Patent Publication Number: US-9422680-B2

Title: Deck

Description:
TECHNICAL BACKGROUND OF THE INVENTION 
     The present invention relates to a deck suitable for supporting a carriageable surface and comprising first structural girders defining a support surface for the carriageable surface; at least a second structural girder suitable to position itself on the opposite side to the carriageable surface in relation to the first structural girders; diagonal girders integrally connecting the structural girders to each other, defining, for the deck, a truss; the deck defining a support surface. In particular, the invention relates to a structure suitable to define a substantially horizontal plane on which to make the carriageable surface and used for the construction of bridges. 
     DESCRIPTION OF THE PRIOR ART 
     As known, bridges are used to overcome an obstacle, such as a watercourse or a valley, which prevents the continuity of a communication route such as a road or a railway network. 
     These consist of a carriageable surface suitable to connect portions of the communication route separated by said obstacle; one or more decks suitable to define the support structure on which to make the carriageable surface: and pylons, abutments or other similar structural elements designed to sustain the deck and thus the carriageable surface suspended over the obstacle. 
     One of the most important structures is the deck which consists of a single body made of concrete/reinforced concrete and a having a flat upper surface on which to build the carriageable surface and a cross-section of maximum width at the end and minimum width in the centre so as to define a substantially arc-shaped profile for the deck. 
     Alternatively, the deck has a slab in reinforced concrete defining said flat upper surface and a steel skeleton suitable to absorb the weight of the deck and the loads acting on it. 
     The prior art mentioned above has several significant drawbacks. 
     A first significant drawback is the difficulty of transporting and installing the deck. 
     This problem is caused by the fact that the decks, on account of the complexity of construction, are made in special factories and must therefore be transported on site arranging expensive and challenging oversized transport. 
     This problem is further increased by the fact that once brought on-site the decks, having to be lifted and placed on pylons and abutments, require special and expensive lifting means. 
     This drawback is particularly relevant in the case of reinforced concrete decks where the high density of said reinforced concrete makes it even more complex and difficult to transport and install. 
     Another drawback is that the decks, especially when made of reinforced concrete, are subject to deterioration from exposure to the elements, to structural movements or exceptional events such as earthquakes. 
     The deterioration factor is further increased by the action of oxygen leading to the formation of rust on the iron reinforcement of the concrete. 
     The formation of rust also causes an increase in volume in the iron reinforcement giving rise to blistering and flaking of the concrete, which interrupts the structural continuity thereof reducing its mechanical strength. 
     In this situation the technical purpose of the present invention is to devise a deck able to substantially overcome the drawbacks mentioned above. 
     Within the sphere of said technical purpose one important aim of the invention is make a deck which is easy to transport and install. 
     Another important purpose of the invention is to make a deck practically immune to deterioration phenomena and thus characterised by high reliability and durability. 
     SUMMARY OF THE INVENTION 
     The technical purpose and specified aims are achieved by a deck suitable for supporting a carriageable surface and comprising first structural girders defining a support surface for the carriageable surface; at least a second structural girder suitable to position itself on the opposite side to the carriageable surface in relation to the first structural girders; diagonal girders integrally connecting the structural girders to each other, defining, for the deck, a truss; the deck defining a support surface; wherein the structural girders comprise a core in concrete material, an external reinforcement partially cladding the core leaving a portion of the core visible, connection means between portions of the first structural girders and the projecting diagonal girders comprising connection elements projecting from the support surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The characteristics and advantages of the invention are clearly evident from the following detailed description of a preferred embodiment thereof, with reference to the accompanying drawings, in which: 
         FIG. 1  shows the deck according to the invention; 
         FIG. 2  shows the deck at an intermediate stage of its manufacture; 
         FIG. 3  shows an assembly of the deck according to the invention; 
         FIG. 4  shows the assembly in  FIG. 3  during said intermediate stage; and 
         FIG. 5  shows an element of the deck according to the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to said drawings, reference numeral  1  globally denotes the deck according to the invention. 
