### 1. The main role of steel bars in roads and bridges
1. **Enhanced load-bearing capacity**:
- The steel bar has a high tensile strength. Embedding it into the concrete structure can effectively enhance the tensile strength of the concrete structure, thereby improving the bearing capacity of road bridges.
2. **Improving stability**:
- During operation, road bridges will be subject to various external forces, such as wind and vehicle loads. Rebars can enhance the overall stability of the concrete structure by bearing the pressure of these external forces, reduce the overall inclination and deformation of the bridge, and ensure the safety and stability of road bridges.
3. **Extend service life**:
- Concrete has a certain degree of carbonization, and cracks, fall off and other phenomena will occur after use for a long time, which will affect the bearing capacity and stability of road bridges. The addition of steel bars can effectively delay the carbonization process of concrete, thereby extending the service life of road bridges.
### 2. Specific use of steel bars in roads and bridges
1. **Bridge Deck Structure**:
- In bridge deck structures, steel bars are usually used to build steel mesh or steel frames of the bridge deck paving layer to improve the load-bearing capacity and crack resistance of the bridge deck.
2. **Pili and support**:
- Piers and support are key parts to support the weight of the bridge. In these areas, steel bars are used to construct steel cages or steel frames to enhance the strength and stability of the concrete structure.
3. **Anti-collision wall and guardrail**:
- Anti-collision walls and guardrails are important facilities to ensure the safety of roads and bridges. In these parts, steel bars are used to build steel mesh or steel frames to improve their impact resistance and stability.
4. **Reinforcement and repair**:
- For road bridges that already have damage or aging, reinforcement can be used for reinforcement and repair work. For example, implant steel bars at cracks in the bridge and grouting and reinforcement, or add steel bar mesh to damaged parts of the bridge for repair.
### 3. Selection and construction requirements of steel bars in roads and bridges
1. **Selective requirements**:
- The appropriate type, specification and quantity of steel bars should be selected based on factors such as the design requirements, use environment and load conditions of the road and bridges.
- When selecting steel bars, they should give priority to their mechanical properties, corrosion resistance and welding performance.
2. **Construction Requirements**:
- The construction of steel bars should be carried out strictly in accordance with the construction drawings and specifications.
- During the processing and pre-assembly of steel bars, the size, shape and quantity of steel bars should be ensured to meet the design requirements.
- During the installation of steel bars, it is necessary to ensure that the layout, spacing and connection methods of steel bars comply with the specifications to ensure the adhesion and overall stability between the steel bars and concrete.
### 4. Innovative application of steel bars in roads and bridges
With the advancement of science and technology and the continuous development of engineering technology, the innovative application of steel bars in roads and bridges is also increasing. For example:
- **Stainless steel steel bars**: Stainless steel bars have excellent corrosion resistance and durability, which can significantly extend the service life of roads and bridges. In some coastal or snowy areas in winter, stainless steel steel bars are particularly widely used.
- **High-strength steel bars**: High-strength steel bars have higher tensile strength and yield strength, which can further improve the bearing capacity and stability of road bridges.
- **Prestressed steel bars**: Prestressed steel bars are used to tension the steel bars before pouring and maintain a certain prestressed state after pouring, thereby significantly improving the bearing capacity and crack resistance of the concrete structure.