JP2015031017A - Repair reinforcement structure of steel beam and construction method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a repair reinforcement structure of a steel beam in which shear load bearing capacity is superior, a material for repair reinforcement is lightweight, workability is superior, and furthermore, a labor of maintenance is reduced and even the cost is advantageous.SOLUTION: A repair reinforcement structure of a steel beam is formed by fixing a repair reinforcement member 7 to a steel beam 1 including a plate-like web 4 formed extending in a vertical direction, and a plate-like lower flange 3 joined to a lower end of the web 4 so that a cross section in the vertical direction combined with the web 4 becomes an inverted T-shape and formed extending in a horizontal direction. In the repair reinforcement structure of a steel beam, the repair reinforcement member 7 is arranged so as to cover at least a portion of a line where a perpendicular plane of the web 4 intersects with an upper surface of the lower flange 3, and to have a fixed surface in an area including at least a portion of the upper surface of the lower flange 3. The repair reinforcement member 7 comprises a hardened body of a specific composition.

Description

  The present invention relates to a steel girder repair / reinforcement structure and a construction method thereof.

At present, the aging of steel structures constructed during the period of high economic growth has become a problem, and appropriate repairs and reinforcements are required.
In particular, in an aging steel bridge, the lower flange near the end fulcrum of the steel girder and the neck weld of the web are prone to corrode due to water accumulation, and early countermeasures are required for this part.
In general, a patch plate reinforcement method is frequently used as a method for repairing and reinforcing steel structures. This method is a method of attaching a reinforcing steel plate to a steel girder by bolts or welding. However, this construction method requires a heavy steel sheet for reinforcement, is inferior in workability, and requires replacement or painting of the steel sheet when the steel sheet for reinforcement itself is corroded. There are problems such as being large and possibly causing damage to the base metal due to welding or drilling when the reinforcing steel plate is attached.
Under such circumstances, various techniques have conventionally been developed for repairing and reinforcing structures for steel girders. As an example, there has been proposed a repair / reinforcement structure for an existing steel girder in which a stud is welded to a reinforcement-required portion of an existing steel girder, a reinforcing bar is attached using the stud, and then concrete is filled (Patent Document 1). In addition, (A) cement, (B) fine particles having a BET specific surface area of 5 to 25 m ² / g, and (C) a brane specific surface area of 3,500 to 10,000 cm ² on a part of the surface of a steel girder belly plate. / G inorganic powder, (D) fine aggregate with a maximum particle size of 2 mm or less, (E) water reducing agent, (F) fiber, and (G) a plate-like member made of a cured product of water A steel girder reinforcing structure has been proposed (Patent Document 2).

JP 2002-266319 A JP 2011-162985 A

The steel girder repair / reinforcement structure described in Patent Document 1 described above has the advantage that the repaired part does not corrode and there is no need for maintenance management such as replacement and painting of steel sheets, but requires concrete filling work, etc. It is inferior in workability. The steel girder reinforcement structure described in Patent Document 2 is intended to reinforce the belly plate of the steel girder, and describes the repair and reinforcement of the lower flange near the end fulcrum of the steel girder and the neck weld of the web. It has not been.
On the other hand, when repairing and reinforcing steel girders, it is also important to improve the shear load resistance.
The present invention is excellent in shear load resistance, lightweight for repair and reinforcement, and does not require concrete filling work, etc., so that it is excellent in workability, and further requires less labor for maintenance and is advantageous in terms of cost. An object is to provide a steel girder repair / reinforcement structure and a construction method thereof.

