Regional loss estimation due to hurricane wind and hurricane-induced surge considering climate variability

This paper presents a framework to assess the potential hurricane damage risks to residential construction. Studies show that hurricane wind, frequency and/or hurricane-induced surge may change as a result of climate change; therefore, hurricane risk assessments should be capable of accounting for the impacts climate change. The framework includes a hurricane wind field model, hurricane-induced surge height model and hurricane vulnerability models. Three case study locations (Miami-Dade County, FL; New Hanover County, NC and Galveston County, TX) are presented for two types of analyses: annual regional loss estimation and event-based regional loss estimation. Demographic information, such as median house value and changes in house numbers, and distribution of houses for different exposures, is used to estimate the time-dependent probability of damage with or without possible climate change-induced change in wind speed, frequency and/or surge height. Through both analyses, it was found that climate change may have a significant impact on regional hurricane damage losses.     

Integrating storm surge modeling with traffic data analysis to evaluate the effectiveness of hurricane evacuation

An integrated storm surge modeling and traffic analysis were conducted in this study to assess the effectiveness of hurricane evacuations through a case study of Hurricane Irma. The Category 5 hurricane in 2017 caused a record evacuation with an estimated 6.8 million people relocating statewide in Florida. The Advanced Circulation (ADCIRC) model was applied to simulate storm tides during the hurricane event. Model validations indicated that simulated pressures, winds, and storm surge compared well with observations. Model simulated storm tides and winds were used to estimate the area affected by Hurricane Irma. Results showed that the storm surge and strong wind mainly affected coastal counties in south-west Florida. Only moderate storm tides (maximum about 2.5 m) and maximum wind speed about 115 mph were shown in both model simulations and Federal Emergency Management Agency (FEMA) post-hurricane assessment near the area of hurricane landfall. Storm surges did not rise to the 100-year flood elevation level. The maximum wind was much below the design wind speed of 150–170 mph (Category 5) as defined in Florida Building Code (FBC) for south Florida coastal areas. Compared with the total population of about 2.25 million in the six coastal counties affected by storm surge and Category 1–3 wind, the statewide evacuation of approximately 6.8 million people was found to be an over-evacuation due mainly to the uncertainty of hurricane path, which shifted from south-east to south-west Florida. The uncertainty of hurricane tracks made it difficult to predict the appropriate storm surge inundation zone for evacuation. Traffic data were used to analyze the evacuation traffic patterns. In south-east Florida, evacuation traffic started 4 days before the hurricane’s arrival. However, the hurricane path shifted and eventually landed in south-west Florida, which caused a high level of evacuation traffic in south-west Florida. Over-evacuation caused Evacuation Traffic Index (ETI) to increase to 200% above normal conditions in some sections of highways, which reduced the effectiveness of evacuation. Results from this study show that evacuation efficiency can be improved in the future by more accurate hurricane forecasting, better public awareness of real-time storm surge and wind as well as integrated storm surge and evacuation modeling for quick response to the uncertainty of hurricane forecasting.     

Wind and rainfall loss assessment for residential buildings under climate-dependent hurricane scenarios

Residential buildings in the US coastal regions face a huge risk against hurricane hazard. The damage and loss in these structures during hurricane can be attributed to two major causes – high intensity wind and rain ingress. These two modes of hurricane losses may be impacted by climate change. Thus, this study investigates in detail the two hurricane loss modes for residential buildings in Miami-Dade County to observe how each mode contributes to the loss as well as how these losses are impacted in future climate. It is found that the hurricane loss is higher in future climate compared to present. Furthermore, the loss due to rain ingress is found to be more than the loss due to wind damage, with the difference between the two becoming even higher in future climate scenarios.     

A probabilistic-based framework for impact and adaptation assessment of climate change on hurricane damage risks and costs

This paper presents a probabilistic-based framework to assess the potential hurricane risks to residential construction under various wind speed change scenarios due to potential climate change. Every year hurricane (cyclone) hazards cause extensive economic losses and social disruption around the world. Annual hurricane damage in the United States (US) is around $6 billion in recent years. Hurricane intensity or/and frequency may change due to the increase in sea surface temperature as a result of climate change. Implications of the changing hazard patterns on hurricane risk assessment warrants an investigation to evaluate the potential impact of climate change. The framework includes probabilistic models of hurricane occurrence and intensity and conditional damage state probabilities (vulnerability model) for typical residential construction in the US, and an assessment of the cost-effectiveness of various climate change adaptation strategies. A case study of Miami-Dade County, Florida is presented to illustrate the framework under various scenarios of change in maximum annual wind speed over 50 years. Demographic information, such as median house value and changes in house numbers, and distribution of houses on different exposure, is used to estimate the time-dependent probable damage with or without possible climate change induced change in wind speed. This study shows that climate change may have a substantial impact on the damage and loss estimation in coastal areas, and that certain adaptation strategies can cost effectively decrease the damage, even if the wind speed does not change.     

