FUZZY-BASED MODEL TO EVALUATE THE DOWNTIME AND THE RESILIENCE OF BUILDING STRUCTURES FOLLOWING AN EARTHQUAKE

Residential buildings are usually designed to withstand earthquake damage through their elastic and plastic deformations. The damage causes the buildings to be unoccupiable for a period of time, called the downtime. This report introduces a methodology to predict the downtime of buildings given an earthquake through the use of Fuzzy logic. Generally, the downtime can be divided into three main components: downtime due to the actual damage (DT1); downtime due to rational and irrational delays (DT2); and downtime due to utilities disruption (DT3). DT1 is evaluated by relating the building damageability of the building’s components to pre-defined repair times. A rapid visual screening questionnaire form has been designed to acquire information about the analyzed building. Then, a fuzzy logic is implemented using a hierarchical scheme to determine the building damageability taking into account the earthquake intensity. DT2 and DT3 are estimated using the REDiTM Guidelines. DT2 considers irrational components through a specific sequence, which defines the order of components repair. DT3 depends on the site seismic hazard and on the infrastructure vulnerability. Due to the fact that the complex network of utilities is widely distributed geographically and, thus, there are different seismic intensities and local site effects, DT3 is computed from data about past earthquake. The Downtime of the building is finally obtained by combining the three components. The proposed method also allows identifying the downtime corresponding to three different recovery states: re-occupancy; functional recovery; and full recovery. Furthermore, the methodology is extended to give a resilience index, which is computed through the combination between the downtime and the building damage. The fuzzy logic system is developed and implemented in Matlab Fuzzy Logic toolbox and Simulink in order to lead a rapid damage evaluation of a given building and in order to realize a sensitivity analysis for evaluating the impact of components towards the building damageability. The thesis also presents a graphical interpolation method to define the fuzzy base rules for the inference step in the fuzzy logic system. Finally, the methodology is illustrated using an unrealistic residential building example, in which the earthquake that hit Northridge in 1994 is considered as the hazard event.