JP2000034703A - Weatherproof steel bridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a cost of a corrosion resistant bridge by forming the splashing part of road surface water containing snow melting salt out of a salinity resistant/weatherproof steel material having a specified composition. SOLUTION: Among bridge girders 3a, 3b, 3c of a bridge 1, a weatherproof steel material excellent in salinity resistance is used for upper/lower flanges 4a, 4b and a web of the bridge girders on the splashing side of road surface water containing snow melting salt, and the other part uses an ordinary weatherproof steel material without painting. Next, the salinity resistant/weatherproof steel material is formed of welding structural steel containing C not more than 0/15, Si not more than 0.7, Mn of 0.2 to 1.5, P of 0.03 to 0.15, S not more than 0.02, AL of 0.01 to 0.1, Cr not more than 0.1, Ni of 0.4 to 4.0, Mo of 0.1 to 1.5 and Cu not more than 0.4 in wt.%. Instead of this, an ordinary weatherproof steel material by painting the scattering part of road surface water containing snow melting salt is used, or a cleaning means and a shielding material are arranged, or a shielding material is arranged to prevent scattering of road surface water to the outside of a road. Thus, progress of corrosion can be prevented, and a construction cost and a maintenance cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weather-resistant steel bridge in which portions of road surface water containing snow-melting salt sprayed to prevent road freezing are protected by means for preventing corrosion of steel materials.

[0002]

2. Description of the Related Art Steel structures such as bridges are usually provided with anticorrosion measures such as strict painting, but in order to reduce the cost of maintenance work such as frequent repainting,
In recent years, the number of cases of using a weather-resistant steel material such as SMA steel material for a bridge girder without painting and increasing the number of bridges is increasing. The weatherable steel material prevents the progress of corrosion by covering the surface of the steel material with dense stable rust enriched with effective elements such as copper, phosphorus, and chromium in an atmosphere exposed to the atmosphere. It is known that a bridge using such a weather-resistant steel material can often be used for several decades without painting because of its high weather resistance.

However, in an environment having a relatively high salt content, such as a coastal area, or in an environment where road surface water containing snow-melting salt is sprayed to prevent road freezing, rust of weather-resistant steel is difficult to stabilize. It is known that a layered peeling rust is generated, so that corrosion of steel cannot be suppressed, and practical corrosion resistance cannot be obtained. The mechanism by which the stabilization of the rust of the weather-resistant steel material is inhibited by the salt is not yet elucidated in many points, but is explained as follows. That is, iron rust is inherently anion-selective and is apt to permeate anions such as Cl ions. When Cl ions pass through the rust layer and reach the steel surface, a so-called Cl nest is formed,
Active sites of corrosion. It is considered that the Cl nest once formed is hard to inactivate and hinders the growth of the dense rust layer, so that the rust is difficult to stabilize.

FIGS. 10 to 12 show a case in which road surface water containing snow-melting salt is sprayed on a bridge using a weather-resistant steel material to prevent road freezing. (1) As shown in FIG. 10, on a road bridge 1 erected along a slope 17 such as a mountain, droplets 20 of road surface water containing snow-melting salt that a traveling vehicle 16 has rolled up flow along the slope 17, It adheres to the bridge girder 3 under the road.

(2) As shown in FIG. 11, in a plurality of road bridges 1a and 1b erected in parallel, road vehicle water 20 containing snow-melting salt rolled up by a traveling vehicle 16 of one of the road bridges 1a.
Adheres to the bridge girder 3 of the other road bridge 1b. (3) As shown in FIG. 12, on a bridge 19 erected on a road 18, a droplet 20 of road surface water containing snow-melting salt, which is rolled up by a traveling vehicle 16 on a lower road 18, forms a bridge girder of the bridge 19. Splashes and adheres.

[0006] As a technique for producing a steel material having improved weather resistance in an environment having a relatively high salt content such as a coastal area or a road bridge on which snow-melting salt is sprayed to prevent freezing of the road, Japanese Patent Laid-Open No. 7-2 is disclosed.
There are inventions disclosed in JP-A-07340, JP-A-7-242993 or JP-A-8-134587. According to these techniques, by adding a large amount of elements such as chromium and nickel, it is possible to improve the weather resistance in an environment having a relatively high salt content.

