Patent Publication Number: US-2023160160-A1

Title: Method for the production of a deck slab for a bridge

Description:
The invention relates to a method for producing a deck slab using a conveyor device with a top concrete layer produced at the installation site for a bridge as well as deck slabs produced according to this method. 
     The production of a deck slab for a bridge using a formwork carriage is described in the “Handbuch Brücken”, section 9.3.2 “Schalung and Fertigung Betonfahrbahnplatte”, published by Gerhard Mehlhorn with the Springer-Verlag in the year 2010. There are mounted support constructions on the longitudinal bridge girder. On the top surface of the support construction, there are installed launching gantries, which provide movement of a formwork carriage in the longitudinal direction of the bridge. For the production of a construction section of the deck slab, the formwork carriage is conveyed to the installation site, being fixed there. Subsequently, the formwork for the construction section to be erected of the deck slab is moved into the scheduled position, the reinforcement is laid and concrete is being introduced. After the concrete has hardened, the formwork is then lowered and the formwork carriage is moved to a further installation site. A construction section usually has a length of 15 m to 35 m. An advantage of this method is that in the final condition, there will be present only a few sectional joints within the deck slab. A disadvantage of this method is the slow construction progress as the assembly of the formwork and the laying of the reinforcement are carried out at the installation site and the formwork will only then be removed from the formwork carriage if the concrete of the construction section last produced has sufficient rigidity. The production of the construction sections using this method is usually realized within one week, wherein the weekend is used for the concrete to harden. 
     The production of the deck slab for a bridge using a formwork carriage, which may be moved directly on the longitudinal bridge girder, is described in the DE 195 44 557 C1. In this method, the effort for producing the support constructions and for mounting the launching gantries is being omitted. Also in this method, there is given the disadvantage of the slow construction progress of a weekly schedule for the production of a construction section of the deck slabs. 
     In DE 25 20 105 A1 there are described prefabricated elements made from reinforced concrete, which are composed of a prefabricated bottom slab and at least one cross beam. In the prefabricated bottom slab, there are arranged the lower transverse reinforcement and the lower longitudinal reinforcement of the deck slab. The prefabricated elements are moved at the installation site using a crane onto the longitudinal bridge girder. Then the splice reinforcement for the lower longitudinal reinforcement, the upper longitudinal reinforcement and the upper transverse reinforcement is being laid. In the next operation, the top concrete layer is then applied. Moving the prefabricated elements at the installation site, sealing the joints in-between the individual prefabricated elements and laying of the reinforcement are time-consuming operations, which is disadvantageous for a fast construction progress in the production of the deck slab. 
     To accelerate construction progress, there is described in WO/2016/187634 A1 a method for producing a deck slab having prefabricated bottom slabs and a top concrete layer arranged above made from in-situ concrete for a bridge having a longitudinal bridge girder. In this method there is produced a conveyor device, which may be moved on support constructions, which are mounted on the top surface of the longitudinal bridge girder, in the longitudinal direction of the bridge. Using the conveyor device, the prefabricated slabs are transported from an assembly site to an installation site. At the installation site, the prefabricated slabs are lowered until the edges of the prefabricated slabs are supported on the longitudinal bridge girder. Upon lowering, the prefabricated slabs are still attached at the conveyor device by means of tendons. Subsequently, there is laid a reinforcement and a top concrete layer is applied. After the top concrete layer has hardened, the anchors of the prefabricated slabs are then removed from the tendons. Subsequently, the conveyor device is then moved to an assembly site to optionally pick up further prefabricated slabs. The disadvantage of the method described in WO/2016/187634 A1 is the anchoring of the tendons within the prefabricated slabs. The load capacity of the anchors of the tendons is low if anchoring of the tendons is realized within the prefabricated slabs. The load capacity of the anchors of the tendons is sufficient if anchoring of the tendons is realized at the bottom surface of the prefabricated slabs. Anchoring at the bottom surface of the prefabricated slabs, however, requires an additional operation for removing the anchors from the bottom surface of the prefabricated slabs. In the method described in WO/2016/187634 A1 it is furthermore disadvantageous that the forces arising within the tendons cause bending moments within the prefabricated slabs, which lead to high bending stress within the thin prefabricated slabs. A further disadvantage of the method described in WO/2016/187634 A1 is that the tendons may only be removed from the conveyor device after the top concrete layer has sufficient rigidity. Awaiting the hardening phase of the top concrete layer is disadvantageous for a rapid construction progress in the production of the deck slab. 
     Also the documents AT 520 614 A1 and KR 101 866 466 B each show methods for the production of deck slabs of a bridge. There are respectively positioned slab-like elements onto longitudinal girders of the bridge, whereupon a reinforce concrete slab will be produced thereon. The methods of these publications have the same disadvantages as the method of the publication WO/2016/187634 A1. 
     The publication JP 2004 116060 A discloses a method, in which there are laid prefabricated cross beams made from reinforced concrete on a longitudinal bridge girder in order to produce a deck slab. Subsequently, there are laid prefabricated slabs made from reinforced concrete on the cross beams. In the next work step, a reinforcement is laid on the prefabricated slabs and then there is applied a top concrete layer. Laying the individual cross beams and subsequently laying the individual prefabricated slabs at the installation site is time consuming and, hence, disadvantageous for a rapid construction progress. 
     It is thus the task of the present invention to create a method for the production of a deck slab, which provides for a faster construction progress than with methods known performing formwork and/or reinforcement works at the installation site and in which in the construction condition an easier anchoring of the tendons is possible and in which the bending stress arising in the construction condition may be better absorbed than with the method known using prefabricated bottom slabs. 
     The task is solved by a method for the production of a construction section of a deck slab for a bridge, wherein:
         a—there is produced at an assembly site from reinforced concrete a bottom layer composed of at least one segment and having cross beams, which are arranged at an angle of between 70° and 90° to a longitudinal axis of a longitudinal bridge girder;   b—the bottom layer having the cross beam is transported for the construction section of the deck slab using at least one conveyor device from the assembly site to an installation site and lowered into an installation position;   c—there is laid onto the bottom layer having the cross beams a top concrete layer for the construction section of the deck slab, wherein there is optionally laid a reinforcement to be arranged within the top concrete layer before the application of the top concrete layer;   d—the bottom layer having the cross beam is removed for the construction section of the deck slab from the conveyor device before or after the application of the top concrete layer.   e—the conveyor device is moved away from the installation site and optionally conveyed to the assembly site in order to pick up there a further bottom layer having cross beams for a construction section of the deck slab.       

