Forrest J. Masters

Post-2004 Hurricane Field Survey of Residential Building Performance

This paper presents the methodology and results of a study of the performance of site-built single-family structures in Florida constructed after Andrew-related changes to the Standard Building Code. A detailed investigation of wind damage as a result of the 2004 hurricane season was conducted. The study provides a quantitative comparison of the relative performance of homes built between 1994 and 2001 with those built after the 2001 Florida Building Code replaced the Standard Building Code.

Toward Objective, Standardized Intensity Estimates from Surface Wind Speed Observations

Extreme wind climatology and event-specific intensity assessments rely heavily on surface wind field observations. The most widely used platforms sited at airports are the Automated Surface Observing System (ASOS) and its predecessor, the Automated Weather Observing System (AWOS). The terrain immediately surrounding most of these stations may be nominally characterized as aero-dynamically very smooth because of the runways and flat expanses of grass that define most airport layouts. Outside of most airports, a wide spectrum of marine, open, suburban, and heavily built-up terrain conditions are present. The results of this research indicate that the wind speeds recorded by AWOS/ASOS are deeply sensitive to this terrain. Prior research has shown that direct usage of the raw surface data can introduce surface-layer wind speed errors on the order of 30%–40% due to terrain effects. Similar values are observed for gust speeds in this paper, when averaging technique and anemometer response characteristics are co...

Post 2004 Hurricane Field Survey -- An Evaluation of the Relative Performance of the Standard Building Code and the Florida Building Code

This paper presents the methodology and results of an ongoing study of the performance of residential structures in the State of Florida. Site built single family homes constructed after Andrew-related changes to the standard building code were in effect were targeted for a detailed investigation of wind damage as a result of the 2004 hurricane season. The purpose of this study is to provide a quantitative statistical comparison of the relative performance of homes built between 1994 and 2001 with those built after the 2001 Florida Building Code replaced the Standard Building Code.

Articulating and Stationary PARSIVEL Disdrometer Measurements in Conditions with Strong Winds and Heavy Rainfall

AbstractThe influence of strong winds on the quality of optical Particle Size Velocity (PARSIVEL) disdrometer measurements is examined with data from Hurricane Ike in 2008 and from convective thunderstorms observed during the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) in 2010. This study investigates an artifact in particle size distribution (PSD) measurements that has been observed independently by six stationary PARSIVEL disdrometers. The artifact is characterized by a large number concentration of raindrops with large diameters (>5 mm) and unrealistic fall velocities (<1 m s−1). It is correlated with high wind speeds and is consistently observed by stationary disdrometers but is not observed by articulating disdrometers (instruments whose sampling area is rotated into the wind). The effects of strong winds are further examined with a tilting experiment, in which drops are dripped through the PARSIVEL sampling area while the instrument is tilted at various angles, s...

Drop-Size Distributions in Thunderstorms Measured by Optical Disdrometers during VORTEX2

AbstractWhen studying the influence of microphysics on the near-surface buoyancy tendency in convective thunderstorms, in situ measurements of microphysics near the surface are essential and those are currently not provided by most weather radars. In this study, the deployment of mobile microphysical probes in convective thunderstorms during the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) is examined. Microphysical probes consist of an optical Ott Particle Size and Velocity (PARSIVEL) disdrometer that measures particle size and fall velocity distributions and a surface observation station that measures wind, temperature, and humidity. The mobile probe deployment allows for targeted observations within various areas of the storm and coordinated observations with ground-based mobile radars. Quality control schemes necessary for providing reliable observations in severe environments with strong winds and high rainfall rates and particle discrimination schemes for distingu...

Non-Gaussian simulation of local material properties based on a moving-window technique

In this paper, a moving-window micromechanics technique, Monte Carlo simulation, and finite element analysis are used to assess the effects of microstructural randomness on the local stress response of composite materials. The randomly varying elastic properties are characterized in terms of a field of local effective elastic constitutive matrices using a moving-window technique based on a finite element model of a given digitized composite material microstructure. Once the fields are generated, estimates of the random properties are obtained for use as input to a simulation algorithm that was developed to retain spectral, correlation, and non-Gaussian probabilistic characteristics. Rapidly generated Monte Carlo simulations of the constitutive matrix fields are used in a finite element analysis to create a series of local stress fields associated with the random material sample under uniaxial tension. This series allows estimation of the statistical variability in the local stress response for the random composite. The identification of localized extreme stress deviations from those of the aggregate or effective properties approach highlight the importance of modeling the stochastic variability of the microstructure.

