JP6755172B2 - Floor slab renewal method - Google Patents

Description

The present invention relates to a method of replacing (renewing) an existing floor slab of a road having a steel main girder, for example, an RC slab (Reinforced-Concrete slab) with a new slab, for example, a steel slab.

When updating the floor slab, it has been common practice to update the entire width of the road (full-width construction method), but since this construction method updates the full width of the road at the same time, the road must be closed. There is a problem that the impact on traffic volume is large and the impact on logistics is also large. In addition, the traffic volume has increased compared to when the existing bridge was installed, and the traffic load has increased accordingly, and the design standards have changed, so the slab thickness will be thicker than before. As a result, the overall load has increased, and if the RC deck designed according to the previous standards is replaced with the RC deck designed according to the latest standards, it will be necessary to reinforce the steel main girder. On the other hand, when the floor slab is renewed, if the stress of the steel main girder remains, there is a concern that the amount of reinforcement to the steel girder will increase when the floor slab is renewed.

To solve the above problem, a division method (half-width method) in which the cross section of the road is divided into two parts and half-width is constructed, and a floor slab for that purpose have been invented so as to reduce the influence on the traffic volume as much as possible (half-width method). Patent Document 1). The half-width construction method regulates traffic in some lanes of the steel bridge, releases traffic in other lanes, updates the floor slab on the side that regulates traffic, and then switches traffic regulation and release to the opposite lane. Since it is a construction method that renews the floor slab on the side that regulates traffic after switching, restrictions on traffic volume are reduced compared to the full-width construction method. Here, the steel bridge refers to a structure composed of a beam-shaped steel main girder, a steel cross girder, and various floor slabs.

Conventionally, a method of reducing the stress of the steel main girder by using an outer cable when updating the floor slab has been proposed (Patent Document 2). In this method, the cable fixing bracket is frictionally welded to the girder using a high-tensile vise, the cable is arranged in the direction of the bridge axis, and a tension is applied to this cable to give a negative bending moment to the girder. It is a construction method that introduces the prestress necessary for producing. However, this method has rarely been implemented so far. The steel main girder was originally designed as a bending member, and applying compressive force causes the possibility of buckling during erection, which reduces safety and cuts the floor slab by applying compressive force. The reason was that sometimes the cutter could not be installed with a can, and the installation to install the bracket on the lower flange was not permitted by vise, and it would be large if frictional joining with high-strength bolts was used.

For the above reasons, the stress of the steel main girder has rarely been improved when updating the plate, and if the stress acting on the steel main girder exceeds the allowable stress, the steel main girder will be replaced. The current situation is that it is being reinforced. In some cases, the allowable deflection may be exceeded, and even in such cases, the current situation is to reinforce the steel main girder.

Japanese Unexamined Patent Publication No. 2015-151768 Japanese Unexamined Patent Publication No. 6-322715

The problem to be solved by the present invention is to enable easy and efficient construction without reinforcing the steel main girder when the cross section of the steel bridge is divided and the floor slab is renewed in the renewal of the floor slab of the steel bridge. The purpose is to enable construction in a short period of time and minimize the impact of traffic regulations. Further, by improving the stress of the steel main girder, the reinforcement to the steel main girder is eliminated or the amount of reinforcement is reduced.

Prior to solving the above problems, the present inventors focused on the structure and construction method of synthetic girders and non-synthetic girders. For the synthetic girder, a concrete slab (RC slab) is installed on the steel main girder and connected and fixed with studs to prevent the RC slab from shifting. In the non-synthetic girder, the RC slab is installed on the steel main girder, but since the steel main girder and the RC slab are not connected and fixed by studs, the RC slab is more likely to be displaced than the synthetic girder. In both the case of synthetic girders and non-synthetic girders, pavement is constructed on the RC plate bridge and balustrades are installed.