     To accelerate constructional progress, it may be advantageous to configure the bottom layer having the cross beams or a segment of the bottom layer to be load-bearing such that it may absorb its own weight and the weight of the top concrete layer and introduce these into the longitudinal bridge girder. In this case, the conveyor device may be moved away from the installation site immediately upon lowering of the bottom layer. 
     To enlarge the load capacity of the bottom layer, there are arranged cross beams within the bottom layer. These cross beams may be laid at the assembly site onto a formwork or a scaffolding before the production of the bottom layer. The cross beams are advantageously equipped with starter bars. In this way, a load-bearing connection of the cross beams to the bottom layer and the top concrete layer is being ensured. There may be arranged anchors for lifting the bottom layer and cladding tubes for tendons within the cross beams. The cross beams may be equipped with steel slabs to provide for a structural steel connection of the cross beams to the bottom layer or of cross beams, which are arranged in different segments. The connection between cross beams and prefabricated slabs or between two cross beams, respectively, which are arranged in different segments of the bottom layer, may be produced by welding, screwing or by starter bars and hardcore filling. 
     There may be arranged terminal anchors and deflection points for tendons in a cross beam. It may be advantageous to produce the top concrete layer in two operations. The second part of the top concrete layer is only produced after the first part of the top concrete layer has reached a predefined minimum rigidity. In this case, the bottom layer may be removed from the conveyor device, after the first part of the top concrete layer has reached a predefined minimum rigidity. The bottom layer may be produced having haunches and variable thickness. A segment of a bottom layer may be shifted transversally to the longitudinal axis of the longitudinal bridge girder and/or rotated in regard thereto after it has been raised at the assembly site, may be transported from the assembly site to the installation site in this shifted and/or rotated position and may then be installed at the installation site by cross shift and/or rotation into the scheduled installation position. It may be advantageous to transport the segments of the bottom layer for a construction section of the deck slabs in several transport operations from the transfer site to the installation site. 
     In an particularly advantageous embodiment of the present invention there is connected a bottom layer composed of at least two segments and having cross beams at the assembly site by a first top concrete layer or by other means such as, for example, screw connections, to a bottom layer composed of one segment. 
     In a particularly advantageous embodiment of the present invention the bottom layer having cross beams is produced at the assembly site from a segment and transported using a conveyor device composed of a front part, a rear part and at least two longitudinal girders from the assembly site to the installation site. The front part and the rear part of the conveyor device are connected to one another by means of the at least longitudinal girders. The conveyor device is moved along the bridge on support constructions. The bottom layer having the cross beams during transport from the assembly site to the installation site is arranged between the front part and the rear part and underneath the longitudinal girder of the conveyor device. Underneath the bottom layer having cross beams, there must not be arranged any constructions elements for connecting the front part and the rear part of the conveyor device during the lowering operation at the installation site. During the transport of the bottom layer from the assembly site to the installation site, it may be useful to connect the front and the rear part of the conveyor device by way of construction elements such as, e.g., ropes, which are arranged underneath the bottom layer having the cross beams, in order to enlarge the rigidity of the conveyor device. 
     In a preferred embodiment of the invention the conveyor device is produced from a front part, a rear part and at least two longitudinal girders. To shift the conveyor device in order to enable the production of the next construction section of the deck slab, the front part and the rear part of the conveyor device are moved on support constructions. The front and the rear part of the conveyor device are connected to one another by at least two longitudinal girders. At the longitudinal girders, there is installed a construction by means of which lifting and/or lowering of the bottom layer having cross beams, which is arranged between the front and the rear part and underneath the longitudinal girders of the conveyor device, is made possible. 
     The conveyor device may be configured as a frame construction or as a truss construction. 
     Using the method according to the invention it is made possible to produce the deck slab of bridges that are straight in plan view and have any curvature. Using the method according to the invention it is made possible to produce deck slabs having any transversal inclination and having variable width. 
     In a further aspect of the invention there is created a construction section of a deck slab, comprising a bottom layer composed of at least one segment and having cross beams, which are arranged at an angle of between 70° and 90° to the longitudinal axis of a longitudinal bridge girder, wherein the bottom layer is produced from reinforced concrete and wherein onto the bottom layer having cross beams there is applied a top concrete layer for the construction section of the deck slab, which optionally has reinforcement. 