Engineering Perspectives on Reducing Hurricane Damage to Housing in CARICOM Caribbean Islands

The annual hurricane related losses to Caribbean residential buildings in the past two decades highlight the societal and socioeconomic vulnerability of these islands. Despite considerable hurricane disaster mitigation activity in the Caribbean Community and Common Market (CARICOM), the housing sector in particular remains at an elevated risk for damage. Improving the structural resiliency of homes has been largely ineffective, as was illustrated by damage to most of the Grenadian housing stock from Hurricane Ivan in 2004. While international and regional interventions have provided emergency postdisaster aid, sustained efforts to improve design and construction practices and foster sustainable mitigation activity are lacking, with the limited projects not gaining much traction in the construction sector. This paper provides an exploratory framework of the issues surrounding wind damage mitigation and the construction of residential structures to improve overall hurricane resilience in the CARICOM states. It synthesizes 35 years of research findings about Caribbean hazard mitigation initiatives, many of which are not available to researchers in other geographic settings. The uniqueness of the Caribbean housing stock, the importance of small-scale economies, the existing socioeconomic constraints, and the effectiveness of regional and international residential construction mitigation strategies are also evaluated. Finally, the paper identifies and prioritizes critical avenues of future research to improve the resiliency of the CARICOM residential building stock.

Mapping of Near-Surface Winds in Hurricane Rita Using Finescale Radar, Anemometer, and Land-Use Data

AbstractData collected from a Doppler on Wheels (DOW) mobile radar deployed in Port Arthur, Texas, near the point of landfall of Hurricane Rita (2005) and from two Florida Coastal Monitoring Program 10-m weather stations (FCMP-WSs) are used to characterize wind field variability, including hurricane boundary layer (HBL) streaks/rolls, during the hurricanes passage. DOW data, validated against nearby weather station data, are combined with surface roughness fields derived from land-use mapping to produce fine spatial scale, two-dimensional maps of the 10 m above ground level (AGL) open-terrain exposure and exposure-influenced winds over Port Arthur. The DOW collected ~3000 low-elevation radar sweeps at 12-s intervals for >10 h during the passage of the hurricane. This study focuses on the 2–3-h period when the western eyewall passed over Port Arthur. Finescale HBL wind streaks are observed to have length scales of O(300 m), smaller than previously identified in other HBL studies. The HBL streaks are track...

Wavelet Analyses of Turbulence in the Hurricane Surface Layer during Landfalls

Abstract Using wavelet transform (WT), this study analyzes the surface wind data collected by the portable wind towers during the landfalls of six hurricanes and one tropical storm in the 2002–04 seasons. The WT, which decomposes a time series onto the scale-time domain, provides a means to investigate the role of turbulent eddies in the vertical transport in the unsteady, inhomogeneous hurricane surface layer. The normalized WT power spectra (NWPS) show that the hurricane boundary layer roll vortices tend to suppress the eddy circulations immediately adjacent to rolls, but they do not appear to have a substantial effect on eddies smaller than 100 m. For low-wind conditions with surface wind speeds less than 10 m s−1, the contributions of small eddies (<236 m) to the surface wind stress and turbulent kinetic energy (TKE) decrease with the increase of wind speed. The opposite variation trend is found for eddies greater than 236 m. However, for wind speeds greater than 10 m s−1, contributions of both small ...

Wind speed perception and risk

Background How accurately do people perceive extreme wind speeds and how does that perception affect the perceived risk? Prior research on human–wind interaction has focused on comfort levels in urban settings or knock-down thresholds. No systematic experimental research has attempted to assess peoples ability to estimate extreme wind speeds and perceptions of their associated risks. Method We exposed 76 people to 10, 20, 30, 40, 50, and 60 mph (4.5, 8.9, 13.4, 17.9, 22.3, and 26.8 m/s) winds in randomized orders and asked them to estimate wind speed and the corresponding risk they felt. Results Multilevel modeling showed that people were accurate at lower wind speeds but overestimated wind speeds at higher levels. Wind speed perceptions mediated the direct relationship between actual wind speeds and perceptions of risk (i.e., the greater the perceived wind speed, the greater the perceived risk). The number of tropical cyclones people had experienced moderated the strength of the actual–perceived wind speed relationship; consequently, mediation was stronger for people who had experienced fewer storms. Conclusion These findings provide a clearer understanding of wind and risk perception, which can aid development of public policy solutions toward communicating the severity and risks associated with natural disasters.