Improved reliability and economic modeling for new and retrofitted low-rise structures subjected to extreme wind hazards

This study proposes a new approach for developing a reliability model for low-rise buildings using the methods of Event Tree and Fault Tree (ET) analysis. ET focuses on the consequence analysis for pre-incident and post-incident applications. It consists of a number of sequences of random variables representing the states of top events—performance of crucial structural subsystems. Each node on the ET is followed by a possible occurrence of a new variable with a probability distribution function being conditional to its previous random variables. The Fault tree (FT) is then constructed and aimed at evaluating the probability of occurrence of top events with logic diagrams. The quantification is then conducted based on components' reliability characteristic and the logic gates linking them together. This study develops a systematic analytical framework that views low-rise residential building as a complete economic entity. The valuation model consists of two fundamental elements: cost and benefit. The decision made by homeowners will depend on whether the cost related to retrofitting exceeds the saving in reduction of potential damage. To take account of the effect of time factors, the concept of life cycle costing is applied so that all expenditures occurred or to be occurred during the lifetime of a structures are discounted to the same time point with a predefined interest rate. In this study, cost is evaluated and grouped into a number of sources: damage to structural components, damage to non-structural components, cost of injury and casualty of occupants, damage to building contents. Sensitivity analysis is followed to measure the effects of controllable factors in the models and identify the candidates for improvement.