    
    
     
       Further details, features and advantages of the invention become obvious from the explanations given below of exemplary embodiments schematically depicted in the drawings  FIG.  1    to  FIG.  39   . The drawings show: 
         FIG.  1    a view of a first embodiment according to the invention after cross beams have been laid on a framework at an assembly site; 
         FIG.  2    a view of the first embodiment according to the invention after the bottom layer has been produced for a construction section of the deck slab on the framework; 
         FIG.  3    a view of the first embodiment according to the invention while the conveyor device is conveyed to the assembly site; 
         FIG.  4    a view of the first embodiment according to the invention while the bottom layer having cross beams is lowered for a construction section of the deck slab at the installation site; 
         FIG.  5    a vertical sectional view according to the section plane V-V indicated in  FIG.  4   ; 
         FIG.  6    a vertical sectional view according to the section plane V-V indicated in  FIG.  4    after the bottom layer has been lowered at the installation site; 
         FIG.  7    the detail A of  FIG.  5   ; 
         FIG.  8    the detail B of  FIG.  6   ; 
         FIG.  9    a view of the first embodiment according to the invention after the top concrete layer has been applied; 
         FIG.  10    a view of the first embodiment according to the invention when the conveyor device is moved from the installation site to the assembly site; 
         FIG.  11    a longitudinal view of the first embodiment according to the invention after the bottom layer having cross beams has been produced for a construction section of the deck slab at the assembly site; 
         FIG.  12    a longitudinal view of the first embodiment according to the invention after the bottom layer having cross beams has been deposited at the installation site; 
         FIG.  13    a longitudinal view of the first embodiment according to the invention after the deck slab has been completed; 
         FIG.  14    a view of a second embodiment according to the invention after the bottom layer composed of three segments and having cross beams has been produced on a formwork at an assembly site; 
         FIG.  15    a view of the second embodiment according to the invention after the three segments of the bottom layer having cross beams have been lowered at the installation site; 
         FIG.  16    a longitudinal view of the second embodiment according to the invention after a bottom layer having cross beams has been produced at the assembly site; 
         FIG.  17    a longitudinal view of the second embodiment according to the invention after the bottom layer having cross beams has been deposited at the installation site; 
         FIG.  18    a longitudinal view of the second embodiment according to the invention after the deck slab has been completed; 
         FIG.  19    a vertical sectional view of a third embodiment according to the invention while the bottom layer having cross beams is transported from the assembly site to the installation site; 
         FIG.  20    a vertical sectional view of the third embodiment according to the invention after the bottom layer having the cross beams has been lowered onto the longitudinal bridge girder and after the top concrete layer has been produced; 
         FIG.  21    the detail C of  FIG.  19   ; 
         FIG.  22    the detail D of  FIG.  20   ; 
         FIG.  23    a vertical sectional view of a fourth embodiment according to the invention after the bottom layer having cross beams has been lowered at the installation site; 
         FIG.  24    a vertical sectional view of the fourth embodiment according to the invention after the conveyor device has been removed from the installation site; 
         FIG.  25    a vertical sectional view of the fourth embodiment according to the invention after a first top concrete layer has been produced; 
         FIG.  26    a vertical sectional view of the fourth embodiment according to the invention after the second top concrete layer has been applied; 
         FIG.  27    the detail E of  FIG.  23   ; 
         FIG.  28    a sectional view along the line XXVIII-XXVIII of  FIG.  27   ; 
         FIG.  29    the detail F of  FIG.  23   ; 
         FIG.  30    a sectional view along the line XXX-XXX of  FIG.  29   ; 
         FIG.  31    a view of a fifth embodiment according to the invention after three prefabricated segments of the bottom layer having cross beams have been laid at the assembly site; 
         FIG.  32    a view of the fifth embodiment according to the invention after a first top concrete layer has been applied at the assembly site; 
         FIG.  33    a view of the fifth embodiment according to the invention while the bottom layer having cross beams and a first top concrete layer for a construction section of the deck slab are transported from the assembly site to the installation site; 
         FIG.  34    a view of the fifth embodiment according to the invention after the bottom layer having cross beams and a first top concrete layer for a construction section of the deck slab has been lowered at the installation site; 
         FIG.  35    a longitudinal view of the fifth embodiment according to the invention immediately before the bottom layer having cross beams and the first top concrete layer for a construction section of the deck slab is lifted at the assembly site; 
         FIG.  36    a longitudinal of the view of the fifth embodiment according to the invention after the bottom layer having cross beams and a first top concrete layer for a construction section of the deck slab has been deposited at the installation site; 
         FIG.  37    a longitudinal view of the fifth embodiment according to the invention after the deck slab has been completed; 
         FIG.  38    a view of a sixth embodiment according to the invention while the bottom layer having cross beams is transported for a construction section of the deck slab from the assembly site to the installation site and 
         FIG.  39    a view of a sixth embodiment according to the invention after the bottom layer having cross beams has been deposited for a construction section of the deck slab at the installation site. 
     
    
    
     The first embodiment of the method according to the invention is depicted in the  FIGS.  1  to  13   . According to  FIG.  1   , there is erected at the assembly site  31  a formwork  23  on mounting girders  20 . The top surface of the formwork  23  has the same shape as a bottom surface  19  of a bottom layer  2  of a construction section. In this exemplary embodiment, in the first method step, the lower longitudinal and transverse reinforcement for the first construction section are laid on the formwork  23 . For reasons of clarity, and because the embodiment of the reinforcement of deck slabs  1  having a top concrete layer  3  can be assumed as known, the reinforcement is not depicted in this exemplary embodiment. Subsequently, there are positioned on the formwork  23  three cross beams  21 , which are pre-fabricated as prefabricated beams  27 . The cross beams  21  are in this example arranged at an angle of 90° to the longitudinal axis of the bridge  4 . In another embodiment example it would be possible that the cross beams were arranged at an angle of 80° to the longitudinal axis of the bridge. The cross beams  21  may preferably be produced from reinforced concrete. 
     In the longitudinal direction of the bridge  4 , there are shifted longitudinal edge beams  28  to simplify in a later method step the concreting works when introducing the top concrete layer  3 . The cross beams  21  as well as the longitudinal edge beams  28  are equipped with starter bars. The deck slab  1  in this embodiment example has two haunches in the final condition. 
     These haunches are to be reproduced already in the production of the cross beams  21  and in the production of the formwork  23 . 
     In the next method step, concrete for the production of the bottom layer  2  is introduced according to  FIG.  2   . The lower longitudinal and transverse reinforcement  27  as well as the starter bars of the prefabricated beams  27  are then embedded in concrete. The bottom layer  2  is in this example produced having a constant thickness. It would also be possible to produce the bottom layer  2  having a variable thickness in order to reduce the weight of the bottom layer  2  for a construction section of the deck slab. The bottom layer  2  for the first construction section has eight recesses  16 . 
     According to  FIG.  3   , a conveyor device  10  is moved in the next method step on a longitudinal bridge girder  5  to the assembly site  21 . The longitudinal bridge girder  5  in the first embodiment example is composed of two steel girders  9 . The steel girders  9  may be connected by transverse bracing or transverse girders, which are not depicted in this embodiment example for reasons of clarity. The conveyor device  10  is in this example composed of a spatial frame construction  49  made from steel. Alternatively, the conveyor device  10  could also be composed of a truss construction. The conveyor device  10  has eight wheels  8 . Moving the conveyor device  10  is realized by a rolling process of the wheels  8  in the two lanes  7  configured on the top surface  18  of the longitudinal bridge girder  5 . The two lanes  7  are each arranged in-between the bracing means  6 . The conveyor device  10  may advantageously be moved to the assembly site  31  only after the reinforcement has been laid, the prefabricated beams  27  have been shifted and the concrete for the bottom layer  2  has been introduced, as the laying of the reinforcement supported by a crane and the shifting of the prefabricated beams  27  as well as the introducing of the concrete for the bottom layer  2  carried out by means of a concrete pump would be easier to realize. At the assembly site  31 , additional means may make it possible that the conveyor device may drive across the cross beams  21  and the reinforcement. 