For both synthetic girders and non-synthetic girders, it is expected that the steel main girder, plate bridge, pavement, and pavement will bend downward due to the total load (δall) of the steel main girder, plate bridge, pavement, and balustrade (not shown). Will be done. In general, in both synthetic girders and non-synthetic girders, the span length exceeds the transportable member length, so an on-site joint is required to join the members on-site. For this reason, at the time of construction, for example, a vent (support work) was placed at the site joint in the width direction of the cross section below the steel main girder, and the expected deflection at the time of factory production was warped upward. Manufactured as a state (with camber) and temporarily received at that position. This state is called a stress-free state because there is no load acting on the steel main girder. In this state, the steel main girder is joined in the field. After that, when the support work is removed, the steel main girder is deflected by the dead load of the steel main girder. At this time, a stress equivalent to the dead load of the steel main girder acts on the steel main girder.

In the case of a synthetic girder, after erection of the steel main girder with the camber, the vent is released, and with the steel main girder flexed by its own weight, concrete is placed on the steel main girder and the RC floor slab is placed. To build. The deflection of the steel main girder at this time is called the pre-dead load. Pre-dead load = δ1 (load of steel main girder) + δ2 (load of plate slab). When the RC plate is hardened, it is combined with the steel main girder. After this synthesis, pavement will be constructed and balustrades will be installed. The dead load that is loaded after the pavement and balustrade steel main girder and RC deck slab are combined is called the post-dead load. Assuming that the load of the pavement is δ3 and the load of the balustrade is δ4, the amount of deflection (total dead load) given at the time of production is δall = δ1 + δ2 + δ3 + δ4. This amount is called camber (raising amount).

In the case of a non-synthetic girder, after the camber is applied, the composite action of the floor slab and the steel main girder is not considered, so that the pre-dead load and the post-dead load are generally not divided. Further, since the floor slab and the steel main girder behave like a lap beam, even if the steel main girder and the floor slab are made of the same material and have the same cross section, the deflection is generally increased and the stress is also increased.

In the floor slab renewal method of the present invention, the existing floor slab of the steel bridge is removed, a new floor slab is installed at the removal trace, and the new floor slab is used as the existing steel bridge for both synthetic girders and non-synthetic girders. It is a floor slab renewal method that joins to the steel main girder, and before joining the new floor slab to the existing steel main girder, the steel main girder is moved from below more than canceling the deflection of the existing steel main girder itself. After jacking up (forced pushing up) upward to alleviate the strain accumulated in the existing steel main girder and reduce the stress state, the existing slab is cut in the direction perpendicular to the bridge axis. Then, divide it into arbitrary sizes, remove the divided floor slabs individually, install a new floor slab at the removal site, join the new floor slab to the existing steel main girder, and jack up at least after the joining. It is a construction method characterized by releasing. In the case of the construction method of updating to a new floor slab while using the existing floor slab, in the floor slab renewal method to not give much tensile force by jacking up to the existing floor slab, jacking up is performed step by step to total jack up. The amount of jack-up is equal to or greater than the amount that cancels the deflection of the existing steel main girder itself, and before the total jack-up amount is reached, the existing floor slab is cut in the direction perpendicular to the bridge axis to achieve the total jack-up amount. It is also possible to cut the existing floor slab in the direction of the bridge axis after becoming. In this case, when the existing slab is cut in the direction perpendicular to the bridge axis, the jack-up amount is set to an amount that can alleviate or cancel the strain of the post-dead load, and the existing slab is cut in the direction of the bridge axis. It is desirable that the jack-up amount of is the total jack-up amount.

The floor slab renewal method of the present invention also includes a full-width renewal method in which traffic is regulated over the entire width of an existing steel bridge to renew the floor slab, and the entire width of the steel bridge is divided into two or more areas, and some areas. After traffic regulation, releasing traffic in other areas, updating the floor slab of the area where traffic is restricted (preceding area), switch traffic regulation and traffic release to other areas, and traffic after switching It can also be applied to the area-specific renewal method for renewing the floor slab of the regulated area (backward side area).

In the case of the full-width renewal method, after jacking up the entire width of the steel bridge, the existing floor slabs in the entire width are cut to an arbitrary size and partitioned, and the partitioned floor slabs are individually removed and removed. A new floor slab will be installed at the site, and the new floor slab will be joined to the existing steel main girder. In the case of the area-specific renewal method, the entire width of the steel bridge is divided into two or more areas, the jack-up amount of the steel main girder is changed for each area, and the existing floor slab is cut to an arbitrary size for each area. Then, the partitioned floor slabs are individually removed, a new floor slab is installed at the removal trace, and the new floor slab is joined to the existing steel main girder.

