of steel bars to be positioned in the constructionsite, since it is strictly reduced to the ones that connect the various prefabricatedpanels;

– possibility of obtaining insulated walls, by inserting a layer of thermal insulatingmaterial in the panels during the prefabrication phases;

– structural flexibility: double plate panels can, in fact, satisfy all the design require-ments, thanks to the great variability of all static parameters (total thickness of thefinal wall; quantity and quality of the reinforcing units; quality of concrete);

The insertion of connecting bars between

two adjacent panels orreinforcing bars at the

end of the walls is simplyperformed

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– drastic reduction of the finishing operations of the outer surfaces: thanks to theperfectly smooth surface created by the casting planes, plaster can be completelyeliminated, and the finishing operations can be limited to the sealing of the jointsbetween panels and to the subsequent painting;

– possibility of finishing the external plate with mosaics of stone slabs or with othermaterials, that are put in place during the prefabrication phase.

Double plate panels consist of two parallel concrete plates, with a thickness of 4 ÷ 6cm (and a weight of about 200 kg/m2); they are stiffened by a system of electrow-elded reinforcement, which consists of two sheets of electrowelded wire mesh (usu-ally Ø 5 mm and 10 x 10 cm spacing) and special Double Plate Pittini lattice gird-ers. These are inserted approximately every 50 cm, in a vertical position and createa safe connection with the wire mesh panels.

Double plate panels can feature different shapes; the overall dimensions, as deter-mined by the production plant, are:

– width: 60 ÷ 300 cm

– height: 100 ÷ 600 cm (usually it is equal to the storey height)

– total thickness: 20 ÷ 45 cm

– thickness of the single plate: 4 ÷ 7 cm.

Right: a view of the stoneslabs installation for aspecial finishing of theouter surface of a dou-

ble-plate panel. Above: detail

of the finished doubleplate panel.

The double plate building system is used for the construction of external and inter-nal load bearing walls. In the construction site the prefabricated panels are placedside by side (they are kept aligned and in a vertical position by means of adjustable

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Figure 3.1: Componentsof double plate panels.

Figure 3.2: Transversal section

of double plate panel

concrete

Double Plate HD Pittini lattice girder

Double Plate HD Pittini lattice girders


Pittini 510 electrowelded wire mesh

250 cm

DOUBLE PLATEELEMENT

~ 25 ~ 25~ 50 ~ 50 ~ 50 ~ 50

props); then, additional connection and structural reinforcement is positioned inside.During this phase, double plate panels are hoisted and transported using hooks thatare connected to the Pittini lattice girders.In the connection areas of two adjacent walls (crossings, corners, intersections) spe-cific double plate panels are used, that are specially shaped so as to facilitate con-nections and the insertion of adequate structural reinforcements (see the technicalsheet “Construction details”).

33

Final concrete cast ofwalls built with double-

plate panels. Above: a double plate

panel equipped with a layer of thermal

insulating material

same way, plates for external walls may contain a layer of acoustic insulation, witha thickness from 2 to 5 cm.We have already mentioned that double plate panels can be executed also with open-ings designed for doors and windows. They are easily executed by arranging ade-quate cast stoppers on the prefabrication tracks.In the construction yard, the openings for doors and windows can be finishedwith prefabricated outer casings – or traditional wood moulds – that act as caststoppers during the execution of the final concrete cast.Double plate panels can be used also for the construction of retaining walls and forfencing.

