METHOD FOR THE PRODUCTION OF A DECK SLAB FOR A BRIDGE

“A method for producing a construction section of a deck slab for a bridge includes the following operations: producing a bottom layer composed of a segment and having cross beams, which are arranged in the transverse direction in regard to the longitudinal axis of the longitudinal bridge girder, from reinforced concrete; transporting the bottom layer having the cross beams for a construction section of the deck slab using a conveyor device from an assembly site to an installation site and lowering it into the installation position; producing a top concrete layer for a construction section of the deck slab on the bottom layer; removing the bottom layer having the cross beams for a construction section of the deck slab from the conveyor device and moving the conveyor device away from the installation site.”

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.

The first embodiment of the method according to the invention is depicted in theFIGS.1to13. According toFIG.1, there is erected at the assembly site31a formwork23on mounting girders20. The top surface of the formwork23has the same shape as a bottom surface19of a bottom layer2of 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 formwork23. For reasons of clarity, and because the embodiment of the reinforcement of deck slabs1having a top concrete layer3can be assumed as known, the reinforcement is not depicted in this exemplary embodiment. Subsequently, there are positioned on the formwork23three cross beams21, which are pre-fabricated as prefabricated beams27. The cross beams21are in this example arranged at an angle of 90° to the longitudinal axis of the bridge4. 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 beams21may preferably be produced from reinforced concrete.

In the longitudinal direction of the bridge4, there are shifted longitudinal edge beams28to simplify in a later method step the concreting works when introducing the top concrete layer3. The cross beams21as well as the longitudinal edge beams28are equipped with starter bars. The deck slab1in this embodiment example has two haunches in the final condition.

These haunches are to be reproduced already in the production of the cross beams21and in the production of the formwork23.

In the next method step, concrete for the production of the bottom layer2is introduced according toFIG.2. The lower longitudinal and transverse reinforcement27as well as the starter bars of the prefabricated beams27are then embedded in concrete. The bottom layer2is in this example produced having a constant thickness. It would also be possible to produce the bottom layer2having a variable thickness in order to reduce the weight of the bottom layer2for a construction section of the deck slab. The bottom layer2for the first construction section has eight recesses16.

According toFIG.3, a conveyor device10is moved in the next method step on a longitudinal bridge girder5to the assembly site21. The longitudinal bridge girder5in the first embodiment example is composed of two steel girders9. The steel girders9may be connected by transverse bracing or transverse girders, which are not depicted in this embodiment example for reasons of clarity. The conveyor device10is in this example composed of a spatial frame construction49made from steel. Alternatively, the conveyor device10could also be composed of a truss construction. The conveyor device10has eight wheels8. Moving the conveyor device10is realized by a rolling process of the wheels8in the two lanes7configured on the top surface18of the longitudinal bridge girder5. The two lanes7are each arranged in-between the bracing means6. The conveyor device10may advantageously be moved to the assembly site31only after the reinforcement has been laid, the prefabricated beams27have been shifted and the concrete for the bottom layer2has been introduced, as the laying of the reinforcement supported by a crane and the shifting of the prefabricated beams27as well as the introducing of the concrete for the bottom layer2carried out by means of a concrete pump would be easier to realize. At the assembly site31, additional means may make it possible that the conveyor device may drive across the cross beams21and the reinforcement.

The bottom layer2having the cross beams21and the longitudinal edge beams28is lifted from the conveyor device10after the concrete has hardened and is then transported from the assembly site31to the installation site32.

FIG.4shows in a view that the bottom layer2is lowered at the installation site32. InFIG.4, there is depicted a state immediately before supporting the bottom layer2onto the longitudinal bridge girder5. The weight of the bottom layer2having the cross beams21is in this condition introduced by the tendons11into the conveyor device10. The bottom layer2having the cross beams21and the longitudinal edge beams28may be classified as a ribbed base plate26in a statics point of view. The net weight of the bottom layer2is introduced via a structural bending action in the bottom layer2into the cross beams21and in the edge regions also partly into the longitudinal edge girders28. The cross beams21absorb the weight of the bottom layer2and of the longitudinal edge girder28and transmit it to the anchors14. Within the anchors14, the net weight of the ribbed base plate26is transmitted to the lower end points13of the tendons11.

