The Research On Performance-based Seismic Retrofitting Of Existing Buildings

There are a large number of buildings constructed in 1970s’ and 1980s’ in China, which is under stage of high-age service within the designed service life. Due to updating of seismic codes, these buildings cannot comply with the current code and it is necessary for the buildings to be retrofitted. The performance-based seismic theory was firstly proposed to further detail the traditional “three seismic fortifications”, and this theory fully considered both life safety and economic loss, which makes the designed buildings behave with predictable performance levels when experiencing certain magnitude of earthquakes. While introducing performance-based theory into seismic retrofitting of existing buildings, the performance of the retrofitted buildings can be easily anticipated, so as to mitigate the buildings’ destruction and decrease earthquake casualty and economic loss. Therefore, it is of great value to carry out the research on performance-based seismic retrofitting.This dissertation has mainly completed the following works:(1) Based on the former research on frame structures, more specified seismic fortifications and buildings’ aseismatic performance levels have been selected to describe the response of the retrofitted structures under future earthquake actions, and the rational performance index has been chosen and quantified analytically.(2) In order to improve the seismic assessment of existing buildings, a simplified method has been proposed to determine the ground motion parameters for existing buildings considering the served years. The concrete carbonation and reinforcement corrosion, which are two main influential factors for seismic performance, have been taken into consideration in this dissertation, and the modeling method to account for the damages in sap2000 has been specified. It concludes that it is necessary to consider the damages of existing buildings during the assessment.(3) It is becoming an increasingly significant aspect for the designers and owners to consider the economic loss of buildings under earthquake action when scheduling retrofitting scheme of existing buildings. A simplified economic loss model has been proposed and proved accurately, which is easier implemented into engineering application than the complex economic loss models proposed before.(4)Through an actual engineering project, the implementing procedure of performance-based seismic retrofitting of existing buildings has been clarified, which has demonstrated the viability of the theory presented in this dissertation. To finalize the proposed schemes optimally, the seismic performance, direct economic loss, investment and construction technology of each scheme under different intensities of earthquake action have been evaluated respectively with the finite element analysis software SAP2000.