The casting of concrete between the two plates is performed very easily in a singlephase. From a structural point of view, monolithic vertical bearing structures are thusobtained, also thanks to the effective connection between the two prefabricatedplates and the concrete cast on-site, resulting from the close arrangement of the lat-tice girders stirrups.As a result, the double plate building system allows to obtain, in addition to a con-siderable resistance to vertical loads, a natural stiffness that absorbs seismic stresseswithout any increase in reinforcement.From this description it is already possible to appreciate the validity of the double-plate building system. If the system is also completed using floors made of lattice girder plates, it is easilyunderstood that the resulting building process, not only allows a considerable reduc-tion of the equipment required on the building site, of the execution times and thenumber of workers but, at the same time, allowings a remarkable quality leap, sinceit offers extremely advanced and wholly industrialized building solutions.As stated above, double plate panels designed for the construction of external wallscan be equipped with an adequate layer of insulating material (polystyrene); in the

An other interesting application of the double plate building system is the construc-tion of artificial, covered canals with a square/rectangular cross-section.After the construction of the foundations, double plate panels are installed on site, toform the lateral walls of the canal. That will be subsequently covered by self-sup-porting lattice girder plates.The concrete casting of the walls and the horizontal slab – that do not require form-

34

Double plate panelswith openings for doorsand windows, equipped

with prefabricated outercasings allowing theexecution in a single

cast for the wholeheight of the wall

An earth retaining wallexecuted with double plate

elements on whose outersurface stone elements

are arranged in a mosaic-like shape.

Above: a fence wall,entirely executed with

double plate panels

work – will result in a monolithic work, able to resist both to internal and externalpressures that can be caused by undergroud laying of the whole structure and by thesuperimposed loads.

35

A length of an artificialcovered canal,

constructed with doubleplate elements and

lattice girder plates

Figure 3.3: transversalsection of an artificialcanal constructed with

double plate panels and covered by self-sup-

porting lattice girderplates

HD Baustrada Pittini lattice girdersself-supporting plates

Double Plate HD Pittini lattice girders

connecting reinforcementfrom the foundation

foundation

double plate element


36

HD Double Plate Pittini lattice girders



reinforcement for negative moments

lattice girder plate floor

Pittini HD 510 electroweldedwire mesh



Connection of the wall to the continuous foundation

Connection between floor and external wall

37

reinforcement for bending stressesof the two walls

reinforcement for bending stressesof the two walls

≤ 50 cm

≤ 50 cm

HD Pittini lattice girders

Corner connection of two walls

Connection of an internal and an external wall

38

Some constructions performed using the double plate building system

39

Prefabrication of double plate panels

The manufacturing process of double plate panels can also be carried out using thesame standard plant with fixed moulds described for the production of lattice girderplate floors. The first plate is manufactured in the same way as a floor, and then the second plateis manufactured after having extracted, tilted and positioned the first plate manuallyon the same mould. The mould is prepared with the concrete and the reinforcement for the second plate,so that the two plates will be constructed perfectly parallel.The new plants for the production of lattice girder plates or double plates are equip-ped with a “carousel” system. This system allows the operators to remain in a fixed position while the moulds areautomatically moved from one working area to the other, following a circular pathcontrolled by appropriate software. In these plants, many processes are automated. Operations such as cleaning the moulds, plotting, positioning the magnets and caststoppers, casting the concrete, tilting the first plate and coupling the plates to obtainthe double plate panel are all carried out automatically so as to rationalize theprocess and avoid human errors.

Equipment for cleaningand placing the trans-

verse cast stoppers (photo CEIS - TN)

40

Carousel production cycleOnce the project is confirmed by the customer, all the construction details of eachdouble plate panel are processed using specific software, so as to provide on-line allthe information required by the various working stations.The process starts after delivering the manufactured articles, when the productiontrack is taken to the cleaning area.

A robotized machine eliminates the residues of concrete of the previous productionand cleans the surface.In the following station, the geometries of the elements are directly drawn on themould with a laser equipment. Then the magnets with relevant cast stoppers and any necessary window or doorframes are automatically positioned together with the prop fixing bushes. A de-moulding compound is automatically spread and then reinforcement, latticegirders and lifting hooks are positioned.In another station, a concrete distributor moves over the mould in order to form aneven layer of concrete having the thickness required by the project; then the concretecasting is compacted by vibration. Once the first plate has been completed, the moulds are stocked in the curing cham-ber using a special lifting equipment.

