Research On Seismic Isolation Performance Of V Shaped Steel Damping Energy Dissipation Pot Bearing

The continuous girder bridge is generally provided with fixed bearings in a peir in a unit and the rest piers are arranged with the movable bearings. The fixed pier whose internal force is significantly larger than that of the movable piers in the earthquake is prone to be destroyed, leading to girder damage. Based on the pot bearing and metal damper, a new type of unidirectional movable bearing-V shaped steel damping energy dissipation pot bearing was proposed, aiming to improve this situation.The structure and working principle of the new bearing was introduced first in detail in this paper. The mechanical behavior of the V shaped steel damper under horizontal force was studied according to its possible deformation in the new bearing. Theoretical expressions for the unidirectional horizontal force-displacement relation of the steel damper were derived without considering the bottom width of the steel plate. By using the fitting of statistical calculation, the correction factor with the consideration of the bottom width was obtained, improving the force-displacement relation further. Considering the convenience of the engineering application, the force-displacement curve of the steel damper was bilinear simplified, and the key parameters of the model were obtained. A bilinear restoring force model was put forward after the hysteretic behavior of steel damper was studied.On the basis of the above, the mechanical behavior of the new bearing in horizontal direction was studied. Piecewise mathematical expressions of relation between new bearing horizontal force and displacement under unidirectional and bidirectional loading were deduced and their correctness were verified with the aid of the finite element numerical simulation. The hysteretic law was summarized after analyzing the deformation characteristics of the bearing in the horizontal force loading. Then the skeleton curve and the restoring force model were put forward, providing a theoretical basis for the simulation in engineering calculation.In the end, the dynamic time history analysis of a 4 span continuous girder bridge arranged with new bearing was carried out. The results indicated that new bearing and sliding pot bearing had the same effect under the E1 earthquake because of the small displacement response of the bridge pier and the main girder. While under the E2 earthquake the new bearing showed a better seismic performance than the sliding pot bearing with more effective control of relative displacement between pier and girder. At the same time, uneven phenomenon of piers’internal force was significantly improved by increasing the internal force of the movable piers and reducing that of the fixed pier. A certain relationship between the steel damper’s mechanical parameters and new bearing’s seismic performance was presented, according to which appropriate steel damper could be selected to achieve the best seismic target. The friction coefficient of the bearing was in change during the earthquake, which would not affect its seismic performance. The new bearing showed better seismic performance when the predominant period of the site was close to that of the longitudinal vibration of the main girder.