The floor slab renewal method of the present invention has the following effects.
(1) Since the existing steel main girder with reduced strain accumulated in the steel main girder is joined to the new floor slab without strain, reinforcement work for the steel main girder becomes unnecessary or reduced. However, it is a construction method with good work efficiency.
(2) In a state where the strain accumulated in the steel main girder is reduced, or the reverse strain, that is, the strain on the compression side is applied to the strain on the lower flange at the center of the support, and the strain on the tension side is applied to the upper flange side. When joined with a new floor slab, the work of reinforcing the steel main girder becomes unnecessary or reduced, and work efficiency is improved. Furthermore, the weight of the entire bridge after renewal will be reduced by the amount that no reinforcing material is used. That is, it becomes a life-and-death load composite girder or a composite girder in which strain is applied to the steel main girder in advance.
Here, a general live load composite girder is called a live load composite girder because the load after the steel main girder and the floor slab are combined is mainly the live load which is the traffic load. On the other hand, the life-and-death load composite girder is effective in the combined cross section of the steel main girder and the floor slab against the pre-dead load because the steel main girder and the floor slab are combined in the pre-dead load state. is there. Therefore, if the cross section has the same stress, strain, and deflection, it will be smaller than the live load composite girder. In other words, even if the load increases to some extent, it may be possible to resist with the current cross section without reinforcement. In general, steel plate girders and cast-in-place concrete girders are life-and-death load composite girders.
(3) Since the existing floor slab is cut vertically in the direction perpendicular to the bridge axis after reducing the strain accumulated in the floor slab, the cutting work becomes easy. The same applies when cutting a steel main girder.
(4) Jack-up is performed step by step to make the total jack-up amount equal to or greater than the amount that cancels the deflection caused by the existing steel main girder itself, and the existing floor slab is made before the total jack-up amount is reached. If you cut in the direction perpendicular to the bridge axis and then cut in the direction of the bridge axis of the existing floor slab after the total jack-up amount is reached, you can cut the existing floor slab in the direction perpendicular to the bridge axis and the existing floor slab. Cutting in the direction of the bridge axis can be performed in a stress state suitable for each cutting, and the floor slab can be cut without applying so much tensile force due to jacking up.
(5) When the amount of jack-up when cutting the existing floor slab in the direction perpendicular to the bridge axis is set to an amount that can alleviate or cancel the strain due to the post-dead load, and when cutting the existing floor slab in the direction of the bridge axis. Even when the jack-up amount is set to the total jack-up amount, each cutting can be performed under a stress state suitable for each cutting, and the floor slab can be cut without applying so much tensile force due to the jack-up. Can be done.
(6) When constructing a steel bridge by dividing it into two or more areas, if the amount of jacking up is large in the steel main girder in the construction area and small in the steel main girder on the unconstructed side, it will be used as the floor slab on the unconstructed side. The amount of push-up applied is suppressed, cracks, damage, etc. are less likely to occur in the floor slab, and the safety of the automobile traveling on the unconstructed side is ensured.
(7) When applying a concrete slab to the floor slab to be renewed, after jacking up the steel main girder, install the concrete slab on the steel main girder and connect it to the steel main girder in a continuous state in the bridge axis direction. After that, if the jack-up is released, a compressive force acts on the concrete floor slab to reduce the occurrence of cracks, which can be expected to improve the durability of the floor slab.

