Novel composite section bar for railway bridge guardrail

Abstract

The utility model discloses a novel composite section bar for a railway bridge guardrail. The novel composite section bar for the railway bridge guardrail comprises an inner layer and an outer layer, the outer layer is a deformable metal tube, and the deformable metal tube is made of a seamless metal tube formed by heating and extruding deformed metal; the inner layer is a glass fiber reinforced thermosetting composite material pipe, and the glass fiber reinforced thermosetting composite material pipe is formed by pultrusion of thermosetting resin and continuous fibers; the deformable metal pipe and the glass fiber reinforced thermosetting composite material pipe form a double-layer structure through a prestress composite technology. According to the invention, the material characteristics of high strength and corrosion resistance of the glass fiber reinforced composite material and metal are brought into full play, the bending strength is further improved structurally through the outer layer metal compounded by prestress, and the defect that the glass fiber reinforced material is not resistant to ultraviolet rays is overcome in performance.

Description

Technical Field

[0001] This utility model relates to the technical field of railway bridge ancillary facilities, specifically to a new composite profile for railway bridge guardrails. Background Technology

[0002] As an auxiliary facility of bridges, the construction and maintenance costs of bridge deck railings directly affect the overall economic benefits of railway transportation. Currently, railway bridge deck railings are mainly made of concrete, steel, and composite materials. However, from the perspective of application, each type of railing has some problems. For example, concrete railings are severely weathered, cannot be repaired, and have high replacement costs; steel railings are not corrosion-resistant, have short maintenance cycles, and high material costs; composite material railings are a new material proposed in the last two years. They are fiber-reinforced polyurethane profiles with a UV-resistant coating. Their main features are lightweight, high strength, corrosion resistance, and low replacement costs. However, due to the characteristics of the material, the service life of the coating layer is not high, and the paint is prone to peeling. When the paint peels off, the polyurethane's lack of UV resistance becomes more apparent, resulting in surface powdering and exposed glass fibers.

[0003] Existing technologies for metal-lined plastic pipes have not solved the aforementioned problems and offer new solutions. Metal-lined plastic pipes are composite pipes with an alloy matrix and a thermoplastic lining. Because they combine the mechanical properties of metals with the corrosion resistance of engineering plastics, they are commonly used as pipelines for transporting various liquid and gas media. However, due to their complex manufacturing process and high production costs, their application areas are extremely limited. Existing technologies have also provided an optimized process for aluminum alloy-lined ultra-high molecular weight polyethylene composite pipes, but the lining uses thermoplastic plastics. However, metal-lined plastic pipes with thermoplastic linings are limited by the mechanical properties of thermoplastic plastics. Compared with thermosetting materials and even stronger and lighter glass fiber thermosetting composite materials, their impact deformation resistance is often significantly different at the same or similar cost. Therefore, they are not suitable for railway bridge railings.

[0004] On the other hand, thermosetting materials cannot be used for rotational molding. Although prestressed composite technology seems feasible, in reality, due to the high stiffness and low elongation of glass fiber thermosetting composite materials, internal fracture is easy to occur during the stretching process when using prestressed composite technology, making it difficult to produce qualified metal-lined plastic composite pipes.

[0005] Therefore, it is necessary to propose a new type of composite profile for railway bridge railings to solve the above problems. Utility Model Content

[0006] The purpose of this utility model is to address the shortcomings of the existing technology by providing a new type of composite profile for railway bridge guardrails, thereby solving the problems existing in the prior art.

[0007] In a first aspect, this utility model provides a novel composite profile for railway bridge railings, comprising: an inner layer and an outer layer;

[0008] The inner layer is a glass fiber reinforced thermosetting resin composite material tube;

[0009] The outer layer is a deformable metal tube;

[0010] Preferably, the inner and outer layers can be circular or square in shape;

[0011] Preferably, the inner wall thickness is greater than that of the outer wall;

[0012] Preferably, the inner tube has a wall thickness of 3-6 mm;

[0013] Preferably, the wall thickness of the outer tube is 0.3-0.8 mm;

[0014] Preferably, the deformable metal tube includes one of stainless steel tube, aluminum alloy tube and wrought magnesium alloy;

[0015] Preferably, the deformable metal tube is made of a seamless tube formed by heating and extruding deformable metal;

[0016] Preferably, the thermosetting resin includes one of polyurethane, epoxy resin, phenolphthalein resin, vinyl ester resin, unsaturated polyester resin, and amino resin.

