Papers by Keyword: Rubber Bearing

Abstract: A detailed FE model for analysis of overturning of concrete box-girder bridge with single-column piers was developed and the failure process was discussed in the presented paper. The result shows that the reason for overturning failure is the non-uniform compression deformation of the loading-side bearing caused by the eccentric external load, which then leads to a large rotating angel of supper structure. Once the friction force between Teflon plate and steel plate in the bearing cannot carry the diagonal component caused by the gravity load and external load, the sliding failure occurs. Based on the simplified mechanical analysis, the condition that bridge overturning occurs is that the tangent value of the rotating angle of box girder is greater than the friction coefficient between Teflon plate and steel plate in rubber bearing.

Abstract: The insufficient consideration of seismic risk caused hidden danger for structural safety in many areas. A promising retrofit method for these structures is base isolation. In order to evaluate the effectiveness of this approach, a hypothetical RC frame based on actual situation is designed to be retrofitted using base isolation. Then, seismic fragilities for both un-retrofitted and isolated frames are analyzed, utilizing the results obtained from nonlinear finite-element analysis. The ground motion of the analysis contains 22 earthquake motions, and the results of considering mainshock-aftershock and those of considering only mainshock are compared. The study proves the well designed base isolation can reduce the seismic fragility of the RC frame effectively, and the exclusive consideration of mainshock will underestimate the seismic hazards for structures.

Abstract: Based on the nonlinear dynamic time history analysis, a multi-span RC highway bridge with high damping rubber bearings was studied, to investigate the damping ratio and seismic performance of the bridge and high damping rubber bearings compared with the rubber bearings. Results show that the application of high damping rubber bearings can reduce the seismic response of substructures of the bridge under longitudinal and transversal seismic excitations to some extent. But what is more important is that high damping rubber bearings wont suffer shear and displacement failure which may happen on rubber bearings. As a result, the pounding response and residual displacement can be dispelled.

Abstract: Rubber bearings are widely used in bridge structures. The aqueduct structures are water bridges, so rubber bearings are often set at the end of the aqueducts. Rubber bearing cannot solve the problems such as temperature stress and supporting inhomogeneous settlement, but also play role of isolation damping. This paper mainly studies on the effects of the water-depth with changing rubber bearing on the seismic performance of the aqueduct-water coupling structure by numerical analysis.

Abstract: In order to investigate isolation effectiveness on seismic performance of the continuous rigid frame bridge, shaking table test with nine sub-tables on 1/10 scaled reinforced concrete rigid frame bridge specimen was performed. The experimental results demonstrate that isolation devices provide flexibility to transform natural period of the scaled model, and additional it can improve the ability of energy dissipation when lead is used. The initial first frequency is 8.17Hz for plate-type rubber bearing and 9.12Hz for leading rubber bearing. The plate rubber bearing and lead-rubber bearing are quite sensitive to seismic wave frequency. The use of various isolation devices affects response of the bridge model. The results show that the more difference in the isolation devices, the more difference in response. Moreover, isolation effect of lead-rubber bearing show obviously more advantage than the one of plate-type rubber bearing, especially in controlling responses of the bridge during major earthquakes.

Abstract: In this paper a new seismic base isolator, called High Damping Hybrid Seismic Isolator (HDHSI), is proposed. It is obtained by the assembly in series of a Lead Rubber Bearing (LRB) and a Friction Slider (FS) with a high friction coefficient. The HDHSI device is in contrast with the Resilient-Friction Base Isolator (R-FBI) with the aim of optimizing the Electricité De France (EDF) system. The mathematical model of a structure base isolated by a HDHSI system is analyzed with a two Degree of Freedom System (2-DOF) in which the superstructure is assimilated to a rigid body. Nonlinear finite elements are adopted for modeling the HDHSI device. A dynamic nonlinear analysis is performed and the hysteretic cycles are derived and evaluated for the single components and for the innovative HDHSI device.

Abstract: In this paper we have analyzed the influence of the strain hardening behavior of High Damping Rubber Bearings (HDRBs) adopted for a base isolation system of a Reinforced Concrete (RC) isolated structure. For the modeling of the rubber isolators we have adopted an evolution of the Bouc-Wen’s hysteretic model taking into account the incremental hardening effect which appears when the shear strain of the HDRB exceeds the limit value around 100% usually adopted in design practice. The incremental hardening effect is sometimes neglected in the design but it is an important aspect because it ensures a seismic protection of the base isolated structure also in presence of exceptional seismic events for intensity or frequency content. In this paper we have highlighted the significant influence of this phenomenon in the seismic response of the isolated structure by reporting the cyclic behavior of a HDRB respectively neglecting and considering this aspect.

Abstract: Water becomes a good application prospect lubricant for its low cost, energy saving, good safety and environment friendly characteristic. A bearing microscopic surface pitting lubrication model was established, the water condition of it was introduced and the effects of the speed and the load on the film thickness were discussed.The result show that with the provided water film thickness increases, the film thickness also increases. However, when it is added to a certain degree, the film thickness will no longer change, there exists a critical point. Under water-lubricated conditions, the film thickness and minimum film thickness are increased greatly with the increase of speed and decreased greatly with the increase of load in both staved and full water conditions.

Abstract: Adopted the coupling method and considered the elastic deformation，the paper did the numerical calculation for a water lubrication rubber bearing used horizontal installation. And by means of the finite element analysis software, the nonlinear contact was studied. The results of water film pressure, water film thickness, carrying capacity and deformation of rubber bush are analysed, and draw some useful conclusions. The results provide design basis and reference information for the dynamic calculation to rubber bearing.

Abstract: The noise of the rubber bearing is closely related to its vibration characteristics, thereby, the study of the natural vibrations is of an important significance for the safety of the warships. Based on the finite element method, this paper analyzes the effect of the structural parameters and material properties on the natural vibrations of the rubber bearings, the numerical results show that in the low frequencies its vibration modes mainly present the shear deformations in its center of the rubber strip. The influences of the variations in the thickness of the built-in steel bars on the natural frequencies are larger than that in the width, and the variations of rubber materials’ mechanical properties on the natural frequencies are remarkable. Thus, increasing the elastic modulus of rubber material will effectively enlarge the value of the natural frequencies, as well as improve their intensive distribution.