[0007]

The steel material containing a large amount of chromium as described above is liable to cause welding defects such as low-temperature cracking, and requires measures to prevent welding defects such as preheating. However, in the case of a bridge, work such as preheating is difficult, and adverse effects such as an increase in construction cost occur. Nickel is an expensive component element, and construction of a bridge using a steel material containing a large amount of nickel increases construction costs. As described above, with these technologies, it is difficult to construct a bridge having practical corrosion resistance at a low cost in an environment having a relatively high salt content such as a road bridge on which snow melting salt is sprayed to prevent road freezing. .

The present invention has been made to solve the above-mentioned problems, and has practical corrosion resistance in an environment having a relatively high salt content such as a road bridge on which snow-melting salt is sprayed to prevent road freezing. An object of the present invention is to obtain a weather-resistant steel bridge using a weather-resistant steel material from which a bridge can be manufactured at low cost.

[0009]

Means for Solving the Problems (1) A weather-resistant steel bridge according to the present invention is a bridge made of weather-resistant steel, which is capable of preventing at least splashing of road surface water containing snow-melting salt sprayed to prevent road freezing. This portion is made of a weather-resistant steel material having excellent salt resistance. (2) Further, at least a portion of the road surface water containing snow-melting salt sprayed to prevent road freezing is made of a painted weather-resistant steel material.

(3) Further, a washing means is provided for washing a portion of road surface water containing snow-melting salt sprayed to prevent road freezing. (4) In addition, a shield is provided at a portion where the road surface water containing snow-melt salt sprayed to prevent the road from freezing is prevented from being splashed. (5) A shield is provided to prevent road surface water containing snow-melting salt sprayed to prevent road freezing from scattering outside the road.

(6) The weather-resistant steel material having excellent salt resistance of the above (1) is, by weight%, C: 0.15% or less, and Si: 0.1% or less.
7% or less, Mn: 0.2 to 1.5%, P: 0.03 to
0.15%, S: 0.02% or less, Al: 0.01 to
0.1%, Cr: 0.1% or less, Ni: 0.4 to 4.0
%, Cu: 0.4% or less, and Mo: 0.1 to 1.5%.

(7) The weather-resistant steel having excellent salt resistance of the above (1) is composed of a titanium clad steel, a steel sheet to which a titanium thin plate or a titanium foil is adhered, or a steel sheet to which a thin titanium clad steel sheet is bonded. .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment 1] In this embodiment, at least a portion of a bridge made of a weather-resistant steel material is exposed to splashes of road surface water containing snow-melting salt sprayed to prevent road freezing. For example, the parts described with reference to FIGS.
In addition, a weather-resistant steel material excellent in salt resistance is used.

FIG. 1 is a schematic diagram for explaining the first embodiment. In the present embodiment, the upper and lower flanges 4a, 4b and the web of the bridge girder (for example, 3a) of the bridge girder 3a, 3b, 3c (main plate girder) of the bridge 1 made of a sheet girder bridge are exposed to the surface water containing snow-melting salt. 4c, a weather-resistant steel material having excellent salt resistance is used, and other bridge girders 3b, 3c and members are made of SMA
A steel material (hereinafter referred to as a normal weather-resistant steel material) is used without painting. 2 is a floor slab.

Further, in a bridge consisting of a box girder bridge, a weather-resistant steel material excellent in salt resistance is used for a lower flange and a web of a main box girder where road surface water containing snow-melting salt is splashed, and other main box girder is used. The members are made of ordinary weather-resistant steel without painting.

According to the present embodiment, a weather-resistant steel material having excellent salt resistance is used in a portion of the bridge 1 where road surface water containing snow-melting salt is splashed, and a normal weather-resistant steel material is not used in other portions. Since it is used for painting, a practical bridge having corrosion resistance can be constructed at low cost.

[Embodiment 2] In this embodiment, in a bridge using weather-resistant steel, at least a portion of road surface water containing snow-melting salt sprayed to prevent road freezing is applied.
This is a painted normal weather-resistant steel material.

