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Irving, TX, United States

Paulikas M.J.,Kent State University | Schmidlin T.W.,Kent State University | Marshall T.P.,Haag Engineering
Weather, Climate, and Society

Two independent datasets (total n 5959) of tornado-stricken passenger vehicles collected from 12 tornado events over a 15-yr time span are combined and tested to determine whether vehicle movement and/or upset are consistent at various wind speed intensities. Impacted vehicles are classified into three categories of upset motions (no movement, lateral shifting, rolling and lofting motions) for each wind intensity category of the Fujita and Enhanced Fujita scales. Vehicles observed by Schmidlin exposed to F1 and F2 winds are statistically assessed to determine if upset distribution values are consistent with those assessed by Marshall at these respective wind speeds; this same approach is subsequently conducted for vehicles at F3/EF3 and F4/EF4 winds. No statistical differences are found between the two sets of field survey data, which are therefore considered to be of the same population. Passenger vehicles are currently not utilized as damage indicators for rating tornado wind intensities, although the results of this study suggest that only 10% of vehicles are typically shifted at EF0 wind speeds, 36% are displaced at EF1 and EF2 winds (5% are rolled or lofted), 63% are displaced at EF3 and EF4 winds (15% are rolled and lofted), and all vehicles exhibit some form of movement or upset at the EF5 wind speed. The results of this study may potentially serve as a basis for providing better tornado safety protocols, designing safer vehicles and infrastructure, and estimating tornado wind speeds where few EF-scale damage indicators are available. © 2016 American Meteorological Society. Source

Quarles S.L.,Insurance Institute for Business and Home Safety | Brown T.M.,Insurance Institute for Business and Home Safety | Cope A.D.,Insurance Institute for Business and Home Safety | Lopez C.,Haag Engineering | Masters F.J.,University of Florida
Advances in Hurricane Engineering: Learning from Our Past - Proceedings of the 2012 ATC and SEI Conference on Advances in Hurricane Engineering

A study at the Insurance Institute for Business and Home Safety (IBHS) Research Center was conducted to evaluate the potential for water entry into the attic through typical vents and through a sealed and unsealed roof deck under wind-driven rain exposures. A duplex building was constructed where sheathing joints on one half of the roof deck were sealed and the other half was not sealed prior to installing an asphalt shingle roof covering. Water entry through gable end and soffited eave vents were also evaluated. Drainage panels were installed between the lower chords of the roof trusses. This drainage system allowed for the collected water to be segregated by zones. A target rain deposition rate of 8-inches per hour was used for all tests. Water entry through gable end vents and soffited eaves was evaluated using up to three wind exposure regimes. Water entry tests for the sealed and unsealed roof decks were conducted after the shingles were removed. Water entry through the un-taped roof deck joints exceeded that through the taped deck and the vents. This study demonstrated the value of sealing the roof deck and provided information on the relative importance of water entry through vents compared to the roof. © ASCE and ATC 2013. Source

Goode J.S.,Haag Engineering | van de Lindt J.W.,University of Alabama
Structure and Infrastructure Engineering

Rural intersections and interchanges often require lighting for driver safety. Although high mast lighting supports, sometimes as tall as 50 m have been installed in many locations, it is becoming apparent that light pollution to nearby residences is an issue. As a response to this problem, the Colorado Department of Transportation is moving towards the use of medium mast lights which are typically 15-20 m in height. This article presents the results of a numerical investigation to develop reliability-based design charts as a function of several key design variables and the mean wind velocity at a site. These medium-mast structures are less than 1 m in diameter at the base and are quite flexible relative to many civil engineering structures. The limit state function is formulated in terms of fatigue life and is computed based on the moments at the base that are produced during multi-mode dynamic excitation as a result of the wind loading. Morison's equation, which provides relative force for slender bodies as a function of flow velocity, was applied within a dynamic finite element framework in order to account for the relative motion between the wind and the motion of the structure. Then, a well-known random vibrations approach was coupled with Miner's rule to estimate the fatigue life of the structural support. Reliability-based design charts for several different design variables such as wall thickness and outside diameter are presented. © 2013 Copyright Taylor and Francis Group, LLC. Source

Wurman J.,Center for Severe Weather Research | Kosiba K.,Center for Severe Weather Research | Robinson P.,Center for Severe Weather Research | Marshall T.,Haag Engineering
Bulletin of the American Meteorological Society

R esearchers, recreational storm chasers, stormchasing tours, storm spotters, television reporters, and others have been pursuing tornadic storms for centuries to satisfy a variety of goals. As early as 1755, Benjamin Franklin describes a tornado chase on horseback (van Doren 1938). Until recently, within the storm-chasing and research community, there have been no known fatalities or significant injuries directly caused by tornadoes. © 2014 American Meteorological Society. Source

Juenger M.C.G.,University of Texas at Austin | Solt S.M.,ExxonMobil | Hema J.,Haag Engineering
ACI Materials Journal

In hot weather, it is a common practice to cool concrete - particularly for mass concrete applications - to prevent thermal cracking and durability problems. An increasingly popular method of cooling is through direct injection of liquid nitrogen (LN2) into the drums of concrete trucks. During an investigation of the effects of LN2 on concrete properties, it was observed that the practice has unexpected impacts on concrete slump and setting time. While it is known that increasing temperature decreases slump for concrete with given mixture proportions, it is surprising that concrete cooled with LN2 has low slump similar to that of a hot mixture, a phenomenon that is not affected by the time at which the concrete is cooled. The initial setting time, however, is actually longer than predicted when there is a significant delay in LN2 cooling. © 2010, American Concrete Institute. All rights reserved. Source

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