     It is suitable to be used to support a carriageable surface such as a road or a railway network and thus to make a bridge, preferably, a bridge or deck with substantially continuous girders and at a variable height, and more preferably, a deck arch bridge. 
     The bridge includes a carriageable surface, one or more decks  1  suitable to support the carriageable surface and defining a support surface  1   a , preferably substantially flat and support structures comprising pylons, abutment and other similar elements positioned at the ends of each deck so as to keep said deck  1  raised from the ground. 
     The deck  1  comprises first structural girders  2  defining a support surface, preferably practically flat, for the carriageable surface; at least one second structural girder  3  suitable to position itself on the opposite side to said carriageable surface in relation to the first structural girders  2 ; and diagonal girders  4  integrally connecting the structural girders  2 ,  3  to each other, defining, for the deck  1 , a truss and connection means  7  between the structural girders  2  and/or  3  to each other and/or to the diagonal girders  4 , suitable to integrally connect said elements to each other by means of screws and bolts, welding, or otherwise. 
     In detail, the deck  1  comprises two first structural girders  2  and one second structural girder  3  substantially equally spaced from the first structural girders  2 . 
     Each of the structural girders  2  and  3 , as described below, has a core in concrete material and an external reinforcement made of metal material and partially cladding the core so as to leave a portion thereof visible. 
     The cores of the structural girders  2  and  3 , just as their external reinforcements are made of the same material. In particular, they are in self-compacting concrete which, thanks to a high degree of fluidity, is able to fill the formwork merely by effect of its weight and, therefore, without external energy input or mechanical vibration. 
     The external reinforcements are open sections, preferably made by press-forming, and in steel, to be precise, in weathering steel and, more precisely, in Cor-Ten Steel®. 
     The first structural girders  2  preferably have an equal cross-section, are specular and comprise a first core  21  and a first external reinforcement  22 . 
     The first external reinforcement  22  is a section, with a constant cross-section, open at the top, i.e. with the opening at the top so that the concrete material of the core  21  is cast inside by gravity. It has a thickness comprised between about 1 and 3 cm and, more specifically, practically equal to 1.6 cm. 
     It is preferably a substantially U-shaped section defining an inner lateral side  221  facing the other first girder  2  and vertical, i.e. substantially parallel to the gravitational gradient; an external lateral side  222 , inclined, preferably by 30°-60° with respect to the inner side  221 ; at least one slab  223  substantially perpendicular to the sides  221  and  222  to which the diagonal girders  4  are connected; and one bottom side  224  connecting the lateral sides  221  and  222  and practically perpendicular to the external lateral side  222 . Said slab  223  forms part of the connection means  7  between the structural girders  2  and/or  3  to each other and/or with the diagonal girders  4 . 
     The first external reinforcement  22  is, at the ends, devoid of partitions so as to allow the concrete material cast into it and constituting the core  21  to spill outside the external reinforcement  22 . 
     The second structural girder  3  comprises a second core  31  and a second external reinforcement  32 . These are preferably made by the press-forming of steel plates. They are also, preferably, filled with self-compacting concrete (SCC). 
     The second external  32  reinforcement comprises a hollow body  321  open at the top comprising partitions  322  closing the ends so as to prevent the concrete material cast inside it from spilling; and, arranged inside the section, a lamina  323  extending over the entire length of the exterior reinforcement  32  and welded to the base of the section. 
     Said hollow body  321  has a practically pentagonal cross-section with a horizontal base, i.e. practically perpendicular to the gravitational gradient, and an opening made at the vertex opposite the base so that the concrete material of the core  31  can be cast inside it by gravity. 
     The hollow body  321 , the partitions  322  and the lamina  323  have a thickness at least equal to the first external reinforcement  21 . In detail, substantially between 100% and 150%, and preferably substantially equal to 125% of the thickness of the first formwork  21 . Said thickness of the second formwork  32  is practically comprised between 1.5 and 4 cm and, in particular, practically equal to 2 cm. 