The upper end points12of the tendons11are attached to the conveyor device10. The conveyor device10is positioned at the installation site32such that the recesses16are arranged above the bracing means6arranged at the top surface18of the longitudinal bridge girder5. The wheels8may be blocked after the precise positioning of the conveyor device10at the installation site32to prevent the conveyor device10from rolling away. Fixing the conveyer device10at the installation site32may also be realized by way of a temporary connection of the conveyor device10to the longitudinal bridge girder5or by other measures.

InFIG.5there is depicted a vertical section through the conveyor device10positioned at the installation site32. The ribbed base plate26is situated at a superelevated position, as during the movement of the conveyor device10from the assembly site31to the installation site32there should be prevented any collision with the bracing means6. The wheels8of the conveyor device10are arranged in the lanes7configured between the bracing means6on the top surface18of the longitudinal bridge girder5. The weight of the conveyor device10and of the ribbed base plate26is transmitted from the wheels8to the longitudinal bridge girder5.

A sectional view corresponding toFIG.5after the ribbed base plate26has been lowered is depicted inFIG.6. After being lowered, the ribbed base plate26is supported on the longitudinal bridge girder5. Depending on the basic geometrical dimensions of the ribbed base plate26, the configuration of the reinforcement and the dimensions of the cross beams21, the ribbed base plate26may be supported on the longitudinal bridge girder5in such a way that the tendons11will be completely relieved. It would, however, also be possible to support the ribbed base plate26on the longitudinal bridge girder5in such a way that only a part of the weight of the ribbed base plate26is supported on the longitudinal bridge girder5and that the remaining part of the weight of the ribbed base plate26is absorbed by the tendons11and introduced into the conveyor device10.

FIG.7shows in a detailed view a wheel8of the conveyor device10, which is arranged between the bracing means6in a lane7on the top surface18of longitudinal bridge girder5. Strips22are adhered onto the top surface18of the longitudinal bridge girder5. The strips22may, for example, be made from an elastomeric material. In a cross beam21, there is installed an anchor14for connection to the lower end point13of a tendon11. This anchor14is composed of a steel slab35and a threaded nut36, which is welded to the top surface of the steel slab35. At the outer surface of the threaded nut36there is attached a sleeve tube37. At the lower end point13of the tendon11there is configured a thread providing for attachment of the tendon11within the anchor14.

FIG.8shows a detailed view corresponding toFIG.7after the ribbed base plate26has been lowered and the ribbed base plate26has been supported on the top surface18of the longitudinal bridge girder5. When transmitting the weight of the ribbed base plate26from the conveyor device10onto the longitudinal bridge girder5, the strips22are pressed together. Pressing these strips22together makes it possible to compensate for any constructional inaccuracy between the bottom surface19of the bottom layer2and the top surface18of the longitudinal bridge girder5. A second important function of the strips22is the production of a sealing between the bottom surface19of the bottom layer2and the top surface18of the longitudinal bridge girder5. The gap24between the bottom surface19of the bottom layer2and the top surface18of the longitudinal bridge girder5corresponding in height to the thickness of the strips22pressed together should be filled with grout or concrete to ensure protection against corrosion of the top surface18of the longitudinal bridge girder5.

According toFIG.9, a top concrete layer3is applied onto the lowered ribbed base plate26. The surface of the ribbed base plate26should be made as rough as possible such that there is given rise to a good bracing effect within the joint between the ribbed base plate26and the top concrete layer3. The weight of the top concrete layer3is in this working step transmitted to a smaller extent via the structural bending action of the ribbed base plate26to the two steel girders9of the longitudinal bridge girder5and to a larger extent via the tendons11into the conveyor device10. The weight of the top concrete layer3that is absorbed by the conveyor device10will be introduced via the wheels8into the longitudinal bridge girder5.