As a result of intensive studies to solve the above-mentioned problems, the present inventor fixed the repair / reinforcing member made of a hardened body of a composition containing a specific material to a specific region of a steel girder. The present invention has been completed.
That is, the present invention provides the following [1] to [7].
[1] A plate-like web formed to extend in the vertical direction, and formed so as to extend in the horizontal direction by being joined to the lower end of the web so that the vertical cross-section combined with the web has an inverted T-shape. A steel girder repair / reinforcement structure in which a repair / reinforcement member is fixed to a steel girder including a plate-like lower flange, wherein the repair / reinforcement member is connected to the vertical surface of the web. Covering at least a part of the line intersecting the upper surface of the lower flange and having a fixing surface in a region including at least a part of the upper surface of the lower flange, for repair and reinforcement Members are (A) cement, (B) fine particles having a BET specific surface area of 5 to 25 m ² / g, (C) inorganic powder having a brane specific surface area of 3,500 to 10,000 cm ² / g, (D) largest particles Fine aggregate with a diameter of 2 mm or less, (E) water reducing agent (F) reinforcing fibers, and (G) steel girder repair and reinforcement structure, characterized by comprising a cured product of the formulation comprising water.
[2] The vertical section is L-shaped so that the repair / reinforcement member has a fixing surface in a region including at least a part of the upper surface of the lower flange and at least a part of the vertical surface of the web. The steel girder repair / reinforcement structure according to [1], which has a shape including a portion.
[3] The steel girder repair / reinforcement structure according to [1] or [2], wherein the repair / reinforcement member is fixed to the steel girder with an adhesive layer interposed therebetween.
[4] The steel girder repair / reinforcement structure according to any one of [1] to [3], wherein the repair / reinforcement member is formed of a plate-like body having a thickness of 5 to 30 mm.
[5] The repair / reinforcement of the steel girder according to any one of [1] to [4], wherein the repair / reinforcement member is disposed as a pair of members so as to sandwich the web from both sides. Construction.
[6] A method for constructing the steel girder repair / reinforcement structure according to any one of [1] to [5], wherein the repair / reinforcement member is bonded to the steel girder using an adhesive. A construction method of steel girder repair / reinforcement structure, characterized by being affixed to the steel.
[7] The steel girder repair / reinforcement according to [6], wherein the surface portion of the steel girder corresponding to the fixing surface of the repair / reinforcement member is blasted before the repair / reinforcement member is attached. How to build the structure.

According to the steel girder repair / reinforcement structure of the present invention, the shear load resistance of the steel girder can be improved.
In addition, the steel girder repair / reinforcement structure of the present invention uses a member made of a hardened body of a compound (ultra high strength fiber reinforced mortar) containing a specific material, so compared to the case of using ordinary mortar Even if the thickness of the member is reduced, it has a sufficient repair / reinforcement effect, and the weight of the repair / reinforcement material can be reduced.
In addition, the steel girder repair / reinforcement structure of the present invention can construct a steel girder repair / reinforcement structure by a simple operation of fixing a member to the surface of the steel girder, which requires concrete placing work. It is excellent in workability in that it does not.
Moreover, the steel girder repair / reinforcement structure of the present invention can prevent corrosion of the lower flange near the end fulcrum of the steel girder and the neck weld of the web.
Furthermore, since the member used for the steel girder repair / reinforcement structure of the present invention is excellent in durability, the repair / reinforcement member is regularly used as compared with the case where a steel plate is used as the member for repair / reinforcement. There is no need to replace or rust prevent painting.
For these reasons, according to the steel girder repair / reinforcement structure of the present invention, it is possible to reduce the maintenance labor and the cost.

It is a perspective view which shows the repair and reinforcement structure of the steel girder of this invention. It is sectional drawing which shows the repair and reinforcement structure of the steel girder of this invention. It is a figure which shows the structure and dimension of a lower girder type steel girder specimen. It is a figure which shows the adhesion position of the member with respect to a steel girder. It is a figure which shows the relationship between a load and a vertical displacement.

First, the material of the repair / reinforcing member used in the present invention will be described.
The repair / reinforcing member used in the present invention includes (A) cement, (B) fine particles having a BET specific surface area of 5 to 25 m ² / g, and (C) a brane specific surface area of 3,500 to 10,000 cm ² / g. It consists of the hardened | cured body of the compound containing inorganic powder, (D) fine aggregate whose maximum particle size is 2 mm or less, (E) water reducing agent, (F) reinforcing fiber, and (G) water. Hereinafter, each component will be described in detail.

[(A) component]
Although it does not specifically limit as a kind of cement used as (A) component, For example, various Portland cements, such as normal Portland cement, early strong Portland cement, moderately-heated Portland cement, low heat Portland cement, are mentioned, for example.
In the present invention, when trying to improve the early strength of the cured body, it is preferable to use early-strength Portland cement, and when trying to improve the fluidity (workability) of the blend, It is preferable to use heat Portland cement or low heat Portland cement.

[Component (B)]
The BET specific surface area of the fine particles used as the component (B) is 5 to 25 m ² / g, preferably 7 to ²⁰ m ² / g. When the BET specific surface area is less than 5 m ² / g, the strength, denseness, and impact resistance of the cured product are lowered. When the BET specific surface area exceeds 25 m ² / g, the amount of water for obtaining a predetermined fluidity increases, and the strength, denseness, and impact resistance of the cured product are lowered.
Examples of the fine particles include silica fume, silica dust, fly ash, slag, volcanic ash, silica sol, precipitated silica, and limestone powder. Among them, silica fume and silica dust are preferable because their BET specific surface area is 5 to 25 m ² / g and they do not need to be pulverized when used as the component (B). Moreover, limestone powder is also suitable from the viewpoint of grindability and fluidity.
(B) The compounding quantity of a component becomes like this. Preferably it is 5-50 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 10-40 mass parts. When the blending amount is less than 5 parts by mass, the strength, denseness, and impact resistance of the cured product may be lowered. If the blending amount exceeds 50 parts by mass, the amount of water for obtaining a predetermined fluidity increases, and the strength, denseness, and impact resistance of the cured product may be reduced. Further, when the blending amount is outside the above numerical range, the shear load resistance of the steel girder may decrease.

