Performance-Based Assessment of Existing Structures Accounting for Residual Displacements

Recent seismic events have highlighted the necessity of demolishing damaged structures due to excessive permanent deformations, even though they did not experience collapse. Moreover, the evaluation of permanent (residual) lateral displacements plays an important role for determining the technical feasibility of retrofitting structures that have been damaged due to earthquake excitation. In addition, an adequate estimation of permanent lateral displacements is important to assess seismic risks from aftershocks events. Thus, an adequate estimation of residual displacement demands that existing structures may experience after earthquake ground shaking should be of primary importance in modern performance-based assessment procedures. For that purpose, this dissertation is aimed to provide further information about residual displacement demands and their dependence on several ground motion and structural features of single-degree-of-freedom (SDOF) and multi-degree-offreedom (MDOF) systems. In particular, this study proposes simplified probabilistic approaches to estimate residual displacement demands for different seismic hazard levels in the context of recently introduced performance-based methodologies.

In this investigation a special emphasis is given to the evaluation of residual displacement demands, although information about maximum (transient) displacement demands is also provided for reference purposes. Thus, the first part of this investigation reports comprehensive statistical studies to quantify residual and maximum displacement demands of inelastic SDOF systems considering a relatively large earthquake ground motion database, and considering a large number of structural parameters. The second part of this study focuses on the evaluation of permanent (residual) and maximum (transient) drift demands of multistory framed building models under different levels of ground motion intensity. Both parts include the formulation and implementation of simplified probabilistic approaches to estimate maximum and residual displacement demands accounting for the uncertainty in the structural response and the ground motion hazard.

It is believed that this study provides further information towards incorporating explicitly the evaluation of residual displacement demands for assessing the seismic performance of existing structures or, even, for the preliminary design phase of new structures where structural damage control is achieved through control of lateral deformation demands.