     The bottom layer  2  having the cross beams  21  and the longitudinal edge beams  28  is lifted from the conveyor device  10  after the concrete has hardened and is then transported from the assembly site  31  to the installation site  32 . 
       FIG.  4    shows in a view that the bottom layer  2  is lowered at the installation site  32 . In  FIG.  4   , there is depicted a state immediately before supporting the bottom layer  2  onto the longitudinal bridge girder  5 . The weight of the bottom layer  2  having the cross beams  21  is in this condition introduced by the tendons  11  into the conveyor device  10 . The bottom layer  2  having the cross beams  21  and the longitudinal edge beams  28  may be classified as a ribbed base plate  26  in a statics point of view. The net weight of the bottom layer  2  is introduced via a structural bending action in the bottom layer  2  into the cross beams  21  and in the edge regions also partly into the longitudinal edge girders  28 . The cross beams  21  absorb the weight of the bottom layer  2  and of the longitudinal edge girder  28  and transmit it to the anchors  14 . Within the anchors  14 , the net weight of the ribbed base plate  26  is transmitted to the lower end points  13  of the tendons  11 . 
     The upper end points  12  of the tendons  11  are attached to the conveyor device  10 . The conveyor device  10  is positioned at the installation site  32  such that the recesses  16  are arranged above the bracing means  6  arranged at the top surface  18  of the longitudinal bridge girder  5 . The wheels  8  may be blocked after the precise positioning of the conveyor device  10  at the installation site  32  to prevent the conveyor device  10  from rolling away. Fixing the conveyer device  10  at the installation site  32  may also be realized by way of a temporary connection of the conveyor device  10  to the longitudinal bridge girder  5  or by other measures. 
     In  FIG.  5    there is depicted a vertical section through the conveyor device  10  positioned at the installation site  32 . The ribbed base plate  26  is situated at a superelevated position, as during the movement of the conveyor device  10  from the assembly site  31  to the installation site  32  there should be prevented any collision with the bracing means  6 . The wheels  8  of the conveyor device  10  are arranged in the lanes  7  configured between the bracing means  6  on the top surface  18  of the longitudinal bridge girder  5 . The weight of the conveyor device  10  and of the ribbed base plate  26  is transmitted from the wheels  8  to the longitudinal bridge girder  5 . 
     A sectional view corresponding to  FIG.  5    after the ribbed base plate  26  has been lowered is depicted in  FIG.  6   . After being lowered, the ribbed base plate  26  is supported on the longitudinal bridge girder  5 . Depending on the basic geometrical dimensions of the ribbed base plate  26 , the configuration of the reinforcement and the dimensions of the cross beams  21 , the ribbed base plate  26  may be supported on the longitudinal bridge girder  5  in such a way that the tendons  11  will be completely relieved. It would, however, also be possible to support the ribbed base plate  26  on the longitudinal bridge girder  5  in such a way that only a part of the weight of the ribbed base plate  26  is supported on the longitudinal bridge girder  5  and that the remaining part of the weight of the ribbed base plate  26  is absorbed by the tendons  11  and introduced into the conveyor device  10 . 
       FIG.  7    shows in a detailed view a wheel  8  of the conveyor device  10 , which is arranged between the bracing means  6  in a lane  7  on the top surface  18  of longitudinal bridge girder  5 . Strips  22  are adhered onto the top surface  18  of the longitudinal bridge girder  5 . The strips  22  may, for example, be made from an elastomeric material. In a cross beam  21 , there is installed an anchor  14  for connection to the lower end point  13  of a tendon  11 . This anchor  14  is composed of a steel slab  35  and a threaded nut  36 , which is welded to the top surface of the steel slab  35 . At the outer surface of the threaded nut  36  there is attached a sleeve tube  37 . At the lower end point  13  of the tendon  11  there is configured a thread providing for attachment of the tendon  11  within the anchor  14 . 
       FIG.  8    shows a detailed view corresponding to  FIG.  7    after the ribbed base plate  26  has been lowered and the ribbed base plate  26  has been supported on the top surface  18  of the longitudinal bridge girder  5 . When transmitting the weight of the ribbed base plate  26  from the conveyor device  10  onto the longitudinal bridge girder  5 , the strips  22  are pressed together. Pressing these strips  22  together makes it possible to compensate for any constructional inaccuracy between the bottom surface  19  of the bottom layer  2  and the top surface  18  of the longitudinal bridge girder  5 . A second important function of the strips  22  is the production of a sealing between the bottom surface  19  of the bottom layer  2  and the top surface  18  of the longitudinal bridge girder  5 . The gap  24  between the bottom surface  19  of the bottom layer  2  and the top surface  18  of the longitudinal bridge girder  5  corresponding in height to the thickness of the strips  22  pressed together should be filled with grout or concrete to ensure protection against corrosion of the top surface  18  of the longitudinal bridge girder  5 . 
     According to  FIG.  9   , a top concrete layer  3  is applied onto the lowered ribbed base plate  26 . The surface of the ribbed base plate  26  should be made as rough as possible such that there is given rise to a good bracing effect within the joint between the ribbed base plate  26  and the top concrete layer  3 . The weight of the top concrete layer  3  is in this working step transmitted to a smaller extent via the structural bending action of the ribbed base plate  26  to the two steel girders  9  of the longitudinal bridge girder  5  and to a larger extent via the tendons  11  into the conveyor device  10 . The weight of the top concrete layer  3  that is absorbed by the conveyor device  10  will be introduced via the wheels  8  into the longitudinal bridge girder  5 . 
