Infilled-pipe damper

• This paper demonstrates the development of a new passive metallic damper.
• The damper is called the infilled-pipe damper.
• The proposed damper is inexpensive, simple to build and highly efficient.
• The results of quasi-static cyclic tests performed on the dampers are presented.
• Excellent ductility, energy absorption and stable hysteresis loops are observed.
• A finite element model is developed and a parametric study is performed.
• Formulas defining the structural characteristics of the device are given.

This paper introduces a new passive control device for protecting structures against earthquakes. The device consists of two welded pipes which have two smaller pipes inside them and the spaces between the pipes are filled with metals such as lead or zinc. The device is loaded in shear and takes advantage of plastification of the outer pipes, the inner pipes and the infilled metals, and the friction between metals as energy absorption mechanisms. Quasi-static cyclic tests are performed on six specimens all showing stable hystereses and high damping. A finite element model is developed and calibrated against test results. The model is used to find the optimum sizes of pipes needed for a better hysteretic response. Equations are given for prediction of key performance parameters of the damper.