According toFIG.10, there is installed in the next step a device15for moving the conveyor device10on the top concrete layer3, once the top concrete layer3has reached a predetermined minimum rigidity. Then in the next step of the method according to the invention the tendons11are disassembled. A complete disassembly of the tendons11, which is depicted inFIG.10, is not absolutely essential. Releasing the connections between the lower end points13of the tendons11and the anchors14installed in the ribbed base plate14is sufficient to introduce the entire weight of the deck slab1via a structural bending action into the longitudinal bridge girder5and to relax the conveyor device10. Following the transfer of weight of the ribbed base plate26and the top concrete layer3, which together form a construction section of the deck slab1, the weight of the conveyor device10is shifted from the wheels8onto the device15for moving the conveyor device10on the second top concrete layer3. This shift may, for example, as depicted inFIG.10, be realized by lifting and turning over the wheels8. Subsequently, the conveyor device10may be moved by means of the device15for moving the conveyor device10on the top concrete layer3to the assembly site31to optionally pick up there a further ribbed base plate26.

A bridge4, which comprises two abutments33, five pillars34and one longitudinal bridge girder5, is depicted inFIG.11toFIG.13. The conveyor device10is moved by way of winches to the assembly site31, which is here arranged above one of the two abutments33. At the assembly site31, the ribbed base plate26, which is composed of the bottom layer2, the cross beams21and the longitudinal edge beams28, is attached at the conveyor device10by means of tendons11. The ribbed base plate26is lifted to prevent any contact with the bracing means6mounted on the longitudinal bridge girder5when the conveyor device10is moved in the longitudinal direction of the bridge4and to make it possible that a construction section already completed of the deck slab1may be driven on. To make it possible to drive over the construction sections already completed of the deck slab1it is necessary to install the device15for moving the conveyor device10on a top concrete layer3.

According toFIG.12the conveyor device10and the ribbed base plate26attached thereto are moved in the next method step from the assembly site31to the projected installation site32. At the installation site32, the ribbed base plate26is lowered until the bottom layer2rests on the top surface18of the longitudinal bridge girder5. Then the top concrete layer3may be applied. After the top concrete layer3has hardened, there is installed a device15for moving the conveyor device10on the top concrete layer3, the tendons11are released from the anchors14in the prefabricated slabs2and the conveyor device10is conveyed to the assembly site31such that the ribbed base plate26may there be received for the next construction section.

In this embodiment example, the ribbed base plate26is attached to the conveyor device10by means of tendons11, while the top concrete layer3is being applied. Only once the top concrete layer3has hardened, the ribbed base plate26is removed from the conveyor device10. Alternatively, it would also be possible to configure the ribbed base plate26to be so rigid such that it would be able to carry its own net weight and the weight of the top concrete layer2. A ribbed base plate26such configured would make it possible that the connection between the ribbed base plate26and the conveyor device10is released immediately after the ribbed base plate26has been lowered and the conveyor device10could be moved back to the assembly site31. This would enable the acceleration of the production of the deck slab1. In this case, however, there should be installed makeshift lanes7on the ribbed base plate26such that it would be possible for the conveyor device10to drive on the ribbed base plate26.

The assembly site31is in the first embodiment example situated on an abutment33. It may also be advantageous to move the assembly site31onto the bridge4, after the first sections of the deck slab1have been produced. It may also be advantageous to provide more than one assembly site31to enable longer hardening of the concrete of the bottom layer2. According toFIG.13, the remaining sections of the deck slab1of the bridge4are produced using the method according to the invention. Subsequently, the bridge4is then completed in the usual manner by applying a sealing onto the surface of the top concrete layer3and by subsequently applying a deck cover.

In this exemplary embodiment, the weight of the ribbed base plate26on the top concrete layer3is introduced from the wheels8into the longitudinal bridge girder5. Alternatively, it would also be possible to install supports and to lift the wheels8before the top concrete layer3is introduced. This may also be of advantage as the supports may be accommodated in the recesses16having smaller dimensions than the recesses16required for the accommodation of the wheels8.

