H. Scott Norville

Wind pressure loading cycles for wall cladding during hurricanes

A wind pressure loading cycle has been developed that aims to simulate the fluctuating wind loads experienced by wall cladding during the passage of a hurricane. Hour long wind pressure records from the Texas Tech University (TTU) Wind Engineering Research Field Laboratory (WERFL) have been used to derive the loading cycle.

Development of a new glass thickness selection procedure

Abstract There are currently significant differences in glass strength information presented by major United States glass manufacturers. These differences have caused considerable confusion among glass designers. Several years ago a glass failure prediction model was developed in an effort to provide a mechanism for restoring continuity to the glass design process. This failure prediction model allows the probability of failure of window glass to be specified in terms of surface flaw parameters and the stresses induced by lateral loads. For the past several years, a task group within ASTM has focused on developing a new set of glass design charts based on the glass failure prediction model. The result of this effort is a “Practice to Determine the Minimum Thickness of Annealed Glass Required to Resist a Specified Load.” The proposed practice presents a method for relating the probability of failure of a rectangular annealed glass plate subjected to a 60 second duration design load. This new ASTM practice is currently in the ASTM ballot process.

Design Methodology for Determining the Load Resistance of Heat-Treated Window Glass

ASTM E 1300-07 employs only two glass type factors to adjust the load resistance of annealed glass for heat treatment, one factor for heat-strengthened glass and one factor for tempered glass. The use of only two factors provides a simplistic approach that fails to utilize the full capacity of heat-treated glass. ASTM E 1300-07 differentiates heat-strengthened from fully tempered glass by the magnitude of the residual compressive surface stress resulting from the heat treating process. Furthermore, ranges of residual compressive surface stress are specified for both heat-strengthened and fully tempered glasses, suggesting the glass type factors should vary with the residual compressive surface stress. This article presents a rational method for determining the load resistance of heat-treated glass based on the residual compressive surface stress. A method incorporating previously accepted design principles with the addition of extensive data computation is advanced to calculate load resistance for heat-tr...

A Virtual Differential Map Matching Algorithm with Improved Accuracy and Computational Efficiency

This paper presents development and application of a real-time virtual differential map-matching approach which makes use of the slow drifting property of the GPS errors and the continuous and gradual evolving characteristic of map errors to improve the accuracy and computational efficiency. A differential vector is created to approximate the real-time deviation, which is corrected continuously along with the vehicle movement during the map-matching process. Real-life application of the algorithm to the City of Hefei, a metropolis of China, shows that it corrects both GPS errors and digital map errors reasonably well with improved computational efficiency.

A simple window glass design chart

Abstract A recently published ASTM standard outlines procedures for determining the strength of glass products used in buildings as windows and cladding. The new standard uses structural mechanics relationships to define the strength of a wide range of products, including monolithic glass, laminated glass and insulating glass. While the new standard is thorough and accurate, it is also complex. The authors offer a simple approach to the design of these glass products that applies to most building conditions, leaving only the exceptions to be treated by the complex process.

Experimental Study of Weathered Tempered Glass Plates from the Northeastern United States

AbstractThe authors performed an experimental study with weathered fully tempered monolithic glass loaded to failure under controlled conditions. The 14 specimens in the study originated from the northeastern United States. The specimens were loaded with monotonically increasing pressure until fracture occurred in accordance with the ASTM E997 test method. The recorded failure load time histories were converted to equivalent 3-s failure loads using a modified load-transformation-integration method that incorporates residual compressive surface stress. Variations of the residual compressive surface stress measurements are presented for each specimen, and the effect that the variations in residual compressive surface stress have on the equivalent 3-s failure load calculations are also explored. Equivalent 3-s failure loads are shown to be proportional to the measured residual compressive surface stress. The equivalent 3-s failure load is compared to the load resistance calculated using ASTM E1300, and the m...

Fracture Origins and Maximum Principal Stresses in Rectangular Glass Lites

AbstractData were studied from tests of new and weathered rectangular annealed glass samples, each consisting of numerous specimens, loaded to fracture. The maximum principal tensile stress at the fracture origin was compared with the single largest maximum principal tensile stress (SLMPTS) within each specimen. The findings indicated that maximum principal tensile stresses at the fracture origins were always less, often significantly so, than SLMPTS in the specimens. In addition, fracture origins rarely, if ever, coincided with the location of SLMPTS in a rectangular glass lite specimen. These results support the notion that glass thickness selection should not be based on a maximum principal stress method.

Method to Determine the Probability of Failure for Annealed Monolithic Window Glass Loaded with a Uniform Wind Load

AbstractASTM E1300-09 uses a glass failure prediction model (GFPM) to quantify the probability that a critical surface flaw with a certain location and orientation will initiate a facture in the glass for a given lite geometry and uniform design load. The nonfactored load charts in ASTM E1300-09 are calibrated to a GFPM probability of breakage of 8/1,000 (0.008) at the first occurrence of the design load. The GFPM probability of breakage only addresses the material properties of the annealed monolithic window glass and does not incorporate the probability of the occurrence of the design load. Because window glass is typically designed to resist wind loads, the probability of the occurrence of the design load was based on ASCE 7-05. Using a Monte Carlo simulation to evaluate the limit-state equation, this paper presents a procedure to quantify the probability of failure incorporating the probability of the wind load and the probability of the window glass load resistance from the GFPM for window glass lite...