(A) is a front view of a normal vehicle running state, (b) is a side view, and (c) is a section explanatory view of a floor slab. (A) is a front view of the pre-regulation work (Step 1: vertical girder, horizontal girder modification) in the floor slab renewal method of the present invention, and (b) is a side view. (A) is a front view of the pre-regulation work (Step2: support girder erection) in the floor slab renewal method of the present invention, and (b) is a side view. (A) is a front view of the pre-regulation work (Step 3: 1 primary jack-up) in the floor slab renewal method of the present invention, and (b) is a side view. (A) is a front view of the pre-regulation work (Step 4: installation of reinforcing member, horizontal cutting of main girder, temporary attachment) in the floor slab renewal method of the present invention, and (b) is a side view. (A) is a front view of the leading side work (Step 5: leading side secondary jack-up, leading side bridge axis perpendicular direction floor slab cutting, leading side reinforcing member installation) in the floor slab renewal method of the present invention, (b). Is a side view. The front view of the work on the leading side at the time of regulation in the floor slab renewal method of the present invention (Step 6: cutting of the bridge axial slab and removal of the existing slab). The front view of the work on the leading side at the time of regulation (Step 7: new floor slab installation / temporary pavement) in the floor slab renewal method of the present invention. The front view of the trailing side work at the time of regulation in the floor slab renewal method of the present invention (Step 8: trailing side tertiary jack up, trailing side bridge axis perpendicular direction slab cutting, trailing side reinforcing member installation). (A) to (c) are side views of FIGS. 7 to 9. (A) is a front view of the trailing side work (Step 9: existing floor slab removal work) in the floor slab renewal method of the present invention, and (b) is a side view of the trailing side work (Step 10: new floor slab installation / temporary pavement). .. (A) is a front view of the trailing side work (Step 11: release of jack-up, removal of reinforcing member, removal of support girder, main pavement work) in the floor slab renewal method of the present invention, and (b) is a side view. Strain (stress) -deflection curve of steel main girder.

The floor slab renewal method of the present invention jacks up the existing steel main girder more than canceling the deflection caused by the existing steel main girder itself to alleviate the strain accumulated in the existing steel main girder and reduce the stress state. Since it is characterized by cutting the existing floor slab, the relationship between the stress (strain) and the deflection of the steel main girder will be described with reference to FIG. 13 prior to the description of the embodiment of the present invention.

FIG. 13 is a diagram of the strain (stress) -deflection curve of the steel main girder. In FIG. 13, the vertical axis Y shows the stress σ or the strain ε of the steel main girder, and the horizontal axis X shows the deflection δ of the steel main girder. Normally, σ: stress, E: Young's modulus, and ε: strain have a relationship of σ = Eε. In the conventional plate renewal, the existing plate is cut with at least a pre-dead load applied to the steel main girder. In the present invention, before updating the existing floor slab, the existing steel main girder is jacked up to the amount equivalent to the front dead load or more, and the steel main girder is deflected by the load of the existing steel main girder itself (δ1 in FIG. 13). Is canceled, the strain accumulated in the existing steel main girder is relaxed to reduce the stress state to ε1 or less and δ1 or less in FIG. 13, and then the existing floor slab is changed in the bridge axis direction (Z in FIG. 1 (c)). It is characterized in that the jack-up is released after updating in the −Z direction) or / and the direction perpendicular to the bridge axis (AA direction and BB direction in FIG. 1C) and joining with the steel main girder. Hereinafter, embodiments of the present invention will be described.

(Embodiment 1: Half-width renewal method for horizontally cutting the steel main girder of the synthetic girder)
This embodiment is a case where the composite girder is renewed by half width, and is a case where the web of the existing steel main girder is horizontally cut to separate the upper flange side and the floor slab of the steel main girder from the lower flange side. In this construction method, as shown in FIGS. 1 (a) and 1 (b), work (pre-regulation work) is performed while the vehicle is running (before traffic regulation on one side lane), and then one-side traffic regulation is performed on the regulated side. This is an example of the case where the floor slab of the above is updated first (work on the leading side is performed), then the one-sided traffic regulation is replaced, and the floor slab on the regulated side after the replacement is updated (work on the trailing side is performed).

(Pre-regulation work)
(1) Step 1: Installation of temporary vertical girders and new horizontal girders The steel bridge in Fig. 1 (a) has three steel main girders 1. In this case, in half-width construction, one steel main girder on one construction side becomes one and the existing floor slab 2 becomes unstable. Therefore, as shown in FIGS. 2A and 2B, the lower side of the existing floor slab 2 Temporary receiving vertical girder 3 is installed in, and a new horizontal girder 4 is installed between the main girder 1.

