Adaptable dual control systems for earthquake resistance

Abstract

The use of passive energy dissipation systems for seismic control has been proven internationally over the past years as most promising. The proposed concept of Adaptable Dual Control Systems (ADCS), presented in the present paper, relies on the seismic performance of braced frames with cables or tension only rods, following a closed circuit, and hysteretic dampers. ADCS are based on a dual function of the component members, resulting in two practically uncoupled systems: a primary and a secondary system. The primary frame is responsible for the normal vertical and horizontal forces, while the closed damper-bracing mechanism, for the earthquake forces and the necessary energy dissipation. The bracing members are fixed at the bottom of the columns and are free to move horizontally at the primary frame’s joints. Relative displacements are induced between the energy dissipation system’s component members and the main frame’s members. The potentials for maximum energy dissipation of the proposed systems are investigated in three configurations of the control system. In all cases the damper utilizes the relative displacement between its end joints to yield in the inelastic region, enabling the primary frame to resist elastically. ADCS may result to significant energy dissipation, when all design parameters involved are accordingly predefined. The predominant parameters that characterize ADCS seismic behavior are verified in respect to the mechanical properties of the control elements under the action of ten selected earthquake records of the Greek-Mediterranean region. A comparative parametric analysis of the three systems’ seismic behavior leads to significant recommendations for their application as alternative energy dissipation systems.