     According to  FIG.  10   , there is installed in the next step a device  15  for moving the conveyor device  10  on the top concrete layer  3 , once the top concrete layer  3  has reached a predetermined minimum rigidity. Then in the next step of the method according to the invention the tendons  11  are disassembled. A complete disassembly of the tendons  11 , which is depicted in  FIG.  10   , is not absolutely essential. Releasing the connections between the lower end points  13  of the tendons  11  and the anchors  14  installed in the ribbed base plate  14  is sufficient to introduce the entire weight of the deck slab  1  via a structural bending action into the longitudinal bridge girder  5  and to relax the conveyor device  10 . Following the transfer of weight of the ribbed base plate  26  and the top concrete layer  3 , which together form a construction section of the deck slab  1 , the weight of the conveyor device  10  is shifted from the wheels  8  onto the device  15  for moving the conveyor device  10  on the second top concrete layer  3 . This shift may, for example, as depicted in  FIG.  10   , be realized by lifting and turning over the wheels  8 . Subsequently, the conveyor device  10  may be moved by means of the device  15  for moving the conveyor device  10  on the top concrete layer  3  to the assembly site  31  to optionally pick up there a further ribbed base plate  26 . 
     A bridge  4 , which comprises two abutments  33 , five pillars  34  and one longitudinal bridge girder  5 , is depicted in  FIG.  11    to  FIG.  13   . The conveyor device  10  is moved by way of winches to the assembly site  31 , which is here arranged above one of the two abutments  33 . At the assembly site  31 , the ribbed base plate  26 , which is composed of the bottom layer  2 , the cross beams  21  and the longitudinal edge beams  28 , is attached at the conveyor device  10  by means of tendons  11 . The ribbed base plate  26  is lifted to prevent any contact with the bracing means  6  mounted on the longitudinal bridge girder  5  when the conveyor device  10  is moved in the longitudinal direction of the bridge  4  and to make it possible that a construction section already completed of the deck slab  1  may be driven on. To make it possible to drive over the construction sections already completed of the deck slab  1  it is necessary to install the device  15  for moving the conveyor device  10  on a top concrete layer  3 . 
     According to  FIG.  12    the conveyor device  10  and the ribbed base plate  26  attached thereto are moved in the next method step from the assembly site  31  to the projected installation site  32 . At the installation site  32 , the ribbed base plate  26  is lowered until the bottom layer  2  rests on the top surface  18  of the longitudinal bridge girder  5 . Then the top concrete layer  3  may be applied. After the top concrete layer  3  has hardened, there is installed a device  15  for moving the conveyor device  10  on the top concrete layer  3 , the tendons  11  are released from the anchors  14  in the prefabricated slabs  2  and the conveyor device  10  is conveyed to the assembly site  31  such that the ribbed base plate  26  may there be received for the next construction section. 
     In this embodiment example, the ribbed base plate  26  is attached to the conveyor device  10  by means of tendons  11 , while the top concrete layer  3  is being applied. Only once the top concrete layer  3  has hardened, the ribbed base plate  26  is removed from the conveyor device  10 . Alternatively, it would also be possible to configure the ribbed base plate  26  to be so rigid such that it would be able to carry its own net weight and the weight of the top concrete layer  2 . A ribbed base plate  26  such configured would make it possible that the connection between the ribbed base plate  26  and the conveyor device  10  is released immediately after the ribbed base plate  26  has been lowered and the conveyor device  10  could be moved back to the assembly site  31 . This would enable the acceleration of the production of the deck slab  1 . In this case, however, there should be installed makeshift lanes  7  on the ribbed base plate  26  such that it would be possible for the conveyor device  10  to drive on the ribbed base plate  26 . 
     The assembly site  31  is in the first embodiment example situated on an abutment  33 . It may also be advantageous to move the assembly site  31  onto the bridge  4 , after the first sections of the deck slab  1  have been produced. It may also be advantageous to provide more than one assembly site  31  to enable longer hardening of the concrete of the bottom layer  2 . According to  FIG.  13   , the remaining sections of the deck slab  1  of the bridge  4  are produced using the method according to the invention. Subsequently, the bridge  4  is then completed in the usual manner by applying a sealing onto the surface of the top concrete layer  3  and by subsequently applying a deck cover. 
     In this exemplary embodiment, the weight of the ribbed base plate  26  on the top concrete layer  3  is introduced from the wheels  8  into the longitudinal bridge girder  5 . Alternatively, it would also be possible to install supports and to lift the wheels  8  before the top concrete layer  3  is introduced. This may also be of advantage as the supports may be accommodated in the recesses  16  having smaller dimensions than the recesses  16  required for the accommodation of the wheels  8 . 
     A second embodiment of the method according to the invention is depicted in the  FIGS.  14  to  18   . According to  FIG.  14   , there are produced on an assembly site  31  on a framework  23  three segments  17  of a bottom layer  2  having cross beams  21 , which are arranged in the transverse direction in regard to the longitudinal axis of the longitudinal bridge girder  5 . In the three segments  17  of the bottom layer  2 , there are contained the lower longitudinal and transverse reinforcement, the shear reinforcement and a part of the upper longitudinal and transverse reinforcement. For reasons of clarity, the reinforcement is not depicted in this embodiment example. Support constructions  29  are arranged between the segments  17 . The support constructions  29  are composed of steel tubes welded to the mounting girders  20 . At the upper end points of the support constructions  29 , there are mounted launching gantries  30 . The launching gantries  20 , for example, are configured as roller bearing or slide bearing such that a conveyor device  30  may be shifted on the launching gantries  30  in the longitudinal direction along the longitudinal bridge girder  5  and on the assembly site  31 . 
     After the concrete of the bottom layer  2  has hardened, a conveyor device  10  will be moved to the assembly site  31 , the three segments  17  of the bottom layer  2  will be attached using tendons  11  to the conveyor device  10 , will be lifted and transported to the installation site  32 . According to  FIG.  15   , the three segments  17  of the bottom layer  2  are lowered at the installation site  32  in such a way that the edges of the segments  17  are supported on the steel girders  9  of the longitudinal bridge girder  5 . 
       FIG.  15    shows that there are formed by the three segments  17  of the bottom layer  2  two cantilevering slabs and a slab arranged between the two steel girders  9  of the longitudinal bridge girder  5 . These three slabs should be separated from one another to make it possible to convey the conveyor device  10  in the longitudinal direction of the bridge  4  and to lower the bottom layer  2 . 