Performance based design extreme wind loads on a tall building

This paper presents a procedure for the calculation of wind loads on a proposed 385 ft tall building located in strong wind and mixed strong wind and hurricane wind regions. The procedure for the computation of design wind loads uses mixed distribution and Monte Carlo simulation. The results of a probabilistic analysis of hurricane wind speeds are combined with the probability distribution of recorded extreme wind speeds (excluding hurricane data) at the site. A 50‐year sample of extreme wind speeds is created and the maximum 50‐year wind (from the hurricane and the recorded data) is noted. The simulation is repeated for a large number of samples (>10000) and the probability distribution of the 50‐year wind speed is computed for use in establishing the design wind speed Copyright © 2001 John Wiley & Sons, Ltd.     

When oceans attack: assessing the impact of hurricanes on localized taxable sales

We examine the impact of hurricanes in Florida on county-level taxable sales revenues. Conditional on the strength of the hurricane, within 6 months after a hurricane strikes a county, revenues decline as much as 17 %, whereas revenues in neighboring counties increase by upward of 17 % over that same time frame. This decline in revenue is found to be dependent on the commercial makeup of a hurricane-stricken county. Particular focus is given to tourism-related subsectors within the local economy. Finally, we show that along the pathways of hurricanes, initially hit counties face a more severe burden, ranging as high as a 33 % immediate decline in taxable revenues in 1 month for coastal counties. As the hurricane weakens, the direct impact is lessened; however, there is evidence of spillover damage in neighboring areas.     

Hurricane hazard modeling: The past, present, and future

Hurricane hazard modeling has become a commonly used tool for assessing hurricane risk. The type of hurricane risk considered varies with the user and can be an economic risk, as in the case of the insurance and banking industries, a wind exceedance risk, a flood risk, etc. The most common uses for hurricane hazard models today include:

(i) Simulation of wind speed and direction for use with wind tunnel test data to estimate wind loads vs. return period for design of structural systems and cladding.

(ii) Estimation of design wind speeds for use in buildings codes and standards.

(iii) Coastal hazard risk modeling (e.g. storm surge elevations and wave heights vs. return period).

(iv) Insurance loss estimation (e.g. probable maximum losses, average annual losses).

This paper presents an overview of the past and present work in hurricane modeling. The wind model is the key input to each of the examples presented above and is the focus herein. We discuss the evolution and current state of wind field modeling, modeling uncertainties, and possible future directions of the hurricane risk modeling process.     

Optimizing the selection of hazard-consistent probabilistic scenarios for long-term regional hurricane loss estimation

Long-term regional hurricane loss estimation is typically conducted by simulating the occurrence of many hurricanes in a region using a historical or synthetic set of hurricanes; estimating losses caused by each hurricane; and using the resulting loss database to calculate loss-exceedence curves for each location. This paper introduces a new way to identify a set of hurricanes to be simulated, so as to substantially reduce the number of events required and thus the computation, while maintaining the spatial coherence of individual scenarios. Using a mixed-integer linear programming formulation, a relatively small subset of all possible hurricanes is identified (tens to a couple hundred), and the annual occurrence probability of each is adjusted so that the regional hazard estimated from the reduced set matches the regional hazard estimated from the full synthetic hurricane simulation. The user can explicitly tradeoff number of hurricanes (i.e., computation) and error based on the intended use of the analysis. The method also allows the user to force errors to be smaller at geographic locations or return periods that are particularly important for a given analysis. In a case study application for North Carolina, the method provides unbiased results with errors that are small enough for practical use.     

Field measurement and wind tunnel simulation of hurricane wind loads on a single family dwelling

During landfall of Hurricane Ivan on the Florida ’panhandle’ in 2004, pressure time-history data were recorded on multiple pressure sensors installed on the roofs of six single-family homes. An analysis approach was developed to determine the peak negative, mean, peak positive, and standard deviation of pressure coefficients for these datasets. This paper presents a comparison of the full scale pressure coefficients from one of these homes, which experienced sustained hurricane force winds, with the results of wind tunnel experiments on a 1:50 scale model of that home. It was determined that the wind tunnel and full-scale mean and rms pressure coefficients matched very closely at almost every monitored location on the roof, while the peak negative pressure coefficients in the wind tunnel study generally underestimated the full-scale values, consistent with observations from previous full-scale/wind tunnel comparative studies. Field-measured hurricane wind loads may prove useful for evaluating existing wind load provisions. However, recommendations in that regard are premature without the analyses of multiple homes in multiple storms, performed by more than one wind tunnel facility. Future work will focus on building such a joint study.     

大跨度屋盖围护结构风荷载计算探刮——对某体育馆屋面破坏的结构计算分析

结合一般大跨屋盖结构风灾破坏的特点,对某体育馆屋面围护结构风荷载作用的计算进行了分析,并对大跨度屋盖围护结构的实用计算重点提出看法。