Use of the laser equipmentto place the magnets and the longitudinal

cast stoppers.(photo CEIS - TN)

41

Tilting stationfor the first plate

(photo CEIS - TN)

Concrete casting of thesecond plate (photo CEIS - TN)

42

The concrete is cured at controlled temperature and humidity.After about six hours, when the concrete has reached a resistance of at least150 kg/cm2, the plate can be extracted from the curing chamber and taken to the tilt-ing station. An automated system lifts and then rotates the mould together with the cured plateby 180° and finally places it over the previously produced plate. The coupling is completed by adding the necessary reinforcements, and then themould with the two plates is taken to the curing chamber.After the curing of the second plate has been completed, the mould is moved withthe special lifting equipment to the extraction station, where an operator removes thecast stoppers. Then the double plate panels are lifted and stacked by an overhead travelling craneequipped with special hooks. The stack is then moved with a fork lift to the storagearea.

Right: after coupling thetwo plates, the unit is

vibrated.Above: storage of a double

plate panel (photo CEIS - TN)

43

PITTINI REINFORCEMENTS: GREAT RELIABILITY ON A WORLDWIDE LEVEL

The production of electrowelded reinforcements (wire fabrics, lattice girders andspecial reinforcements) is characterized by a continuous research on typology and,above all, by a constant process control. The final testing of the product, performed by official material testing laboratories,guarantees that the Pittini steel is suitable to be used in the most severe conditionsand according to the various standards present in the world.These are the reasons why the Pittini Group represents a concrete and reliable world-wide reference point.The Group offers a wide range of steel wire fabrics and latticegirders having high quality standards. The production process is guaranteed by a quality system certified by IGQ. The cus-tomer service is completed by a wide availability of standard products with extreme-ly quick delivery and a specialized technical and calculation Assistance Service. In the next pages the production tables are given for the Pittini reinforcements, forthe realization of prefabricated plank and plate floors and of double plate panels.

The IQNet and IGQ Quality System Certificates according to the International standard ISO 9001.

44

Properties of the reinforcing steel

The reinforcing steels manufactured in Ferriere Nord S.p.A., company of PittiniGroup, are delivered in bars, coils, welded fabric and lattice girders conforms thestandard prEN10080:1999.The values are given in the following table.

Property Specified characteristic value

Steel grade B450C B500B B500A

Yield strength Re (N/mm2) ≥ 450 ≥ 500 ≥ 500

Ratio Rm/Re ≥ 1.15 and ≤ 1.35 ≥ 1.08 ≥ 1.05

Elongation Agt (%) ≥ 7.5 ≥ 5.0 ≥ 2.5

On order are available test reports in according to EN10204.

The reinforcing steels named PITTINI HD are classified B450C according to prEN10080.

Above: the PittiniGroup’s hot rolling mill

Right: Pittini Group’selectrowelded mesh

department

45

Weldable, deformed bars and coils for reinforced concreete

Diameters and packaging

Type Ø mm Weight (kg) Max weight (kg) Ø int. (mm) Ø ext. (mm) Height (mm) Length (m)

Coil 8 ÷ 10 1500 – 2000 — 800 1200 1500 ÷ 2000 —

Spool “Jumbo” HD Pittini 10 ÷ 16 1800 – 2400 — 700 1000 ÷ 1200 700 —

Bars HD Pittini 8 ÷ 32 2400 2500 — — — 6 ÷ 14

ht

Øs

Øi

ds

NotesThe table shows the geometrical properties of standard lattice girders typeTOP, DL and Baustrada available in stock (12 m length).On order are available lattice girders with the following properties:- height from 7 to 40 cm- upper chord diameter from 7 to 16 mm- lower chord diameter from 6 to 16 mm- stirrups diameter from 5 to 10 mm- the ratio (Fmin / Fmax) ≥ 0.60 are respected

All types of lattice girders are available in length as multiple of 20 cm (minlength 3.6 m).The reinforcing steels named PITTINI HD are classified B450C accordingto prEN10080.

