Carol J. Friedland

Remote Sensing Classification of Hurricane Storm Surge Structural Damage

The concept of spatially-tiered reconnaissance has been introduced as a method of providing increasingly detailed levels of analysis in post-disaster situations [Adams 2006, Womble, 34-38]. Remotely sensed data is becoming more widely available on a systematic basis following natural disasters at various spatial, spectral and temporal resolutions. Depending on these resolutions, each dataset is capable of providing different levels of information. Figure 1 illustrates the three tiers that are used within spatially-tiered reconnaissance – Tier 1 (Regional), Tier 2 (Neighborhood), and Tier 3 (Per building), using storm surge damage sustained after Hurricane Katrina as an example.

Isotropic and anisotropic kriging approaches for interpolating surface-level wind speeds across large, geographically diverse regions

ABSTRACT Windstorms result in significant damage and economic loss and are a major recurring threat in many countries. Estimating surface-level wind speeds resulting from windstorms is a complicated problem, but geostatistical spatial interpolation methods present a potential solution. Maximum sustained and peak gust weather station data from two historic windstorms in Europe were analyzed to predict surface-level wind speed surfaces across a large and topographically varied landscape. Disjunctively sampled maximum sustained wind speeds were adjusted to represent equivalent continuously sampled 10-minute wind speeds and missing peak gust station data were estimated by applying a gust factor to the recorded maximum sustained wind speeds. Wind surfaces were estimated based on anisotropic and isotropic kriging interpolation methodologies. The study found that anisotropic kriging is well-suited for interpolating wind speeds in meso- and macro-scale areas because it accounts for wind direction and trends in wind speeds across a large, heterogeneous surface, and resulted in interpolation surface improvement in most models evaluated. Statistical testing of interpolation error for stations stratified by geographic classification revealed that stations in coastal and/or mountainous locations had significantly higher prediction errors when compared with stations in non-coastal/non-mountainous locations. These results may assist in mitigating losses to structures due to excessive wind events.

DEVELOPMENT OF A LOSS-CONSISTENT WIND AND FLOOD DAMAGE SCALE FOR RESIDENTIAL BUILDINGS

This paper sets forth a new damage scale for use in assessing physical damage to single family houses caused by wind and flood events. A new methodology is presented for assessing both structural and nonstructural physical damage caused by flood events, ranging from slow-rise inundation flooding to coastal high velocity flooding with wave action. The flood scale is integrated with FEMAs HAZUS wind damage scale to allow users to assess a buildings overall level of physical damage on a loss-consistent basis. The damage scale additionally expands and improves FEMAs HAZUS wind damage scale by including two new categories to assess more severe levels of damage. This combined wind and flood damage scale (the WF Damage Scale) ranges from WF-0 (no damage to very minor damage) to WF-6 (complete collapse). Qualitative and quantitative damage descriptions are provided to ease field implementation.

Combined Flood and Wind Mitigation for Hurricane Damage Prevention: Case for Amphibious Construction

AbstractSome initiatives that are intended to mitigate extreme flood events do not fully consider the impact of less catastrophic but more commonly occurring wind-induced damage, which is a signifi...

Automatic urban debris zone extraction from post-hurricane very high-resolution satellite and aerial imagery

Automated remote sensing methods have not gained widespread usage for damage assessment after hurricane events, especially for low-rise buildings, such as individual houses and small businesses. Hurricane wind, storm surge with waves, and inland flooding have unique damage signatures, further complicating the development of robust automated assessment methodologies. As a step toward realizing automated damage assessment for multi-hazard hurricane events, this paper presents a mono-temporal image classification methodology that quickly and accurately differentiates urban debris from non-debris areas using post-event images. Three classification approaches are presented: spectral, textural, and combined spectral–textural. The methodology is demonstrated for Gulfport, Mississippi, using IKONOS panchromatic satellite and NOAA aerial colour imagery collected after 2005 Hurricane Katrina. The results show that multivariate texture information significantly improves debris class detection performance by decreasing the confusion between debris and other land cover types, and the extracted debris zone accurately captures debris distribution. Additionally, the extracted debris boundary is approximately equivalent regardless of imagery type, demonstrating the flexibility and robustness of the debris mapping methodology. While the test case presents results for hurricane hazards, the proposed methodology is generally developed and expected to be effective in delineating debris zones for other natural hazards, including tsunamis, tornadoes, and earthquakes.

