A. James Clark School of Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/1654
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item Behavior of fiber reinforced polymer piles with octagonal cross-sections in integral abutment bridge foundations(2020) Gupta, Kavach; Amde, Amde M; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Billions of dollars worth of losses are incurred due to corrosion and degradation of bridges in the United States. In a conventional bridge, deicing salts and chemicals cause rapid degradation in expansion joints, stiffeners, and other structural components. One of the solutions to tackle such a problem is to eliminate expansion joints in the system and design the whole bridge as an integral abutment bridge. In this type of bridge, the abutment and the deck act as a monolithic system. An integral abutment bridge has no expansion joints. Movement due to thermal expansion and contraction is accommodated by the abutments, which in turn transfer the movement to the piles. The maintenance costs of integral abutment bridges are considerably lower than the traditional jointed bridges; therefore, most state highway departments in the United States recommend the use of integral abutment bridges whenever possible. Using alternatives to conventional piling materials is another solution discussed in this thesis and will be the main focus of the same. Fiber Reinforced Polymer (FRP) piles have some advantages in corrosion resistance and hence can be economical in aggressive environments. In this thesis, FRP piles with octagonal cross-sections were analyzed for their behavior in integral abutment bridges. The octagonal section can easily be manufactured using a vast array of manufacturing methods, especially by the filament winding method, which is a cheaper manufacturing option as compared to other methods like pultrusion. Octagonal sections provide flat surfaces that make operations like bolting easy. In addition to this, irregular octagonal sections can provide stiffness and flexibility about two perpendicular axes simultaneously. Three-dimensional models were made and analyzed using ANSYS Workbench with the help of ANSYS Composite PrePost (ACP) modules. Over 300 soil-pile models were analyzed in this study. The results in this thesis depict the trends captured by varying different parameters for various soil-pile models.Item THERMO-MECHANICAL FATIGUE OF STEEL PILES IN INTEGRAL ABUTMENT BRIDGES(2012) Razmi, Jafar; Aggour, M.Sherif; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The issue of fatigue in steel piles of Integral Abutment Bridges (IABs) is investigated. A three-dimensional, non-liner finite element (FE) model is constructed for a bridge located in a harsh climate. Historic temperature data for the region is obtained and a sinusoidal model was developed to represent the daily and seasonal temperature changes. The FE is parametrically run for 5 cases with bridge lengths varying between 400 and 1800 feet under the cyclic load of daily and seasonal temperature variations. The pile behavior and stresses in the piles are evaluated and a fatigue model is used to determine the fatigue life of the piles. The Palmgren-Miner rule is used to evaluate the combined effects and contribution of both types of temperature cycles. The critical location of the pile is modeled locally utilizing a global-local modeling approach. "Successive initiation" in conjunction with a strain-based fatigue damage model is implemented in the local model to determine the thermo-mechanical fatigue crack initiation site, propagation path, and rate in the piles. The results show that maximum stress occurs in the pile furthest from the center of the bridge in its flange right below the concrete abutment. Plastic deformation is observed in all the piles and in all the cases studied indicating the possibility of low cycle fatigue. Lateral displacement and maximum plastic deformation in the piles increases as the length of the bridge increases. A linear relationship was found between the length of the bridge and the lateral displacement for both seasonal and daily temperature variations. The longer the bridge is the shorter the fatigue life. The crack modeling results indicate that the crack initiates in the tip of the flange. Multiple cracks form in the flange, which causes an increased propagation rate. The propagation rate decreases when the crack reaches the web. The crack could initiate in the pile in the first decade, but it will take several decades to reach the web. The final failure of the pile may not occur for several decades.Item Behavior and Analysis of an Instrumented Slab Bridge(2009) Jeong, Sungki; Fu, Chung C.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Because of quick construction and cost effectiveness, adjacent precast, prestressed box girder bridges have been used nowadays more often for short-span bridges, and the standardization of this modular bridge is highly desired. Maryland intends to revise its current practice of using tie-rods for the transverse post-tensioning in slab bridge design. The new design of using high strength rods will provide a more tightly integrated modular slab bridge system with higher post-tensioning forces. With the new design, the Maryland State Highway Administration is highly interested in the performance of the new design, especially compared with the old design. This thesis presents the procedure of test, live load test results and analysis results in association with the finite-element model simulated in a newly-built bridge.