Pittini electrowelded lattice girders type HD “Baustrada” (stirrup spacing: 20 mm)

Pittini electrowelded lattice girders type HD Double Plate (stirrup spacing: 20 mm)


Pittini electrowelded lattice girders type TOP (stirrup spacing: 20 mm)

TOPØ of wires (mm) Height

(mm)hLower (Øi) Upper (Øs) Stirrup (ds)

5/7/5 h = 7,0 5 7 5 70

5/7/5 h = 9,5 5 7 5 95

6/7/5 h = 9,5 6 7 5 95

5/7/5 h = 12,5 5 7 5 125

HD BaustradaØ of wires (mm) Height


8/10/6 h = 12,5 8 10 6 125

8/10/6 h = 16,5 8 10 6 165

8/12/7,2 h = 16,5 8 12 7,2 165

HD BaustradaØ of wires (mm) Height


8/12/7,2 h = 20,5 8 12 7,2 205

10/12/8 h = 25 10 12 8 250

12/16/10 h = 20,5 12 16 10 205

HD Double PlateØ of wires (mm) Height


6/8/6 h = 22,5 6 8 6 225

6/8/6 h = 25 6 8 6 250

6/8/6 h = 27 6 8 6 270

HD Double PlateØ of wires (mm) Height


8/8/7 h = 32 8 8 7 320

8/8/7 h = 37 8 8 7 370

TOPØ of wires (mm) Height


6/7/5 h = 12,5 6 7 5 125

5/7/5 h = 16,5 5 7 5 165

5/8/5 h = 20,5 5 8 5 205

46

200

x30

022

5x

400

Wal

lsPr

ecas

t

Standard electrovelded wire fabric

TypeØ wire Mesh size (mm) Sheet size (mm) Sheet

surface(m2)

Long.sectional

area(mm2/m)

Trans.sectional

area(mm2/m)

Sheetweight

(kg)

Weight/m2

(kg/m2)Sheets/bundle

Bundleheight(mm)

Bundleweight

(kg)