High Resolution Imagery Collection for Post- Disaster Studies Utilizing Unmanned Aircraft Systems (UAS)

This paper examines the use of unmanned aircraft systems (UAS) to capture imagery for use in post-disaster field studies at the neighborhood and individual building level. A discussion of post-disaster imagery collection including satellite, aerial, and ground-based platforms is first presented. Applications of UAS in recent disasters as described in the literature are then surveyed, and a case study investigating UAS capabilities for imagery collection following an EF-3 tornado in northern Alabama on 02 March 2012 is presented. Case study considerations include the multi-rotor unmanned aerial vehicle (UAV) equipment and ground station, onboard imagery devices, flight considerations and capabilities, and imagery and metadata collection capabilities of the UAS. Sample post-tornado imagery of building damage is shown, demonstrating the order of magnitude improvement in imagery resolution compared to traditional post-disaster aerial photography.

Development of a Hurricane Storm Surge Damage Model for Residential Structures

This paper presents the design framework of a hurricane storm surge damage model for residential structures. Current flood damage models include depth-damage functions for slowly rising, low velocity floodwaters, but do not model building damage resulting from coastal flooding with high velocity flows and wave action. The proposed framework uses hazard information obtained from storm surge models and analysis of wave forces combined with building inventory data as inputs to an engineering model that estimates building damage.

Enforceability of Limitation of Liability Clauses in Engineering Contracts

AbstractThis paper demonstrates the importance of limitation of liability clauses for many engineering services agreements. Engineers, engineering firms, and clients often negotiate extensively over the specific terms of the limitation clause. However, little thought is given to whether or not the limitation would be upheld in a court of law despite the very real possibility that it would not be enforced should a dispute arise. It is concluded that following a list of guidelines will greatly increase the likelihood of enforcement of a limitation clause. This paper discusses the different types of limitation of liability clauses, the likelihood of their enforcement in a legal action, and the major factors that will affect whether the clauses are enforced on the basis of and lessons learned from several litigated/settled cases.

Evaluating Pile Setup Using Numerical Simulation and Introducing an Elastoplastic Constitutive Model for Clays

An elastoplastic constitutive model was developed to define cohesive soil behavior. During pile installation in saturated ground, the soil adjacent to the pile disturbs causing large displacements and numerous variation in the porewater pressure in the soil-pile interface zone. Therefore, the soil disturbance and the corresponding decline in the soil shear strength were included in the developed constitutive model. After end of pile driving (EOD), the surrounding disturbed soil tends to regain its strength over time due to both consolidation and thixotropic effects. In this paper, the soil thixotropy was simulated by applying a time-dependent reduction parameter, β, which affects both the interface friction and the soil shear strength parameters. In order to examine the proposed model, numerical simulation of pile installation and the following increase in the pile capacity over time (pile setup) was performed for a full-scale pile load test case study. Finite element (FE) software Abaqus utilized to simulate the pile installation and following pile load tests. Dissipation of the induced excess porewater pressure was modeled through applying conventional consolidation theory. The proposed model was developed based on disturbed state concept and application of the modified Cam-Clay model. Pile installation was modeled by combination of two phases in an axisymmetric FE model: creating a volumetric cavity expansion followed by applying a vertical shear displacement (penetration). The FE simulation results included: (1)-developed excess porewater pressure in the soil body during pile installation and its dissipation over time after EOD, (2)-increase in effective lateral stresses at the pile-soil interface, and (3)-the pile setup values attributed to both the soil consolidation and its thixotropic responses. Comparison of the FE simulation results with the measured values obtained from load tests conducted on a full-scale instrumented pile indicated that the developed constitutive model is able to appropriately predict pile installation and following setup.

Personal Liability of the Practicing Engineer

AbstractPersonal liability is a topic to which many practicing engineers do not give serious consideration. When it is discussed, the magnitude of potential personal liability is frequently poorly understood. The reality is that engineers can be personally liable through tort law theories even when practicing for an employer. As a result, engineers place all of their assets at risk in the practice of their profession—as do many practicing professionals in fields other than engineering. Similarly, the effect on personal liability of obtaining a professional engineering (P.E.) license or sealing plans is equally misunderstood among practicing professionals. This paper examines the scenarios in which a practicing engineer can face personal liability for mistakes, errors, or omissions made by that engineer. It also explores whether being licensed or unlicensed creates or protects an engineer from personal liability, as well as the liability created or avoided by sealing (or not sealing) plans and specificatio...