For example, in a bridge composed of a sheet girder bridge, the upper and lower flanges and the web of the main sheet girder on the side where the road surface water containing snow-melting salt is splashed are coated with ordinary weather-resistant steel materials, and other sheet girder. Normal weather-resistant steel is used for bridges and members without painting, or in box girder bridges, the lower flange and web of the main box girder on the side where the surface water containing snow-melting salt is splashed are painted. A weather-resistant steel material is used, and a normal weather-resistant steel material is used for other main box girders and members without painting. As the paint used for coating, a heavy-duty anticorrosive paint such as an epoxy resin paint, a urethane resin paint, a modified epoxy resin paint, or a tar epoxy resin paint is used.

According to the present embodiment, a normal weather-resistant steel material coated on a portion of the bridge where road surface water containing snow-melting salt is sprayed is used, and a normal weather-resistant steel material is applied on other portions without painting. Since it is used, a practical bridge having corrosion resistance can be constructed at low cost.

[Embodiment 3] In this embodiment, in a bridge using a weather-resistant steel material, this portion is provided near a portion where road surface water containing snow-melting salt sprayed to prevent road freezing receives splashes. Is provided with a washing means for washing.

FIG. 2 is a schematic diagram for explaining the present embodiment, and FIG. 3 is a sectional view taken along line AA of FIG. In both figures, 1
Is a bridge, 2 is a floor slab, 3a, 3b, 3c are bridge beams using ordinary weather-resistant steel materials, 4a, 4b are upper and lower flanges, 4c
Is a web and 5 is a pier. Reference numeral 6 denotes a tank for storing rainwater or tap water, for example, and reference numeral 7 denotes one end connected to the tank 6 via the pump 10 and is installed along the upper part of the bridge girder 3a on the side receiving the splash of road surface water containing snow-melting salt. In the water distribution pipe, a plurality of branch pipes 8 provided at predetermined intervals are provided with a plurality of injection nozzles 9 facing the upper flange 4a, the web 4c, and the lower flange 4b. Reference numeral 11 denotes a water supply pipe for supplying tap water or the like to the tank 6.

In the present embodiment configured as described above, when road surface water containing snow-melting salt is present (mainly in winter), the pump 10 is driven periodically or as appropriate to drive the tank 6.
The inside of the bridge girder 3a is washed by blowing water from the inside to the water distribution pipe 7 and jetting water from the injection nozzle 9 to wash out the salt attached to the bridge girder 3a. Thus, rust can be prevented from being generated without coating the bridge girder 3a using a normal weather-resistant steel material. Note that the tank 6 may be omitted and tap water or the like may be directly supplied.

[Embodiment 4] In this embodiment, in a bridge using a weather-resistant steel material, a splash is applied to a portion which receives a spray of road surface water containing snow-melting salt sprayed to prevent road freezing. This is provided with a shield for preventing the occurrence of the light. FIG.
FIG. 2 is a schematic diagram illustrating the present embodiment. In the present embodiment, for example, in the bridges 1a and 1b arranged side by side, the droplets 20 of the road surface water containing snow-melting salt by the vehicles running on one of the bridges (for example, 1a) are splashed on the bridge girder 3c of the other bridge 1b. A shield 12 (for example, a cover or a louver) made of a corrosion-resistant metal material excellent in saltwater corrosion resistance, FRP (reinforced plastic) material, painted steel, or the like is provided on the outer surface on the side receiving the water.

In the present embodiment configured as described above, the side of the bridge girder 3c where the road surface water containing snow-melting salt is splashed is made of a corrosion-resistant metal material, FRP material, coated steel or the like having excellent corrosion resistance against salt water. Since the cover, which is a shield 12, is provided, it is possible to prevent rusting due to splash of road surface water on the bridge girder 3c, and when the function is deteriorated, it is sufficient to replace only the cover. When a cover is provided, repainting of only the cover may be performed. Furthermore, when a louver is used as the shield 12, only the louver needs to be replaced in the same manner, so that the bridge can be constructed at low cost.
Maintenance costs can also be reduced. As a matter of course, a shield 12 may be provided on the bridge girder 3b which receives the splash of the road surface water of the bridge 1b, or the bridge 1a,
1b.