Sheets/pile

Sheets/load

Weight/load(kg)long. trans. long. trans. widht length

510 5 5 100 100 2000 3000 6.00 196 196 18.480 3.080 50 275 924 450 1620 29938

515 5 5 150 150 2000 3000 6.00 131 131 12.628 2.105 50 275 631 450 1800 22730

520 5 5 200 200 2000 3000 6.00 98 98 9.240 1.540 90 500 832 450 1800 16632

610 HD 6 6 100 100 2000 3000 6.00 283 283 26.640 4.440 50 330 1332 350 1120 29837

615 HD 6 6 150 150 2000 3000 6.00 189 189 18.204 3.034 50 330 910 400 1400 25486

620 HD 6 6 200 200 2000 3000 6.00 142 142 13.320 2.220 50 330 666 400 1600 21312

810 HD 8 8 100 100 2000 3000 6.00 503 503 47.400 7.900 50 440 2370 250 600 28440

815 HD 8 8 150 150 2000 3000 6.00 335 335 32.390 5,398 50 440 1620 300 900 29151

820 HD 8 8 200 200 2000 3000 6.00 251 251 23.700 3.950 50 440 1185 300 1100 26070

1020 HD 10 10 200 200 2000 3000 6.00 393 393 37.020 6.170 50 550 1851 200 800 29616

510 5 5 100 100 2250 4000 9.00 196 196 28.020 3.114 50 275 1401 450 1050 29429

515 5 5 150 150 2250 4000 9.00 131 131 18.595 2.066 50 275 930 450 1350 25103

520 5 5 200 200 2250 4000 9.00 98 98 14.322 1.591 90 500 1289 450 1350 19335

610 HD 6 6 100 100 2250 4000 9.00 283 283 40.404 4.489 50 330 2020 300 750 30303

615 HD 6 6 150 150 2250 4000 9.00 189 189 26.807 2.979 50 330 1340 400 1050 28147

620 HD 6 6 200 200 2250 4000 9.00 142 142 20.646 2.294 50 330 1032 400 1200 24775

810 HD 8 8 100 100 2250 4000 9.00 503 503 71.890 7.988 25 220 1797 150 400 28756

815 HD 8 8 150 150 2250 4000 9.00 335 335 47.696 5.300 50 350 2384 250 600 28618

820 HD 8 8 200 200 2250 4000 9.00 252 252 36.735 4.082 50 440 1837 300 800 29388

1020 HD 10 10 200 200 2250 4000 9.00 393 393 57.381 6.376 25 270 1435 225 500 28691

1220 HD 12 12 200 200 2250 4000 9.00 566 566 82.584 9.176 25 330 2065 150 350 28904

1420 HD 14 14 200 200 2250 4000 9.00 770 770 112.344 12.483 15 240 1685 120 260 29209

TypeØ wire Mesh size (mm) Sheet size (mm) Sheet

surface(m2)

Long.section-al area

(mm2/m)

Transv.section-al area

(mm2/m)

Sheetweight

(kg)

Weight/m2

(kg/m2)Sheets/bundle

Bundleheight(mm)

Bundleweight

(kg)

Sheets/pile

Sheets/load

Weight/load(kg)long. trans. long. trans. widht length

520 L 5 5 190 250 1180 6000 7.08 103 78 10.829 1.530 90 500 975 900 1800 19492

520 A 5 5 190 250 2360 6000 14.16 103 78 21.659 1.530 90 500 1949 450 900 19493

520 B 5 5 200 200 2470 6000 14.82 98 98 23.423 1.580 50 275 1171 450 900 21081

SETTO 1 S HD 8 6 300 150 2300 2850 6.56 168 189 18.707 2.852 50 390 935 300 1200 22448

SETTO 1 C* HD 8 6 300 150 2300 3500 8.05 168 189 20.761 2.579 50 390 1038 300 900 18685

SETTO 2 S HD 8 7 200 150 2300 2850 6.56 252 257 26.706 4.074 50 430 1335 300 1100 29377

SETTO 2 C* HD 8 7 200 150 2300 3500 8.05 252 257 29.787 3.700 50 430 1489 300 900 26808

* Special sheets with 70 cm overhangs in the long. wires

The reinforcing steels named PITTINI HD are classified B450C in according to prEN10080.

i i i i i i i

a

a

a

a

a

a

a

Ø Longitudinal

Ø Transversal

i : Longitudinal spacinga: Transversal spacing

NoteValues reported are indicative and subject to varia-tions depending on evolution in both the standardsand production tecniques.For updated values please ask the Ferriere Nord SalesDepartment for technical specifications.

If you need detailed fabric, please define in a fullydimensioned drawing the mesh arrangement or com-bination of wire sizes (twin wires, special overhang,etc.).

TECHNICAL SPECIFICATIONSWeldable Deformed Steel Bars for ConcreteItaly Market: “Pittini HD” Bars

1. DESCRIPTIONWeldable steel bars for concrete grade FeB44k produced by THERMEX process, for Italy market, conforming DM.9.1.96 andEN10080 - B450C, named PITTINI HD.

2. CHEMICAL COMPOSITION OF HEAT

Limits C % P % S % N % Ceq %

PITTINI max 0.22 0.050 0.050 0.012 0.50

DM 09/01/96 - EN10080 max 0.22 0.050 0.050 0.012 0.50

Standard Steel gradeDiameter

range mm

Weight tol. %

Length tol.mm

Y.P. min

N/mm2

T.S. min

N/mm2

T.S/Y.S min

OverStrength

Limit

Agt min %

A5 min %

Bend αα, k %

PITTINI 450 8 ÷ 26 * 0/+100 450 550 1.13 <1.35 8 15 **

DM 09/01/96 FeB44K 5 ÷ 26 ±10 ÷ ±5 – 430c 540c 1.13m <1.35 – 12 **

EN10080 B450C 6 ÷ 40 ±4.5 0/+100 450c – 1.15c <1.35 8c – **

3. MECHANICAL PROPERTIES AND DIMENSION TOLERANCES

NOTE: c - characteristic values; m - average values* average value +5% for diameter 8 mm, and average value equal to nominal for diameter 10 ÷ 26 mm.

