JP5535440B2 - Composite steel slab that prevents cracking - Google Patents

Description

  In the composite steel floor slab paved with mortar or concrete as the base layer, the present invention suppresses the growth of cracks that are likely to occur in the negative bending region directly above the stiffening member such as the main girder and suppresses the influence of the cracks. The present invention relates to composite steel slabs used for bridges and the like.

Road pavement of steel floor slab bridges widely used for elevated roads and bridges is usually done by forming a base layer with goose asphalt with high waterproof property and forming an asphalt layer as a surface layer on it. .
The conventional general steel slab has a structure in which a stiffening member such as a plurality of U ribs is welded to a steel plate deck plate, and a high-density goose asphalt is paved on the top surface of the deck plate. Pave ordinary asphalt with water permeability into the surface layer. The surface layer is often subjected to asphalt pavement using drainage asphalt or dense grained asphalt from the viewpoint of running performance.

  In recent years, the steel plate slab manufacturing process tends to be streamlined by increasing the distance between the longitudinal ribs and increasing the thickness of the deck plate. However, when the vertical rib interval is widened, the stress due to local deformation increases when the wheel load is fitted between the vertical ribs, and fatigue cracks are likely to occur in the welded portion of the steel deck deck plate and the vertical rib. . In order to prevent this, it is effective to further increase the thickness of the deck plate, but there remains a problem in economy.

On the other hand, in order to improve the fatigue durability of the steel deck deck plate, instead of forming the base layer with soft goose asphalt, the base layer is formed with rigid concrete pavement or mortar pavement. Composite steel slabs that improve rigidity with these composites have also been adopted.
Even in composite steel slabs synthesized with concrete, many cracks occur in the concrete when a large bending moment caused by the wheel load acts repeatedly. Since the rigidity and strength of the concrete layer decrease due to the occurrence of cracks, the rigidity and strength of the steel slab also decrease, increasing the amount of distortion due to wheel load and making it easier to vibrate, as well as rainwater through the cracks. There is a problem in that the steel plate deck plate is corroded and the corrosion of the steel plate deck progresses to deteriorate the durability of the composite steel deck.

Patent Document 1 discloses a composite steel slab that has a rubber latex mortar layer that is less prone to cracking and has excellent durability, waterproofness, and rust prevention properties, and can increase rigidity. In the disclosed composite steel slab, a rubber latex mortar layer is placed on the upper surface of a steel slab in which a plurality of stiffening members are welded to the lower surface of a steel plate deck plate. The rubber latex mortar layer is excellent in adhesive strength, has good adhesion to the deck plate, and is elastic, so that cracks are hardly generated.
However, the rubber latex mortar layer may crack and deteriorate the durability of the steel deck.

Patent Document 2 discloses a method of inserting lattice bars formed of fiber reinforced plastics using carbon fiber or the like into a base layer in order to suppress cracking and prevent progress in concrete pavement and mortar pavement.
According to the disclosed construction method, cracks are reduced, and even if cracks or peeling occurs, it is said that there is an effect of preventing scattering.

However, even in the disclosed steel slab, cracks are generated immediately above the main girder provided parallel to the traveling direction of the vehicle in a loaded state of the wheel load. Rainwater that propagates through cracks cannot be stopped even by waterproofing, and it is inevitable that rainwater will invade through cracks penetrating from the surface layer to the steel deck deck plate and the steel deck will deteriorate over time.
In addition, the disclosed construction method has a poor workability, such as the need to accurately place a thick lattice line in a thin base layer, or the lattice line moves due to the vibration of the finisher. There were problems such as skin separation that caused the base layer to separate.
JP 2006-009353 A JP 2007-162417 A

  Therefore, the problem to be solved by the present invention is to provide a structure that suppresses the occurrence of bending cracks generated directly above the stiffening member of the steel deck, particularly the main girder belly plate. Moreover, the problem to be solved by the present invention is to provide a configuration that prevents rainwater from entering the steel deck deck plate even when a crack occurs directly above the main girder or the like.