(2) Step2: Installation of support girder or support girder As shown in FIGS. 3A and 3B, the support girder 5 is erected below the steel main girder 1. In this case, the reaction force base 6 and the cross girder 7 are provided. A vent (support work) can be installed in place of the support girder 5, or an erection girder can be installed. Installation of support works and installation of erection girders are done by the usual method.
The support girder is supported below the target steel main girder, is supported by holding a space where a jack can be provided at the upper part, and the lower part of the steel main girder is jacked at the span. It refers to a temporary beam that supports, so to speak, has the function of a lap beam.
For the erection girder, support works are provided in front of the piers or abutments at both ends on the target bridge side, and jacks, etc. are placed below the steel main girders for beam-shaped structures on the support works on both sides. A temporary structure that is provided at a position that holds a space that can be provided and that can be supported by a jack or the like provided above the erection girder.

(3) Step3: Primary jack-up After Steps 1 and 2, as shown in FIGS. 4A and 4B, three steel main girders 1 are jacked up (primary jack-up) by the hydraulic jack 8. , The stress (strain) corresponding to the post-dead load accumulated in the steel main girder 1 is reduced. If the jack-up exceeds the post-death load, a tensile force is generated on the existing floor slab 2 and cracks occur, which poses a danger to the running of the vehicle. Therefore, the primary jack-up is a death loaded on the steel main girder after the floor slab is installed. It is desirable to keep it within the post-dead load, which is the load. The reinforcing member 9 is temporarily attached to the cut portion. The required amount of jack-up may be performed step by step or all at once (the same shall apply hereinafter).

(4) Step4: Main girder horizontal cutting / temporary attachment In the primary jack-up state, the steel main girder 1 is cut horizontally in the axial direction as shown in FIGS. 5A and 5B, and the existing floor is used. Separate the upper flange side of the plate 2 and the main girder 1 from the lower flange side.

(Preceding work)
After the completion of the pre-regulation work, traffic is regulated on one side of the lane, and the floor slab on the regulated side is updated. This updating work (preceding side work) can be performed as follows.

(5) Step 5: Secondary jack-up / cutting of slab in the direction perpendicular to the bridge axis After Step 4, as shown in FIGS. 6 (a) and 6 (b), the three steel main girders 1 are further jacked up than in the primary jack-up state. Jacking up (secondary jacking up) cancels the stress corresponding to the pre-dead load and releases the strain accumulated in the lower flange of the steel main girder 1 on the leading side. In this case, it is desirable that the secondary jack-up amounts G1, G2, and G3 of the three steel main girders 1 are gradually reduced from the G1 side to the G3 side. As an example of the jack-up amount, G1 is set to 80% of the front dead load deformation amount of the steel main girder 1, and the distribution is determined based on this so that the uplift does not occur in the other steel main girder 1. For example, it is desirable to jack up at a ratio of about G1: 100%, G2: 62.5%, and G3: 25%. The reason for this is that if the jack-up amount is greater than the pre-dead load, a tensile force is also generated on the floor slab on the traveling side to cause cracks and the traveling performance is not deteriorated. In the state of the secondary jack-up, as shown in FIG. 1 (c), the existing floor slab 2 and the steel main girder 1 on the leading side are moved in the direction perpendicular to the bridge axis (in the direction of the virtual line AA in FIG. 1 (c)). It is cut into a leading compartment floor slab 10 of an arbitrary size.

(6) Step 6: Cutting the slab in the direction of the bridge axis and removing the existing slab The leading side compartment slab 10 partitioned by Step 5 is removed as shown in FIGS. 7 and 10 (a). A new floor slab 11 will be installed at the removal trace of the preceding side compartment floor slab 10. The new floor slab 11 may be a steel floor slab, a precast RC floor slab, or a precast PC floor slab. In addition, cast-in-place concrete slabs may be applied. Finally, the main girder and the RC floor slab or PC floor slab are joined to the main girder by a filling material such as mortar or concrete, and the steel floor slab is joined to the main girder by high-strength bolts or welding.

(7) Step 7: Installation of new floor slab / temporary pavement After repeating the removal of the preceding side section floor slab 10 of Step 6 and the installation of the new floor slab 11, the new floor slab 11 is as shown in FIGS. 8 and 10 (b). Temporarily pave on top.

