Torsional hysteretic damper for seismic protection of structures

Salem Milani, Ali
During the past decades, use of supplementary systems for seismic control of structures has gained increasing acceptance, and research has flourished on development and performance characterization of such systems. These include isolation systems and energy dissipation devices (dampers). This study is devoted to development of a new hysteretic damper for seismic protection of structures. The new system is a stand-alone damper, named Multi-directional Torsional Hysteretic Damper (MTHD). MTHD is composed of eight energy dissipaters in the shape of a cylinder with enlarged top and bottom. The cylindrical dissipaters are designed to yield in torsion created in them via arms while being supported against bending by a stiff central column. MTHD is capable of large force and displacement capacities, can be coupled with various types of bearings due to its 2-part configuration (upper rail system and lower base device) and shows a variable and controllable-via-design post-elastic stiffness. The new damper has gone through many stages of design refinement, prototype verification tests and development of computer codes to facilitate its implementation in practice. Practicality of the new device, as an offspring of an academic sphere, is assured through extensive collaboration with industry in its final design stages, prototyping and verification tests. The scope of this research includes all developmental phases of the MTHD device, including conceptual design, analytical and numerical studies and verification tests. The experimental part of the study is comprised of two phases: verification tests on a prototype MTHD, and a series of torsional low-cycle fatigue tests on cylindrical steel specimens. Torsional low-cycle fatigue tests were aimed at studying the fatigue performance of the cylindrical energy dissipaters of MTHD and to use the data in cyclic strain-life design.
Citation Formats
A. Salem Milani, “Torsional hysteretic damper for seismic protection of structures,” Ph.D. - Doctoral Program, Middle East Technical University, 2014.