  The steel slab of the present invention has a base layer formed by paving concrete or mortar on the upper surface of a steel slab deck plate in which a belly plate of a stiffening member including any of a main girder, a cross girder, and a lateral rib is welded to the lower surface. The synthesized composite steel slab is a steel slab in which a fiber sheet having a fiber base as a core is bonded to the upper surface of the base layer above the stiffening member web, and a waterproof film is formed on the fiber sheet. Asphalt and other surface layers are paved from the top of the steel slab to form a crack-suppressing steel slab bridge.

  In the steel slab of the present invention, the fiber sheet is interposed between the base layer and the surface layer immediately above the stiffening member belly plate, which is prone to cracking, so even if cracks occur in the concrete or mortar layer, the cracks progress. To prevent. Moreover, even if a crack occurs, the waterproof film applied to the fiber sheet prevents rainwater from entering through the cracks on the surface layer, thereby preventing rainwater from reaching the base layer. Therefore, deterioration of the steel deck deck plate is prevented and the durability of the steel deck is improved.

The fiber substrate was formed into a woven fabric, knitted fabric, non-woven fabric, braided fabric, net, etc. using organic synthetic fibers such as polyester, nylon, polyvinyl alcohol (trade name: vinylon), aramid, and inorganic fibers such as glass fibers and carbon fibers. It is preferable.
In particular, it has been found that when an aramid fiber or glass fiber woven fabric, nonwoven fabric, or net is used, the deterrence performance against the development of cracks is high, and the durability of the steel deck is increased.

The fiber sheet is preferably configured by embedding a fiber base material in a resin whose curing is accelerated by adding heat, light such as visible light or ultraviolet light, moisture, or the like. Moreover, you may comprise and apply | coat hardening acceleration resin to a fiber base material.
The fiber sheet is pre-embedded with a fiber base material in resin, and is supplied in a prepreg state that is wrapped and protected by a protective film so that the resin does not cure. It may be formed by sticking and accelerated curing.
Such a prepreg fiber sheet is soft before construction, deforms and adheres to the unevenness of the construction surface, and is fixed to the base layer surface by curing with a lamp or electric heater after application, so construction on site is easy It is also advantageous when used for repair work that requires traffic regulation.

In addition, a fiber sheet can also be arrange | positioned on a base layer upper surface through waterproofing asphalt. For example, a fiber base material can be wrapped with a highly adhesive asphalt-based coating film waterproofing material (for example, Nichireki Co., Ltd. trade name Fresh Coat) to serve as a waterproof film as a fiber sheet.
Further, an uncured fiber sheet formed by wrapping a fiber base material in a resin can be fixed to the surface of the base layer with a waterproof coating material.

In addition, the waterproof membrane to be constructed in the construction work is coated with a solvent-type bridge pavement adhesive (for example, Nichireki Co., Ltd., trade name “Kachi Coat”) and then with an asphalt-based waterproof membrane. It is preferable to apply asphalt waterproofing.
Since the asphalt pavement of the surface layer is joined to the base layer via an asphalt waterproofing work, even when the surface layer is dragged by the frictional force of the tire, it adheres to the base layer and does not peel off.

  In addition, the steel floor slab bridge of the present invention not only protects against cracks directly above the main girder, but also suppresses the progress of cracks that occur just above the cross beams and horizontal ribs, and rainwater is generated in the cracks. It goes without saying that it can be prevented from entering.

  Hereinafter, the composite steel slab of the present invention will be described in detail using examples. 1 is a partially cutaway perspective view of a crack-inhibiting steel floor slab bridge using this embodiment, FIG. 2 is a perspective view showing an example of the construction status of a crack-inhibiting structure part, and FIG. 3 is a side sectional view of the construction part. 4 is a partial side sectional view for explaining a fiber sheet construction method, FIG. 5 is a partial side sectional view for explaining another fiber sheet construction method, and FIG. 6 is a result of a test for confirming the effect of the fiber sheet. It is a table to represent.

  In this embodiment, a steel floor slab bridge 10 used for an elevated expressway and a bridge portion is constructed by laying mortar mixed with rubber latex on the upper surface of a steel floor slab deck plate 11 in place of conventional goose asphalt. 12 is used.

