JP4329535B2 - Mobile work vehicle for overhanging slabs - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a mobile work vehicle for an extended floor slab for placing casted floor slabs on both sides of a central part of a main girder in a bridge with struts such as a PC box girder bridge with struts or a bridge without struts. Is.

  The PC box girder bridge with struts is a type of box girder bridge that supports the overhanging slab with diagonal struts arranged at equal intervals in the bridge axis direction, and the width of the overhanging slab is wider than the conventional PC box girder bridge The cross-sectional area of the main girder can be reduced, and the superstructure can be lightened. For such PC box girder bridges with struts, in the case of wide main cross-section girder with wide width, the cross-section precast segment construction method is used in which the main girder is divided into three in the direction perpendicular to the bridge axis. Is manufactured and installed as a precast core segment, and the remaining overhanging slab is manufactured and installed as a precast overhanging slab, or the overhanging slab is cast in place (Patent Documents 1 to 3).

  Conventionally, mobile work vehicles have been used for the construction of floor slabs, all of which are mechanisms for suspending a formwork from an upper frame. FIG. 9 (a) shows an example in which the overhanging floor slabs 2 are cast in place on both the left and right sides of the precast core segment 1 in the cross-section precast segment method of the PC box girder bridge with struts. A mold 51 is installed on a lower scaffold 50 suspended by a suspension material.

  FIG. 9B shows an example in which the overhanging slab 2 is installed in place while the strut 3 is attached to the existing precast core segment 1 using the mobile work vehicle 60. The strut 3 needs to be supported until the concrete is placed, and the strut support frame 62 is installed on the lower surface scaffold 61.

In addition, as a prior art document related to the present invention, a moving support work method for a bridge floor slab overhang part in which a steel slab concrete overhang part slab work is carried out by a mobile support work (Patent Document 4), articulated joint There are a mobile support using a structural formwork (Patent Document 5) and a bridge floor slab overhanging mobile support work (Patent Document 6) of a type in which a slide formwork is supported by a main girder.
JP 2001-164512 A JP 2001-164513 A JP 2001-336117 A JP 2000-265417 A JP 2003-293319 A JP 2001-146718 A

  In the case of the above-described conventional mobile work vehicle, the formwork is suspended from the upper frame, so that the rigidity of the upper frame is increased to limit the bending of the formwork, and the weight of the mobile work vehicle is increased.

  In addition, when the gantry supporting the struts is assembled from the bottom scaffold of the mobile work vehicle in the bridge with the struts, the weight of the mobile work vehicle increases. Further, when the mobile work vehicle moves to the next block, in order to avoid interference between the attached strut and the support frame, it is necessary to partially disassemble or jack down the support frame, which reduces work efficiency.

  The present invention has been made to solve such problems, and in a bridge with a strut such as a PC box girder bridge with a strut or a bridge without a strut, an overhanging floor slab is placed in place on both sides of the central part of the main girder. The rigidity of the upper frame of the mobile work vehicle to be installed can be kept small, making it possible to reduce the weight of the mobile work vehicle. In addition, it is not necessary to provide a separate strut support for the mobile work vehicle in a bridge with struts. An object of the present invention is to provide a mobile work vehicle for an overhanging slab that can reduce the weight of the vehicle and that does not interfere with an existing strut and its support frame when the mobile work vehicle is moved, thereby improving work efficiency.

Claim 1 of the present invention is a mobile work vehicle for cast-in-place a floor slab on both sides of the upper part of the central part of the main girder, and an outer frame suspended from both sides of the upper frame and the upper frame. and the main digit cross section moving shoring frame which is formed in a substantially gate-shaped when viewed from the front surrounding from above is installed to be traveling by the traveling device on the main girder central portion of the existing, the overhanging deck to the outer frame A temporary strut is attached to the side of the lower part of the central part of the main girder, and a temporary strut is detachably connected to the lower part of the central part of the main girder. moved on the main girder central portion as the tip of the temporary strut by fixing the bottom side of the main girder central portion, it is characterized in that the said temporary struts and adapted to support the outer frame It is an overhanging deck for a mobile work vehicle.

