Wave Loads and Structural Fragility Behind Impermeable and Permeable Obstacles

University Of Notre Dame, Notre Dame IN

Investigators

Abstract

Inundation from storm waves and tsunamis has caused great damage to buildings and infrastructure both in the United States and worldwide. Reduction of damage and overall risk mitigation remain priorities for coastal communities now and in the future, but these goals are in some ways limited by engineering design and analysis tools. Damage from storm waves and tsunamis is well known to be diminished behind structures or vegetation, but it has proven surprisingly difficult to translate this general knowledge to specific guidelines and standards for engineers and planners. This project will use theory, numerical models, and results from field and laboratory measurements to investigate the degree of damage reduction behind sheltering structures. Two notable features of this analysis will be the consideration of sheltering obstacle degradation during an event, and a framework for probabilistic analysis that will allow design for different levels of risk. Useful quantification of loading for sheltered structures will remove a major impediment to accurate design and planning for inundation events. This project will help to improve load estimates in ways that will be directly applicable to many instances of engineering design. Unlike hazards such as earthquakes, Inundation Event (IE) loading from storm waves or tsunamis can vary on scales of O(10m), and is greatly affected by the surrounding natural and built environments. Uncertainty in computing the local hazard and local loading remains the greatest obstacle in determining fragility for planning and structural design: Loads behind obstacles have been shown to decrease significantly when compared those from bare-earth conditions, but these decreases cannot yet be quantified for general conditions. Prediction becomes even more difficult when considering that some obstacles may be permeable to flow (vegetation), or may degrade over the course of the IE, changing loading. This project will examine IE hazard intensities, loading, and fragility for structures located behind a single row of obstacles using (1) Scaling and theoretical analyses; (2) Computational fluid dynamics simulations; (3) Structural analyses; (4) Existing field and laboratory data. Analyses will further consider the effects of obstacle degradation using fragility modeling of the obstacle itself. Results will consider uncertainties using surrogate modeling, which will both illuminate the major factors in loading and fragility uncertainties, and will suggest avenues through which results might be improved.