A second embodiment of the method according to the invention is depicted in theFIGS.14to18. According toFIG.14, there are produced on an assembly site31on a framework23three segments17of a bottom layer2having cross beams21, which are arranged in the transverse direction in regard to the longitudinal axis of the longitudinal bridge girder5. In the three segments17of the bottom layer2, 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 constructions29are arranged between the segments17. The support constructions29are composed of steel tubes welded to the mounting girders20. At the upper end points of the support constructions29, there are mounted launching gantries30. The launching gantries20, for example, are configured as roller bearing or slide bearing such that a conveyor device30may be shifted on the launching gantries30in the longitudinal direction along the longitudinal bridge girder5and on the assembly site31.

After the concrete of the bottom layer2has hardened, a conveyor device10will be moved to the assembly site31, the three segments17of the bottom layer2will be attached using tendons11to the conveyor device10, will be lifted and transported to the installation site32. According toFIG.15, the three segments17of the bottom layer2are lowered at the installation site32in such a way that the edges of the segments17are supported on the steel girders9of the longitudinal bridge girder5.

FIG.15shows that there are formed by the three segments17of the bottom layer2two cantilevering slabs and a slab arranged between the two steel girders9of the longitudinal bridge girder5. These three slabs should be separated from one another to make it possible to convey the conveyor device10in the longitudinal direction of the bridge4and to lower the bottom layer2.

For this reason it is also not possible to lay the entire reinforcement at the assembly site31. The upper transverse reinforcement required for connecting the cantilevering slabs and the slab arranged between the steel girders9of the longitudinal bridge girder5may only be laid at the installation site32after the bottom layer2has been lowered.

A bridge4comprising two abutments33, five pillars34and one longitudinal bridge girder5is depicted in the illustrationsFIGS.16to18. As shown inFIG.16, the support constructions29are mounted on the longitudinal bridge girder5and on the assembly site31, which is situated on one of the two abutments33. The conveyor device10, which is configured as a spatial frame construction49, is moved with the aid of winches to the assembly site31, which is here arranged above one of the two abutments33. At the assembly site31, the bottom layer2is attached by means of tendons11to the conveyor device10. The bottom layer2is mounted in a lifted superelevated position to prevent any contact with the bracing means6mounted on the longitudinal bridge girder5when conveying the conveyor device10in the longitudinal direction of the bridge4and to make it possible to drive on the top concrete layer3of construction sections already completed of a deck slab1.

According toFIG.17, the conveyor device10and the bottom layer2suspended therefrom are moved from the assembly site31to the scheduled installation site32in the next method step. At the installation site32, the bottom layer2is lowered until the edges of the segments17of the bottom layer2rest on the upper flanges of the steel girders9of the longitudinal bridge girder5. Then the top concrete layer3may be applied. After the top concrete layer3has been hardened, the tendons11are released from the bottom layer2and the conveyor device10is conveyed to the assembly site31, such that the bottom layer2may be mounted for the next construction section at the conveyor device10.

The assembly site31is situated in this embodiment example on an abutment33. It may also be advantageous that the assembly site31is moved to the bridge4after the first sections of the deck slab1have been produced.

According toFIG.18all support constructions29are removed after the production of the deck slab1by cutting off the steel profiles in the vicinity of the surface of the top concrete layer3. Subsequently, the bridge4is completed in the usual manner by applying a sealing onto the surface of the top concrete layer3and by subsequently applying a deck cover.

A third embodiment of the method according to the invention is depicted in the illustrationsFIGS.19to22.

FIG.19shows a vertical section through a conveyor device10, which is configured as a spatial frame construction49, and through a bottom layer2composed of three segments17, during the transport from the assembly site31to the installation site32. The conveyor device10is moved on launching gantries30, which are mounted on support constructions29. The three segments17of the bottom layer2are produced at the assembly site31having cross beams21. Within the cross beams21, there are installed cladding tubes38, which are installed in the bracing wire produced in a later step.

During transport to the installation site31, the segment17arranged between the steel girders9is in a raised position to prevent collision with the bracing means6welded to the steel girders9and the construction sections already completed of the deck slab1. The segment17depicted inFIG.19at the left hand-side is in a raised and laterally shifted outwards position during the transport of the bottom layer2to the installation site32in order prevent a collision of the cross beams21with the support constructions28and the bracing means6. The segment17depicted inFIG.19at the left-hand side is in a raised and turned position during the transport of the bottom layer2to the installation site32to prevent a collision of the cross beams21with the support construction29and the bracing means6.