  The invention of claim 1 is applied to a bridge with a strut such as a PC box girder bridge with a strut or a bridge without a strut. It can also be applied to post-installation of overhanging slabs and widening of bridges. The overhanging slab is driven for each overhanging portion placing block having a predetermined length, and the support frame has a length corresponding to the overhanging portion placing block in the bridge axis direction. Therefore, a plurality of temporary struts are arranged at predetermined intervals in the bridge axis direction. In the case of a bridge with a strut, it is arranged at the position of the main strut in order to be used as a strut support frame as described later. Moreover, it is preferable that the temporary struts are arranged obliquely with their lower ends fixed detachably to the lower part of the existing central part of the main girder and their upper ends fixed to the middle in the vertical direction of the outer frame.

  In the construction as described above, the lower end of the temporary strut is fixed to the center of the existing main girder when the overhanging slab is installed, and the reaction force is taken from the center of the existing main girder by this temporary strut, thereby The amount of deformation can be suppressed, whereby the rigidity of the upper frame can be reduced, and the weight of the mobile work vehicle can be reduced. When the lower end of the temporary strut is fixed, the mobile work vehicle can be moved to the next overhanging portion placing block.

  According to a second aspect of the present invention, in the mobile work vehicle for the overhanging floor slab according to the first aspect, a lower scaffold that extends horizontally toward the center portion of the main girder is provided at the lower portion of the outer frame. This is a mobile work vehicle for overhanging slabs. The temporary strut can be mounted on the lower scaffold, and the temporary strut lowered and retracted during the movement can be carried on the lower scaffold.

  According to a third aspect of the present invention, in the mobile work vehicle for the overhanging floor slab according to the first or second aspect, the hinge mechanism for supporting the formwork so that the base of the formwork of the overhanging floor slab can rotate in the vertical direction. It is a mobile working vehicle for an overhanging slab characterized by being attached to the outer frame via By rotating down or up around the hinge mechanism, the mold can be easily attached and removed. In the case of a bridge with a strut, the mold can be easily retracted to the lower side of an existing main strut when moving. The part of the formwork where the main struts are arranged is a space, and after the main struts are installed, the part is closed with a space formwork.

  According to a fourth aspect of the present invention, in the mobile work vehicle for an extended floor slab according to any one of the first to third aspects, the hinge mechanism in which the base portion of the temporary strut supports the temporary strut so as to be rotatable in the vertical direction. This is a mobile work vehicle for an overhanging slab characterized in that a pressing member (screw jack or the like) that is attached to the outer frame via the front and rear and extends and contracts at the tip of the temporary strut is provided. The temporary strut can be easily attached and detached by rotating and lowering or rotating up around the hinge mechanism and attaching and detaching with a pressing member. In the case of a bridge with a strut, the temporary strut can be easily retracted below the existing main strut during the movement.

  According to a fifth aspect of the present invention, in the mobile work vehicle for an overhanging floor slab according to any one of the first to fourth aspects, a back scaffold located at a lower portion of the formwork is provided integrally with the temporary strut. This is a mobile work vehicle for an overhanging floor slab. Work on the back of the formwork is possible simultaneously with the installation of the temporary struts.

  According to a sixth aspect of the present invention, in the mobile work vehicle for an overhanging slab according to any one of the first to fifth aspects, the bridge supports the overhanging slab with a permanent strut extending along a direction perpendicular to the bridge axis. A mobile work vehicle for an overhanging slab, characterized in that it is a bridge with struts, and the temporary struts are guide struts that guide and support the main struts.

  That is, in the case of a PC box girder bridge with struts, a temporary strut is used instead of the support strut of the main strut. The main struts transported in the direction of the bridge axis are hung on the guide struts, guided, supported, and positioned, and the lower ends of the main struts are joined to the center of the existing main girder. The upper end of the main strut is joined and integrated with the tip of the overhanging slab by placing concrete in the formwork.

  As described above, if the temporary struts are used to support the main struts, it is not necessary to provide a separate strut support frame, and the mobile work vehicle can be further reduced in weight. By simply removing the temporary struts, interference with the existing main struts is avoided, so that the movement can be performed easily and quickly, and the working efficiency can be improved.