[0017] Furthermore, in glass fiber reinforced thermosetting composite pipes, the mass percentage of glass fiber is greater than the mass percentage of thermosetting resin.

[0018] Furthermore, preferably, the glass fiber content is greater than 75%.

[0019] Preferably, the inner layer and the outer layer are composited using a prestressing process to form a double-layer structure.

[0020] Furthermore, the outer layer can be formed into a dense protective film on its surface by anodizing or sealing with resin powder.

[0021] After the outer layer is anodized or sealed with resin powder, a dense protective film is formed on the surface, which further improves the corrosion resistance and aesthetics of the outer layer. Resin powder sealing can form a uniform and dense protective film on the outer surface, preventing oxidation and corrosion, while increasing the surface hardness and wear resistance.

[0022] Secondly, this utility model provides a method for preparing the above-mentioned novel reinforcement for railway bridge guardrails, comprising:

[0023] Step 1: Glass fiber and thermosetting resin are pultruded to obtain a glass fiber reinforced thermosetting material tube, which is the inner layer;

[0024] Step 2: The deformable metal is heated and extruded to obtain a seamless metal tube. The seamless metal tube is then cut, and the cut seamless metal tube is anodized or sealed with resin powder to form the outer layer.

[0025] Step 3: Apply a uniform layer of stress-dispersing agent to the outer surface of the glass fiber reinforced thermosetting material tube, with a coating thickness of 0.1-0.5cm, and then insert it into the outer layer. After the prestressed composite process, a new type of composite profile for railway bridge guardrails is obtained.

[0026] Preferably, in step two, taking into account both lightweight and cost reduction requirements, deformable metal is made of deformable aluminum alloy.

[0027] Furthermore, when polyurethane is used as the thermosetting resin, step one specifically involves sequentially passing glass fiber through a preforming mold and a polyurethane pultrusion mold to the traction clamping part of the hydraulic pultrusion equipment; heating the preforming mold and the polyurethane pultrusion mold, and after the temperature reaches the set value, starting the hydraulic pultrusion equipment for traction; before traction, inserting the cut inner and outer felts into the opening of the preforming mold and lubricating with DOP; starting the low-pressure casting machine to inject material until the resin and glass fiber are cured and formed to the cutting point; cutting according to the required size to obtain a glass fiber reinforced thermosetting reinforced material tube.

[0028] Furthermore, in step one, the temperatures of zones one through three are set to 100-105℃, zone two to 145-150℃, and zone three to 185-190℃, respectively.

[0029] Further, in step three, the length of the aluminum alloy tube is greater than the length of the glass fiber reinforced thermosetting material tube; after the inner layer is inserted into the outer layer, it is placed into the prestressing strengthening machine, allowing it to pass sequentially through the strengthening mold and clamping system of the prestressing strengthening machine; the longer end of the aluminum alloy tube is placed into the clamping system; the prestressing strengthening machine is started, and the strengthening speed is adjusted. When the non-clamped end of the strengthening tube has completely passed through the prestressing strengthening mold, the strengthening is completed. The strengthened strengthening tube is then cut at both ends to obtain a new type of composite profile for railway bridge railings.

[0030] Furthermore, in step three, the length of the aluminum alloy tube is greater than the length of the glass fiber reinforced thermosetting material tube, with a reserved length of 10-20cm.

[0031] Furthermore, in step three, the stress dispersing agent comprises 1 mole of NCO-terminated polyurethane prepolymer, 1-1.5 moles of 2-furan ethylamine, and 1-1.5 moles of bismaleimide.

[0032] Further, preferably, the molar percentage of NCO in the NCO-terminated polyurethane prepolymer is 2-5%.

[0033] Furthermore, preferably, the stress dispersion aid requires pretreatment. Weigh out -NCO-terminated polyurethane prepolymer and 2-furan ethylamine, react at 50-60℃ for 1-2 hours to generate furan-terminated polyurethane prepolymer, then add bismaleimide, mix evenly, and set aside.