(Backward work)
After the work on the preceding side of Step 7 is completed, the traffic regulation is switched to the opposite side, and then the floor slab updating work (work on the trailing side) on the traffic regulation side is performed as follows.

(8) Step8: Third-order jack-up / Bridge axis orthogonal slab cutting Three steel main girders 1 are tertiary-jacked up and the three main girders 1 are pushed up to cancel the stress equivalent to the pre-dead load. Then, the strain accumulated in the lower flange of the main girder 1 on the trailing side is released. The tertiary jack-up amounts G1, G2, and G3 are larger in the trailing main girder 1 and less in the leading girder 1. For example, G3 is set to 80% of the front dead load amount of the main girder 1, and the distribution is determined based on this so that the uplift does not occur in the other main girder 1. For example, it is desirable to jack up at a ratio of G3: 100%, G2: 62.5%, and G1: 25%. The reason for this is that the jack-up amount is large on the G1 side, and if the same amount is used, the G1 side may become high and the running performance may be hindered. Therefore, it is desirable that the jack-up amount is the sum of the first to third orders so that the amount of all steel main girders is finally about the same amount, or about the same ratio with respect to the camber amount. In the state of the tertiary jack-up, as shown in FIG. 1 (c), the existing floor slab 2 and the steel main girder 1 on the leading side are cut in the direction perpendicular to the bridge axis (in the direction of the virtual line BB in FIG. 1 (c)). Then, it is divided into arbitrary sizes to form a trailing side partition plate 12.

(9) Step 9: Removal of existing floor slab The trailing side partition floor slab 12 partitioned by Step 8 is removed as shown in FIG. 11 (a).

(10) Step 10: Installation of new floor slab / temporary pavement As shown in Fig. 11 (b), the new floor slab 11 is installed at the removal trace of the trailing side compartment floor slab 12.

Since the side views of Steps 8 to 10 are the same as the side views of Steps 5 to 7, they are omitted.

After all the existing floor slabs have been updated to the new floor slabs by the work of Steps 1 to 10, the jack-up is released, the support girder 5 or the support work is removed, and the main pavement is performed to complete the floor slab update. Become.

(Embodiment 2: Half-width update without horizontally cutting the main girder of the composite girder)
This embodiment is a case where the main girder of the composite girder is updated by half width without horizontal cutting. In this case, the main girder horizontal cutting work and temporary attachment of Step 4 of the first embodiment are unnecessary, but the work of the other steps is performed in the same manner as in the case of the first embodiment. Instead of performing the main girder horizontal cutting work, it is necessary to separate the existing floor slab 2 from the steel main girder 1 by scraping the steel main girder 1 with a breaker or the like in any step.

(Embodiment 3: Half-width update of non-synthetic girder)
This embodiment is a case where the non-composite girder is updated by half width. This half-width update is basically the same as in the case of the first embodiment, and the pre-regulation work, the leading side work, and the trailing side work are performed, but the steel main girder and the floor slab are separated from the synthetic girder in the non-synthetic girder. Since the structure is easy to use, it is not necessary to perform the work of cutting the steel main girder 1 horizontally in the axial direction thereof, and the other work is the same as that of the second embodiment.

(Embodiment 4: Full width update of synthetic girder or non-synthetic girder)
This embodiment is a case of full-width update in which the floor slab of a synthetic girder or a non-synthetic girder is updated over the entire width. In this full-width update, instead of alternately restricting traffic and updating the floor slab alternately, it is a construction method in which traffic is regulated over the entire width and the full-width plate is updated. In the case of any of the digits, the primary jack-up is performed, but the secondary jack-up and the tertiary jack-up are not necessary. The reason is that it is not necessary to run a general vehicle during the renewal work, and it is not necessary to consider cracks in the floor slab. In the case of a synthetic girder, the work of the other steps of the first embodiment is performed with the entire steel main girder jacked up without performing horizontal cutting and temporary attachment of the steel main girder of Step 4 of the first embodiment. In the case of a non-synthetic girder, the entire steel main girder is jacked up, and the same work as in the third embodiment is performed to update the floor slab.

