2, the classification of the bridge:
According to availability, it can be divided into highway bridges, highway-railway dual-purpose bridges, pedestrian bridges, tractor-ploughing bridges, water-crossing bridges, etc.
According to the span size and total length of multiple spans, it can be divided into small bridges, medium bridges, large bridges and extra large bridges.
Bridge classification: total length of multi-hole span L (m) single-hole span L0 (m)
L≥500 L0≥ 100 of extra large bridge
Bridge L≥ 100 L0≥40
Bridge 30
Small bridge 8 ≤ L ≤ 300 5
Culvert l < 8l0 < 5
Culverts l < 8 L0<5 can be divided into underpass bridges, semi-underpass bridges and underpass bridges according to the location of the carriageway. According to the stress of load-bearing components, it can be divided into beam bridge, slab bridge, arch bridge, steel structure bridge, suspension bridge and composite system bridge (cable-stayed bridge and suspension bridge). According to the service life, it can be divided into permanent bridge, semi-permanent bridge and temporary bridge. According to the material type, it is divided into wooden bridge, masonry bridge, reinforced concrete bridge, prestressed bridge and steel bridge.
Bridges enable roads, railways or sidewalks to cross rivers, lakes, valleys, canyons or other roads. Bridges are mostly fixed, but some bridges can be raised or rotated. No matter what kind of bridge, the design and construction problems faced by engineers are to make the bridge structure firm and not sink or break due to weight. There are several ways to solve this problem.
The beam of truss girder bridge is very strong, and there are supports at both ends. The earliest bridges were built according to this idea. They are just tree trunks or stones across the river. Modern truss girder bridges usually use long hollow trusses made of steel or concrete as beams. This makes the bridge light and strong. Bridges built in this way are called box girder bridges.
Cantilever bridge is divided into long and solid parts, similar to truss bridge, but each part is supported by the middle, not the two ends.
The arch bridge bears the stress of the main span by pushing the arched bridge body to the ground at both ends of the bridge. Modern arch bridges usually adopt light open structure.
Suspension bridge is the best design for building long-span bridges. The bridge deck of highway or railway is suspended in the air by steel cables, which are firmly suspended between bridge towers. Some older suspension bridges use chains, and some even use ropes instead of steel cables.
Steel cables are tied to the pillars of cable-stayed bridges. The steel cable supports the weight of the bridge deck and transfers the weight to the bridge column, which puts great pressure on the bridge column.
Glass bridge A bridge made of pure glass.
Three kinds of bridges
Bridges are actually divided into three categories: beam bridges, arch bridges and suspension bridges.
Beam bridges are generally built in long-span and shallow water areas, which are composed of bridge columns and bridge slabs, and the weight of objects is transferred from the bridge slabs to the bridge columns.
Arch bridges are generally built on the water with small span, and the bridge body is arched. There are usually several bridge holes, which have the function of flood discharge. The weight in the middle of the bridge is transferred to both ends of the bridge, and both ends are transferred to the middle.
Suspension bridge is the most practical bridge today. Bridges can be built in places with large span and deep water. It consists of bridge columns, iron cables and bridge decks. Early suspension bridges can withstand wind and rain and will not break. Now the suspension bridge can be basically indifferent when the storm comes.