Component-Based Vulnerability Analysis for Residential Structures Subjected to Storm Surge Impact from Hurricane Sandy

In this study, manual and light detection and ranging (LiDAR) surveys of physical damage to structures in Ortley Beach, New Jersey, following Hurricane Sandy are used to assess the vulnerability of residential structures to storm surge. First, using photographs from the manual survey, the performance of building components prone to surge damage (foundations, exterior walls, and wall siding) is assessed according to failure mechanism, construction type, and material. General observations include widespread failure of closed foundations, significant vulnerability of exterior walls to surge loads and waterborne debris impact, and the extensive loss of vinyl lap siding. The effect of the built environment is also investigated, revealing that the study area consists of two regions: one heavily damaged due to the failure of coastal dunes and another partially protected by large oceanfront structures acting as artificial breakwaters. The performance of individual structures is likewise found to strongly influence the performance of nearby buildings, either by shielding inland structures from surge loads or by generating damaging waterborne debris. Next, a statistical analysis of various vulnerability parameters characterizing structures and the built environment reveals that the distance of buildings from the coast is the most significant damage predictor, with additional factors such as house age and elevation off the ground also affecting component performance. Vulnerability curves and vulnerability surfaces giving the probability of component failure as functions of these significant vulnerability parameters are then developed across different surge environments, component types, and failure mechanisms, providing a quantification of the observed damage features. Fragility curves are also developed to depict the severity of waterborne debris impact. Finally, using airborne and mobile LiDAR surveys, a method for rapidly assessing foundation failure by detecting changes in a structure's location is proposed and validated for Ortley Beach. Applying this method to other New Jersey communities experiencing a similar surge (Seaside Heights and Normandy Beach), overall coastal performance is found to largely reflect the failure mode of the community's dunes. This study presents a framework for rigorously understanding storm surge impact through improved survey methods, assessment procedures, and statistical analyses. The specific findings from Hurricane Sandy highlight the significant vulnerabilities of coastal residential structures and can serve as a basis for improving resilience. (C) 2015 American Society of Civil Engineers.