Design and Experimental Performance Evaluation of Lens-type Shear Panel Dampers for Highway Bridge Bearings

Abstract

This paper describes lins-type shear damper newly developed for highway bridge bearing. It utilizes low-yield steel LY100 and concave lins-shape panels. Both properties provide low strength and high ductility which are major requirements for damping devices, then contributes to high energy dissipation against seismic motion. Large deformation due to high speed strain velocity causes steel lens plate heating up to 400-500 centigrade in a moment. Earthquake energy is converted both to strain energy and heat energy. Cumulative deformation capacity of lens identity determines ultimate state of failures associated with strength and life time, dependent on time history of level-2 desibn earthquake(EQ). Fracture is roughly estimated by Miners rule esing damage index method. Prediction matches well with testing results. As case study with dampers, dynamic analysis on the existing continuous bridges has been conducted with some design parameters. The base shear acceleration due to livel-2 earthquake reduces down to 0.45g～0.5g from 0.8g of lead rubber bearing system. For planning of bridge system with dampers, 1-DOF model is simply useful to roughly know the base shear with dampers at the initial stage of planning onil when dead load is known. Design methods and experimental performance evaliation results are reported.