[Component (C)]
The brane specific surface area of the inorganic powder used as the component (C) is 3,500 to 10,000 cm ² / g, preferably 4,000 to 9,000 cm ² / g, more preferably 5,000 to 9,000 cm ^2. / G. When the Blaine specific surface area is less than 3,500 cm ² / g, the strength, denseness, and impact resistance of the cured product are lowered. When the Blaine specific surface area exceeds 10,000 cm ² / g, the fluidity of the blend, the strength, the compactness, and the impact resistance of the cured product, and the shear load resistance of the steel girder are reduced.
Examples of the inorganic powder include inorganic particles other than cement, such as slag, limestone powder, feldspar, mullite, alumina powder, quartz powder, fly ash, volcanic ash, silica sol, carbide powder, and nitride powder. Of these, slag, fly ash, limestone powder, and quartz powder are preferred from the viewpoint of cost reduction and quality stability of the cured product.
(C) The compounding quantity of a component becomes like this. Preferably it is 5-55 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 10-50 mass parts. If the blending amount is out of the above numerical range, the fluidity of the blend, the strength of the cured product, the denseness, the impact resistance, and the shear load resistance of the steel girder may decrease.

[(D) component]
Examples of the fine aggregate used as the component (D) include river sand, land sand, sea sand, crushed sand, silica sand, and mixtures thereof.
The maximum particle size of the fine aggregate is 2 mm or less, preferably 1.5 mm or less, more preferably 1 mm or less. When the maximum particle size of the fine aggregate exceeds 2 mm, the strength of the cured body may be reduced. Moreover, it may be difficult to reduce the thickness of the cured body (for example, a thickness of 5 to 30 mm).
(D) The compounding quantity of a component becomes like this. Preferably it is 50-250 mass parts with respect to 100 mass parts of (A) component, More preferably, it is 80-180 mass parts. If the blending amount is out of the above numerical range, the strength of the cured body may decrease, the shrinkage may increase, and the shear load resistance of the steel girder may decrease.

[(E) component]
Examples of the water reducing agent used as the component (E) include lignin-based, naphthalenesulfonic acid-based, melamine-based or polycarboxylic acid-based water reducing agents, AE water reducing agents, high performance water reducing agents, and high performance AE water reducing agents. Among these, a polycarboxylic acid-based high-performance water reducing agent or a high-performance AE water reducing agent is preferable. By mix | blending a water reducing agent, the fluidity | liquidity of a compound and the intensity | strength and denseness of a hardening body can be improved.
The blending amount of the water reducing agent is preferably 0.1 to 4.0 parts by mass, more preferably 0.1 to 1.0 part by mass in terms of solid content with respect to 100 parts by mass of the component (A). If the blending amount is less than 0.1 parts by mass, it is difficult to knead the blend, and the fluidity becomes extremely low, so that molding may be difficult. When the blending amount exceeds 4.0 parts by mass, material separation of the blend may occur. In addition, the strength and denseness of the cured body and the shear load resistance of the steel girders may be reduced.

[(F) component]
Examples of reinforcing fibers used as the component (F) include metal fibers, organic fibers, and carbon fibers.
Examples of metal fibers include steel fibers and amorphous fibers. Among these, steel fibers are preferable from the viewpoints of high strength, low cost and easy availability.
The metal fiber preferably has a diameter of 0.01 to 1.0 mm and a length of 2 to 30 mm. When the diameter is less than 0.01 mm, the strength of the fiber itself is insufficient, and the fiber tends to break when subjected to tension. When the diameter exceeds 1.0 mm, the number of the same compounding amount decreases, and the effect of improving the shear load resistance of the steel girder may be reduced. Moreover, if this length is less than 2 mm, the effect which improves the shear load-bearing capacity of a steel girder may fall. If the length exceeds 30 mm, fiber balls are likely to be produced during kneading.
The blending amount of the metal fibers is preferably 0.1 to 4.0%, more preferably 0.5 to 3.0%, particularly preferably 0.7 to 3.0% in the total volume of the blend. . If the blending amount is less than 0.1%, the bending strength and fracture energy of the cured body become small, and the effect of improving the shear load resistance of the steel girder may be reduced. If the blending amount exceeds 4.0%, a large amount of water is required to ensure workability during kneading, and thus the strength, fracture energy, and the like of the cured body may be reduced. In addition, the effect of improving the shear load resistance of the steel girder may be reduced.