     For this reason it is also not possible to lay the entire reinforcement at the assembly site  31 . The upper transverse reinforcement required for connecting the cantilevering slabs and the slab arranged between the steel girders  9  of the longitudinal bridge girder  5  may only be laid at the installation site  32  after the bottom layer  2  has been lowered. 
     A bridge  4  comprising two abutments  33 , five pillars  34  and one longitudinal bridge girder  5  is depicted in the illustrations  FIGS.  16  to  18   . As shown in  FIG.  16   , the support constructions  29  are mounted on the longitudinal bridge girder  5  and on the assembly site  31 , which is situated on one of the two abutments  33 . The conveyor device  10 , which is configured as a spatial frame construction  49 , is moved with the aid of winches to the assembly site  31 , which is here arranged above one of the two abutments  33 . At the assembly site  31 , the bottom layer  2  is attached by means of tendons  11  to the conveyor device  10 . The bottom layer  2  is mounted in a lifted superelevated position to prevent any contact with the bracing means  6  mounted on the longitudinal bridge girder  5  when conveying the conveyor device  10  in the longitudinal direction of the bridge  4  and to make it possible to drive on the top concrete layer  3  of construction sections already completed of a deck slab  1 . 
     According to  FIG.  17   , the conveyor device  10  and the bottom layer  2  suspended therefrom are moved from the assembly site  31  to the scheduled installation site  32  in the next method step. At the installation site  32 , the bottom layer  2  is lowered until the edges of the segments  17  of the bottom layer  2  rest on the upper flanges of the steel girders  9  of the longitudinal bridge girder  5 . Then the top concrete layer  3  may be applied. After the top concrete layer  3  has been hardened, the tendons  11  are released from the bottom layer  2  and the conveyor device  10  is conveyed to the assembly site  31 , such that the bottom layer  2  may be mounted for the next construction section at the conveyor device  10 . 
     The assembly site  31  is situated in this embodiment example on an abutment  33 . It may also be advantageous that the assembly site  31  is moved to the bridge  4  after the first sections of the deck slab  1  have been produced. 
     According to  FIG.  18    all support constructions  29  are removed after the production of the deck slab  1  by cutting off the steel profiles in the vicinity of the surface of the top concrete layer  3 . Subsequently, the bridge  4  is completed in the usual manner by applying a sealing onto the surface of the top concrete layer  3  and by subsequently applying a deck cover. 
     A third embodiment of the method according to the invention is depicted in the illustrations  FIGS.  19  to  22   . 
       FIG.  19    shows a vertical section through a conveyor device  10 , which is configured as a spatial frame construction  49 , and through a bottom layer  2  composed of three segments  17 , during the transport from the assembly site  31  to the installation site  32 . The conveyor device  10  is moved on launching gantries  30 , which are mounted on support constructions  29 . The three segments  17  of the bottom layer  2  are produced at the assembly site  31  having cross beams  21 . Within the cross beams  21 , there are installed cladding tubes  38 , which are installed in the bracing wire produced in a later step. 
     During transport to the installation site  31 , the segment  17  arranged between the steel girders  9  is in a raised position to prevent collision with the bracing means  6  welded to the steel girders  9  and the construction sections already completed of the deck slab  1 . The segment  17  depicted in  FIG.  19    at the left hand-side is in a raised and laterally shifted outwards position during the transport of the bottom layer  2  to the installation site  32  in order prevent a collision of the cross beams  21  with the support constructions  28  and the bracing means  6 . The segment  17  depicted in  FIG.  19    at the left-hand side is in a raised and turned position during the transport of the bottom layer  2  to the installation site  32  to prevent a collision of the cross beams  21  with the support construction  29  and the bracing means  6 . 
     At the installation site  32 , the three segments  17  of the bottom layer  2  are brought into the scheduled position. According to  FIG.  20   , there is required lowering the segment  17  arranged in-between the steel girders  9 , lowering and shifting transversally to the right the segment  17  arranged in  FIG.  19    at the left-hand side as well as lowering and turning the segment  17  arranged in the  FIG.  19    at the right-hand side. The scheduled position depicted in  FIG.  20    is reached when the upper edges of the cross beams  21  are in a horizontal position and when the front faces of the cross beams  21  touch. Using the method according to the invention it is also possible to reach a different position of the segments, for exampling having a constant transversal inclination, in the scheduled final position. 
     According to  FIG.  21   , a conveyor device  10  is mounted on launching gantries  30 . The launching gantries  30  are, for example, configured as roller bearings or as sliding bearings such that the conveyor device  10  may be shifted in the longitudinal direction along the longitudinal bridge girder  5  of the bridge  4 . The launching gantries  30  are attached at the upper end points of support constructions  29 . The support constructions  29 , which herein are configured as steel profiles, are connected in a flexurally rigid manner to the upper flanges of the steel girders  9  of the longitudinal bridge girder  5 . The bottom layer  2  is depicted in  FIG.  21    in a raised or superelevated, respectively, position and in  FIG.  2    in a lowered position. In the superelevated position, the bottom layer  2  should be raised so much so that it is possible to drive on the bracing means  6  and the top concrete layer  3  of construction sections already completed. In the lowered position according to  FIG.  22   , the wheels of the bottom layer  2  are supported on the upper flanges of the steel girders  9  of the longitudinal bridge girder  5 .  FIG.  21    shows that within the cross beams  21 , which are connected to the segments of the bottom layer  2 , there are arranged cladding tubes  38 . 
     According to  FIG.  22   , the segment depicted at the left-hand side of  FIG.  19    of the bottom layer  2  is moved as far to the right until the front faces of the cross beams  21  touch one another. If the front faces of the cross beams  21  have been very accurately produced or post-finished, then contact splice may be performed. Alternatively, also the production of a splice connection with a coupling of the cladding tubes  38  and a grouting joint would be possible. After the segments of the bottom layer  2  have been accurately aligned, the top concrete layer  3  is produced. Subsequently, bracing wires  39  are inserted into the cladding tubes  38 . By tensioning the bracing wires  39 , a transverse preload may be applied onto the deck slab  1 . 