  According to a seventh aspect of the present invention, in the mobile work vehicle for an extended floor slab according to the sixth aspect, the temporary struts are disposed between the pair of guide struts and a pair of guide struts spaced apart in the bridge axis direction. A movable working vehicle for an overhanging slab, comprising a guide roller for guiding and supporting the main strut so as to be movable in a direction perpendicular to the bridge axis. The guide rollers are arranged at two positions in the longitudinal direction of the guide strut, that is, the upper and lower portions in the direction perpendicular to the bridge axis, corresponding to the mounting inclination angle of the main strut. The guide roller is preferably provided with a position adjusting device in the direction of the bridge axis and the direction perpendicular to the bridge axis. The main strut can be set in a predetermined inclined mounting state simply by suspending and placing the main strut on the guide roller between the guide struts.

  (1) In a mobile work vehicle in which overhanging floor slabs are cast in place on both sides of the upper part of the main girder central part, a pair of left and right outer frames of a substantially gate-shaped moving support frame in front view are connected to the central part of the main girder. By supporting with a temporary strut whose tip is detachably connected to the side surface in the lower part, the deformation amount of the formwork can be suppressed, and thereby the rigidity of the upper frame can be reduced, and the weight of the mobile work vehicle is reduced. Can be achieved.

  (2) In the case of a bridge with struts, a temporary strut is composed of a pair of guide struts and guide rollers, and the temporary struts are used to support the main struts. The mobile work vehicle can be further reduced in weight. Furthermore, since the interference with the existing main strut can be avoided simply by removing the temporary strut, the movement can be performed easily and quickly, and the working efficiency can be improved.

  Hereinafter, the present invention will be described based on the illustrated embodiments. This embodiment is an example of a mobile work vehicle for an overhanging slab in which the overhanging slab is installed in place in the cross-section precast segment construction method of a PC box girder bridge with struts. FIG. 1 is a front view showing an embodiment of a mobile work vehicle for an overhanging slab of the present invention.

  In FIG. 1, a PC box girder bridge with struts is composed of a precast core segment 1 having a cross-sectional box shape constituting a central portion of a main girder, and an overhanging floor slab 2 that is placed on both the left and right sides in the upper part of the core segment 1 The overhanging slab 2 is supported by struts 3 that are configured and arranged in parallel to the direction perpendicular to the bridge axis and are arranged at a predetermined interval in the bridge axis direction. On both sides of the upper portion of the core segment 1, an overhanging portion 1 c continuous with the floor slab portion 1 a is integrally projected outward, and the base end of the overhanging floor slab 2 is provided at the distal end of the overhanging portion 1 c. The part is joined and integrated by the joining part 4 using an anchor or the like.

  As the strut 3, a precast concrete member, a steel pipe, a concrete-filled steel pipe, an H-shaped steel, or the like is used. The lower end of the strut 3 is joined and integrated by a joint portion 5 using an anchor or the like to an attachment portion 1d having a triangular cross section protruding from the outer surface of the bottom plate portion 1b of the core segment 1. The upper end of the strut 3 is joined and integrated by a joining portion 6 using an anchor or the like to a mounting section 2a having a triangular cross section that is formed to protrude from the lower surface of the front end portion of the overhanging slab 2.

  The precast core segment 1 is installed by, for example, a span-by-span construction method, and the strut 3 is attached to the existing precast core segment 1 and the cast-in-place construction of the extended floor slab 2 is predetermined using the movable work vehicle 10 for the extended floor slab. It is carried out for each length projecting block. 2 is a front view and a side view of the mobile work vehicle of FIG. FIG. 3 is a side view of the mobile work vehicle of FIG. 1 with the outer frame removed, and a plan view with the upper frame removed. FIG. 4 is a plan view showing the upper frame of the mobile work vehicle of FIG.

  As shown in FIGS. 1 to 4, the mobile work vehicle 10 for the overhanging floor slab has a gate structure in a front view and a length of a mobile support frame 11 corresponding to the overhanging portion placing block in the bridge axis direction. In addition, the mold 12, the temporary struts 13, the back surface scaffold 14, and the lower surface scaffold 15 are installed.

  The movable support frame 11 is mainly composed of an upper frame 16, a pair of left and right outer frames 17, and a pair of left and right support frames 18, and travels in the bridge axis direction by a traveling device 19 provided at the lower part of the support frame 18. To do. The upper frame 16 is configured by arranging a plurality of truss transverse beams 20 parallel to the direction perpendicular to the bridge axis at intervals in the bridge axis direction and connecting and integrating them with a connecting material, and a roof 21 is provided on the upper surface thereof.

