Development of crawler steel damper for bridges

• A new damper was developed for large deformation demand.
• The new damper has perfect low cycle fatigue performance.
• Four damper specimens were tested by using cyclic loading schemes.
• Finite element analyses were carried out to supplement the physical test.
• Accurate equations were proposed to estimate the strength of the damper.

Dampers for bridges commonly require enormous capacity for strength and deformation; therefore, ordinary steel dampers have difficulties in satisfying the requirements. In this paper, a novel crawler steel damper has been developed and tested. The damper consists of two U-shaped steel energy dissipation plates and two connection plates, and the two U-shaped steel plates are bolted to the upper and lower connection plates. Energy is dissipated through the plastic deformation of energy dissipation plates. Equations to estimate the strength of the damper were derived based on equilibrium and compatibility equation and the virtual work principle. Four dampers were tested by using quasi-static cyclic loading schemes, and the thickness of the energy dissipation plates and the height of the dampers were adopted as test parameters. Finite element analyses were carried out to supplement the physical test results, and to improve the accuracy of equations for strength estimation. Major conclusions obtained in this study are as follows: (1) the performance of the damper is mainly controlled by the thickness and height of the energy dissipation plates. (2) Finite element analyses can simulate the mechanical behavior of the damper well. (3) Equations considering the steel isotropic hardening can estimate the strength of the damper with satisfactory accuracy.