     According to  FIG.  22   , the steel profiles of the support constructions  29  are embedded into concrete when applying the top concrete layer  3 . The tendons  11  are protected by means of a sheath tube  37  against direct contact with the top concrete layer  3 . This enables removal of the tendons  11  after the top concrete layer  3  has been hardened and re-use of the tendons  11  in the next construction section. The steel profiles are cut off in the vicinity of the surface of the top concrete layer  3  after the top concrete layer  3  has been hardened and the launching gantries  30  have been disassembled. 
     A fourth embodiment of the method according to the invention is depicted in the illustrations  FIGS.  23  to  30   . 
       FIG.  23    shows a vertical section through a conveyor device  10 , which is configured as a spatial frame construction  49 , and a bottom layer  3  composed of three segments  17  at the installation site  32 . The three segments  17  of the bottom layer  2  are attached at the conveyor device  10  by means of tendons  11 . The segments  17  are in this embodiment example not supported on the longitudinal bridge girder  5  composed of two prestressed concrete beams  40  but rather positioned next to the prestressed concrete beams  40 . This has the advantage that the longitudinal bridge girder  5  may be configured having a larger statically effective depth. After the bottom layer  2  having cross beams  21  has been positioned as scheduled, the three segments  17  are connected to one another via the prestressed concrete beams  40  by means of structural steel connections. In order to realize the structural steel connection, there are installed steel panels  42  within the cross beams  21 . At the installation site  32 , these steel panels  42  are connected to one another in a flexurally rigid manner with additional steel panels  35  and screw connections  41 . After the three segments  17  have been connected in a flexurally rigid manner, the tendons  11  are relaxed and dismantled. The conveyor device  10  is no longer required at the installation site  32  and may be moved back to the assembly site  31 . 
       FIG.  24    shows the installation site  32  after removal of the conveyor device  10 . 
     In the next working step according to  FIG.  25   , the support constructions  29  and the launching gantries  30  are removed at the installation site. A first top concrete layer  3  is applied onto the bottom layer  2 . The weight of the top concrete layer  3  is introduced from the bottom layer  2  into the cross beams  21  and from these to the prestressed concrete beams  40 . The structural steel connection of the cross beams  21  should be able to absorb any stresses arising. If the first top concrete layer  3  reaches a predetermined concrete compression strength, there is applied according to  FIG.  26    onto the first top concrete layer  3  a second top concrete layer  3 . After the concrete of the top concrete layers  3  has hardened, the bottom layer  2 , the cross beams  21 , the first top concrete layer  3  and the second top concrete layer  3  are to be considered a construction component produced in a monolithic way, in combination forming the deck slab  1 . 
     The detail E of  FIG.  23    is depicted in  FIG.  27    and  FIG.  28   , showing the structural steel connection of the two cross beams  21 . In the two cross beams  21 , there are installed steel panels  42  projecting beyond the front faces of the cross beams  21 . Upon lowering the bottom layer  2  and the cross beams  21 , the steel panels  42  are supported on the prestressed concrete beams  40 . Subsequently, there is produced by using two steel slabs  35  and screw connections  41  a flexurally rigid connection of the two cross beams  21 . 
     An alternative embodiment for producing a flexurally rigid connection of the two cross beams  21  is shown in the  FIG.  29    and the  FIG.  30   . There is installed in the prestressed concrete beam  40  a steel panel  42 . Front faces  43  are welded to the steel panel  42  at the left and right side. At the front faces of the cross beams  21 , there are attached front faces  43  made from steel, which are connected by means of starter bars not depicted in the cross beams  21 . Upon lowering the bottom layer  2  having the embedded cross beams  21 , there is produced a flexurally rigid connection of the cross beams  21  with the prestressed concrete beam  40  by way of the screw connections  41 . Such a connection may also be advantageous if only cantilevering segments  17  are to be connected to a longitudinal bridge girder  5  having a box-section-like cross-section. 
     A fifth embodiment of the method according to the invention is depicted in the illustrations  FIG.  31    to  FIG.  37   . 
     According to  FIG.  31    at the assembly site  31  three prefabricated elements  47  are laid on mounting beams  20 . Each prefabricated element  47  is composed of three prefabricated slabs  50  and one cross beam  21  configured as prefabricated beam  27  and connecting the three prefabricated slabs  50  one to another. The bottom layer  2  is formed in this mounting state of three segments  17 . 
     In the next working step, there is laid a reinforcement onto the bottom layer  2  and there is produced a first top concrete layer on the prefabricated slabs  50 . The three segments  17  of the bottom layer  2  are joined to one segment  17  by the first top concrete layer  3 .  FIG.  32    shows the state at the assembly site  31  after the first top concrete layer  3  has been produced. 
       FIG.  33    shows the transport of the bottom layer  2  having cross beams  21  and a first top concrete layer  3  for a construction section of the deck slab  1  from the assembly site  31  to the installation site  31 . The transport is carried out using a conveyor device  10 . The conveyor device is composed of a front part  44  and a rear part  45 , which are configured as frame constructions  49 . The front part  44  and the rear part  45  of the conveyor device  10  are connected to one another by way of two longitudinal girders  46 . The conveyor device  10  is moved in the longitudinal direction of the bridge  4  on support constructions  29 , which are situated on longitudinal bridge girder  5 , which is in this example composed of two steel girders  9 . The weight of the bottom layer  2  having the cross beams  21  and the first top concrete layer  3  is introduced in this transport state into six tendons  11 . The lower end points  13  of the tendons  11  are arranged within the cross beams  21 . The upper end points  13  of the tendons  11  are attached at the top surface of hydraulic hollow piston jacks  48 . During transport, the bottom layer  2  having the cross beams  21  and the first top concrete layer  3  is in a raised position to prevent any contact of the cross beams  21  with the bracing means  6 , which are not depicted in  FIG.  33    for reasons of clarity and mounted on the longitudinal bridge girder  5 , and to make it possible to drive on construction sections already completed of the deck slab  1 .  FIG.  33    shows that the pistons  51  of the hollow piston jacks  48  are in an extracted position in order to be able to transport the bottom layer  2  having the cross beams  21  and the first top concrete layer in a raised position. 