Examples of organic fibers include vinylon fibers, polypropylene fibers, polyethylene fibers, and aramid fibers. Among these, vinylon fibers are preferable from the viewpoints of strength, cost, availability, and the like.
Examples of the carbon fiber include PAN-based carbon fiber and pitch-based carbon fiber.
The organic fibers and carbon fibers preferably have a diameter of 0.005 to 1.0 mm and a length of 2 to 30 mm. When the diameter is less than 0.005 mm, the proof stress of the fiber itself is insufficient, and it may be easily broken when subjected to tension. When the diameter exceeds 1.0 mm, the number of the same compounding amount decreases, and the effect of improving the fracture energy or the like may be reduced. If the length is less than 2 mm, the adhesion to the matrix may be reduced, and the effect of improving the fracture energy may be reduced. If the diameter exceeds 30 mm, fiber balls may be easily generated during kneading.
The compounding amount of the organic fiber or carbon fiber is preferably 0.5 to 10%, more preferably 1.0 to 7.0%, particularly preferably 1.5 to 5.0% in the total volume of the compound. is there. If the blending amount is less than 0.5%, the fracture energy of the cured body becomes small, and the effect of improving the shear load resistance of the steel girder may be reduced. If the blending amount exceeds 10%, a large amount of water is required to ensure workability during kneading, so the strength of the hardened body, the fracture energy, etc. are reduced and the shear load resistance of the steel girder is improved. May reduce the effect.

[(G) component]
(G) As a component (water), tap water etc. can be used.
The water / cement ratio in the blend is preferably 10 to 30% by weight, more preferably 15 from the viewpoint of making the fluidity of the blend and the strength, durability, denseness, impact resistance, etc. of the cured product appropriate. -25% by mass. If the ratio is less than 10% by mass, the blending is difficult to knead and the fluidity becomes extremely small, so that molding becomes difficult. When the ratio exceeds 30% by mass, the strength and denseness of the cured body may be lowered, and the effect of improving the shear load resistance of the steel girder is also lowered.

[Others]
The blend may further include fibrous particles and / or flaky particles. By using fibrous particles and / or flaky particles, the toughness of the cured product can be increased.
Examples of the fibrous particles include wollastonite, bauxite, mullite, and the like. Examples of the flaky particles include mica flakes, talc flakes, vermiculite flakes, and alumina flakes.
The fibrous particles and / or flaky particles preferably have an average particle size of 1 mm or less. By using particles having such a particle size, the toughness of the cured product can be improved. When the average particle size exceeds 1 mm, the fluidity of the blend, the strength of the cured product, and the like may decrease, which is not preferable. The particle size of the particle is the size of the maximum dimension (particularly, the length of the fibrous particle).
The blending amount of the fibrous particles and / or flaky particles (the total amount when these two types of particles are used in combination) is preferably 35 parts by mass or less with respect to 100 parts by mass of the cement (component (A)). More preferably, it is 0.1-20 mass parts. By setting the blending amount of the fibrous particles and / or the flaky particles within the above range, the fluidity of the blend, the toughness of the cured body, and the like can be improved.
In addition, as a fibrous particle, it is preferable to use a thing with a needle-like degree represented by ratio of length / diameter 3 or more from a viewpoint of improving the toughness of a hardening body.

In the present invention, the kneading method of the blend is not particularly limited, and a usual method can be used. Also, the apparatus used for kneading is not particularly limited, and any type used for ordinary concrete kneading may be used. For example, an omni mixer, a pan-type mixer, a twin-screw kneading mixer, a tilt cylinder mixer, etc. Used.
The method of molding and curing the composition is not particularly limited, but considering the productivity and strength development of the cured body (repair / reinforcing member), a method of performing primary curing and secondary curing is preferable. . Examples of such methods include the following methods.
First, the kneaded compound is molded using a predetermined mold and subjected to primary curing. Here, the molding method is not particularly limited, and a conventional molding method such as casting can be employed. Examples of the primary curing method include a method in which the mixture kneaded in a mold is stored at 5 to 40 ° C. for a predetermined time, for example, 3 to 48 hours. After completion of the primary curing, the mold is removed, and then the secondary curing is performed to produce a cured body (a member for repair / reinforcement). The compressive strength of the cured body at the time of demolding after primary curing is preferably 10 N / mm ² or more. If the compressive strength is less than 10 N / mm ^2, demolding becomes difficult. Examples of the secondary curing method include a steam curing method at 75 to 95 ° C. for 10 to 48 hours.