[0034] This utility model has the following beneficial effects: The novel composite profile for railway bridge railings provided by this utility model is made of glass fiber reinforced thermosetting material tube and deformable metal tube through prestressing reinforcement technology, fully utilizing the corrosion-resistant material properties of both the glass fiber reinforced thermosetting material and the deformable metal tube. In this utility model, the inner layer uses a glass fiber reinforced thermosetting material tube, whose tensile strength and flexural modulus are far higher than those of conventional thermoplastic tubes. By adding a deformable metal tube to the outer layer for prestressing reinforcement, not only is the disadvantage of glass fiber reinforced material's poor UV resistance solved, but the flexural strength is further improved. The deformable metal tube has a more aesthetically pleasing metallic texture, and its corrosion resistance is also better after surface strengthening.

[0035] This invention creatively proposes a technical solution using glass fiber reinforced thermosetting material tubes as the inner layer, breaking through the existing technology that uses thermoplastic materials such as polyethylene and polypropylene as the inner layer. The resulting composite profile has excellent impact resistance and can be applied in fields such as railway bridge railings where high resistance to deformation and stability of materials are required.

[0036] Compared to thermoplastic materials, using glass fiber reinforced thermosetting material tubes as the inner layer, due to their high stiffness and low elongation, makes it difficult to match the deformation of the outer metal layer during prestressed reinforcement traction and stretching. This can easily lead to internal fractures during production. Therefore, the dimensions of the inner and outer layers require extremely precise control, and the parameters of the prestressing machine must be precisely controlled and highly stable. In particular, in the technical solution of this utility model, in order to ensure the strength of the new reinforcement for railway bridge railings, the amount of glass fiber used is greater than that of thermosetting resin. The addition of a large amount of glass fiber further reduces the elongation at break of the glass fiber reinforced thermosetting material tube, thus making the production technology very difficult and the production cost too high.

[0037] To address the aforementioned issues, this invention employs an inner and outer felt covering of the pre-forming mold opening during the fabrication of the glass fiber reinforced thermosetting material tube. This ensures the tube wall is as smooth as possible, resulting in more uniform stress distribution and fewer stress concentration points. Simultaneously, this invention provides a stress-dispersing agent with excellent flowability, stress dispersion, and curability. After uniformly coating the outer surface of the glass fiber reinforced thermosetting material tube with the stress-dispersing agent, it is then inserted into a deformable metal tube. The resulting reinforced tube further disperses stress during prestressed reinforcement and stretching, resulting in more uniform stress distribution. This reduces the prestressing reinforcement technical parameters required by the performance requirements of thermosetting material tubes, thereby lowering production difficulty and cost.

[0038] Meanwhile, after the prestressing process is completed, the stress dispersion agent is extruded into a thin layer with a thickness of less than a micrometer and self-cures into a thermosetting resin to form a stress dispersion layer. This stress dispersion layer contains thermally reversible covalent bonds. During use, the cross-linking state of the internal molecular chains can be adjusted through cross-linking and de-cross-linking, thereby solving the stress concentration problem between the material and the deformable metal tube caused by temperature difference or other reasons, avoiding cracking of the composite surface. This not only further improves the durability of the reinforcing material of this utility model, but also significantly improves its overall performance. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the structure of this utility model.

[0041] Illustration: 1-Inner layer; 2-Outer layer. Detailed Implementation

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be pointed out that the following detailed description is illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0043] Example 1

[0044] Please see Figure 1In the first aspect, this utility model embodiment provides a novel composite profile for railway bridge guardrails, comprising: an inner layer 1 and an outer layer 2.

[0045] The inner layer is a glass fiber reinforced polyurethane resin composite tube.

[0046] The outer layer is an aluminum alloy tube.

[0047] The inner wall thickness is greater than that of the outer wall.

[0048] The glass fiber reinforced polyurethane resin composite pipe has a wall thickness of 3mm. The outer aluminum alloy pipe has a wall thickness of 0.7mm.

[0049] In glass fiber reinforced polyurethane resin composite pipes, the mass percentage of glass fiber is greater than that of thermosetting resin, with glass fiber accounting for 76% of the mass.

