Civil and Environmental Engineering
Evaluation of Oklahoma Department of Transportation (ODOT) Retroreflective Sheeting Policy
Nighttime visibility of traffic signs is usually accomplished through the use of retroreflective sheetings on the sign face. When illuminated by the vehicle's headlamps, signs appear bright in proportion to their ability to reflect the incident illumination back toward the driver. The primary objectives of this research were to evaluate ODOT's policy on use of retroreflective sheeting products and to identify any necessary changes to this policy based on driver visibility needs, durability of sheeting materials, life-cycle cost, and other practical considerations.
Sponsors: Oklahoma Department of Transportation and the Federal Highway Administration
PI: S. A. Ahmed
RAs: Fred Myers, Derek Garvin, Ian Cyr, James Rosson, and Sean Kelly
Automated Structure Symmetry Detection and Utilization
It is well known that observing and taking advantage of symmetry in structural analysis can reduce solution time. In the existing state-of-the-art, however, it is required that the analyst recognize symmetry and combine intermediate solution results manually. In this project, an algorithm will be developed in which single- and double-symmetry are detected, the intermediate solution process is set up, and solutions are combined automatically in a direct stiffness analysis procedure. All efficiencies allowed by utilization of symmetry will be provided for. With the developed algorithm, user time required for a computer-based symmetry analysis should be cut by 50% or better. A commensurate reduction of user data input errors should be realized. Computer solution time using the algorithm as compared to analysis without utilization of symmetry should be cut in the order of 25%.
Sponsor: Egyptian Cultural and Educational Bureau
PI: Timothy D. Hogue
RA: Khaled El-Mokadem
Fatigue Performance of Tubular Connections
Offshore structures are being designed for the Gulf of Mexico and other deep water locations where the drill string between the platform and the ocean floor will see heavy wave forces during severe storms. The connections between segments of casing must be able to withstand these fatigue loads for 40 or more years. Tests are being conducted to develop information about the basic fatigue characteristics of standard API connectors as well as modified or premium connectors. Four-point bending tests will be conducted for pipe with outside diameters ranging from 4-1/2 to 11-3/4 inches. In addition to pipe size and style of connector, tests will consider the influence of mean bending stress and stress amplitude.
Sponsor: Shell Offshore, Inc.
PI: J. P. Lloyd
RA: Khaled El-Mokadem
Extension of the Sheer Ring Method to Anchored Systems
Anchored Sheet pile wall systems are studied by a step-by-step nonlinear finite element method with the basic objective of extending the newly developed Shear Ring method to anchored systems. Both excavation and filling cases are considered. The influence of anchor placement schedule on the structural and soil stresses and deformations are studied. The Shear Ring method has been extended to cover these new areas using the results of these studies.
Sponsor: U.S. Army Waterways Experiment Station
PI: Mete Oner
Instrumentation and Evaluation of Bridge Approach Embankments--U.S. 177 Bridges Over Salt Fork River
A problem shared by all state transportation departments involves the "bump at the end of the bridge." Specifically, the problem involves localized settlement of approach embankments whether caused by settlement of the approach embankment itself, settlement of the foundation soils, or a combination of both. The research project involves evaluation of different approach embankment construction procedures. Five of the six approach embankments for the three new bridges on U.S. 177 have been constructed using different procedures. The procedures used include: geotextile reinforced wall, controlled low strength backfill, dynamically compacted granular backfill, flooded and vibrated granular backfill, and a control section using conventional compaction of unclassified borrow. Evaluation of the performance of the different approach embankments will be based on measured stress and deformation values taken from instrumentation installed under and in the backfill materials. Instrumentation used includes total pressure cells in the back of the abutment wall, settlement gages beneath the backfill, inclinometers through the backfill, and piezometers. Surface movement points will be installed following paving to further monitor overall settlement. To date, all approach embankments have been constructed and all instrumentation, except surface movement points, have been installed and are being monitored.
Sponsor: Oklahoma Department of Transportation
PI: Donald R. Snethen
RAs: John M. Benson, Shannon Koeninger, and Shannon Hudson
In Situ Volatilization: Evaluation of Volatilization Models
Technologies used for the remediation of hazardous waste sites have recently been developed that rely on the injection of an airstream into the subsurface environment. Depending on the technology utilized, air can be injected into the unsaturated zone (bioventing) or the saturated zone (air sparging). Many mathematical models that simulate these technologies are appropriate for clean-up based on specific conditions (i.e., site geology, contaminant chemicals).
Sponsor: U.S. Army Waterways Experiment Station
PI: John N. Veenstra
RA: Mansour S. Bader
Edge Distance, Spacing, and Bearing in Bolted Connections
Recently a change was proposed to the specifications for edge distance and spacing in bolted connections. During consideration of the proposed change by the Research Council on Structural Connections, it was determined that the current specifications are based entirely on tests with one-bolt connections. Since most structural connections are fabricated with multiple bolts, it was decided that a series of tests should be conducted with two-bolt connections to evaluate the accuracy of the existing and proposed specifications. The outcome of these tests will directly impact the design procedure for structural bolted connections in the United States.
Sponsors: American Institute of Steel Construction and W&W Steel of Oklahoma City
PI: Farrel Zwerneman
RA: Brian Lewis
Fatigue Assessment of Bridge Members Based on In-Service Stresses
Structural designs are necessarily based on conservative assumptions regarding support conditions, loads, and load distributions. Typically, these same assumptions are used to calculate stresses in existing structures, resulting in calculated stresses higher than the true stresses in the structure. The first objective of this project is to develop a data acquisition system that the Oklahoma Department of Transportation (ODOT) can use to measure the stresses in a functioning highway bridge. The second objective is to develop an analytical procedure allowing ODOT to use the acquired data to more accurately assess the structural status of the bridge. This more accurate assessment will both improve safety and help direct maintenance funds to locations where they are most needed.
Sponsors: Oklahoma Department of Transportation and Federal Highway Administration
PI: Farrel J. Zwerneman
RAs: Paul Poynter and John Kelly
Fracture Mechanics Investigation of Tubular Joint Weld Toe Cracks
Offshore platforms are typically built from tubular members with intersecting members welded at the joints. These welded joints are the critical location for fatigue crack growth due to wave loads. A great deal of time and effort is spent inspecting and maintaining these structures, and the owners are very interested in improving their ability to estimate remaining service life. The objective of this research is to develop a more accurate analytical model for fatigue crack growth at the weld toe in tubular joints. This research involves both laboratory tests and extensive finite element analyses.
Sponsors: Amoco, ARCO, British Gas, Chevron, Conoco, Exxon, Mobil, Phillips Petroleum Company, Shell Development Company, and Texaco
PI: Farrel Zwerneman
RAs: Michael Magill and Chung Ming Ho
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