Rubber latex is an emulsion for blending cement mortar with styrene butadiene rubber as the main ingredient, and is an adhesion enhancer used by blending with water when blending cement paste and mortar.
The rubber latex mortar layer of the base layer 12 is made of mortar mixed with rubber latex, and has high adhesion performance and is integrated with the deck plate, so that it becomes a composite plate and the bending rigidity as a steel floor slab is improved compared to goose asphalt. Without increasing the thickness of the steel deck deck plate, high fatigue durability can be provided at low cost. Moreover, since rubber latex mortar is highly waterproof, corrosion of the steel slab can be suppressed.

The surface of the base layer 12 is coated with a waterproof film 13 formed of an asphalt-based coating waterproof material, and an asphalt layer with good water permeability is placed thereon as a surface layer 14 to improve the running performance of the vehicle.
The steel deck slab deck plate 11 is provided with members that are welded to the lower surface of the steel deck, such as a main girder 15, a cross girder 16, and a lateral rib 17, to prevent vertical deformation. Further, in order to increase the rigidity of the steel deck deck plate 12, a U rib 19 is provided.
When a vehicle travels over a bridge overhang or the like, a negative bending moment acts on the surface of the base layer directly above the stiffening member such as the main girder. Occurrence may not be suppressed.

The steel slab bridge 10 to which the steel slab of this embodiment is applied has a fiber sheet 20 for preventing cracks attached and laid on an area directly above the upper surface of the base layer 12 of rubber latex mortar with an adhesive. .
The steel deck slab bridge 10 in this embodiment uses a steel deck slab in which members such as a main girder 15, a transverse girder 16, and a lateral rib 17 are welded to the lower surface of a steel plate deck plate 11. A rubber latex mortar layer having an appropriate thickness is formed on the upper surface of the base layer 12. Further, a fiber sheet 20 having a size covering the main girder 15, the cross girder 16, and the lateral rib 17 is directly bonded to a region where the main girder 15, the cross girder 16, and the horizontal rib 17 are welded. After applying Nichireki Co., Ltd. trade name Cachi Coat), an asphalt-based coating waterproofing material (for example, Nichireki Co., Ltd. trade name fresh coat) is applied to form a waterproof film 13, and a surface layer 14 is paved thereon.

The fiber sheet 20 is formed into a sheet shape by wrapping a fiber base material with a resin base material or attaching the fiber base material with an accelerated curable resin, and can also be formed at a construction site.
As used herein, the fiber base material means a woven fabric, a knitted fabric, or a net, and a woven fabric or a net such as an aramid fiber, a carbon fiber, a polyester fiber, a polyvinyl alcohol fiber, or a glass fiber is selected and used according to each characteristic. Can do. In particular, when polyvinyl alcohol fiber, aramid fiber or glass fiber is used, the deterrence performance against the progress of cracking is high and the durability of the steel deck is high.

The resin is preferably an accelerated curable resin that accelerates curing when heat, light, moisture, or the like is applied in order to shorten the construction time on site. Examples of accelerated curable resins include thermosetting epoxy resins that are cured by heat, photocurable epoxy resins and acrylic resins that are accelerated by ultraviolet rays and visible light, and underwater cured epoxy resins that are accelerated by moisture. There are adhesives.
When using a light-promoting curable resin as a base material, the fiber base material needs to transmit light when impregnated with the resin. preferable.

When the fiber sheet 20 is formed at the construction site, as shown in FIG. 4, a solvent-type bridge pavement adhesive (for example, a cuff coat) or the like is directly above the main girder belly plate on which the fiber sheet on the surface of the base layer 12 is formed. The adhesive 24 is applied, the fiber base material 21 is laid on the part where the adhesive is applied, and the adhesive 25 is further applied in an overlapping manner to solidify the adhesive.
In addition, you may form the fiber sheet 20 by affixing a fiber base material on the surface of the base layer 12 using various accelerated curable resin.
Alternatively, the fiber sheet 20 can also be used as a waterproof film by wrapping a fiber base material with an asphalt-based waterproof coating material having high adhesiveness.

In addition, when the light accelerating curable resin is used as an adhesive, curing can be accelerated and cured at high speed by irradiating a suitable light such as a metal halide lamp or black light on the site, which is effective in shortening construction time.
After the fiber sheet 20 is formed, the entire surface of the base layer 12 including the fiber sheet 20 is waterproofed, and the surface layer is paved to complete the steel deck bridge.