[0050] The aluminum alloy tube is made into a seamless tube by heating and extrusion. Before prestressing composite, the wall thickness is 1mm. The surface of the aluminum alloy tube is anodized and has an oxide film sealing layer of not less than 10μm. After prestressing composite, the outer aluminum alloy tube wall thickness is 0.7mm.

[0051] The inner layer and the outer layer are combined using a prestressing process to form a double-layer structure.

[0052] Secondly, this utility model provides a method for preparing the above-mentioned novel composite profile for railway bridge guardrails, including:

[0053] Step 1: Glass fiber and polyurethane resin are pultruded to obtain a glass fiber reinforced polyurethane resin composite tube, which is the inner layer.

[0054] Step 2: The aluminum alloy tube is heated and extruded to obtain a seamless metal tube. The seamless metal tube is then cut, and the cut seamless aluminum tube is anodized to form the outer layer.

[0055] Step 3: A uniform stress-dispersing agent is applied to the outer surface of the glass fiber reinforced thermosetting material tube, and then inserted into the outer layer. After a prestressed composite process, a new type of composite profile for railway bridge guardrails is obtained.

[0056] In step one, alkali-free continuous fiber yarn with a linear density of 9600 is used.

[0057] Step one involves sequentially passing the alkali-free continuous fiber yarn through a preforming mold and a polyurethane pultrusion mold to the traction clamping part of the hydraulic pultrusion equipment. The preforming mold and the polyurethane pultrusion mold are heated until the temperature reaches the set value. The hydraulic pultrusion equipment is then started for traction. Before traction, the cut inner and outer felts are inserted into the opening of the preforming mold and lubricated with DOP. The low-pressure casting machine is then started to inject the material until the resin and glass fiber are cured and formed at the cutting point. The material is then cut to the required size to obtain a glass fiber reinforced thermosetting material tube.

[0058] The temperatures for Zones 1 through 3 are set as follows: Zone 1: 100-105℃, Zone 2: 145-150℃, and Zone 3: 185-190℃, respectively.

[0059] In step three, the length of the aluminum alloy tube is greater than the length of the glass fiber reinforced thermosetting material tube. After the inner layer is inserted into the outer layer, it is placed into the prestressing strengthening machine, passing it sequentially through the strengthening mold and clamping system of the prestressing strengthening machine; the longer end of the aluminum alloy tube is placed into the clamping system. The prestressing machine is started, and the profile's travel speed is adjusted. When the non-clamped end of the inner tube has completely passed through the prestressing strengthening mold, the strengthening is complete. The strengthened tube is cooled, dried, and cut at both ends to obtain a new type of composite profile for railway bridge railings.

[0060] The stress dispersion aid is: 1 mole of -NCO-terminated polyurethane prepolymer, 1 mole of 2-furan ethylamine, and 1 mole of bismaleimide.

[0061] The NCO molar percentage of the NCO in the -NCO-terminated polyurethane prepolymer is 2%. The stress dispersion aid needs to be pretreated. Weigh the -NCO-terminated polyurethane prepolymer and 2-furan ethylamine, react at 50-60℃ for 1-2 hours to generate a furan-terminated polyurethane prepolymer. Then add bismaleimide, mix well and set aside.

[0062] Before prestressing, the inner diameter of the outer aluminum alloy tube is larger than the outer diameter of the inner reinforcing material tube. After prestressing, the inner diameter of the outer aluminum alloy tube is equal to the outer diameter of the inner reinforcing material tube, and there is no gap between the two layers.

[0063] A uniform layer of stress-dispersing agent is applied to the surface of the glass fiber reinforced polyurethane resin composite tube. The coating thickness of the stress-dispersing agent is 0.1 cm. Then, it is inserted into the aluminum alloy tube. The length of the aluminum alloy tube is greater than the length of the glass fiber reinforced polyurethane resin composite tube, and a 15 cm allowance is reserved.

[0064] Example 2

[0065] This utility model embodiment provides a novel composite profile for railway bridge guardrails, comprising: an inner layer 1 and an outer layer 2.

[0066] The inner layer is a glass fiber reinforced epoxy resin composite tube.

