STUDY ON SEISMIC RESPONSE CONTROL DESIGN METHOD CONSIDERING PLASTICITY OF BUILDING FRAME

－Simplified placement method of viscous-type dampers for a MDOF model－

Abstract

 Seismic design has been conducted usually by parametric studies. So a lot of simplified design method have been reported in recent years. The proposed method is able to minimize the total number of necessary dampers for a MDOF model to keep the maximum ductility factor under the specified value. Design examples of the optimum story-wise placement of oil dampers are shown for two MDOF building models. Time history response analyses are carried out for buildings installed with the necessary number of dampers subjected to the design earthquake. The results demonstrate the effectiveness of the proposed design method.

 Based on these studies, the following results are obtained.
 1) By means of optimum design based on the fixed-point theory and seismic performance design diagram, the necessary damping for criteria is obvious. We can determine damper placement for MDOF easily and rationally.
 2) If considering elastic-plastic behavior of main frame, we can minimize total number of dampers with placement of seismic control devices that depends on natural period of the building for design. If first mode is dominant, the combination of proportion to story stiffness (arrange1), constant for all stories (arrange2) and proportion to interstory modal shape (arrange3) is rational design. The influence of higher mode is significant, the combination of arrange1 and arrange2 is better.
 3) If considering elastic-plastic behavior of main frame, non-linear dynamic behavior of a certain story without dampers tends to be progressing. Seismic control devices of each floor are desirable.

 The extension of proposed method for seismic control device except oil damper and bending shear model which is assumed super high rise buildings is made will be an issue to be addressed in the future.