1, bridge span structure
The main load-bearing structure that crosses obstacles when the line is interrupted.
2. Pier and abutment
It is a building that supports the bridge span structure and transfers dead loads and live loads such as vehicles to the foundation.
Abutment is usually located at both ends of the bridge. In addition to the above functions, it is also connected with the embankment to resist the earth pressure of the embankment and prevent the landslide and collapse of the embankment fill.
3. Foundation
The laying part of the foundation at the bottom of the pier transfers all loads to the foundation, which is usually called foundation. This is the key to ensure the safe use of the bridge. Because the foundation is often buried deep in the soil and needs to be constructed underwater, it is also a difficult point in bridge construction.
4. Superstructure
Usually, people also habitually call the bridge-span structure the superstructure of the bridge. A pier or abutment is called the substructure of a bridge.
Step 5 support
In bridges, the force transfer devices installed at the supports of bridge spans, piers or abutments are called bearings.
It must not only transfer huge load, but also ensure that the bridge-span structure can produce certain deformation.
6. Tapered slope protection
At the junction of embankment and abutment, stone cone slope protection is set on both sides of abutment. Ensure the stability of the slope of the waterfront embankment.
In bridge construction, in addition to the above-mentioned basic structures, auxiliary projects such as bank protection and diversion structures, such as culverts, are often built as needed.
The three main components of a bridge are superstructure, substructure and accessory structure.
The superstructure consists of bridge-span structure and load-bearing system.
Bridge span structure
Or bridge hole structure, is the load-bearing structure part of the bridge, spanning the bridge hole and above the bearing. According to different stress diagrams, it can be divided into basic systems such as beam, arch, rigid frame and suspended cable, which constitute various combined systems. Including the main load-bearing structure, vertical and horizontal connection system, arch building, bridge deck structure and bridge deck pavement, drainage and waterproof system, deformation joints and safety protection facilities.
Bearing system
Force transmission and connection devices arranged between the upper and lower structures of the bridge. Its function is to transfer all kinds of loads of the superstructure to the pier, and adapt to the displacement caused by live load, temperature change and concrete shrinkage and creep, so that the actual stress of the bridge conforms to the structural calculation diagram. Generally divided into fixed bearings and movable bearings.
The substructure consists of pier, abutment and abutment foundation.
Pier and abutment
It is a building that supports the superstructure of bridges on both sides of the river or on the shore. Abutment is located at both ends, and pier is between two abutments, as shown in the following figure. In addition, the abutment should be connected with the embankment to prevent it from collapsing. In order to protect abutment and embankment fill, some protection and diversion works are often done on both sides of abutment.
Pier foundation
Ensure the safety of piers and abutments and transfer the load to the structural part of the foundation.
Schematic diagram of bridge composition
Auxiliary components mainly include expansion joints, lighting, bridge deck pavement, drainage and waterproof system, railings (or anti-collision railings) and so on.
________________________________________
expansion joint
There is a gap between the superstructure of the bridge span or between the superstructure of the bridge span and the end wall of the abutment to ensure the displacement of the structure under various factors. In order to drive straight on the bridge deck without bumping, expansion joint structure should be set here. In particular, the expansion joints of bridges or urban bridges should not only be firm in structure and smooth in appearance, but also need to regularly clean the garbage and soil that go deep into the expansion joints to ensure their functions.
Lighting illumination
In modern cities, iconic long-span bridges are equipped with various lighting equipment, adding a dazzling night scene to the city.
Bridge deck pavement
It is also the road surface of the garage. The smoothness, wear resistance, no shell warping and no water seepage of the road surface are the keys to ensure driving comfort. Especially, the technical requirements for paving asphalt pavement on steel box girder are very strict.
Drainage waterproof system
The accumulated water on the bridge deck should be removed quickly to minimize the possibility of water seepage. In addition, the drainage system of urban bridges should ensure that there is no dripping and structural leakage under the bridge.
Railings (or crash barriers)
It is not only a structural measure to ensure safety, but also the best decorative piece for viewing.
1. Generally speaking, a bridge consists of a superstructure, a substructure and an accessory structure, and the superstructure refers to the main load-bearing structure and the deck system; The substructure includes abutment, pier and foundation; Accessory buildings refer to bridge end transition slab, cone slope protection, bank protection, diversion works, etc.
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.
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.
3. grade crossing
The intersection of two or more roads is called a road intersection. Road intersections are generally divided into two types: plane intersections and three-dimensional intersections. Three-dimensional interchanges are divided into simple interchanges and interchanges with unconnected upper and lower roads, that is, separated interchanges. The intersection where the upper and lower roads are connected by ramps is called interchange. Interchange is divided into rhombic interchange, trumpet interchange, circular interchange, cloverleaf interchange and directional interchange.