[Embodiment 5] This embodiment is intended to prevent road surface water containing snow-melting salt sprayed to prevent road freezing from splashing out of the road in a bridge using weather-resistant steel. In addition, a shield is provided to prevent road surface water from scattering outside the road. FIG. 5 is a schematic diagram illustrating the present embodiment. In the present embodiment, for example, one of the bridges 1a and 1b (for example, 1a)
Is provided with a fence or a shield 13 composed of a sufficiently high wall railing on the side of the road on the other bridge 1b side. The material of the shield 13 is excellent in salt water corrosion resistance such as concrete and painted steel. The material used is

In the present embodiment, one of the bridges 1a and 1b arranged side by side (for example, 1a) and the other bridge 1
Since the shield 13 is provided on the side of the road on the side b, one of the bridges 1
Even if road surface water containing snow-melting salt is scattered by a vehicle running on a, the road surface water is blocked by the shield 13 and does not adhere to the bridge girder of the other bridge 1b. Although the figure shows the case where the shield 13 is provided on the bridge 1b side of one bridge 1a, the shield 13 may be provided on the bridge 1a side of the other bridge 1b, or the bridge 1a, 1b A shield 13 may be provided on both. According to the present embodiment, a bridge having corrosion resistance can be constructed at low cost.

[Embodiment 6] In this embodiment, a welded structural steel containing the following weight percent elements is used as the weather-resistant steel excellent in salt resistance in the above-described embodiment. is there. C: 0.15% or less, Si: 0.7% or less, Mn: 0.
2 to 1.5%, P: 0.03 to 0.15%, S: 0.0
2% or less, Al: 0.01 to 0.1%, Cr: 0.1%
Hereinafter, Ni: 0.4 to 4.0%, Cu: 0.4% or less,
Mo: 0.1 to 1.5% The reason for limiting the content of the above elements will be described below.

C: C is added to secure a predetermined strength, but if it exceeds 0.15%, the weldability and toughness decrease. Therefore, the upper limit is set to 0.15%. Si: Si is added for the purpose of improving the deoxidizing agent and strength during steelmaking. However, excessive addition of Si significantly reduces toughness. Therefore, the upper limit is set to 0.7% or less.

Mn: Mn is added in an amount of 0.2% or more to secure a predetermined strength. However, if it is added in excess of 1.5%, a bainite structure is likely to occur, and mechanical properties, particularly toughness, deteriorate. Therefore, the Mn content is set to 0.1.
The range was 2 to 1.5%. P: P is an important element in the weather-resistant steel material excellent in salt resistance according to the present invention, and has an effect of improving the strength of the steel and an effect of improving the corrosion resistance. But,
Addition of less than 0.03% has no effect on improving corrosion resistance.
If it exceeds 0.15%, the weldability deteriorates. Therefore,
The P content was in the range of 0.03 to 0.15%.

S: S is an element harmful to corrosion resistance.
02% or less. Al: Al is added in an amount of 0.01% or more as a deoxidizing agent at the time of steel making. However, if it is added excessively, inclusions serving as corrosion starting points are likely to be generated. Therefore, the Al content is set in the range of 0.01 to 0.1%. Cr: Cr has the effect of promoting perforated corrosion in an environment with a large amount of salt, and significantly reduces weldability. Therefore, the amount of Cr is set to 0.1% or less.

Ni: Ni is an important element in the weather-resistant steel material having excellent salt resistance according to the present invention, and has an effect of improving corrosion resistance in an environment with a high salt content by coexistence with Mo. However, the addition of less than 0.4% has no effect,
If it exceeds 4%, it is disadvantageous in terms of economy. Therefore,
The amount of Ni was set to 0.4 to 4%. Cu: Cu has an effect of improving the corrosion resistance, and is added in a necessary amount. However, if it exceeds 0.4%, the effect is saturated, and it is disadvantageous in terms of economy. Therefore, the Cu content is set to 0.4% or less.

Mo: Mo is also an important element in the weather-resistant steel material having excellent salt resistance according to the present invention, and has an effect of improving corrosion resistance in an environment with a high salt content by coexisting with Ni. However, adding less than 0.1% has no effect, while adding more than 1.5% is disadvantageous in terms of economy. Therefore, the amount of Mo was made into the range of 0.1 to 1.5%.

[Embodiment 7] In this embodiment, in a bridge using a weather-resistant steel material, a portion where road surface water including snow-melting salt sprayed to prevent road freezing is splashed has excellent salt resistance. A weather-resistant steel material is attached. 6 and 7 are schematic diagrams illustrating the present embodiment. In the present embodiment, for example, as shown in FIG. 6, in the bridges 1a and 1b arranged side by
The bridge girder 3c of the bridge (for example, 1b) on the side where
In areas where 0 is applied, titanium clad steel, titanium sheet,
The bridge girder 3c, which is made of a weather-resistant steel material having excellent salt resistance and affixed with a titanium foil 14 or the like, as shown in FIG. And a thin titanium-clad steel plate 15 joined thereto and made of a weather-resistant steel material excellent in salt resistance.

