Steel Structure Bridges: Explore 3 Classification

Steel Structure Bridges: Explore 3 Classification

Steel structure bridges refer to bridges whose main load-bearing structure uses structural steel. The beam and the leg or pier (pedestal) body form a rigid connection. Due to the consolidation of the pier and beam, the beam and pier are stressed. The pier not only bears the vertical pressure caused by the load on the beam but also the bending moment and horizontal thrust.

The structural forms of steel structure bridge:

The structural forms can be divided into portal rigid frame bridges, inclined leg rigid frame bridges, T-shaped rigid frame bridges, and continuous rigid frame bridges.

The main beams of steel structure bridges generally need to withstand positive and negative bending moments, and the cross-section should be box-shaped. In the type cross-section, the stress of the main beam of the continuous steel structure bridge is the same as that of the continuous beam, and the cross-sectional form and size are the same as that of the continuous beam.

Classification of steel structure bridges:

1. Suspension bridge.

Suspension bridges are generally long-span with a theoretical maximum span of up to 4 kilometers. They are also one of the preferred types of bridges over a kilometer. The suspension bridge supports the upper part of the bridge through the main cable on the cable tower and the cables anchored on both banks.

The cable is the most essential load-bearing component. Due to the force balance condition, its shape forms a nearly parabolic cable shape from the middle to both banks. A suspension rod is hung from the cable to suspend the bridge deck, and stiffening beams are provided between the suspension rod and the bridge deck. Combining the two can effectively reduce the deflection deformation of the bridge caused by the load.

2. Cable-stayed bridge.

Also known as a cable-stayed bridge, its structure is relatively simple, mainly composed of stay cables, main beams, and cable towers. This bridge fixes all wires through the bridge tower and is connected to the beam body through the cables for pressure-bearing purposes.

In cable-stayed bridges, cables serve as multi-span elastically supported continuous beams instead of piers. This method of building a bridge can effectively reduce the internal bending moment of the beam and, at the same time, reduce the height of the building. The overall structure is lighter and consumes less material.

3. Arch steel structure bridge.

Arch steel bridge is also one of the most common steel structure bridges. Its load-bearing structure is mainly arch ribs, which bear axial force and have little or no bending moment. In the construction of steel arch bridges, the central arch is made of multiple steel pipes, and the cross beams and central arch can be hoisted and welded on site separately. This can effectively solve the problem of overweight one-time hoisting and greatly facilitate on-site construction. Shortening the construction period also plays an important role.

Advantages of steel structure bridges:

High strength:

Steel has high tensile strength, compressive strength, and apparent advantages in steel structure bridges’ load-bearing capacity. Steel structures can achieve the exact load requirements more lightly than concrete structures under the same conditions.

Lightweight and flexible:

The density of steel is relatively small, and its weight is light, which can effectively reduce the bridge’s weight. This is especially important for tall and long-span bridges, as the bridge’s weight affects the structure’s stability and reliability. At the same time, steel has good plasticity and is easy to process and manufacture, so various shapes and complex structures can be easily realized.

Fast construction:

Compared with traditional concrete bridge structures, the manufacturing and installation period of steel structure bridges is usually shorter. Steel elements can be prefabricated in a factory and assembled and installed on-site. This on-site assembly method can shorten construction time, reduce interference with traffic, and reduce project costs.

Easy maintenance:

Steel structure bridges are more accessible for routine maintenance and repair than concrete bridges. The steel structure allows easy inspection and access to various parts, making repairs more convenient. Traditional concrete structures may require more time and effort to maintain and repair.

Good durability:

Steel has high corrosion resistance and can effectively resist corrosion from the atmosphere and other environments. Steel is often coated and treated with anti-corrosion coatings for longer life and durability. This enables steel structure bridges to be used in harsh environments for a long, reducing the frequency and cost of maintenance and replacement.


The application of steel structures in bridge projects aligns with sustainable development. Steel can be recycled and reused, reducing resource consumption and environmental pollution. In addition, steel structures can achieve energy conservation and emission reduction and reduce their impact on the environment through life cycle assessment and optimized design.

Good seismic resistance:

Steel structures have good seismic resistance and can withstand earthquake and wind loads effectively. In contrast, traditional concrete structures have certain limitations in their seismic performance.

In conclusion

Applying steel structures in bridges has the advantages of high strength, lightness, flexibility, fast construction, easy maintenance, good durability, sustainability, and earthquake resistance. These advantages make steel structures an essential choice in modern bridge engineering, able to meet various complex design requirements and provide reliable transportation infrastructure.

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