The compression strength of the obtained cured product is preferably 120 N / mm ² or more, more preferably 130 N / mm ² or more, and particularly preferably 140 N / mm ² or more. Further, the flexural strength of the cured resin, preferably 20 N / mm ² or more, more preferably 23N / mm ² or more, and particularly preferably 25 N / mm ² or more.
The compressive strength and bending strength are values measured according to “JIS A 1108 (Concrete compressive strength test method)” and “JIS R 5201 (Cement physical test method)”, respectively.
By having the compressive strength and the bending strength, the repair / reinforcement member made of the hardened body can exert a sufficient repair / reinforcement effect on the steel girder. Further, the thickness of the repair / reinforcement member can be reduced while maintaining a sufficient repair / reinforcement effect, and the weight of the repair / reinforcement material can be reduced.

Next, the steel girder repair / reinforcement structure of the present invention will be described with reference to FIGS.
In the present invention, the steel girder 1 to which the repairing / reinforcing member 7 is fixed has a plate-like web 4 formed extending in the vertical direction, and a vertical cross section combined with the web 4 has an inverted T-shape. Thus, it includes a plate-like lower flange 3 that is joined to the lower end of the web 4 and extends in the horizontal direction. The steel girder 1 is usually a steel I girder (a steel girder whose cross section is I-shaped) having an upper flange 2 on the top of the web 4. Furthermore, the steel beam 1 may have a horizontal stiffener 5 and a vertical stiffener 6. A floor board through which vehicles and people pass is arranged on the upper surface of the upper flange 2.
In the repair / reinforcement structure of the present invention, the repair / reinforcement member 7 covers at least a part of the line (joining line 8) where the vertical surface of the web 4 of the steel girder 1 and the upper surface of the lower flange 3 intersect. And it is arrange | positioned so that it may have a fixed surface in the area | region including at least one part of the upper surface of the lower flange 3. As shown in FIG.
By arranging the repair / reinforcing member 7 in the above region, it is possible to exert an excellent shear load resistance against a load in the vertical direction (for example, a vertically downward load by a passing vehicle on a bridge). it can.
Further, the repair / reinforcing member 7 is disposed so as to cover a region where corrosion is expected on a line where the vertical surface of the web 4 and the upper surface of the lower flange 3 intersect or a region where corrosion has already occurred. By doing so, it is possible to prevent the occurrence of corrosion in the base material (steel girders) and the progress of corrosion that has already occurred.

The shape of the repairing / reinforcing member 7 used in the present invention covers at least a part of the line (joining line 8) where the vertical surface of the web 4 of the steel girder 1 and the upper surface of the lower flange 3 intersect, and There is no particular limitation as long as it can be disposed so as to have a fixing surface in a region including at least a part of the upper surface of the lower flange 3.
For example, as shown in FIGS. 2A to 2E, the vertical cross section includes an L-shaped portion, and the vertical length and the horizontal length of the L-shaped cross section are as follows. An equal mountain-shaped repairing / reinforcing member 9 (hereinafter also referred to as an “equilateral mountain-shaped member”), or a shape in which the vertical cross section includes an L-shaped portion, and the vertical length of the L-shaped cross section Covering the mountain-shaped repairing / reinforcing member 11 (hereinafter also referred to as “irregular mountain-shaped member”) having different horizontal lengths, the lower region of the web 4, the upper surface, the side surface, and the lower surface of the lower flange 3. A repair / reinforcement member 12 (hereinafter, also referred to as “gypsum-type member”) molded according to the shape of the steel girder 1 or a plate-like repair / reinforcement member 13 (hereinafter “plate-like”). Also referred to as “member”).

  The repair / reinforcing member may be disposed on only one surface of the upper surface of the lower flange 3 with the web 4 interposed therebetween, but the web 4 is sandwiched from both sides from the viewpoint of improving the shear load resistance. Thus, it is preferable to arrange | position as a pair of member (refer (a)-(e) of FIG. 2).