In the present embodiment, a titanium clad steel plate, a titanium thin plate, a titanium foil or the like is adhered to a portion of the bridge girder 2 made of weather resistant steel which is exposed to the surface water containing snow melting salt, or a thin titanium clad steel plate or the like. The bridge can be constructed at low cost.

[Example 1] Next, examples of the first and sixth embodiments will be described. As an example, a test bridge of a sheet girder bridge was manufactured, and a test for examining corrosion resistance was performed by spraying water containing snow-melting salt. In the test, weather resistant steel materials with excellent salt resistance were used for the upper and lower flanges and web of one of the outer girders of the sheet girder bridge, and the other main sheet girders and members were tested using normal weather resistant steel materials without painting. Made a bridge. Further, as a comparative example, a test bridge in which all main girder members and members were formed using ordinary weather-resistant steel material without painting was manufactured. Table 1 shows the components of the used weather-resistant steel material having excellent salt resistance and ordinary weather-resistant steel material.

[0036]

[Table 1]

The test bridges of the above example and the comparative example were installed at the exposure test site, and water containing sodium chloride as snow melting salt was periodically sprayed from the outside of the main girder of both the example and the comparative example. Exposure tests were performed for 5 years.
After the end of the exposure test, the thickness reduction of each part of the outer girder of both test bridges sprayed with water containing snow-melting salt was measured. Table 2 shows the measurement results.

[0038]

[Table 2]

As is evident from Table 2, in the examples of the present invention, the reduction in the plate thickness was small, and it was confirmed that the sheet can be used for a long time. On the other hand, in the comparative example, it was clarified that a remarkable decrease in the plate thickness occurred.

[Example 2] Next, an example of the second embodiment will be described. In the test, as an example,
Modified epoxy resin paint on normal weather resistant steel with a film thickness of 5
A test piece coated so as to have a thickness of 0 μm was prepared. Also,
As a comparative example, a test piece which was not coated on a normal weather-resistant steel material was prepared.

Then, the test piece of the example and the test piece of the comparative example were set in an exposure test site, and water containing sodium chloride as a snow-melting salt was periodically sprayed on both to carry out an exposure test for three years. During the exposure test, the change with time in the amount of reduction in thickness was measured. FIG. 8 shows the measurement results. As is clear from the figure, in the example of the present invention, there was almost no reduction in the plate thickness, and it was confirmed that the present invention was applied to a bridge and could withstand long-term use.
On the other hand, in the comparative example, it was clarified that a remarkable decrease in the plate thickness occurred.

Example 3 In the example of the third embodiment, a test piece was manufactured from a normal weather-resistant steel material in both the example and the comparative example. The test piece of the example and the test piece of the comparative example were installed in an exposure test site, water containing sodium chloride as a snow melting salt was sprayed periodically, and the test piece of the example was periodically washed with water. Exposure tests were performed over a three year period with the pieces intact. During the exposure test, the change with time in the amount of reduction in thickness was measured. FIG. 9 shows the measurement results. As is clear from the figure, in the example of the present invention, the reduction in the plate thickness was small, and it was confirmed that the invention was applied to a bridge and could withstand long-term use.
On the other hand, in the comparative example, it was clarified that a remarkable decrease in the plate thickness occurred.

[0043]

(1) The weather-resistant steel bridge according to the present invention is characterized in that at least portions of road surface water containing snow-melting salt sprayed to prevent road freezing are exposed to weather-resistant steel material excellent in salt resistance. Or (2) at least a portion of the road surface water containing snow-melting salt sprayed to prevent road freezing from splashing is made of a painted weather-resistant steel material. Since the corrosion of the steel is prevented from progressing, the construction cost and the maintenance cost can be reduced.

(3) Further, the weather-resistant steel bridge according to the present invention is provided with a washing means for washing a portion of road surface water containing snow-melting salt sprayed to prevent road freezing. It is possible to prevent the corrosion of the steel material from progressing due to the occurrence of peeling rust.

