def check_pipeline_utilization(Te, Mx, My, Pi, Pe, D, t, SMYS, SMTS, alpha_fab=0.96):
    """
    DNV-OS-F101 combined loading utilization check for pipelines.
    Sec.5 D400 — system collapse check (simplified).
    """
    # Pressure containment
    p_b = (2 * t * SMYS) / (D - t)  # Burst pressure
    UC_pressure = (Pi - Pe) / p_b

    # Bending + tension utilization (DNV Eq. D-5)
    M_resultant = (Mx**2 + My**2)**0.5
    M_p = SMYS * (D - t)**2 * t    # Plastic moment capacity
    T_yield = SMYS * math.pi * (D - t) * t   # Yield tension

    UC_combined = (M_resultant / M_p)**2 + (Te / T_yield)**2

    return {
        "UC_pressure": UC_pressure,
        "UC_combined": UC_combined,
        "PASS_pressure": UC_pressure < 1.0,
        "PASS_combined": UC_combined < 1.0,
    }

UC_axial = |Te| / (SMYS × A_steel)                          # ≤ 0.67 (ASD)
UC_bending = |M_resultant| × (OD/2) / (SMYS × I / (OD/2))  # ≤ 0.75
UC_combined = UC_axial + UC_bending                         # ≤ 1.0