There are two types of commonly used bridge seismic isolation devices: flexible bearing device and damping device. Rubber bearing is a flexible bearing device that is widely used and has good practicability. The rubber bearing is composed of thin steel plate And thin Rubber sheet It is formed by alternating lamination, vulcanization and bonding at high temperature. Generally, the rubber used is Natural rubber And neoprene.
Characteristics of LNR horizontal dispersion force rubber bearing of bridge:
1) . It has a good ability to adapt to the free expansion and rotation of the beam body;
2) . It can meet the requirements of large shear displacement under the action of temperature change and earthquake, and the integrity of the bearing is good;
3) . The support is effectively connected with the main beam and pier, and each pier is stressed together. Especially for curved beam bridges, the horizontal force dispersion effect is good.
4) High resilience, no residual deformation after large displacement shear deformation, and small change in characteristics;
5) Good creep property and stable performance;
6) The surface of the bearing is covered with a rubber layer to protect the internal rubber from ozone, UV, etc., with better aging resistance;
Design basis of LNR horizontal dispersion force rubber bearing of bridge:
General Code for Design of Highway Bridges and Culverts (JTG D60-2004)
Standard for Design Loads of Urban Bridges (CJJ 77-98) ***
Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG D62-2004)
Detailed Rules for Seismic Design of Highway Bridges (JTG/T B02-01-2008)
Code for Seismic Design of Urban Bridges (CJJ 166-2011)
The LNR horizontal dispersion rubber bearing of the bridge is an important component to connect the superstructure and substructure of the bridge. The LNR horizontal dispersion rubber bearing can reliably transfer the reaction and deformation (displacement and corner) of the bridge superstructure to the substructure of the bridge, so that the structural stress is consistent with the theoretical calculation diagram.
The layout of LNR horizontal dispersion rubber bearings for bridges is mainly related to the structural form of the bridge. Whether the layout of bearings is reasonable will directly affect the stress condition of bearings, and then affect the stress condition of the bridge. The layout principle of LNR horizontal dispersion type bearings for bridges is to facilitate the transmission of bearing reaction, and make the bearings fully adapt to the free deformation of the beam.
LNR series horizontal force dispersed rubber bearing is an important part of connecting the superstructure and substructure of the bridge. It can reliably transfer the reaction and deformation (displacement and rotation angle) of the superstructure of the bridge to the substructure of the bridge, so that the stress of the structure is consistent with the theoretical calculation diagram.
Because the proportion of bearings in the cost of bridge engineering is very small, engineering technicians often fail to pay enough attention to them. Before the 1970s, the roads and * * * bridges in our country often had no bearings or only traditional steel bearings. With the development of bridge construction, various types of long-span bridges are also emerging. Therefore, the requirements for the bearing capacity of bridge bearings and the ability of bearings to adapt to displacement and rotation are constantly improving, and it is necessary to research and develop various new bridge bearings to adapt to them.
The layout of bridge bearings is mainly related to the structural form of the bridge. Whether the layout of bearings is reasonable or not will directly affect the stress condition of bearings, and then affect the stress condition of the bridge. The layout principle of bridge bearings is to facilitate the transmission of bearing reaction, and to make the bearings fully adapt to the free deformation of the beam.
China is an earthquake prone country, which belongs to the seismically active zone. After the Wenchuan earthquake, Qinghai earthquake and other natural disasters, whether it is to people's minds or local economic development, it has caused serious impact. Through years of technical discussions with relevant people, it is advocated that houses, bridges and other Isolation rubber bearings are used in structural construction. The isolation rubber bearings include rubber bearings (LNR), lead rubber bearings (LRB) and high damping rubber bearings (HDR).
Ordinary rubber bearings are mainly used for houses, bridges or other structures, and are mainly used for bearing pressure and shock absorption. Including plate bearing and pot bearing. LNR rubber bearing (LNR) shock isolation rubber bearing made of rubber; The lead rubber bearing (LRB) contains a vertical lead rubber bearing.
High damping rubber bearing (HDR) is an isolated rubber bearing with high damping performance made of rubber; The performance of isolation rubber bearing when it is damaged, buckled or rolled over under compression shear load. Very high performance curve: refers to the curve number of the relationship between high shear force and shear displacement of the isolation rubber bearing.