(4) In addition, the weather-resistant steel bridge according to the present invention is provided with a shield for preventing the splash of the surface water containing snow-melting salt sprayed to prevent the road from freezing. Or (5) a shield is provided to prevent road surface water containing snow-melting salt sprayed to prevent road freezing from scattering outside the road, so that the same effect as in (1) above is obtained. Obtainable.

(6) The weather-resistant steel material having excellent salt resistance of the above (1) is obtained by adding, by weight%, C: 0.15% or less and Si: 0.
7% or less, Mn: 0.2 to 1.5%, P: 0.03 to
0.15%, S: 0.02% or less, Al: 0.01 to
0.1%, Cr: 0.1% or less, Ni: 0.4 to 4.0
%, Cu: 0.4% or less, Mo: 0.1 to 1.5%, composed of welded structural steel, or (7) a titanium clad steel material, a titanium thin plate or a steel material to which a titanium foil is attached, Alternatively, since the steel material is formed by joining a thin titanium clad steel plate, the progress of corrosion of the steel material can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of Embodiment 1 of the present invention.

FIG. 2 is a schematic diagram of a third embodiment.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a schematic diagram of a fourth embodiment.

FIG. 5 is a schematic diagram of a fifth embodiment.

FIG. 6 is a schematic diagram of a seventh embodiment.

FIG. 7 is a schematic diagram of a seventh embodiment.

FIG. 8 is a diagram showing a change with time of a sheet thickness reduction amount between Example 2 and a comparative example.

FIG. 9 is a diagram showing a time-dependent change in the thickness reduction amount between Example 3 and Comparative Example.

FIG. 10 is an explanatory diagram showing a state in which road surface water containing snow-melting salt sprayed for preventing road freezing is scattered by traveling vehicles.

FIG. 11 is an explanatory diagram showing a state in which road surface water containing snow-melt salt sprayed to prevent road freezing is scattered by traveling vehicles.

FIG. 12 is an explanatory diagram showing a state in which road surface water containing snow-melt salt sprayed to prevent road freezing is scattered by traveling vehicles.

[Explanation of symbols]

 1, 1a, 1b Bridge 3a, 3b, 3c, 3d Bridge girder 4a Upper flange 4b Lower flange 4c Web 7 Water distribution pipe 9 Nozzle 12, 13 Shielding object 20 Spray of road surface water containing snow-melting salt

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Isamu Kano 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 2D059 AA07 GG01 GG22

Claims (7)

[Claims] In a bridge using weather-resistant steel material, at least a portion of road surface water containing snow-melting salt sprayed to prevent road freezing is made of weather-resistant steel material excellent in salt resistance. A weather-resistant steel bridge. 2. A bridge using weather-resistant steel material, wherein at least a portion of road surface water containing snow-melting salt sprayed to prevent road freezing is made of painted weather-resistant steel material. Weatherproof steel bridge. 3. A bridge made of a weather-resistant steel material, wherein a cleaning means is provided for cleaning a portion of road surface water containing snow-melting salt sprayed to prevent road freezing. Bridge. 4. A bridge using a weather-resistant steel material, wherein a shield is provided on a portion of road surface water containing snow-melting salt sprayed to prevent road freezing from splashing. A weather-resistant steel bridge. 5. A bridge using a weather-resistant steel material, wherein a shield is provided for preventing road surface water containing snow-melting salt sprayed to prevent road freezing from scattering outside the road. Weathering steel bridge. 6. The weather-resistant steel material having excellent salt resistance is contained in a weight%.
C: 0.15% or less, Si: 0.7% or less, Mn: 0.
2 to 1.5%, P: 0.03 to 0.15%, S: 0.0
2% or less, Al: 0.01 to 0.1%, Cr: 0.1%
Hereinafter, Ni: 0.4 to 4.0%, Cu: 0.4% or less,
The weather-resistant steel bridge according to claim 1, wherein the steel is a welded structural steel containing Mo: 0.1 to 1.5%. 7. The steel material according to claim 1, wherein the weather-resistant steel material having excellent salt resistance is a titanium clad steel material, a steel material having a titanium thin plate or a titanium foil adhered thereto, or a steel material having a thin titanium clad steel plate bonded thereto. Weatherproof steel bridge.