  The outer frame 17 is suspended from both the left and right sides of the upper frame 16, and a suspension member 22 such as H-shaped steel suspended from the end of each truss transverse beam 20 of the upper frame 16 is connected and integrated with a coupling material. It is configured. The upper part of the suspension material 22 and the truss horizontal beam 20 are connected and reinforced by an oblique material 23. A seat wall 24 is provided outside the outer frame 17.

  The support frame 18 is constituted by connecting and integrating struts 25 suspended from the intermediate portion of each truss horizontal beam 20 with a connecting material. Diagonal members 26 are provided on both left and right sides of the support column 25 to reinforce them. A traveling device 19 is provided below each column 25. The traveling device 19 is a wheel or roller system, and is guided by a rail 27 (see FIG. 3) such as a grooved steel laid on the upper surface of the existing core segment 1. The movement is performed by an electric winch 28 for traveling and a manual winch 29 for rubbing (see FIG. 3 (a)). The traveling / driving method is not limited to the illustrated example, and other methods may be used.

  As shown on the left side of FIG. 1, the mold frame 12 and the temporary strut 13 are attached to the vertical middle portion of the outer frame 17 via the hinge mechanism 30 and supported so as to be rotatable in the vertical direction. Yes. The mold frame 12 is rotated upward from the state of being retracted downward, and the tip end portion of the mold frame 12 is suspended and fixed by the suspension bolts 31 provided on the overhanging portion 1c of the existing core segment 1. Become. The intermediate portion of the mold 12 is also supported by the suspension material 32.

  The temporary strut 13 is also rotated upward from the retracted state, and the tip end portion is fixed to the corner portion on the triangular section mounting portion 1d of the existing core segment 1 to be in an oblique support state. 17 is supported by the existing core segment 1. For example, a screw jack 33 is provided at the tip of the temporary strut 13 as a pressing member that expands and contracts so that the temporary strut 13 can be easily attached and detached.

  Here, the mold 12 is disposed over the entire length of the overhanging portion placement block B shown in FIG. 3 (a). After setting the mold 12 and before placing concrete, It is necessary to suspend and attach the strut 3. Therefore, as shown in FIG. 3 (b), the mold frame 12 is not provided with the mold frame 12a by the hinge mechanism at the position of each main strut 3 (each temporary strut 13). As shown in FIG.

  As shown in FIGS. 1 and 3 (b), the back surface scaffold 14 is fixed to the temporary strut 13 via a support member 34 so as to be positioned below the mold 12a by the hinge mechanism. Is set to rotate upward, it is arranged in parallel below the mold 12a so that various operations can be performed on the back of the mold.

  As shown in FIG. 1, the lower surface scaffold 15 is provided at the lower part of the outer frame 17 so as to extend horizontally toward the existing core segment 1, and is reinforced with a diagonal member 35 at the position of the suspension member 22. Such a lower surface scaffold 15 is disposed over the entire length of the overhanging portion placing block as shown in FIG. 3 (b). The equipment on the lower surface scaffold 15 shown on the left side of FIG.

  As shown in FIG. 4, the main strut 3 is loaded onto the existing extended floor slab 2 by a truck up to the mobile work vehicle 10 for the extended floor slab, and is arranged on the lower surface of the upper frame 16 in parallel with the bridge axis direction. The chain block rail 37 and the chain block 38 (see FIG. 1) traveling along the rail are transferred to a predetermined main strut mounting position.

  The temporary strut 13 is used to reduce the weight of the work vehicle while suppressing the amount of deformation of the formwork by taking the reaction force from the existing girder. It can also be used as a guide strut. 5 to 7 show one embodiment. 5 is an overall front view, FIG. 6 is an upper partial front view and a sectional view, and FIG. 7 is a lower partial front view and a sectional view.

  As shown in FIGS. 5 to 7, the temporary strut 13 includes a pair of guide struts 40 that are parallel to the direction perpendicular to the bridge axis and at a predetermined interval in the bridge axis direction, an upper main strut support device 41, and a lower part. The main strut support device 42 is configured such that the main strut 3 suspended by a chain block or the like is inserted between the pair of guide struts 40 and can be held in a predetermined inclined mounting state. Yes.

