What is the difference between a fiberglass bridge and an aluminum alloy bridge?

1. Material characteristics

FRP bridge:

Composition and formation: FRP is fiber reinforced plastic, which is made of glass fiber and its products (such as glass cloth, tape, felt, etc.) as reinforcing materials, and synthetic resin (such as epoxy resin, unsaturated polyester resin, etc.) as the matrix material, and is compounded through a certain process. Through this compound, it combines the high strength of glass fiber and the chemical corrosion resistance of resin.

Performance characteristics: The density is relatively small, and the weight is usually only one-fourth to one-fifth of the same volume of steel material, which is easy to carry and install; it has good insulation and can effectively avoid electrical problems such as cable leakage and short circuit; it has excellent corrosion resistance and has strong resistance to chemical substances such as acid, alkali, and salt, and is suitable for various corrosive environments.

Aluminum alloy bridge:

Composition and formation: Based on aluminum, some other alloy elements (such as magnesium, silicon, copper, etc.) are added, and bridge profiles of different shapes are made through casting, extrusion and other processing processes. The addition of alloy elements improves some properties of pure aluminum, such as strength and hardness.

Performance characteristics: The density is relatively small, the weight is light, and it is easy to install and construct; it has good electrical and thermal conductivity, but this characteristic sometimes needs to consider its impact on electrical lines in bridge applications; it has a beautiful appearance, and the surface can be anodized and other treatments, which can present different colors and have certain corrosion resistance. The corrosion resistance mainly depends on the alloy composition and surface treatment.

2. Mechanical properties

FRP bridge:

Strength performance: Through reasonable structural design and the reinforcement of glass fiber, its overall strength is relatively high, and it can carry a certain weight of cables and other pipelines, meeting the laying requirements in general engineering scenarios. However, its strength is greatly affected by the quality, content and process of the resin matrix and glass fiber.

Stiffness and toughness: It has a certain stiffness and can keep the shape of the bridge stable, but the toughness is relatively limited. When it is impacted by a large external force, it may be partially damaged, but its impact resistance can be improved by optimizing the structure and increasing the thickness.

Aluminum alloy bridge:

Strength performance: Different aluminum alloy series have different strengths. Generally speaking, some high-strength aluminum alloy bridges can withstand heavier loads, and their strength is relatively uniform and stable, and the quality is well controlled because there are mature alloy production standards and processing technology.

Strength and toughness: The stiffness is good, which can maintain the good shape of the bridge. At the same time, the aluminum alloy itself has good toughness. When subjected to a certain degree of external force impact, it is less likely to crack and have better anti-deformation ability than the fiberglass bridge.

3. Fireproof performance

Fiberglass bridge:

Flame retardant: It is an organic composite material and is flammable. However, many products now add flame retardants and other ingredients during the production process to improve its flame retardant properties, so that it can slow down the spread of flames to a certain extent, reduce fire hazards, and produce relatively less smoke and low toxicity during combustion, which is conducive to the evacuation of personnel during fire and reduce pollution to the environment.

Fire resistance limit: The fire resistance limit of FRP bridges made of different processes and formulas is different, but generally speaking, the overall fire resistance performance is at a certain level. In order to meet the fire protection requirements of conventional buildings, it is necessary to select products with appropriate specifications and flame retardant grades according to specific circumstances.

Aluminum alloy bridge:

Flame retardant: Aluminum alloy is a metal material and is non-flammable. From this point of view, it has a natural advantage in fire prevention and there is no problem of burning and spreading.

Fire resistance limit: Although it will not burn itself, aluminum alloy will soften and deform under high temperature conditions, and its structural stability will be affected. Therefore, when considering the fire resistance limit, it is necessary to combine the specific building fire protection design requirements and the time requirements for the bridge to maintain structural integrity in the fire.

 

IV. Appearance and decoration

Fiberglass bridge:

Appearance characteristics: It can be made into various shapes through molds and other processes, such as common styles such as trough, ladder, and tray, and the surface can be painted and other treatments. The color selection is relatively rich and can be customized according to different use environments and architectural styles to achieve better decorative effects.

Long-term appearance changes: If it is in a harsh environment such as outdoor for a long time, affected by ultraviolet rays, wind and sand, rain and other factors, the surface may fade and age. However, high-quality products can delay such changes by adding anti-aging agents and other measures.

Aluminum alloy bridge:

Appearance characteristics: The surface texture is good and has a metallic luster. Through surface treatment processes such as anodizing and electrophoretic coating, it can present different colors and appearance effects. It is beautiful and generous, and the durability of the appearance is relatively good. It is not easy to fade and other problems. It is more popular in some places with high requirements for appearance quality.

Long-term appearance changes: Over time, there may be slight oxidation in outdoor environments, but it usually does not significantly affect the overall appearance like fiberglass, and its appearance stability is relatively good.

5. Installation and maintenance

Fiberglass bridge:

Installation convenience: It is light in weight, does not require large-scale lifting equipment during installation, and has various connection methods, such as snap-on and bolted connections, which are convenient for on-site assembly, can effectively shorten the construction period, and reduce the difficulty of construction.

Maintenance cost: Good corrosion resistance, daily maintenance mainly involves simple cleaning work, checking for structural damage, etc., and does not require regular anti-corrosion treatment like metal bridges. In the long run, the maintenance cost is relatively low.

Aluminum alloy bridge:

Installation convenience: It is also light in weight and easy to install, but its connection parts may need to be handled more carefully to ensure that the connection is firm and the electrical conductivity is good (if there is a requirement for electrical conductivity), and the overall installation process is also smooth and efficient.

Maintenance cost: Daily maintenance requires attention to whether the surface has scratches, oxidation, etc. that affect the appearance and performance. Surface repair treatment is required when necessary. Moreover, if used in a corrosive environment, its corrosion resistance is not as good as that of the FRP bridge, and additional protective measures may be required. The long-term maintenance cost is slightly higher than that of the FRP bridge in some cases.

6. Cost

FRP bridge:

Material cost: The cost of raw materials is affected by price fluctuations of resins, glass fibers, etc. Overall, under the same specifications and load-bearing capacity requirements, the material cost may be slightly lower than that of some high-quality aluminum alloy bridges.

Comprehensive cost: Considering the low installation cost and low maintenance cost, the comprehensive cost has certain advantages in many application scenarios throughout the life cycle, especially for projects that are more cost-sensitive and have strong environmental corrosion.

Aluminum alloy bridge:

Material cost: The price of aluminum alloy itself is relatively high, especially some aluminum alloy materials with rare alloy elements and special properties are more expensive, which makes the initial material cost of aluminum alloy bridges often at a high level.

Comprehensive cost: Although it is more convenient to install, it may require additional maintenance investment (such as surface treatment maintenance, etc.), and the comprehensive cost may be higher than that of FRP bridges in some application scenarios. However, in some places with high requirements for quality, appearance and fire protection, its cost disadvantage will be compensated by other advantages.

In summary, the bridge of FRP structure and the aluminum alloy bridge have their own characteristics. In practical applications, they need to be comprehensively selected and used according to multiple factors such as specific engineering environment, performance requirements, budget cost, etc.