[0067] The outer layer is a stainless steel tube.

[0068] The inner wall thickness is greater than that of the outer wall.

[0069] The wall thickness of the glass fiber reinforced epoxy resin composite pipe is 6mm.

[0070] In glass fiber reinforced epoxy resin composite pipes, the mass percentage of glass fiber is greater than that of thermosetting resin, with glass fiber accounting for 78% of the mass.

[0071] The stainless steel pipe is made of seamless pipe through heating and extrusion molding. Before prestressing and composite, the stainless steel pipe has a wall thickness of 1mm and the surface of the stainless steel pipe is sealed with resin powder, forming a sealing layer of not less than 10μm.

[0072] After prestressing and composite treatment, the wall thickness of the stainless steel pipe is 0.8mm.

[0073] The inner layer and the outer layer are combined with prestress to form a double-layer structure.

[0074] Secondly, this utility model provides a method for preparing the above-mentioned novel composite profile for railway bridge guardrails, including:

[0075] Step 1: Glass fiber and epoxy resin are pultruded to obtain a glass fiber reinforced thermosetting material tube, which is the inner layer;

[0076] Step 2: The stainless steel tube is heated and extruded to form a seamless metal tube. The seamless metal tube is then cut, and the cut seamless stainless steel tube is anodized to form the outer layer.

[0077] Step 3: A uniform stress-dispersing agent is applied to the outer surface of the glass fiber reinforced epoxy resin reinforced material tube, and then inserted into the outer layer. After a prestressed composite process, a new type of composite profile for railway bridge guardrails is obtained.

[0078] In step one, alkali-free continuous fiber yarn with a linear density of 9600 is used;

[0079] Step one involves sequentially passing glass fiber through a preforming mold and an epoxy resin pultrusion mold to the traction clamping part of the hydraulic pultrusion equipment. The preforming mold and the epoxy resin pultrusion mold are heated until the temperature reaches the set value. The hydraulic pultrusion equipment is then started for traction. Before traction, the cut inner and outer felts are inserted into the opening of the preforming mold and lubricated with DOP. The low-pressure casting machine is then started to inject the material until the resin and glass fiber are cured and formed at the cutting point. The material is then cut to the required size to obtain a glass fiber reinforced epoxy resin composite tube.

[0080] The temperatures for Zones 1 to 3 are set as follows: Zone 1: 70-80℃, Zone 2: 80-90℃, and Zone 3: 100-110℃, respectively.

[0081] In step three, the length of the stainless steel tube is greater than the length of the glass fiber reinforced thermosetting material tube. After the inner layer is inserted into the outer layer, it is placed into the prestressing strengthening machine, passing sequentially through the strengthening mold and clamping system of the prestressing strengthening machine. The longer end of the stainless steel tube is placed into the clamping system. The prestressing machine is started, and the profile's travel speed is adjusted. When the non-clamped end of the inner tube has completely passed through the prestressing strengthening mold, the strengthening is complete. The strengthened tube is then cooled, dried, and cut at both ends to obtain a new type of composite profile for railway bridge railings.

[0082] Further, in step three, the stress dispersing agent is: 1 mole of NCO-terminated polyurethane prepolymer, 1.5 moles of 2-furan ethylamine, and 1.5 moles of bismaleimide.

[0083] The NCO molar percentage of the NCO in the —NCO-terminated polyurethane prepolymer is 5%. The stress dispersion aid requires pretreatment. Weigh the —NCO-terminated polyurethane prepolymer and 2-furan ethylamine, react at 50-60℃ for 1-2 hours to generate a furan-terminated polyurethane prepolymer. Then add bismaleimide, mix thoroughly, and set aside.

[0084] Before prestressing, the inner diameter of the outer aluminum alloy tube is larger than the outer diameter of the inner reinforcing material tube. After prestressing, the inner diameter of the outer aluminum alloy tube is equal to the outer diameter of the inner reinforcing material tube, and there is no gap between the two layers.

[0085] A uniform stress-dispersing agent is applied to the outer surface of the glass fiber reinforced epoxy resin composite tube with a coating thickness of 0.3 cm. The tube is then inserted into a stainless steel tube with a length greater than that of the glass fiber reinforced thermosetting material tube, and a 20 cm allowance is provided.