  That is, as shown in FIGS. 6 and 7, the upper and lower main strut support devices 41 and 42 are provided with a pair of guide rollers 43 for guiding and supporting the main strut 3 so as to be movable in the direction perpendicular to the bridge axis. It is provided between the struts 40. When the cross section of the main strut 3 is circular, the drum-shaped guide roller 43 having an arc surface corresponding to the circular cross section is used, and the suspended main strut 3 is slid toward the core segment 1 while being guided, The lower end portion can be brought into contact with the inclined surface of the mounting portion 1d.

  As shown in FIGS. 6 and 7, the guide roller 43 is rotatably attached to a support shaft 44 parallel to the bridge axis direction, and both ends of the support shaft 44 are supported by support levers 45 that can be tilted in the vertical direction. To do. In the upper main strut support device 41, the base end portion of the support lever 45 is rotatably fixed to the guide strut 40 with a pin so that the guide roller 43 is positioned above the guide strut 40, and the upper main strut support device is supported. In the device 42, the base end of the support lever 45 is rotatably fixed to the guide strut 40 with a pin so that the guide roller 43 is positioned below the guide strut 40, and the main strut 3 is supported at a predetermined mounting inclination angle. It can be so.

  The pair of guide struts 40 and both ends of the support shaft 44 are respectively connected by a screw jack type vertical direction adjusting device 46, and the upper and lower support shafts 44 are vertically adjusted so that the main struts are positioned. The mounting inclination angle of 3 can be adjusted. Furthermore, the support shaft 44 is also provided with a screw jack type horizontal adjustment device 47, and the position of the main strut 3 in the bridge axis direction can be adjusted by adjusting the position of the guide roller 43 in the horizontal direction.

  FIG. 8 shows the work by the extended floor slab mobile work vehicle 10 configured as described above in the order of steps, and the work is performed according to the following procedure. The precast core segment 1 is manufactured at an on-site manufacturing yard or the like, and is constructed by, for example, a span-by-span construction method, and a main girder central portion is formed by tensioning with a PC steel material in the main direction.

  (1) The construction of the overhanging floor slab of the previous overhanging portion placing block is completed, the temporary strut 13 is rotated and lowered to the retracted state, and the lower end portion thereof is supported on the lower surface scaffold 15. The back scaffold 14 integrated with the temporary strut 13 is also in a descending and retracting state. The formwork 12 is also in the lowered and retracted state and is supported by the temporary struts 13. In this state, the formwork 12, the temporary struts 13, and the back scaffold 14 are positioned below the already installed main struts 3, and the extended floor slab mobile work vehicle 10 is obstructed to the next overhanging portion placing block. It can be moved without.

  (2) When the movement of the extended floor slab mobile work vehicle 10 is completed, the entire scaffold (form 12, temporary strut 13, back scaffold 14) is lifted by lifting the back scaffold 14 using a chain block or the like to temporarily install it. The temporary struts 13 are fixed by pressing the screw jacks 33 of the struts 13 against the corners on the mounting portions 1d having a triangular cross section of the existing core segment 1.

  (3) The formwork 12 is slightly raised using a chain block or the like and temporarily fixed.

  (4) Using the space of the space between the molds, the transported main strut 3 is suspended on the temporary strut 13 using a chain block or the like and slid along the pair of guide struts 40. After holding and adjusting the position as necessary, the lower end portion of the main strut 3 is fixed to the attachment portion 1d.

  (5) Assemble the padded formwork on the main strut 3, adjust the formwork, fix the formwork, and then assemble the rebar.

  (6) Concrete is cast on the mold 12 fixed by the suspension bolts 30 and the suspension members 31 to form the overhanging slab 2. By repeating the above steps for each overhanging portion placing block, the overhanging floor slab 2 supported by the strut 3 is installed.

  In addition, although the above demonstrated the cross-section division type precast segment construction method of the PC box girder bridge with a strut, it can apply also to a bridge with other struts, and a bridge without a strut. It can also be applied to post-installation of overhanging slabs and widening of bridges.