The shape of the fixing surface facing the upper surface of the lower flange of the repair / reinforcing member used in the present invention is usually a rectangle whose longitudinal direction is parallel to the web and the longitudinal direction.
The length of the repair / reinforcement member (the length in the longitudinal direction of the rectangle) varies depending on the size of the steel girder, but is preferably within 300 cm, more preferably within 250 cm from the viewpoint of workability during mounting. Particularly preferably, it is within 200 cm.
If the lower limit of the length of the repair / reinforcement member is too small, it is necessary to use a large number of repair / reinforcement members, and the installation work becomes complicated. Therefore, the length is preferably 30 cm or more, more preferably 50 cm or more. is there.
In addition, the width of the fixing surface of the repair / reinforcement member facing the upper surface of the lower flange (the length in the short direction of the rectangle) is determined from the viewpoint of obtaining a sufficient repair / reinforcement effect from the vertical surface of the web and the lower flange. The length of the line between the upper surfaces of the lower flange and the length to the edge of the upper surface of the lower flange is preferably 100% or more, more preferably 100 to 120%.
Specifically, although the width varies depending on the size of the lower flange, the width is preferably 3 to 20 cm, more preferably 4 to 15 cm. Especially preferably, it is 5-10 cm.

Further, the repair / reinforcement member may be fixed to a region including at least a part of a vertical surface of the steel girder web. By fixing the repair / reinforcing member to the region, it is possible to prevent the occurrence of corrosion in the base material (steel girders) and the progress of the corrosion that has already occurred. Moreover, the shear load resistance of the steel girder is improved.
Specifically, as shown in FIGS. 2A and 2B, the equilateral mountain-shaped member 9 or the unequal mountain-shaped member 11 has at least a part of the upper surface of the lower flange 3 and at least one of the vertical surfaces of the web 4. It arrange | positions so that it may have a fixed surface in the area | region containing a part.
Further, as shown in FIG. 2C, the cast member 12 has a fixing surface in a region including at least a part of the upper surface, side surface, and lower surface of the lower flange 3 and at least a part of the vertical surface of the web 4. It is arranged as follows. By using the cast member 12, the entire lower flange 3 can be covered with a repair / reinforcing member, and corrosion of the entire lower flange 3 can be prevented. Moreover, peeling and dropping of the repair / reinforcing member (the cast-type member 12) accompanying an increase in load can be prevented, and durability can be increased against deterioration of the adhesive accompanying aging deterioration.
Further, as shown in FIG. 2E, a plurality of plate-like members 13 and 14 are prepared, and the plate-like member 13 having a fixing surface in a region including at least a part of the upper surface of the lower flange 3 is A plate-like member 14 disposed on the upper surface of the flange 3 and having a fixing surface in an area including at least a part of the vertical surface of the web 4 is brought into contact with the upper surface of the plate-like member 13 on the vertical surface of the web 4. It may be fixed. Here, in order to prevent a gap from being generated between the plate-like member 14 fixed to the vertical surface of the web 4 and the plate-like member 13 fixed to the upper surface of the lower flange 3, It is preferable from the viewpoint of preventing erosion.

Among these, from the viewpoint of improving the shear load resistance, a chevron member (for example, an equilateral chevron member or an unequal chevron member) in which repair / reinforcing members are integrated is preferable. Moreover, the ratio of the length in the vertical direction and the length in the horizontal direction (vertical length / horizontal length) of the L-shaped cross section of the angle member is preferably 1.0 to 3.0, More preferably, it is 1.5-2.0.
In addition, although the length in the vertical direction of the fixing surface facing the web of the repair / reinforcement member varies depending on the size of the steel girder, it is preferably 3 to 30 cm, more preferably from the viewpoint of workability at the time of mounting. Is 4 to 20 cm, particularly preferably 5 to 15 cm.

The repair / reinforcing member used in the present invention is preferably a plate-like body having a thickness of 5 to 30 mm, more preferably 5 to 20 mm, and particularly preferably 5 to 15 mm. If the thickness is less than 5 mm, the manufacture becomes difficult and deformation such as warpage may occur in the repair / reinforcing member. In this case, the effect of improving the shear load resistance may also be reduced. If the thickness exceeds 30 mm, the weight of the repair / reinforcing member increases, which makes it difficult to attach the steel girder to the steel girder and increases the material cost.
When the repair / reinforcement member is a mountain-shaped member having an L-shaped cross section in the vertical direction (for example, an equilateral mountain-shaped member or an unequal mountain-shaped member), for repairing / reinforcing a portion extending in the vertical direction of the mountain-shaped member The thickness of the member and the thickness of the repair / reinforcing member extending in the horizontal direction may be the same or different.