At the installation site32, the three segments17of the bottom layer2are brought into the scheduled position. According toFIG.20, there is required lowering the segment17arranged in-between the steel girders9, lowering and shifting transversally to the right the segment17arranged inFIG.19at the left-hand side as well as lowering and turning the segment17arranged in theFIG.19at the right-hand side. The scheduled position depicted inFIG.20is reached when the upper edges of the cross beams21are in a horizontal position and when the front faces of the cross beams21touch. 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 toFIG.21, a conveyor device10is mounted on launching gantries30. The launching gantries30are, for example, configured as roller bearings or as sliding bearings such that the conveyor device10may be shifted in the longitudinal direction along the longitudinal bridge girder5of the bridge4. The launching gantries30are attached at the upper end points of support constructions29. The support constructions29, which herein are configured as steel profiles, are connected in a flexurally rigid manner to the upper flanges of the steel girders9of the longitudinal bridge girder5. The bottom layer2is depicted inFIG.21in a raised or superelevated, respectively, position and inFIG.2in a lowered position. In the superelevated position, the bottom layer2should be raised so much so that it is possible to drive on the bracing means6and the top concrete layer3of construction sections already completed. In the lowered position according toFIG.22, the wheels of the bottom layer2are supported on the upper flanges of the steel girders9of the longitudinal bridge girder5.FIG.21shows that within the cross beams21, which are connected to the segments of the bottom layer2, there are arranged cladding tubes38.

According toFIG.22, the segment depicted at the left-hand side ofFIG.19of the bottom layer2is moved as far to the right until the front faces of the cross beams21touch one another. If the front faces of the cross beams21have 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 tubes38and a grouting joint would be possible. After the segments of the bottom layer2have been accurately aligned, the top concrete layer3is produced. Subsequently, bracing wires39are inserted into the cladding tubes38. By tensioning the bracing wires39, a transverse preload may be applied onto the deck slab1.

According toFIG.22, the steel profiles of the support constructions29are embedded into concrete when applying the top concrete layer3. The tendons11are protected by means of a sheath tube37against direct contact with the top concrete layer3. This enables removal of the tendons11after the top concrete layer3has been hardened and re-use of the tendons11in the next construction section. The steel profiles are cut off in the vicinity of the surface of the top concrete layer3after the top concrete layer3has been hardened and the launching gantries30have been disassembled.

A fourth embodiment of the method according to the invention is depicted in the illustrationsFIGS.23to30.

FIG.23shows a vertical section through a conveyor device10, which is configured as a spatial frame construction49, and a bottom layer3composed of three segments17at the installation site32. The three segments17of the bottom layer2are attached at the conveyor device10by means of tendons11. The segments17are in this embodiment example not supported on the longitudinal bridge girder5composed of two prestressed concrete beams40but rather positioned next to the prestressed concrete beams40. This has the advantage that the longitudinal bridge girder5may be configured having a larger statically effective depth. After the bottom layer2having cross beams21has been positioned as scheduled, the three segments17are connected to one another via the prestressed concrete beams40by means of structural steel connections. In order to realize the structural steel connection, there are installed steel panels42within the cross beams21. At the installation site32, these steel panels42are connected to one another in a flexurally rigid manner with additional steel panels35and screw connections41. After the three segments17have been connected in a flexurally rigid manner, the tendons11are relaxed and dismantled. The conveyor device10is no longer required at the installation site32and may be moved back to the assembly site31.

FIG.24shows the installation site32after removal of the conveyor device10.

In the next working step according toFIG.25, the support constructions29and the launching gantries30are removed at the installation site. A first top concrete layer3is applied onto the bottom layer2. The weight of the top concrete layer3is introduced from the bottom layer2into the cross beams21and from these to the prestressed concrete beams40. The structural steel connection of the cross beams21should be able to absorb any stresses arising. If the first top concrete layer3reaches a predetermined concrete compression strength, there is applied according toFIG.26onto the first top concrete layer3a second top concrete layer3. After the concrete of the top concrete layers3has hardened, the bottom layer2, the cross beams21, the first top concrete layer3and the second top concrete layer3are to be considered a construction component produced in a monolithic way, in combination forming the deck slab1.