  As shown in FIG. 5, the fiber sheet 20 can also be formed in advance in the form of a prepreg sheet 23 that is easy to construct in the factory. The prepreg sheet 23 is a sheet formed by wrapping the fiber base material 21 with the accelerating curable resin 22, and a protective film (not shown) that can be peeled off at the site is attached to the surface, and is not cured until it is brought into the site, It is preferable that the protective film is peeled off at the site, applied to the surface of the base layer 12, and cured when subjected to a predetermined treatment such as light irradiation.

The prepreg sheet 23 using the accelerating curable resin 22 is soft until it is fixed to the target position on the site with an adhesive, and is deformed to fit the target shape. However, the necessary light can be obtained using a metal halide lamp 26 or a black light. It cures rapidly upon irradiation. Accordingly, the quality of the fiber sheet 20 is constant, the construction is simplified and the construction time is shortened, so that construction management is facilitated.
If the adhesive 24 is also an accelerated curable resin having the same curing acceleration mechanism as the base material of the prepreg sheet, the bonding of the fiber sheet 20 and the base layer 12 and the curing of the fiber sheet 20 can be performed at the same time. Effective in shortening the construction time.

FIG. 6 is a table showing results of a test for confirming the effect of the fiber sheet.
The test evaluated the crack suppression effect about the fiber sheet material and the construction method, and the table in FIG. 6 shows the result compared with the conventional method. Here, the brazing substrate refers to a substrate in which fibers are aligned in one direction, and the aligned fibers are sealed with warp knitting, entanglement weave, adhesive nonwoven fabric, or the like. Here, the method of sealing is not limited.

Samples used in the test were prepared as composite steel floor slab samples in which a 45 mm thick rubber latex mortar layer was formed on a 15 mm thick iron plate having a square of 500 mm on each side. It is a product created by attaching a fiber sheet reinforcing material. The test was conducted without surface mortar.
In the test, a load was applied from the iron plate surface side of the sample, and a cracked state generated in the rubber latex mortar layer due to negative bending stress was observed.

  The table in FIG. 6 shows the material and form of the fiber base material selected as the fiber sheet reinforcing material, using a prepreg sheet in which the fiber base material is embedded in a photocurable resin and bonded to the base layer with an adhesive. With a method of irradiating and curing a metal halide lamp, and fixing the fiber base material to the base layer with a solvent-type bridge pavement adhesive (Nachireki Co., Ltd. Kachi Coat) and an asphalt-based waterproofing material (Nichireki Co., Ltd. Fresh Coat) This shows the performance of reinforcing materials such as a cracked state caused by a negative bending load when one of the methods for constructing a waterproofing membrane is selected.

In the column for prepreg sheet and waterproofing, the presence / absence of adoption is indicated by ○ ×, and in the column for experimental results, the column for general evaluation evaluating the heat resistance, cracking and waterproofing performance of the reinforcing material and the overall performance. In terms of durability, workability, and economy, the inferior ×, intermediate Δ, and excellent ○ are indicated. In the column showing the crack state, ○ indicates that the cracks are dispersed and a plurality of cracks are generated with a small width (dispersion type), whereas ◎ is that one small crack is generated (restraint type) ).
For comparison, a sample in which a reinforcing material is not provided (a fiber base is not used) and a sample in which a lattice of carbon fiber reinforced resin is embedded in a rubber latex mortar layer (a fiber base is a CFRP lattice) The results of the same evaluation are shown.

  From this test result, cracks are reduced and waterproof performance is reduced compared to the case where the reinforcing material is not added to the fiber base material such as polyvinyl alcohol fiber (trade name vinylon), aramid fiber, polyester fiber, glass fiber, etc. It can be seen that the durability is improved. However, since polyvinyl alcohol and polyester are not sufficiently heat resistant, they may be weakened by heat when molten asphalt of 180 ° C. to 200 ° C. is applied by waterproofing, and may cause large cracks. In particular, the deterioration of the reinforcing material was observed when the vinylon net and the polyester raschel knitting were joined together by waterproofing.

