Ms. Mary Ann Triska, M.S., Civil Engineering - Structures (Advisor: Dr. Chris Higgins)"Flexural Steel Anchorage Performance at Diagonal Crack Locations"
A significant number of reinforced concrete deck girder bridges constructed in Oregon during the 1950s have developed diagonal cracking in the stems. Compared to the present AASHTO standards, the provisions of the 1950s allowed for higher shear stress in the concrete, thus reducing the amount of transverse steel required. Further, service loading has increased over time. When load rating these structures, the current design specification check of tension reinforcement anchorage often controls the capacity of these bridges. This check compares the applied tensile force in the reinforcement to the tensile force developed by the bond between the reinforcement and the concrete. The applied tensile force is controlled be the load-induced shear, the number of stirrups, and the diagonal crack angle. However, the crack angle considered in the design specification is flatter then the angle of the vertically oriented cracks generally noted in field inspections. The tensile force that can be developed in the bar depends on the diameter of the bar and the embedment length, however, little information is currently available regarding the bond stresses developed in larger diameter bars for full-size specimens in the presence of diagonal cracks.
If it can be shown from experiment that anchorage capacity is controlled by the observed field inspection angle rather than the AASHTO design specified angle, then current bridge ratings could be improved. Similarly, load ratings may improve with a more detailed understanding of bond stresses under these conditions. Ultimately, improved understanding of the response of these bridge girders can maintain the operational safety and freight mobility of the transportation system thereby allowing optional use of available resources for repair or replacement of truly deficient bridges
Ms. Kelly Liu, M.OcE., Coastal & Ocean Engineering (Advisor: Dr. Harry Yeh)"Tsunami Evacuation Building - Cannon Beach City Hall"
The project is redesign Cannon Beach City Hall. In order to evaluate the tsunami evacuation building, a test is conducted in the O.H. Hinsdale Wave lab. Previous research of tsunami effect on structures usually considers a structure a vertical wall in a 2-D environment. But in reality, the 3-D effect cannot be neglect, because actual buildings have finite breadth. In addition, friction of terrain in a real case can be significant too. The test will investigate tsunami forces on 3-D building model, and study the effect of terrain friction and a small step in front of the building. This test will give a better understanding of 3-D effect of tsunami flow around buildings. Also, data obtained in the test will help improve Yeh's method for computing tsunami forces by taking friction of terrain into consideration. The test provides the effectiveness of a step formation in front of the building as well.
Mr. Tengfei Fu, M.S., Civil Engineering - Structures (Advisor: Dr. Jason Ideker)"Introduction of Calcium Aluminate Cement"
This report introduces basic knowledge on the chemistry and performance of calcium aluminate cements (CACs). Due to different chemistry and microstructure, CAC possesses unique properties such as high early strength, ability to harden under low-temperature and superior durability to a wide range of chemically aggressive conditions. However, with issues like strength loss due to conversion, the use of CAC has been limited for structural applications. Therefore, applications and durability of CAC are main concerns in the report. Also several potential research interests are proposed in this report.
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