The repair / reinforcing member used in the present invention is preferably fixed between the steel beam 1 and the adhesive layer 10. By using an adhesive in the fixing work of the repair / reinforcing member, the work can be easily and quickly performed without damaging the steel girder that is the object to be reinforced.
Examples of the adhesive for forming the adhesive layer 10 include synthetic resin adhesives such as acrylic resin adhesives and epoxy resin adhesives. Commercially available acrylic resin adhesives include “Acrysilup” manufactured by Mitsubishi Rayon Co., Ltd. Examples of commercially available epoxy resin adhesives include “E256” and “E258” manufactured by Konishi.
When the cast member 12 is used, the adhesive is injected and filled by applying pressure to the gap between the steel beam 1 and the cast member 12.
In the present invention, an anchor can be used together with an adhesive. Further, the repair / reinforcement member may be fixed to the steel beam using bolts and nuts in combination,
When fixing the repair / reinforcing member, it is desirable to blast the surface portion of the steel beam corresponding to the fixing surface of the repair / reinforcing member. By blasting, the surface of the abdominal plate is roughened, and the fixing strength can be improved.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[1. Preparation of materials]
The following materials were used as materials for the blend.
(A) Cement: Low heat Portland cement (manufactured by Taiheiyo Cement)
(B) Fine powder: Silica fume (BET specific surface area 10 m ² / g)
(C) Inorganic powder: Quartz powder (Brain specific surface area 7,000 cm ² / g)
(D) Fine aggregate: silica sand No. 5 (maximum particle size 0.6mm or less)
(E) Water reducing agent: Polycarboxylic acid-based high-performance water reducing agent (F) Metal fiber: Steel fiber (diameter: 0.2 mm, length: 15 mm)
(G) Water: Tap water

[2. Preparation of compound and measurement of physical properties of cured product]
Low heat Portland cement 100 parts by mass, silica fume 32 parts by mass, quartz powder 35 parts by mass, fine aggregate 105 parts by mass, water reducing agent 0.8 parts by mass (solid content conversion), water 22 parts by mass, and steel fibers (of steel fibers) The amount was determined to be 2% of the total volume of the cement composition.) Was charged into a biaxial kneader and kneaded to obtain a blend. The flow value (0 strike) of the obtained blend was 270 mm.
In addition, the flow value (0 strike) of a compound is a value measured in the method described in “JIS R 5201 (Cement physical test method) 11. Flow test” without performing 15 drop motions.
Next, a cured product was produced using the above blend, and used as a sample for measuring compressive strength and bending strength.
Specifically, the above-mentioned compound was molded using a predetermined mold (mold for measuring compressive strength; φ50 × 100 mm, mold for measuring bending strength; 4 × 4 × 16 cm) at 20 ° C. After leaving still for 24 hours (primary curing), the mold was removed, and further steam curing (secondary curing) was performed at 90 ° C. for 48 hours to obtain a cured body. Then, the compression strength and bending strength of the obtained cured product were measured according to “JIS A 1108 (Concrete compressive strength test method)” and “JIS R 5201 (Cement physical test method)”, respectively.
As a result, compression strength 210N / mm ^2, was flexural strength 47N / mm ^2.
In addition, a result is an average value with respect to three hardening bodies.

[3. Preparation of steel girders]
As a steel I-girder specimen (steel girder with an I-shaped cross section), by providing a healthy-type specimen and an unwelded section, the lower flaw type simulating that the lower flange is missing due to corrosion. Two types of specimens (see FIG. 3) were prepared. In addition, the said healthy type test body is what the unwelded area was welded in the steel girder of FIG.

[Example 1]
Using the same formulation as the formulation prepared in “2. Preparation of formulation and measurement of physical properties of cured product”, the cross-sectional dimensions are L-80 × 80 × 10 mm and the length is 500 mm. After being molded using the above-mentioned formwork, left to stand at 20 ° C. for 24 hours (primary curing), demolded, and further steam-cured (secondary curing) at 90 ° C. for 48 hours to repair / reinforce member 9 ( An equilateral mountain-shaped member having a cross-sectional dimension of L-80 × 80 × 10 mm and a length of 500 mm was obtained.
As shown in FIG. 4 (shown on the right side of the cross-sectional view of FIG. 2 (a)), the repair / reinforcement member 9 obtained was bonded to the unwelded section of the lower chipped steel girder using an adhesive. Glued to the containing area. The number of repair / reinforcing members 9 is two in total, one on one side and one on the other side across the web 4 of the lower flange 3 (see FIGS. 2A and 4). Prior to bonding, the bonding surface of the steel beam 1 was blasted, and the bonding surface of the repair / reinforcing member 9 was surface-treated with a grinder. As the adhesive, an acrylic resin-based adhesive (manufactured by Mitsubishi Rayon Co., Ltd., trade name “Acrysilup”) was used. The bonding work is to apply the adhesive to both the steel beam 1 and the repair / reinforcement member 9, and then press and fix the steel beam 1 and the repair / reinforcement member 9, and leave it in that state for 24 hours. Performed.
A shear load resistance test of a steel girder was performed on the obtained repair / reinforcement specimen using a 1,000 kN universal testing machine. The loading point 16 and the fulcrum 15 are as shown in FIG.
The relationship between the obtained load and the vertical displacement is shown in FIG.

