An Innovative Energy Dissipation System For Resisting Soft Story Behavior of Buildings

In recent decades, several methods have been proposed by earthquake engineering specialists for seismic multi-story building response reduction. However, many of these techniques have not been acknowledged by the engineering community due to either high costs, or high technology required for their manufacturing, installation and maintenance. Among the proposed methods, using controlled soft story seems to be more desired from cost and technology points of view. This idea can specifically useful for the buildings which have open spans in their lowest story because of the architectural requirements. In this thesis, a method is presented for employing the controlled soft story concept in multi-story RC buildings by using multi-linear hardening springs with multi-phase yielding process at the lowest story of the building, only in the central bays in each main direction, not to disturb the responsiveness of the building to the architectural needs. To show the efficiency of the proposed technique, the multi-linear hardening springs have been inserted in the computer model of some multi-story RC buildings, and by considering various values for the initial, secondary and third stiffness of the system, as well as their yielding displacements. By using a set of selected earthquakes, a number of nonlinear time history (NLTHA) analyzes have attempted to decrease buildings' seismic response to keep their performance at Immediate Occupancy (IO). Results of the conducted NLTHA show that by assigning appropriate stiffness and yielding displacement values of the multi-linear plastic springs, it is possible to control the response of the buildings and keep them basically in the desired IO performance level. Keywords: Nonlinear Time History Analyses (NLTHA), Soft Story, Multi-linear Plastic Springs