Validation of Time-Dependent Repair Recovery of the Building Stock Following the 2011 Joplin Tornado

Abstract

This paper seeks to calibrate an existing analytical framework to develop building repair fragility models using a restoration dataset collected through a longitudinal field study in the city of Joplin, Missouri, after the catastrophic 2011 Enhanced Fujita 5 tornado. First, an existing recovery data set from Joplin is documented and the main findings pertaining to the observed recovery trajectory of the buildings are highlighted. In the next step, various empirical functionality fragilities conditioned on the initial functionality level (and associated damage) of the buildings are generated and compared to the analytical repair time/functionality fragilities. Results revealed moderate to significant differences between empirical and analytical functionality fragilities depending on the extent of the initial damage and the initial associated functionality state of the buildings. This finding was anticipated, and one of the goals of this study was to quantify this discrepancy, which is caused by not including the delay time resulting from cumbersome circumstances during the aftermath. A number of methods available in the literature are first explored to address these differences by introducing the various sources of initial delays into the repair time, and further modified to realistically represent the associated delay factors. These modifications included: (1) modifying the formulations used to aggregate different types of delays to calculate the initial delay of the buildings’ repair process and (2) using more representative distributions for various types of delays based on available real-world data sets. The main delays included are inspection delay, time to obtain adequate financial resources, delays in finding and hiring contractors, and construction permitting delays. The proposed methodology was integrated with the analytical framework to generate updated repair time/functionality fragilities. The updated analytical fragilities resulted in a more realistic prediction of the recovery trajectory of the building stock when compared with the empirical fragilities for the city of Joplin.