Browsing by Subject "Steel pipe"

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    Mechanical Response of a Composite Steel, Concrete-Filled Pile
    (Minnesota Department of Transportation, 2018-06) Hu, Chen; Sharpe, Jacob; Labuz, Joseph
    A steel pipe-pile section, filled with concrete, was instrumented and tested under axial load. Two types of strain gages, resistive and vibrating wire, were mounted to the steel-pipe pile and checked by determining the known Young’s modulus of steel E^s. The steel section was filled with concrete and a resistive embedment gage was placed in the concrete during the filling process to measure axial strain of the concrete. The axial load – axial strain responses of the steel (area A^s) and concrete (area A^c) were evaluated. The stiffening of concrete, related to curing, was also studied. Assuming the boundary condition of uniform axial displacement, i.e., equal axial strain in the steel and concrete, εz^s = εz^c = εz, the sum of the forces carried by the two materials, F^s + F^c, where F^s = εz * E^s * A^s and Fc = εz * E^c * A^c, provides a reasonable estimate – within 3% – of the pile force. For the particular specimen studied (12 in. ID, 0.25 in. wall thickness), the stiffness of the composite section of steel and concrete was about three times larger compared to the steel section without concrete. Further, the concrete carried about 70% of the load, but the axial stress in the concrete, at an applied force of 150,000 lb, was less than 20% of the compressive strength of the concrete.
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    Minnesota Steel Culvert Pipe Service-Life Map
    (Center for Transportation Studies, University of Minnesota, 2015-06) Heitkamp, Barbara; Marr, Jeffrey
    The goal of this project was to develop a series of steel pipe service-life maps for the state of Minnesota. The California Method 643 is utilized to estimate steel pipe service life at locations throughout the state. Over 560 soil resistivity and pH samples were collected statewide during summer 2014 along embankments of state-trunk and county highways. Concurrent observations of soil texture, surrounding landscape, roadway type, and water presence were also made; water pH and conductivity measures were made where applicable. Data verification efforts to build confidence in field-measured soil pH and soil resistivity included comparing data to other available datasets including geology, soil pH, electrical conductivity, and soil texture, as well as observations available from district and county engineers. Field-measured soil pH data, with some exceptions in Districts 2 and 6, generally aligned with the available STATSGO soil pH data, indicating that this layer could reasonably be used in service-life calculations as it has greater resolution than provided by field data. In the absence of a statewide soil resistivity or electrical conductivity map, field-classified soil textures and the statewide STATSGO soil texture map were used to estimate soil resistivity values. Calculations of service life using the above data were completed for 18-, 16-, 14-, 12-, 10- and 8-gage galvanized and aluminized steel pipe across Minnesota. These maps were then compiled into a zone map and table that presents the 90th percentile service- life estimate for various gages and types of steel pipe. Caveats and limitations to this analysis are also discussed.