     According to  FIG.  34   , the pistons  51  of the hollow piston jack  48  are retracted at the installation site  32  to be able to lower the bottom layer  20  having the cross beams  21  and the first top concrete layer  3  into the scheduled final position. Immediately following the lowering operation, the lower end points  13  of the tendons  11  may be released and the conveyor device  10  may be moved from the assembly site  32  to the installation site  31  to pick up there a further bottom layer  2  having cross beams  21  and a first top concrete layer  3  for a further construction section of the deck slab  1 . At the installation site  32 , immediately after the conveyor device  10  has left or at a later point of time, there may be laid the starter bars to a neighbouring construction sections and the second top concrete layer  3  may be applied. The weight of the additional reinforcement and of the second top concrete layer  3  is absorbed by the bottom layer  2 , the cross beams  21  and the first top concrete layer  3 . In order to reach the goal of the bottom layer  2 , the cross beams  21  and the two top concrete layers  3  in the final condition of the deck slab  1  behaving like a construction section produced in one pour, it is necessary to configure the surfaces rough and to provide the necessary starter bars. 
     A bridge  4  comprising two abutments  33 , five pillars  34  and one longitudinal bridge girder  5  is depicted in the illustrations  FIG.  35    to  FIG.  37   . As shown in  FIG.  35   , the support constructions  29  are mounted on the longitudinal bridge girder  5  and the assembly site  31 , which is situated on one of the two abutment  33 . The conveyor device  10  is composed of a front part  44  and a rear part  45 , which are connected to one another by two longitudinal girders  46 . On the assembly site  31 , the bottom layer  2  having the cross beams  21  and the first top concrete layer  3  is raised by extracting the pistons  51  of the six hollow piston jacks  48 . The bottom layer  2  having the cross beams  21  and the first top concrete layer  3  is arranged in this condition between the front part  44  and the rear part  45  and underneath the longitudinal girders  46  of the conveyor device  10 . 
     According to  FIG.  36   , the bottom layer  2  having the cross beams  21  and the first top concrete layer  3  is moved in the next method step from the assembly site  31  to the installation site  32 . At the installation site  32 , the bottom layer  2  having the cross beams  21  and the first top concrete layer  3  is lowered until the cross beams  31  are supported on the top surface  18  of the longitudinal bridge girder  5 . To enable the lowering operation of a bottom layer  2  composed of a segment  17  and having cross beams  21  and a first top concrete layer  3  at the installation site  32 , there must not be arranged any construction elements for connecting the front part  44  and the rear part  45  of the conveyor device  10  underneath the segment  17 . 
     Immediately following the lowering operation, the lower end points  13  of the tendons  11  may be released from the cross beams  21  and the conveyor device  10  may be moved from the installations site  32  back to the assembly site  31  to pick up there a further bottom layer  2  having cross beams  32  and a first top concrete layer  3  for a further construction section of the deck slab  1 . 
     In this embodiment example it is particularly advantageous that at the installation site  32  it is not necessary to wait for the top concrete layer  3  to harden. The conveyor device  10  may be moved away from the installation site  32  immediately after the bottom layer  2  having the cross beams  21  and the first top concrete layer  3  has been lowered. In this way it is possible to produce one construction section of the deck slab  1  per day. Producing the second top concrete layer  3  is independent of the bottom layer  2  having cross beams  31  and first top concrete layer being laid and may be realized at any point of time. 
     According to  FIG.  37   , after the production of the deck slab  1 , all support constructions  29  are removed by cutting off the steel profiles in the vicinity of the surface of the top concrete layer  3 . Subsequently, the bridge  4  is completed in the usual manner by applying a sealing onto the surface of the top concrete layer  3  and subsequently applying a deck cover. 
     A sixth embodiment of the method according to the invention is depicted in the illustrations  FIG.  38    and  FIG.  39   . 
     The bottom layer  2  having cross beams  21  is produced at the assembly site  31  on a framework  23 . The bottom layer  2  having cross beams  21  is composed in this embodiment example of one segment  17 , as the three cross beams  21  extend across the entire width of the deck slab  1  to be produced and, in this way, a continuous construction component is being developed.  FIG.  38    shows the transport of the bottom layer  2  having cross beams  21  for a construction section of the deck slab  1  from the assembly site  31  to the installation site  32 . In this embodiment example raising the bottom layer  2  having the cross beams  21  is realized by extracting the pistons  51  of the hollow piston jacks  48 , which are arranged between the longitudinal girders  46  and the front part  44  or the rear part  45 , respectively, of the conveyor device  10 . 
     According to  FIG.  39   , the pistons  51  of the hollow piston jacks  48  are retracted at the installation site to be able to lower the bottom layer  2  having the cross beams  21  into the scheduled final position. Immediately after depositing the bottom layer  2  having the cross beams  31  at the installation site  32 , the lower end points  13  or the upper end points  12  of the tendons  11  may be released and the conveyor device  10  may be moved to the assembly site to pick up a further bottom layer  2  having cross beams  21  for a further construction section of the deck slab  1 . 
     LIST OF REFERENCES 
     
         
           1  deck slab 
           2  bottom layer 
           3  top concrete layer 
           4  bridge 
           5  longitudinal bridge girder 
           6  bracing means 
           7  lane 
           8  wheel 
           9  steel girder 
           10  conveyor device 
           11  tendon 
           12  upper end point of a tendon 
           13  lower end point of a tendon 
           14  anchor 
           15  device 
           16  recess 
           17  segment of a bottom layer 
           18  top surface of a longitudinal bridge girder 
           19  bottom surface of a bottom layer 
           20  mounting girder 
           21  cross beam 
           22  strip 
           23  formwork 
           24  gap 
           25  bottom surface of a bottom layer 
           26  ribbed base plate 
           27  prefabricated beam 
           28  longitudinal edge beam 
           29  support construction 
           30  launching gantry 
           31  assembly site 
           32  installation site 
           33  abutment 
           34  pillar 
           35  steel slab 
           36  threaded nut 
           37  sleeve tube 
           38  cladding tube 
           39  bracing wire 
           40  prestressed concrete beam 
           41  screw connection 
           42  steel panel 
           43  front slab 
           44  front part of a conveyor device 
           45  rear part of a conveyor device 
           46  longitudinal girder of a conveyor device 
           47  prefabricated element 
           48  hollow piston jack 
           49  frame construction 
           50  prefabricated slab 
           51  piston