** in bending test D mandrel = k * d; α = 180° and k = 4 for d ≤ 12mm; for d>12mm α = 90° and bending 20° after ageing, k = 8 ford = 14 ÷ 18 mm, k = 10 for d = 20÷25 mm, k = 12 for d ≥ 26 mm.

4. STANDARD PACKINGIn bundles with standard length 14 m or 12 m, of max 2.5 t, or 6 m and 1.4 ÷1.6 t, tied with wire rod 5.5 mm (4 o 3 bindings) or wirerod diam. 7 mm (3 o 2 bindings). For diameters ø ≥ 22 mm it can be max. 2% in weight of short bars with minimum length 6 m.

~ 2 m ~2 m ~ 1 m ~ 1 m

5. STANDARD IDENTIFICATIONEach bundle with label reporting: FERRIERE NORD S.p.A. Logo IGQ+MPA NRW

I - 33010 OSOPPO (UD) ITALIAD.M. 09-01-1996 FeB44kBARRE PITTINI HD HEAT N° .....DIAMETER mm .....LENGTH m .....

6. STANDARD CERTIFICATIONAccording EN 10204 on demand.

7. APPROVALSMinistero Infrastrutture e Trasporti

8. IDENTIFICATION MARKMark 4-7

FERRIERE NORD

Document SPF 201

Revision 8 i

Date 08.10.03

Page 1 / 1SAQ

APPROVED BY: R.AQ. – DIR. LAM.

1. DESCRIPTIONWeldable ribbed steel wire in wound layer coils for concrete reinforcement according to D.M. 09.01.96 grade FeB44knamed JUMBO PITTINI HD.

2. CHEMICAL COMPOSITION OF HEAT

Limits C % P % S % N % Ceq %

PITTINI max 0.22 0.050 0.050 0.012 0.50

DM 09/01/96 max 0.22 0.050 0.050 0.012 0.50

3. MECHANICAL AND DIMENSIONAL PROPERTIES

Standard Steel gradeDiameter

range mm

Weight tol. %

Yield S. fy minN/mm2

Tensile S. ft minN/mm2

ft/fy min

OverStrength

Limit

Agt min %

A5 min %

Bend αα, k %

PITTINI 450 10 ÷ 16 * 450 550 1.13 <1.35 7 12 **

DM 09/01/96 FeB44K 5 ÷ 26 ±10 ÷ ±5 430c 540c 1.13m <1.35 – 12 **

NOTE: c – characteristic values; m – average value; test after ageing 250 °C / 30’. * Average value equal to nominal.

** Bend test: D mandrel = k*d; for d = 12 mm α = 180° e k = 4; for d > 12 mm bend with α = 90° and rebend with β = 20°after ageing, k = 8.

4. STANDARD PACKINGCoils of about 1.8 – 2.4 t, height = 700 mm, internal diameter = 700 mm, tied with 4 strips..

5. STANDARD IDENTIFICATIONEach coil must be followed by label reporting:

FERRIERE NORD S.p.A. Logo IGQ+MPA NRWI - 33010 OSOPPO (UD) ITALIAD.M. 09-01-1996 FeB44kHEAT N° .....DIAMETER mm .....

6. STANDARD CERTIFICATIONOn demand document according EN10204.

7. APPROVALS

Material qualified by Ministero Infrastrutture e Trasporti

8. IDENTIFICATION MARK

Mark 4-7

TECHNICAL SPECIFICATIONSSteel Wire in coils FeB44K“Jumbo Pittini HD” FERRIERE NORD

Document SPF 289

Revision 0 i

Date 15.11.02

Page 1 / 1SAQ

APPROVED BY: R.AQ. – DIR. LAV.FR.

Documents

Pittini electrowelded steels