It is a front view which shows one Embodiment of the mobile work vehicle for the overhanging floor slab of this invention. FIG. 1A is a front view and FIG. 2B is a side view showing the entire mobile work vehicle for an overhanging slab of FIG. 1. FIG. 1A is a side view of the mobile work vehicle of FIG. 1 excluding an outer frame, and FIG. It is a top view which shows the upper frame of the mobile work vehicle of FIG. It is an enlarged front view which shows the temporary strut part of the mobile work vehicle of FIG. FIG. 5A is a partial front view and FIG. 5B is a cross-sectional view showing a permanent strut support device at an upper portion of the temporary strut of FIG. 5. FIG. 5A is a partial front view and FIG. 5B is a cross-sectional view showing a permanent strut support device below the temporary strut of FIG. 5. It is a partial front view which shows the operation | work by the mobile work vehicle for overhanging floor slabs of this invention in order of a process. It is the conventional mobile work vehicle for an overhanging floor slab, (a) is a partial front view which shows an example, (b) is a front view which shows another example.

Explanation of symbols

1 …… Center part of main girder (precast core segment)
DESCRIPTION OF SYMBOLS 1a ... Floor slab part, 1b ... Bottom slab part, 1c ... Overhang part, 1d ... Mounting part 2 ... Overhang floor slab, 2a ... Mounting part 3 ... Main strut 4, 5, 6 ... Joining part 10 ... Overhang Moving work vehicle for floor slab 11 …… Moving support frame 12 …… Formwork 13 …… Temporary strut 14 …… Back scaffold 15 …… Lower scaffold 16 …… Upper frame 17 …… Outer frame 18 …… Support frame 19… ... traveling device 20 ... truss cross beam 21 ... roof 22 ... hanging material 23 ... diagonal material 24 ... seat wall 25 ... post 26 ... slanting material 27 ... rail for traveling 28 ... electric winch 29 ... ... Manual winch 30 ... Hinge mechanism 31 ... Suspension bolt 32 ... Suspension member 33 ... Screw jack 34 ... Support member 35 ... Diagonal member 36 ... Lifting equipment 37 ... Chain block rail 38 ... Chain block 40 ...... Guide strike 41 ... Upper main strut support device 42 ... Lower main strut support device 43 ... Guide roller 44 ... Support shaft 45 ... Support lever 46 ... Vertical adjustment device 47 ... Horizontal adjustment apparatus

Claims (7)

A mobile work vehicle for erection place concrete overhangs deck on both sides of the upper portion of the main girder central portion, the upper main girder cross section with an outer frame which is vertically provided from both sides of the upper frame and the upper frame A moving support construction frame formed in a substantially gate shape in front view surrounding from is installed so that it can be run by a traveling device on the center part of an existing main girder , and a formwork of an overhanging floor slab is attached to the outer frame , A temporary strut whose tip is detachably connected to the side surface at the lower portion of the main girder central portion is installed, and the tip of the temporary strut is removed from the lower side surface of the main girder central portion so as to be in a retracted state over the central portion of the main girder. the moved, the tip of the temporary strut by fixing the bottom side of the main girder central, overhanging deck for moving operation, characterized in that the said temporary struts and adapted to support the outer frame Car.   The extended floor slab mobile work vehicle according to claim 1, wherein a bottom scaffolding that extends horizontally toward the center portion of the main girder is provided at a lower portion of the outer frame. car.   3. A mobile work vehicle for an overhanging floor slab according to claim 1 or 2, wherein the base of the formwork of the overhanging floor slab is attached to the outer frame via a hinge mechanism that rotatably supports the formwork. A mobile work vehicle for overhanging floor slabs.   4. The extended floor slab mobile work vehicle according to claim 1, wherein the base of the temporary strut is attached to the outer frame via a hinge mechanism that rotatably supports the temporary strut in the vertical direction. A movable working vehicle for an overhanging slab, wherein a pressing member that expands and contracts is provided at the tip of the temporary strut.   The overhanging floor working vehicle according to any one of claims 1 to 4, wherein a back scaffold located at a lower portion of the formwork is integrally provided on the temporary strut. Mobile work vehicle for floor slabs.   The mobile work vehicle for an overhanging slab according to any one of claims 1 to 5, wherein the bridge is a bridge with a strut that supports the overhanging slab with a main strut extending in a direction perpendicular to the bridge axis. A mobile working vehicle for an overhanging slab, wherein the strut is a guide strut that guides and supports the main strut. The mobile work vehicle for an overhanging slab according to claim 6, wherein the temporary struts are disposed between the pair of guide struts at a distance in the bridge axis direction and the main struts are perpendicular to the bridge axis. A mobile work vehicle for an overhanging slab, comprising a guide roller that guides and supports it so as to be movable in a direction.

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