A. Finite Element Analysis, Failure Risk Analysis 1. Perform structural analysis of pipe, failure risk analysis and finite element analysis. Consider loads and conditions as appropriate for particular pipe and pipelines. Display failure risk curves on plots where Y axis is Pressure (0-450 psi) and X axis is the Number of Wire Breaks. 2. Consider the serviceability, damage and strength limit state criteria including Microcracking, Visible Cracking, Yield Strength and other limit states at Operational and Operational plus surge Pressure. 3. Assist Tucson Water in pipeline data analysis and pipe segment validation. B. Thrust Restraint Analysis 1. Consider the combined effects of working and transient pressure, pipe and water selfweight, soil weight, and interaction between the pipe and surrounding soil. 2. For single bends, performed thrust restraint analyses according to the provisions of AWWA M9 using the program TRDP. Performed separate analyses for the up station and down station legs of each bend where the available pipe laying schedules indicate that pipe properties (e.g., steel cylinder thickness) and geometries (e.g., length of thrust restraint) are not symmetric and vary on each side of the bend. Modeled the elbows and fittings with geometric details provided in the pipe lay schedules. Performed two sets of TRDP analyses, one using the design pressures specified in the design sheets, and one using actual operating pressures. Performed thrust restraint analyses also according to AWWA M9 (1979), which was the then-effective manual when the pipeline was designed, using design pressures. 3. For compound bends, performed pipe-to-soil interaction analysis using finite element analysis (FEA) with actual working pressures. Calculate the factors of safety against yield and ultimate strength defined in AWWA M9 for the pipe segments adjacent to each side of the bends based on the results obtained from TRDP for single bends and FEA for compound bends. Calculated the axial force and bending moment interaction diagram for each pipe adjacent to the analyzed bends and calculate factors of safety for the demand axial force and bending moment obtained from TRDP and FEA. Identified pipes with factors of safety below the values recommended by AWWA M9: 1.3 against the onset of yielding and 1.56 against ultimate strength.