The detail E ofFIG.23is depicted inFIG.27andFIG.28, showing the structural steel connection of the two cross beams21. In the two cross beams21, there are installed steel panels42projecting beyond the front faces of the cross beams21. Upon lowering the bottom layer2and the cross beams21, the steel panels42are supported on the prestressed concrete beams40. Subsequently, there is produced by using two steel slabs35and screw connections41a flexurally rigid connection of the two cross beams21.

An alternative embodiment for producing a flexurally rigid connection of the two cross beams21is shown in theFIG.29and theFIG.30. There is installed in the prestressed concrete beam40a steel panel42. Front faces43are welded to the steel panel42at the left and right side. At the front faces of the cross beams21, there are attached front faces43made from steel, which are connected by means of starter bars not depicted in the cross beams21. Upon lowering the bottom layer2having the embedded cross beams21, there is produced a flexurally rigid connection of the cross beams21with the prestressed concrete beam40by way of the screw connections41. Such a connection may also be advantageous if only cantilevering segments17are to be connected to a longitudinal bridge girder5having a box-section-like cross-section.

A fifth embodiment of the method according to the invention is depicted in the illustrationsFIG.31toFIG.37.

According toFIG.31at the assembly site31three prefabricated elements47are laid on mounting beams20. Each prefabricated element47is composed of three prefabricated slabs50and one cross beam21configured as prefabricated beam27and connecting the three prefabricated slabs50one to another. The bottom layer2is formed in this mounting state of three segments17.

In the next working step, there is laid a reinforcement onto the bottom layer2and there is produced a first top concrete layer on the prefabricated slabs50. The three segments17of the bottom layer2are joined to one segment17by the first top concrete layer3.FIG.32shows the state at the assembly site31after the first top concrete layer3has been produced.

FIG.33shows the transport of the bottom layer2having cross beams21and a first top concrete layer3for a construction section of the deck slab1from the assembly site31to the installation site31. The transport is carried out using a conveyor device10. The conveyor device is composed of a front part44and a rear part45, which are configured as frame constructions49. The front part44and the rear part45of the conveyor device10are connected to one another by way of two longitudinal girders46. The conveyor device10is moved in the longitudinal direction of the bridge4on support constructions29, which are situated on longitudinal bridge girder5, which is in this example composed of two steel girders9. The weight of the bottom layer2having the cross beams21and the first top concrete layer3is introduced in this transport state into six tendons11. The lower end points13of the tendons11are arranged within the cross beams21. The upper end points13of the tendons11are attached at the top surface of hydraulic hollow piston jacks48. During transport, the bottom layer2having the cross beams21and the first top concrete layer3is in a raised position to prevent any contact of the cross beams21with the bracing means6, which are not depicted inFIG.33for reasons of clarity and mounted on the longitudinal bridge girder5, and to make it possible to drive on construction sections already completed of the deck slab1.FIG.33shows that the pistons51of the hollow piston jacks48are in an extracted position in order to be able to transport the bottom layer2having the cross beams21and the first top concrete layer in a raised position.

According toFIG.34, the pistons51of the hollow piston jack48are retracted at the installation site32to be able to lower the bottom layer20having the cross beams21and the first top concrete layer3into the scheduled final position. Immediately following the lowering operation, the lower end points13of the tendons11may be released and the conveyor device10may be moved from the assembly site32to the installation site31to pick up there a further bottom layer2having cross beams21and a first top concrete layer3for a further construction section of the deck slab1. At the installation site32, immediately after the conveyor device10has 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 layer3may be applied. The weight of the additional reinforcement and of the second top concrete layer3is absorbed by the bottom layer2, the cross beams21and the first top concrete layer3. In order to reach the goal of the bottom layer2, the cross beams21and the two top concrete layers3in the final condition of the deck slab1behaving like a construction section produced in one pour, it is necessary to configure the surfaces rough and to provide the necessary starter bars.

