![]() Where, FD = Drag force vector/unit length FI = Inertia force vector/unit length CD = Drag Coefficient Cm = Inertia/added mass Coefficient ρ = Water mass density Vr = Reference volume/unit length Vd = Displaced volume/unit length V = Velocity vector (combined wave and current) normal to axis A = Projected area normal to axis/unit length (=D, for circular cylinder) Hydrodynamic Force Computation Morison’s Equation on Slender (λ/D > 5) member Gap Ratio, H/D Inertia Coefficients Variation 30.5 and API RP 2Aģ) APPURTENANCES should be defined as INACTIVE members in STAAD.Pro basic input fileĢ) ALPHA values should be used in STAAD.Pro basic input file to define whether members are flooded or buoyant Re Drag Coefficients for Circular Cylinders Theoretical Background: Drag/Inertia Coefficients, CD, Cm Reynold’s number, Re Keulegan-Carpenter number, Kc Relative Surface Roughness, k/D Current/Wave Velocity Ratio, r Gap Ratio between Cylinder and fixed boundary, H/D User defined grid of Velocities and Accelerations H Applicability Function of H, Tapp and d.Theoretical Background: Steps to Compute Environmental Forces Additional user supplied loads and analysis commands can be added to this STAAD.Pro file.Generates wave load cases, a single buoyancy load case in a new STAAD.Pro input file, filename_wave.std.Calculate weight & submerged buoyancy of structure.Total Base Shear and Overturning Moment are calculated.Sections include pipe, tubes and open sections such as Ibeams, etc.Computes design wave forces (drag & inertia) on 3D structures in the global X, Y and Z-directions.Computes particle velocities and accelerations.Use STAAD.Pro Results due to wave loads to compute Fatigue Damage of Joints The inertial forces are generally to be computed using the appropriate period and amplitude by combining roll with heave and pitch with heaveĬomputes Loads/Load Cases to be used with STAAD.Pro.The inertial forces beside gravity are generated due to motion of the vessel on which the structure is mounted due to combined random effects of wave, wind, current, etc.API RP-2A-WSD/API RP-2A-LRFD Most popular and used standardsĮNVIRONMENTAL LOADS: Due to natural phenomena of general importance:ĭue to natural phenomena of specific importance:.Classification Notes/Design Guidelines/Recommended Practices from Class (DnV’s CN-30.5, RP-C203).Rules/Regulations from various Classification Societies such as ABS, DnV, Lloyds, BV, etc.General Dead Loads Live Loads Environmental Loads Transportation Loads Impact Loads Others Drilling Jackets Production Platform Caissons
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