Italcementi

Gipieffe Architettura Studio Associato

Industria Prefabbricati Affini I.p.a. S.p.a.

I.p.a. S.p.a. Industria Prefabbricati

Antonio Migliacci

Giancarlo Bono

Luigi Cassar

Gian Luca Guerrini

Piero Tognoli

Gianfranco Cremaschi

Vincenzo Collina

Pietro Tognoli

A method for manufacturing a composite girder including one or more vertical cores of steel plate, associated and cooperating with one or more horizontal slabs or flanges of concrete. At least one of the horizontal slabs or flanges is made from high-performance concrete in order to allow mutual forces or co-actions to be imposed between the several components of the girder which are much higher/stronger than the mutual forces/co-actions which can be imposed by way of other methods and materials. If the composite girder is at least partially manufactured at the prefabrication factory, according to the present method, the starting element will be an I girder preflexed or inflexed with welded connections; the I girder will be positioned on the prefabricating bench imposing such constraints as to straighten the girder, then in a suitable position steel cables are installed prestressed between external anchoring points, and the concrete casting is carried out in a flange in which the cables are associated with high-performance concrete. After setting is complete, the auxiliary constraints are cut and removed. In such a way, the by now set concrete, by being integral with the iron girder thanks to the iron reinforcer elements and welded connections and with the cables by adhesion, causes the several components to mechanically cooperate and the composite beam to be endowed with much better characteristics.

Method for manufacturing a composite girder and so manufactured girder

Ballastless railroad lines are laid on prefabricated reinforced concrete slabs, which can eliminate the need for periodic maintenance of the ballast of traditional railroad lines, such maintenance being expensive and often difficult to carry out. Prefabricated, possibly prestressed, slabs are thereby positoned upon a steel reinforced concrete block having the functions of a foundation and connector for the prefabricated slabs with the interposition of a concrete-asphalt mortar layer between the slabs and block. The slabs are secured to the foundation block either by means of two half-cylinders, forming parts of the slab structure, or by shoulders formed by upturned sides of the foundation block (tub).

Components for ballast-less railroad lines laid on pre-fabricated

Workpieces of prestressed concrete, specifically railroad ties, are molded in a form having its bottom covered with several transversely separated templates whose outline corresponds to that of respective ties to be produced; the form is longitudinally traversed by reinforcing rods or cables attached to its ends under tension. Each template is provided with several countersunk nuts to be engaged by retaining bolts which pass through upright screw anchors with downwardly opening throats loosely occupied by internally threaded centering sleeves that come to rest on the associated template. With the form compartmented by removable spacers separating the templates, concrete is poured into each compartment and allowed to harden about the screw anchors rising therein; the retaining bolts are then withdrawn along with the spacers to provide the resulting concrete blocks with a certain mobility whereupon the tensioned reinforcing armatures are released to prestress these blocks and are subsequently cut between them. The blocks can now be individually extracted from the form, with the aid of lifting hooks or draw bars threaded from above into the centering sleeves; after removal of these sleeves from the inverted blocks, mounting bolts are threaded into the screw anchors by way of cleats serving to hold two rails in position on each tie-forming block.

Process and apparatus for precasting prestressed-concrete workpieces

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Milan, Italy

Antonio Migliacci