A bridge4comprising two abutments33, five pillars34and one longitudinal bridge girder5is depicted in the illustrationsFIG.35toFIG.37. As shown inFIG.35, the support constructions29are mounted on the longitudinal bridge girder5and the assembly site31, which is situated on one of the two abutment33. The conveyor device10is composed of a front part44and a rear part45, which are connected to one another by two longitudinal girders46. On the assembly site31, the bottom layer2having the cross beams21and the first top concrete layer3is raised by extracting the pistons51of the six hollow piston jacks48. The bottom layer2having the cross beams21and the first top concrete layer3is arranged in this condition between the front part44and the rear part45and underneath the longitudinal girders46of the conveyor device10.

According toFIG.36, the bottom layer2having the cross beams21and the first top concrete layer3is moved in the next method step from the assembly site31to the installation site32. At the installation site32, the bottom layer2having the cross beams21and the first top concrete layer3is lowered until the cross beams31are supported on the top surface18of the longitudinal bridge girder5. To enable the lowering operation of a bottom layer2composed of a segment17and having cross beams21and a first top concrete layer3at the installation site32, there must not be arranged any construction elements for connecting the front part44and the rear part45of the conveyor device10underneath the segment17.

Immediately following the lowering operation, the lower end points13of the tendons11may be released from the cross beams21and the conveyor device10may be moved from the installations site32back to the assembly site31to pick up there a further bottom layer2having cross beams32and a first top concrete layer3for a further construction section of the deck slab1.

In this embodiment example it is particularly advantageous that at the installation site32it is not necessary to wait for the top concrete layer3to harden. The conveyor device10may be moved away from the installation site32immediately after the bottom layer2having the cross beams21and the first top concrete layer3has been lowered. In this way it is possible to produce one construction section of the deck slab1per day. Producing the second top concrete layer3is independent of the bottom layer2having cross beams31and first top concrete layer being laid and may be realized at any point of time.

According toFIG.37, after the production of the deck slab1, all support constructions29are removed by cutting off the steel profiles in the vicinity of the surface of the top concrete layer3. Subsequently, the bridge4is completed in the usual manner by applying a sealing onto the surface of the top concrete layer3and subsequently applying a deck cover.

A sixth embodiment of the method according to the invention is depicted in the illustrationsFIG.38andFIG.39.

The bottom layer2having cross beams21is produced at the assembly site31on a framework23. The bottom layer2having cross beams21is composed in this embodiment example of one segment17, as the three cross beams21extend across the entire width of the deck slab1to be produced and, in this way, a continuous construction component is being developed.FIG.38shows the transport of the bottom layer2having cross beams21for a construction section of the deck slab1from the assembly site31to the installation site32. In this embodiment example raising the bottom layer2having the cross beams21is realized by extracting the pistons51of the hollow piston jacks48, which are arranged between the longitudinal girders46and the front part44or the rear part45, respectively, of the conveyor device10.

According toFIG.39, the pistons51of the hollow piston jacks48are retracted at the installation site to be able to lower the bottom layer2having the cross beams21into the scheduled final position. Immediately after depositing the bottom layer2having the cross beams31at the installation site32, the lower end points13or the upper end points12of the tendons11may be released and the conveyor device10may be moved to the assembly site to pick up a further bottom layer2having cross beams21for a further construction section of the deck slab1.

LIST OF REFERENCES

1deck slab2bottom layer3top concrete layer4bridge5longitudinal bridge girder6bracing means7lane8wheel9steel girder10conveyor device11tendon12upper end point of a tendon13lower end point of a tendon14anchor15device16recess17segment of a bottom layer18top surface of a longitudinal bridge girder19bottom surface of a bottom layer20mounting girder21cross beam22strip23formwork24gap25bottom surface of a bottom layer26ribbed base plate27prefabricated beam28longitudinal edge beam29support construction30launching gantry31assembly site32installation site33abutment34pillar35steel slab36threaded nut37sleeve tube38cladding tube39bracing wire40prestressed concrete beam41screw connection42steel panel43front slab44front part of a conveyor device45rear part of a conveyor device46longitudinal girder of a conveyor device47prefabricated element48hollow piston jack49frame construction50prefabricated slab51piston