What are the building materials for bridges?

Bridges are natural things made of natural materials, and rocks and trees are natural building materials. The rock itself is weathered to form a beam bridge, which can grow into a suspension bridge by guiding the roots, weaving with ropes, cutting down trees and chiseling stones. The components of manual intervention are aggravated in turn, and the technical level is getting higher and higher.

After that, artificial materials began to enter the bridge building, and the time series is shown in Table 1. Joseph maunier (1823- 1906), a gardener in Paris, exhibited flowerpots and sleepers made of reinforced concrete at the Paris World Expo in 1867. Obtain a patent right. 1875, with the help of designers, maunier presided over the construction of Paris, which is also the first reinforced concrete bridge in the world. The bridge is a pedestrian arch bridge with a length of16m and a width of 4m. According to the physical structure, steel bars are also arranged in the section and axis of arch members.

1. Steel-concrete hybrid bridge

Because of the great difference in strength between steel and cement concrete, the volume per unit span required to bear the same internal force is also very different, which creates the characteristics of modern steel-concrete hybrid bridge.

There is a steel-concrete transition section at the joint of this bridge, and shear studs is set at the upper and lower parts of the steel box to transfer the bending moment to the concrete in the form of shear force, but the normal pressure transfer effect of the steel-concrete end face is very small and can not be included in the calculation. In structural design, we should also pay attention to the waterproof and moisture-proof measures in the transition section. Once corroded, it can't be maintained, which will lead to major accidents.

2. Steel-concrete composite bridge

Steel-concrete composite bridge is composed of I-shaped, H-shaped, U-shaped steel, pipeline steel or welded members and concrete slabs through shear connectors. Concrete slabs should have good impermeability and crack resistance, and once corroded, they cannot be maintained; If the steel plate is removed and replaced, the combined action will be partially ineffective and the consequences will be serious.

3. Prestressed steel-concrete composite bridge

Prestressed steel-concrete composite bridge is a kind of composite structure bridge, which is composed of I-beam, H-beam, U-beam, steel tube and concrete slab through shear connectors. In the steel-concrete composite bridge, prestress is applied to the steel beam, concrete slab or concrete filled steel tube core or outside according to the need and possibility. This composite structure has been widely used in large and medium-span bridges at home and abroad.