(Embodiment 5: Gradual jack-up)
The floor slab renewal method of the present invention is the above-mentioned method, but in the present invention, the jack-up is performed in stages, and the total jack-up amount is equal to or equal to the amount of canceling the deflection due to the existing steel main girder itself. With the above jack-up amount, cut the existing floor slab in the direction perpendicular to the bridge axis with the desired jack-up amount before reaching the total jack-up amount, and after the total jack-up amount is reached, the bridge shaft of the existing floor slab. It is also possible to cut in the direction. The amount of jack-up when cutting the existing floor slab in the direction perpendicular to the bridge axis should be an amount that can alleviate or cancel the strain due to the post-dead load, and jack-up when cutting the existing floor slab in the direction of the bridge axis. The amount can also be the total jack-up amount.

The work process and work procedure of the above-described embodiment are examples of the present invention. These work processes and work procedures can be changed to the extent that the problems of the present invention can be solved. For example, other steps may be added as needed, and some steps may be deleted. In addition, the front and back of the step may be interchanged.

The half-width construction of the above embodiment is a case where the steel bridge is divided into two regions in the cross-sectional direction (horizontal width direction) and the steel bridge is constructed by alternately restricting traffic. In the present invention, the steel bridge is constructed in the cross-sectional direction (width). It is not limited to the case of dividing into two areas in the direction), and when there are many lanes (when the width of the steel bridge is wide), the construction can be divided into three or more areas.

1 (Existing) Steel main girder 2 (Existing) Floor slab 3 Temporary receiving vertical girder 4 New horizontal girder 5 Support girder or support 6 Reaction force stand 7 Horizontal girder 8 Hydraulic jack 9 Reinforcing member 10 Leading side section Floor slab 11 New floor Plate 12 Backward side section Floor plate 13 Span length

Claims (5)

In the floor slab renewal method in which the existing floor slab of the steel bridge is removed, a new floor slab is installed at the removal trace, and the new floor slab is joined to the existing steel main girder of the steel bridge.
Before joining the new floor slab to the existing steel main girder, jack up the existing steel main girder from the bottom to the top so that the amount of the existing steel main girder cancels the deflection of the existing steel main girder itself or more. After relaxing the strain accumulated in the existing steel main girder to reduce the stress state, the existing floor slab is cut to an arbitrary size in the direction perpendicular to the bridge axis and partitioned, and the partitioned floor. The slabs are individually removed, a new floor slab is installed at the removal site, the new floor slab is joined to the existing steel main girder, and the jack-up is released at least after the joining.
A floor slab renewal method characterized by this. In the floor slab renewal method according to claim 1,
Jack up is performed step by step to make the total jack up amount equal to or greater than the amount that cancels the deflection caused by the existing steel main girder itself, and before the total jack up amount is reached, the bridge shaft of the existing floor slab. Cut in the perpendicular direction, and after the total jack-up amount is reached, cut the existing floor slab in the direction of the bridge axis.
A floor slab renewal method characterized by this. In the floor slab renewal method according to claim 2,
The amount of jack-up when cutting the existing floor slab in the direction perpendicular to the bridge axis is set to an amount that can relax or cancel the strain due to the post-dead load, and jack-up when cutting the existing floor slab in the direction of the bridge axis. Let the amount be the total jack-up amount,
A floor slab renewal method characterized by this. In the plate renewal method according to any one of claims 1 to 3,
After jacking up the steel main girder over the entire width of the steel bridge, the existing floor slabs in the entire area are cut to any size and partitioned, and the partitioned floor slabs are individually removed to create a new floor at the removal trace. Install a plate and join the new floor slab to the existing steel main girder,
A floor slab renewal method characterized by this. In the plate renewal method according to any one of claims 1 to 3,
The entire width of the steel bridge is divided into two or more areas, the jack-up amount of the steel main girder is changed for each area, the existing slab is cut to an arbitrary size for each area, and the divided slabs are individually divided. A new floor slab is installed at the removal trace, and the new floor slab is joined to the existing steel main girder.
A floor slab renewal method characterized by this.

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