[0086] Comparative Example 1

[0087] The difference from Example 1 is that it only contains a glass fiber reinforced polyurethane composite tube, and the structure of the glass fiber reinforced polyurethane inner tube is the same as that of Example 1.

[0088] Comparative Example 2

[0089] The difference from Example 1 is that the glass fiber content is 45%.

[0090] Comparative Example 3

[0091] The difference from Example 1 is that, in step three, no stress dispersing agent is added, and the glass fiber reinforced polyurethane resin composite tube is directly inserted into the aluminum alloy tube for prestressed composite process.

[0092] The longitudinal tensile strength and longitudinal tensile modulus of elasticity shall be tested in accordance with the provisions of GB / T 1447.

[0093] The longitudinal bending strength and longitudinal bending modulus of elasticity shall be tested in accordance with the provisions of GB / T 1449.

[0094] The interlaminar shear strength between the inner and outer layers is tested according to the method in GB / T 1450.1.

[0095] The weather resistance test shall be carried out by performing the following three accelerated aging tests respectively, and then testing the longitudinal bending strength of the specimen according to the provisions of GB / T 1449, and calculating the longitudinal bending strength retention rate.

[0096] a) Weathering: Simulate the natural aging effect of the product under sunlight in the actual use environment according to GB / T 16422.3, and use artificial climate aging (method A) or type 2 (UVB-313) lamp (method C) exposure cycle for at least 1000h.

[0097] b) Salt spray aging: Aging for at least 1000 hours according to the neutral salt spray test (NSS) method required by GB / T 10125;

[0098] c) Damp heat aging: Aging for at least 720 hours according to the damp heat test method required by GB / T 2573.

[0099] As can be seen from the above embodiments, the new composite profile for railway bridge guardrails provided by this utility model fully utilizes the corrosion-resistant material properties of glass fiber reinforced materials and metal materials. By using prestressed composite outer metal, the bending strength is further improved in structure, and the shortcomings of glass fiber reinforced materials being not resistant to ultraviolet light are solved in terms of performance.

[0100]

[0101] As can be seen from the above embodiments, the new composite profile for railway bridge guardrails provided by this utility model fully utilizes the corrosion-resistant material properties of glass fiber reinforced materials and metal materials. Through the prestressed outer metal layer, the bending strength is further improved in structure, and the shortcomings of glass fiber reinforced materials in terms of performance are solved by the fact that they are not resistant to ultraviolet rays.

[0102] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A novel composite profile for railway bridge railings, characterized in that, include: The inner layer and the outer layer are: an inner layer is a glass fiber reinforced thermosetting resin composite tube; the outer layer is a deformable metal tube; the wall thickness of the inner layer is greater than that of the outer layer, and the inner layer and the outer layer are formed into a double-layer structure through a prestressed composite process.

2. The novel composite profile for railway bridge railings as described in claim 1, characterized in that, The inner and outer layers can be circular or square in shape; the inner layer tube has a wall thickness of 3-6 mm; and the outer layer tube has a wall thickness of 0.3-0.8 mm.

3. The novel composite profile for railway bridge railings as described in claim 1, characterized in that, The deformable metal tube includes one of stainless steel tube, aluminum alloy tube, and deformable magnesium alloy; the thermosetting resin includes one of polyurethane, epoxy resin, phenolphthalein resin, vinyl ester resin, unsaturated polyester resin, and amino resin.

4. The novel composite profile for railway bridge railings as described in claim 1, characterized in that, The deformable metal tube is made of a seamless tube formed by heating and extruding deformable metal.

5. A novel composite profile for railway bridge railings as described in claim 1, characterized in that, The glass fiber mass ratio in the glass fiber reinforced thermosetting composite tube is greater than the thermosetting resin mass ratio.

6. A novel composite profile for railway bridge railings as described in claim 5, characterized in that, The glass fiber content is greater than 75% by mass.

7. A novel composite profile for railway bridge railings as described in claim 1, characterized in that, The outer layer can be formed into a dense protective film on its surface by anodizing or sealing with resin powder.

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