  In addition, a sample in which a known CFRP lattice line is embedded in a rubber latex mortar layer has small cracks and good heat resistance, but the surface of the lattice line is liable to peel off, resulting in poor waterproof performance and insufficient durability. Since high construction accuracy is required at the time of construction, workability is poor and economic efficiency is poor. Therefore, it became clear that the reinforcing material using the fiber sheet is superior in durability, workability, and economy as compared with this known technique. Moreover, it was found that the cracked state was also superior to the CFRP lattice when the aramid net prepreg sheet and the glass tinned prepreg sheet were employed.

As mentioned above, in a composite steel deck bridge with a rubber latex mortar layer formed on the upper surface of a deck plate welded to the lower surface of main girders, cross girders, horizontal ribs, etc., when the vehicle load is loaded, Negative bending stress is generated in the upper part.
In the crack-suppressing steel floor slab bridge of the present invention, the fiber sheet diffuses and relaxes this negative bending stress to suppress the occurrence of cracks that occur directly above the main girder, etc., and the crack width when cracks occur. Therefore, there is an effect of suppressing the generation and expansion of cracks.

In addition, even if a crack occurs, the cracked part is covered with a fiber sheet, and the waterproof film applied to the lower surface and surface of the sheet or the resin layer constituting the fiber sheet remains without being damaged. It is possible to prevent rainwater from penetrating into the base layer portion and to prevent corrosion of the steel deck deck plate.
Therefore, the durability of the steel deck slab bridge can be improved.

Further, even when the base layer is broken, the fiber sheet prevents the shattered pieces from being scattered, so that the progress of the aging deterioration of the steel deck bridge can be suppressed.
In addition, the structure of a present Example can be utilized also in order to construct and reinforce the existing steel deck slab bridge in service. In this case, since the construction can be completed relatively easily and quickly, there is an advantage that the time requiring traffic regulation is short and easy to use.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway perspective view of a crack-inhibiting steel deck bridge using one embodiment of a steel deck according to the present invention. It is a perspective view showing an example of the construction situation of the crack suppression structure part in a present Example. It is side surface sectional drawing of the construction part of the crack suppression structure in a present Example. It is a partial side sectional view explaining the construction method of the fiber sheet in a present Example. It is a partial side sectional view explaining another fiber sheet construction method in a present Example. It is the table | surface which evaluated the crack suppression effect about the fiber sheet material and construction method in a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Steel deck slab bridge 11 Steel deck slab deck plate 12 Base layer 13 Waterproof membrane 14 Surface 15 Main girder 16 Cross girder 17 Lateral rib 19 U rib 20 Fiber sheet 21 Fiber base material 22 Accelerating curable resin 23 Prepreg sheet 24 Adhesive 25 Adhesive Agent 26 Metal halide lamp 30 Cracks

Claims (7)

In the composite steel slab which synthesized the base layer formed by paving concrete or mortar on the upper surface of the steel deck deck plate welded to the lower surface of the belly plate of the stiffening member including any of the main girder, cross girder, and horizontal rib, by bonding a crack suppressing fiber sheet of the stiffening member webs upward have a fibrous substrate base layer of the base layer surface, and characterized by forming a waterproof film on the fiber sheet Composite steel slab. 2. The composite steel slab according to claim 1, wherein the fiber base material is any one of a woven fabric, a knitted fabric, a nonwoven fabric, a braided fabric, and a net including any of synthetic fibers, carbon fibers, and glass fibers. . 3. The composite steel slab according to claim 1, wherein the fiber sheet comprises a resin whose curing is accelerated by light, heat, or moisture and the fiber base material. The fiber sheet is formed by supplying a protective film so as not to be cured, removing the protective film at the time of construction, and affixing to the base layer with an adhesive and curing. The composite steel slab described. The fiber sheet, the composite steel slab according to any one of claims 1 4, characterized in that is obtained by bonding the base layer upper surface using asphalt waterproofing membrane material. Forming a surface layer by paving asphalt through an asphalt waterproofing work in which an asphalt-based coating waterproofing material is formed on a solvent-type bridge pavement adhesive on the surface of the base layer to which the fiber sheet is attached. composite steel slab according to any one of claims 1-5, wherein. The composite steel deck according to any one of claims 1 to 6, wherein the base layer is formed of rubber latex mortar.

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