     The second external reinforcement  32  and, therefore, the second girder  3  have a first tapered portion  3   a  with its maximum cross-section at the ends of the deck  1 ; and a second portion  3   b  with a constant cross-section equal to that the minimum cross-section of the first portion. Alternatively, the second girder  3  has two first portions  3   a  and one second portion  3   b  interposed between the portions  3   a.    
     The diagonal girders  4  integrally connect the structural girders  2  and  3  so as to define, for the deck  1 , a truss, appropriately, a substantially triangular truss. 
     The diagonal girders  4  ( FIG. 5 ) define a truss comprising adjacent pyramidal architectures  4   a , appropriately with a square base, integral with one another and having the vertexes of the base and apexes integral with respect to the first girders  2  and to the second girder  3 . 
     In particular, they are at least partially housed in the external reinforcements  22  and  23  and protrude from them through respective first openings  22   a  and second openings  32   a  of the external reinforcement  32  counter-shaped to the diagonal girders  4 . More specifically, the diagonal girders  4  have one end integral with the formworks  22  and protruding from them so as to be embedded in the concrete material constituting the carriageable surface. 
     Each diagonal girder comprises a section  41 ; and a first plate  42  and a second plate  43  integrally connected, preferably by welding, and more preferably by full penetration welding, at the ends of the section  41  closing the ends, and respectively, to the first external reinforcement  22  and the second external reinforcement  32 . 
     The section  41  is identifiable in a section open at the top, appropriately with a U shape, having a thickness between 1 and 3 cm and, more precisely, practically equal to 1.6 cm. 
     The first plate  42  is a flat plate made integral with the slab  223  by bolts and to another first plate  43  so as to enclose the slab  223  between two first plates  42 . 
     Said plates  42  and  43  thus form another part of the connection means  7 . 
     Advantageously, the connection means  7  comprise connection elements  7   a , not parallel, and preferably perpendicular to the main direction of extension of the deck  1 , composed in particular of the plates  42 ,  43  and the slab  223 , projecting from the support plane  1   a , and possibly also from the surface of the second structural girders  3 , and suitable to create a support for external elements. 
     Each second plate  43  is an L-shaped plate made integral, preferably by bolting on one side to the panel  323  and on the other to another second plate  43  so that four diagonal girders  4  are connected to the same portion of panel  223  forming the apex of a pyramidal architecture  4   a.    
     The plates  42  and  43  have a thickness substantially comprised between 1.5 cm and 4 cm and preferably substantially equal to 3 cm. 
     The section  41  and the plates  42  and  43  are made of the same material as the formworks of the external reinforcements  22  and  32 . Consequently, they are made of steel and, to be precise, weathering steel and, more precisely, Cor-Ten Steel®. 
     Additionally, the diagonal girders  4  may provide for a third core filling the space defined by the section  41  and by the plates  42  and  43  and made of concrete material and, to be precise, in self-compacting concrete. 
     The deck  1  may lastly provide for stiffeners  5  of the truss and, in detail, of the pyramidal architectures  4   a  suitable to connect the vertexes of the base of each pyramidal architecture  4   a  to each other; and supports  6 , preferably one for each end of the first girders  2 , defining the support surfaces of the deck  1  on the support structures. 
     Preferably, the deck  1  has four stiffeners subtended between the internal lateral sides  221 . 
     These are identifiable in single or double T sections connected by welding and in particular by full penetration welding to opposite first external reinforcements  22 . 
     The supports  6  are substantially similar to the girders  2 ,  3  and  4  and, therefore comprise an additional core  61  in concrete material and, in detail, in self-compacting concrete; and an additional formwork  62  suitable to clad, preferably exclusively, a limited portion of the additional core  61  and made of steel and, to be precise, of weathering steel and, more precisely, Cor-Ten Steel®. 
     The additional external reinforcement  62  is a section open at the top, of a thickness substantially equal to that of the second external reinforcement  32 . Said thickness is therefore substantially comprised between 1.5 and 4 cm and, in particular, practically equal to 2 cm. 