[Example 2]
A shear load resistance test of a steel girder was performed in the same manner as in Example 1 except that the cast member 12 was used as a repair / reinforcement member (see FIG. 2C).
In the cast-type member 12, the vertical length of the fixing surface facing the web 4 is 80 mm. The length of the cast member 12 in the longitudinal direction is 500 mm, and the thickness is 10 mm. Further, the shape of the cast member 12 is formed so that the entire lower flange 3 can be covered by disposing the pair of cast members 12 on the steel beam 1. The bonding work was performed by injecting an adhesive from the gap between the steel beam 1 and the cast member 12 after the cast member 12 was disposed on the steel beam 1.
The relationship between the obtained load and the vertical displacement is shown in FIG.

[Comparative Example 1]
A shear load resistance test of a steel girder was performed in the same manner as in Example 1 except that a sound type steel I girder specimen was used and a repair / reinforcing member was not attached.
The relationship between the obtained load and the vertical displacement is shown in FIG.
[Comparative Example 2]
The steel girder was subjected to a shear load resistance test in the same manner as in Example 1 except that a lower chip type steel I girder specimen was used and no repair / reinforcement member was attached.
The relationship between the obtained load and the vertical displacement is shown in FIG.

When the peak load of Comparative Example 1 is 1.0, the peak load of the lower chip type steel I-girder specimen (Comparative Example 2) is as low as 0.83.
On the other hand, the peak load increased to 1.04 in Example 1 in which the lower fracture type steel I girder specimen was reinforced using the equilateral mountain-shaped member.
Moreover, in Example 2 which reinforced the lower chip | tip type | mold steel I girder specimen using the cast type | mold member, the peak load rose to 1.07.

1 Steel Girder 2 Upper Flange 3 Lower Flange 4 Web 5 Horizontal Stiffener 6 Vertical Stiffener 7 Repair / Reinforcement Member 8 Joining Line 9 Repair / Reinforcement Member (Equilateral Mountain Shape Member)
10 Adhesive Layer 11 Repair / Reinforcement Member (Unequal Side Angle Member)
12 Repair / Reinforcement member (Gypsum type member)
13 Repair / Reinforcement Member (Plate Member)
14 Repair / Reinforcement Member (Plate Member)
15 fulcrum 16 loading point

Claims (7)

A plate-like web formed to extend in the vertical direction, and is formed to extend in the horizontal direction by being joined to the lower end of the web so that the vertical cross-section combined with the web has an inverted T-shape. A steel girder repair / reinforcement structure in which a repair / reinforcement member is fixed to a steel girder including a plate-like lower flange,
The repair / reinforcement member has a fixing surface in an area including at least a part of the upper surface of the lower flange so as to cover at least a part of a line where the vertical surface of the web and the upper surface of the lower flange intersect. Arranged to have,
The repair / reinforcing member is (A) cement, (B) fine particles having a BET specific surface area of 5 to 25 m ² / g, (C) inorganic powder having a Blaine specific surface area of 3,500 to 10,000 cm ² / g, (D) Repair of a steel girder characterized by comprising a hard aggregate of a fine aggregate having a maximum particle size of 2 mm or less, (E) a water reducing agent, (F) a reinforcing fiber, and (G) water.・ Reinforcement structure.   The repair / reinforcement member includes a portion having an L-shaped cross section in the vertical direction so that the repairing / reinforcing member has a fixing surface in a region including at least part of the upper surface of the lower flange and at least part of the vertical surface of the web. The steel girder repair / reinforcement structure according to claim 1, having a shape.   The steel girder repair / reinforcement structure according to claim 1 or 2, wherein the repair / reinforcement member is fixed to the steel girder with an adhesive layer interposed therebetween.   The steel girder repair / reinforcement structure according to any one of claims 1 to 3, wherein the repair / reinforcement member is formed of a plate-like body having a thickness of 5 to 30 mm.   The repair / reinforcement structure for a steel girder according to any one of claims 1 to 4, wherein the repair / reinforcement member is disposed as a pair of members so as to sandwich the web from both sides.   It is a method for constructing the steel girder repair / reinforcement structure according to any one of claims 1 to 5, wherein the repair / reinforcement member is affixed to the steel girder using an adhesive. A construction method for steel girder repair and reinforcement structures.   The method for constructing a repair / reinforcement structure for a steel girder according to claim 6, wherein the surface portion of the steel girder corresponding to the fixed surface of the repair / reinforcement member is blasted before the repair / reinforcement member is attached. .

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