Research Of Mechanical Properties And Application Of LRB In Continuous Beam Bridge

High intensity earthquakes have happened more frequently since 21st century. As the most significant projections, many bridges have been destroyed in many serious earthquakes. As a result, more and more countries take into account for the damage of bridges caused by earthquakes. The traditional anti-seismic designs of bridge are mainly in accordance with the strength and ductility of the structure, which may consume a large number of materials and are often difficult to meet the anti-seismic requirements in high-intensity zone. However, seismic isolation technology which can can effectively reduce the effect of earthquake is widely used. Seismic isolation technology is mainly fit for the continuous beam bridges that are largely constructed, and to reduce the response through setting bearings which provides flexible support and causes energy dissipation at the junction of the top of pier and the bottom of beam. LRB is the most widely used bearing in bridge bearings. Further in-depth study of the mechanical properties of LRB which is suitable for bridge are quite necessary. Nevertheless, simplified calculation method which integrates with current norms has practical significance to the application of isolating technology in bridge. In this paper, based on LRB which is suitable for seismic isolation of continuous beam bridge, research is carried out in the following areas:1 Theoretical analysis of LRB properities. Firstly, getting the calculation expression of longitudinal and horizontal stiffness of LRB through longitudinal compressed stiffness of rubber and the longitudinal apparent elastic modulus which are derived by rubber elasticity theory. Then deriving expression of the lingitudinal stress distribution of the bottom of rubber. Finally, according to the data, deriving the expression of shear distribution at the bottom of steel plate. after that, discussing the questions in the design of the square bearing and multi-lead-bearing according to the distribution of stress.2 Experimental Analysis of LRB. The experiments reveal the mechanical properties of varieties of bearings in different circumstances. Using different horizontal displacement, different frequencies in the dynamic mechanical properties test, ultimate shear deformation test, ultimate stress test, bearing fatigue test, verifying square bearings is a reliable bearing in the isolatation of bridge; Using different horizontal displacement, different frequencies in the dynamic mechanical properties test, ultimate shear deformation test, ultimate stress test, bearing fatigue test, verifying multiple lead core rubber bearings is a reliable bearing in the isolatation of bridge; Doing simulated static load test on the bearings in different diameters, and the results shows that there are something different between the static properties and the dynamic properties of bearing. Doing temperature test on the bearings, and the results reveals the changes of mechanical properties at different temperatures and different horizental displacement. Getting the fisrt and the second stiffness, and yield force variation curve of bearing, then draw quantitative conclusions of temperature properity of bearing.3 Analysis of dynamic characteristics of LRB, based on three-dimensional nonlinear dynamic finite element program. Compared with the experimental results and find that the results agree well with the experimental results, so finite element analysis can be developed as a means of the research and invention of bearings. The anisotropy of square rubber bearings is researched by using three-dimensional nonlinear dynamic finite element analysis, and researched the bearing porperity, stress on the rubber bearings, stress on steel plate when lead is located in different parts, and make a comparation with the theoretical value.4 Compared analysis between the different current equivalent linear method. Summary the main difference between the various methods and find that the equivalent damping ratio and the structure damping coefficient are the primary problem of equivalent linear method. When it comes to a bridge, compared with some seismic response time history results, assess different equivalent linearization methods through examples of different equivalent linearization method. According to the mechanical parameters and the temperature curve obtained by test and using equivalent linearization methods and elastic response spectrum method of seismic response of compute the response of isolated bridge, get the response range that bearing may be effected by temperature.