     In particular, the additional external reinforcement  62  is identifiable in a U shape open section suitable to contain, for each first girder  2 , one end and having lateral sides  621  suitable to keep in the concrete material of the additional core  61  preventing it from spilling outside before hardening. 
     The functioning of a bridge provided with a deck, described above in a structural sense, is as follows. 
     In particular, such embodiment defines an innovative method of constructing a bridge comprising an assembly step in which the external reinforcements  22 ,  32  and diagonal girders  4  are connected to each other creating one or more trusses; a foundation step in which the pylons, abutments or other support structures for the trusses are made; a transport step in which said truss is transported close to the construction site of the bridge; a laying step in which the ends of each girder are laid and connected to the support structures; a casting step in which the concrete material is cast into the truss forming the deck  1 ; and a final step in which the carriageable surface is made on the deck  1 . 
     In the assembly step the sections  41  are integrally connected, using the connection means  7 , in particular by welding (appropriately full penetration welding), to the plates  42  and  43  forming the diagonal girders  4 , which are then inserted through the openings  22   a  and  32   a  in the first external reinforcements  22  and in the second external reinforcement  32  and connected to them by bolting or full penetration welding making the pyramidal architecture  4   a  and thus a truss ( FIGS. 2 and 4 ). 
     It is to be noted how, to prevent unwanted spillage of the concrete material from the openings  22   a  and  32   a , the diagonal girders  4  and in particular the sections  41  are welded, preferably with full formwork penetration welding to the external reinforcements  22  and  32  at said openings  22   a  and  32   a.    
     Lastly, this step is completed by welding, appropriately full penetration welding, stiffeners  5  to the internal lateral sides  221  and two additional formworks  62  to the ends of the first formworks  22 . 
     After completing this assembly step the transport and laying steps are performed in which the truss, i.e. the deck  1  without concrete material, is transported and then firmly attached to the support structure. 
     After completing these steps, the method provides for casting the concrete material which when solidified will constitute the cores  21 ,  32  and  61  ( FIGS. 1 and 5 ). 
     In particular, at this step the concrete material is cast, by gravity, inside the second external reinforcement  32  and the first external reinforcements  21  from the ends of which it escapes to fill the additional external reinforcements  62 . Even the diagonals  4 - 4   a  are appropriately filled with concrete. 
     Lastly, the method provides for the laying step in which the carriageable surface is made by casting concrete material onto the first structural girders  2  so as to encompass within it the ends of the diagonal girders  4  protruding from said first girders  2 , also constituting the connection means  7  for upper portions of the carriageable surface  7 . 
     The invention achieves important advantages. 
     A first advantage is the fact that the deck  1 , by permitting the definition of an innovative method, is simple and quick to build, and, in particular, does not require plants fitted with expensive machinery. 
     This advantage is given by the special girders  2  and  3  and, additionally, by the stiffeners  5  which, having a core  21 ,  31  and  61  in concrete material and an external reinforcement  22 ,  32  and  62  cladding only partially said cores, makes it possible to make the core at a later time. 
     In fact, as may be seen from the method, such a solution makes it possible to create a truss  4   a  which being devoid of cores  21 ,  31  and  61 , is lightweight and easy to transport. 
     This aspect has been further increased by the use, as concrete material, of self-compacting concrete which shrinks whatever the shape of the formworks  22 ,  32  and  62  by effect of its own weight and without the input of external energy or vibrations. 
     Another advantage is given by the conformation of the connection means  7  and connection elements  7   a , which permits the connection of elements above the support surface  1   a.    
     A further advantage, given by the use of external reinforcements  22 ,  32  and  62  and diagonal girders  4  in weathering steel and, more precisely, Cor-Ten Steel®, is identifiable in the high resistance to external agents, and thus, in the long duration of the deck  1 . All the external reinforcements in steel sheeting are preferably made by press-forming sheets of suitable thickness. This solution makes it possible to reduce by about 50% the usual quantities of structural metalwork. 
     The invention is susceptible to variations within the inventive concept. All the elements as described and claimed may be replaced with equivalent elements and the details, materials, shapes and dimensions may be as desired.